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BS Tuli - Textbook of Ear, Nose and Throat

  2. 2. Editor-in-Chief Lt Col BS Tuli Professor Department of ENT Government Medical College, Patiala Commanding Officer GH (TA) Editor Isha Preet Tuli Department of ENT Government Medical College Patiala Co-Editors Amandeep Singh Navneet Kaur Tuli Government Medical College Patiala Textbook ofTextbook ofTextbook ofTextbook ofTextbook of EAR, NOSE AND THROATEAR, NOSE AND THROATEAR, NOSE AND THROATEAR, NOSE AND THROATEAR, NOSE AND THROAT JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi
  3. 3. Published by Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd EMCA House, 23/23B Ansari Road, Daryaganj New Delhi 110 002, India Phones: +91-11-23272143, +91-11-23272703, +91-11-23282021, +91-11-23245672 Fax: +91-11-23276490, +91-11-23245683 e-mail: Visit our website: Branches • 202 Batavia Chambers, 8 Kumara Krupa Road Kumara Park East, Bangalore 560 001 Phones: +91-80-22285971, +91-80-22382956, +91-80-30614073 Tele Fax : +91-80-22281761 e-mail: • 282 IIIrd Floor, Khaleel Shirazi Estate, Fountain Plaza Pantheon Road, Chennai 600 008 Phones: +91-44-28262665, +91-44-28269897 Fax: +91-44-28262331 e-mail: • 4-2-1067/1-3, 1st Floor, Balaji Building, Ramkote Cross Road Hyderabad 500 095, Phones: +91-40-55610020, +91-40-24758498 Fax: +91-40-24758499 e-mail: • 1A Indian Mirror Street, Wellington Square Kolkata 700 013, Phone: +91-33-22451926 Fax: +91-33-22456075 e-mail: • 106 Amit Industrial Estate, 61 Dr SS Rao Road Near MGM Hospital, Parel, Mumbai 400 012 Phones: +91-22-24124863, +91-22-24104532, +91-22-30926896 Fax: +91-22-24160828 e-mail: Textbook of Ear, Nose and Throat © 2005, Lt Col BS Tuli All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the editor and the publisher. This book has been published in good faith that the material provided by contributors is original. Every effort is made to ensure accuracy of material, but the publisher, printer and editor will not be held responsible for any inadvertent error(s). In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only. First Edition : 2005 ISBN 81-8061-446-8 Typeset at JPBMP typesetting unit Printed at Replika Press Pvt. Ltd., 310 EPIP, HSIDC, Kundali, Sonepat, Haryana
  4. 4. Dedicated to • My grandfather’s trust (Tuli Sunder Dass Seva Kendra, Samana, Patiala) • My father, S Balwant Singh Tuli for his uncompromising principles of his life • My mother, Smt Kartar Kaur Tuli for leading me into intellectual pursuits • My wife, Smt Ranjit Kaur for her excellent devotion to the family • My children, Dr Mandeep and Dr Navneet for making my life worthwhile • My grandchildren, Abhai and Mehr for lovely smile when I needed it the most • And above all “Almighty God” for giving me the courage to take up this project • Lastly to my students and postgraduates for their constant innovations • There is one GOD. He is the supreme truth. He, the creator, is without fear and without hate. —Guru Nanak • If thou shouldst say, “It is enough, I have reached perfection,” all is lost. For it is the function of perfection to make one know one’s imperfection. —Saint Augustine • “The best way to get to the top is by being the best man at the bottom.” —VH Jones • “The great aim of education is not knowledge but action.” —Herbert Spencer
  5. 5. Contributors Dr TS Anand Professor Deptt of ENT, LHMC, New Delhi Dr Sanjay Arora Deptt of ENT Govt Medical College, Patiala Mr Pawan Kumar Bhardwaj Deputy Chief Accounts Officer PSEB, Patiala Dr Prasun Chattopadhaya Deptt of ENT Govt Medical College Patiala Dr Hemant Chopra Professor and Head Deptt of ENT Dayanand Medical College Ludhiana Dr Arjun Dass Professor and Head Deptt of ENT, Govt Medical College Chandigarh Dr RC Deka Chairman Professor and Head Deptt of ENT, AIIMS, New Delhi Dr GPS Gill Project Officer Deptt of ENT, Govt Medical College Patiala Dr RK Gorea Professor and Head Deptt of Forensic Medicine Govt Medical College, Patiala Dr Ashok Gupta Director, Principal and Head Deptt of ENT and HNS RNT Medical College, Udaipur Dr Sunanda Gupta Professor Deptt of Anaesthesia RNT Medical College, Udaipur Dr Vikas Kakkar Associate Professor Deptt of ENT, PGIMS, Rohtak Dr Abhilash Kapila Professor and Head, Deptt of Radiology Govt Medical College, Patiala Dr Harjot Kaur Professor and Head Deptt of Radiotherapy Govt Medical College, Patiala Dr M Lateef Professor and Head Deptt of ENT, Govt Medical College Srinagar Dr Chander Mohan Professor and Head Deptt of ENT, IGMC, Shimla
  6. 6. viii Textbook of Ear, Nose and Throat Dr Karan Sharma Associate Professor Deptt of ENT Govt Medical College, Amritsar Dr Amandeep Singh Deptt of Forensic Medicine Govt Medical College, Patiala Dr Baldev Singh Associate Professor Deptt of ENT Govt Medical College, Patiala Dr Sukhbir Singh Deptt of ENT GMC, Patiala Dr BS Sohal Assistant Professor Deptt of ENT, Govt Medical College Patiala Dr Alok Thakar Assistant Professor Deptt of ENT, AIIMS New Delhi Dr Jagjit Singh Tuli Professor and Head Deptt of Community Medicine Govt Medical College Patiala Dr Navneet Kaur Tuli Deptt of Ophthalmology Govt Medical College Patiala Dr SK Verma Professor and Head Deptt of ENT Govt Medical College Patiala
  7. 7. Foreword Another book on diseases of the Ear, Nose and Throat! Why? The question struck me when I saw the book. And on reading the book, I knew the answer. The increasing realms of knowledge, the decreasing time spent on the subject by the universities and the need to comprehensively combine the two facts probably prompted Dr BS Tuli to write this book so as to enable the student to learn, with a degree of under- standing, the basic principles of the speciality. Change occurs slowly with only occasional starting breakthrough and it becomes the duty of a teacher to not only keep abreast with these changes himself but also to encourage the students and practitioners of the subject to keep abreast with them. A very laudable attempt has been made in this book to achieve an essentially practical approach and to discuss the basic principles, analyse them and give a positive support to the learning curve. The author has shown a devotion to the subject and has presented the topics in a comprehensive and concise manner the various aspects of the subject and would be of immense help to the students pursuing the undergraduate course in ENT and also for the senior students and practitioners of the subject as a valuable handbook. The book has been written in a simple way with all the essentials available in a well illustrated form. I congratulate Dr Tuli on writing this book. Dr AK Agarwal Director Professor and Head Department of ENT Maulana Azad Medical College New Delhi
  8. 8. The “Textbook of Ear, Nose and Throat” written by Dr (Lt Col) BS Tuli, Professor of ENT at Rajindra Hospital and Govt Medical College, Patiala (Punjab), gives a meticulous description of various diseases of ear, nose and throat well-supported by photographs and sketch diagrams. At the end of each chapter, the key points outline the gist of that chapter and these will leave an imprint in the mind of the reader. The material in the book appears to be an excellent outcome of his life long experience and hardwork in ENT. The book will really go a longway to fulfil the academic requirements of undergraduates and postgraduates as well as practising ENT doctors. I wish him all the success. Dr JK Sahni Professor and Head ENT Lady Hardinge Medical College and Smt SK Hospital New Delhi Foreword
  9. 9. Foreword It was a matter of delight to know that our dear friend Dr (Lt Col) BS Tuli, Professor of ENT Government Medical College, Patiala, is coming out with a “Textbook of Ear, Nose and Throat”. Dr (Lt Col) BS Tuli is a senior respected teacher and academician in our alma mater and is the first ENT surgeon to publish the knowledge and experience he has amassed over the years. On his visit to the USA where he visited many reputed institutions, we had found it to be very comprehensive and concise condensation of his vast knowledge. It will definitely be very informative and student-friendly for undergraduates and postgraduates, besides all ENT surgeons. We wish him all the best. Dr Jassi Dr N Bual Dr B Chahal New Jersey Houston Tomball, TX USA USA USA
  10. 10. Preface The present book is the outcome of my humble experience as a medical man and teacher of Otorhinolaryngology. Although intended primarily as a textbook for undergraduate students, this book should appeal to postgraduate students as well since technical and specialised details have also been included. The salient features of this book include coloured photographs, flow charts, latest trends in surgical procedures, salient key points and attractive student-friendly layout. In keeping with the latest concepts of holistic healing, I have also included a chapter on Yoga besides Skull Base, HIV in ENT, Imaging in ENT, Computers in ENT, Medicolegal Aspects of Injuries and Sleep Apnoea Syndrome to name a few. I wish to express my sincere appreciation to all my friends and colleagues for all the assistance and critical comments during the preparation of this book. I am deeply indebted to many doctors, who have contributed valuable chapters for this book, such as Dr RC Deka (New Delhi), Dr M Lateef (Srinagar), Dr Arjun Dass (Chandigarh), Dr Hemant Chopra (Ludhiana), Dr Ashok Gupta (Udaipur), Dr TS Anand (New Delhi), Dr Karan Sharma (Amritsar), Dr Chander Mohan (Shimla), Dr SK Verma; Dr RK Gorea; Dr A Kapila; Dr Harjot Kaur; Dr Baldev Singh; Dr BS Sohal; Dr GPS Gill (Patiala). I am very grateful to Dr AK Aggarwal from Maulana Azad Medical College and Dr JK Sahni of Lady Hardinge Medical College for going through the manuscript and giving their very valuable suggestions. I am also indebted to my friends from USA, Dr B Chahal, Dr N Bual and Dr Jassi for writing the foreword for this book. I will be failing in my duties if I do not thank Dr Sanjay Arora, Dr Sukhbir Singh, Dr Charanjit Singh, Dr Amandeep Singh and Dr Isha Preet Tuli for their invaluable support in reading the manuscript, preparing the photographs and for their student-friendly suggestions. I also thank my residents Dr Manjit Singh, Dr Prasun Chattopadhaya, Dr Parwinder Singh, Dr Rajwant Kaur, Dr Ramesh and Dr Ravinder Singh for their timely and valuable help in writing this book. My deepest gratitude is also to my wife Principal Ranjit Kaur and my son Dr Mandeep Singh IPS for their constant encouragement throughout my life to write the book under a registered trust “Tuli Sunder Dass Seva Kendra”. Finally, I would like to thank God Almighty for making all this possible through M/s Jaypee Brothers Medical Publishers (P) Ltd., to bring out this book in your hands. Lt Col BS Tuli
  11. 11. Acknowledgements I acknowledge my greatest gratitude to all my colleagues in ENT who gave me unstinted support and stood solidly beside me in our joint venture to write this book. Although, artists and expert photographers have drawn most of the coloured photographs including text, however I apologise for any inadvertent resemblance to anyone by oversight. The book itself will bear an indelible imprint of the meticulous effort of all the following contributors to bring out the first edition of the book under the registered trust “Tuli Sunder Dass Seva Kendra”. We further welcome any positive comments concerning omissions and errors for improvement in subsequent editions. Dr AK Aggarwal Dean, Professor and Head Deptt of ENT Maulana Azad Medical College New Delhi Dr Alok Thakar Assistant Professor Deptt of ENT, AIIMS, New Delhi Dr Amrik Singh Head Deptt of ENT Guru Ram Dass Medical College, Amritsar Dr Arjun Dass Professor and Head Deptt of ENT, Govt Medical College Chandigarh Dr Achal Gulati Professor Deptt of ENT, MAMC, New Delhi Dr Baldev Singh Associate Professor, Deptt of ENT Govt Medical College, Patiala Dr Abhilash Kapila Professor and Head, Deptt of Radiology Govt Medical College, Patiala Dr Amandeep Singh Deptt of Forensic Medicine Govt Medical College, Patiala Dr Aniece Chaudhary Professor and Head Deptt of ENT, Govt Medical College Jammu Dr Ashok Gupta Director, Principal and Head Deptt of ENT and HNS RNT Medical College, Udaipur Dr BS Sohal Assistant Professor Deptt of ENT, Govt Medical College Patiala Dr Chander Mohan Professor and Head Deptt of ENT IGMC, Shimla
  12. 12. Acknowledgements xvii Dr Charanjeet Singh Deptt of ENT Govt Medical College, Patiala Dr GPS Gill Project Officer Deptt of ENT, Govt Medical College Patiala Dr Harjot Kaur Professor and Head Deptt of Radiotherapy Govt Medical College, Patiala Dr Jagjit Singh Tuli Professor and Head Deptt of Community Medicine Govt Medical College, Patiala Dr Masood A Khan Associate Professor Deptt of ENT, GMC Srinagar Dr MK Bandlish Professor and Head, Surgery Medical Superintendent Rajindra Hospital, Patiala Dr Navneet Kaur Tuli Deptt of Ophthalmology Govt Medical College, Patiala Dr NK Mohindroo Associate Professor Deptt of ENT, IGMC, Shimla Dr PP Singh Professor and Head Deptt of ENT, UCMS New Delhi Dr Dalbir Singh Assistant Professor Deptt of ENT, Govt Medical College Patiala Dr Hemant Chopra Professor and Head Deptt of ENT Dayanand Medical College, Ludhiana Dr Isha Preet Tuli Deptt of ENT Govt Medical College, Patiala Dr J Paul Professor and Head Deptt of ENT, Medical College, Jammu Dr JK Sahni Professor and Head Deptt of ENT Lady Hardinge Medical College New Delhi Dr M Lateef Professor and Head Deptt of ENT, Govt Medical College Srinagar Dr Mandeep Singh Tuli Indian Police Services Distt Namchi, Sikkim Dr Prasun Chattopadhaya Deptt of ENT Govt Medical College, Patiala Dr RK Gorea Professor and Head Deptt of Forensic Medicine Govt Medical College, Patiala
  13. 13. xviii Textbook of Ear, Nose and Throat Dr Rafiq Ahmad Associate Professor Deptt of ENT Govt Medical College Srinagar Dr SBS Mann Professor and Head Deptt of ENT, PGIMER Chandigarh Dr Sukhchain S Bhullar Associate Professor Deptt of ENT GMC, Faridkot Dr Sunder Singh Deptt of ENT Govt Medical College Patiala Dr Sanjay Arora Deptt of ENT Govt Medical College Patiala Dr Vikas Kakkar Associate Professor Deptt of ENT PGIMS, Rohtak Mr Pawan Kumar Bhardwaj Deputy Chief Accounts Officer PSEB, Patiala Dr RC Deka Chairman Professor and Head Deptt of ENT, AIIMS, New Delhi Dr RK Saxena Professor and Head Deptt of ENT HIMS Jolly Grant, Dehradun Dr SK Verma Professor and Head Deptt of ENT, Govt Medical College Patiala Dr Sukhbir Singh Deptt of ENT GMC, Patiala Dr Sunanda Gupta Professor Deptt of Anaesthesia RNT Medical College, Udaipur Dr TS Anand Professor Deptt of ENT, LHMC, New Delhi Dr SPS Yadav Associate Professor Deptt of ENT, PGIMS, Rohtak Shri JP Vij Chairman and Managing Director M/s Jaypee Brothers Medical Publishers (P) Ltd., New Delhi Friends lets remember “Success is a journey, not a destination”
  14. 14. Contents Section 1: DISEASES OF EAR 1. Surgical Anatomy of Ear 3 2. Applied Physiology of Hearing and Equilibrium 17 3. History Taking and Physical Examination of Ear 24 4. Functional Assessment of Hearing and Vestibular Function Tests 28 5. Diseases of External Ear 43 6. Acute Otitis Media 52 7. Chronic Suppurative Otitis Media 58 8. Complications of SOM 66 9. Nonsuppurative Otitis Media 74 10. Otospongiosis 79 11. Facial nerve 83 12. Tumours of Ear 94 13. Vertigo and Ménière’s Disease 102 SK Verma 14. Deafness and Various Rehabilitative Measures 110 15. Tinnitus 125 Section 2: DISEASES OF NOSE AND PARANASAL SINUSES 16. Anatomy and Physiology of Nose 131 17. History Taking and Method of Examination of Nose and PNS 140 18. Diseases of External Nose and Nasal Cavity 146 19. Diseases of Nasal Septum 152 20. Inflammatory and Other Disorders of Nasal Cavity 157 21. Nasal Allergy and Allied Conditions 165 TS Anand 22. Nasal Polypi 171 23. Epistaxis 176 24. Anatomy and Physiology of PNS 181 25. Acute Sinusitis 186 26. Chronic Sinusitis and its Complications 191 Karan Sharma
  15. 15. xx Textbook of Ear, Nose and Throat 27. Faciomaxillary Injuries 198 28. Tumours of Nose and PNS 204 Section 3: DISEASES OF ORAL CAVITY AND SALIVARY GLANDS 29. Surgical Anatomy of Oral Cavity 213 30. Diseases of Oral Cavity 216 31. Diseases of Salivary Glands 221 Section 4: DISEASES OF PHARYNX 32. Surgical Anatomy and Physiology of Pharynx 227 33. History Taking and Method of Examination of Pharynx 233 34. Diseases of Pharynx 236 35. Diseases of Tonsils and Adenoids 240 36. Diseases of Nasopharynx 248 M Lateef 37. Deep Neck Infections 257 Hemant Chopra 38. Tumours of Oropharynx 265 Baldev Singh 39. Tumours of Hypopharynx 271 Baldev Singh Section 5: DISEASES OF LARYNX AND TRACHEA 40. Anatomy and Physiology of Larynx 279 41. History Taking and Method of Examination of Larynx 285 42. Laryngotracheal Infections and Stridor 288 Chander Mohan 43. Hoarseness 298 44. Neurological Disorders of Larynx 301 Arjun Dass 45. Laryngotracheal Trauma 307 46. Tumours of the Larynx 309 AK Gupta, Sunanda Gupta 47. Surgical Anatomy of Tracheobronchial Tree 318 48. Diseases of Trachea and Bronchi and Foreign Bodies in Air Passages 320
  16. 16. Section 6: DISEASES OF OESOPHAGUS 49. Anatomy and Physiology of Oesophagus 327 50. Diseases of Oesophagus including Dysphagia 333 Section 7: DISEASES OF HEAD AND NECK 51. The Skull Base 345 RC Deka, Alok Thakar 52. The Thyroid Gland 350 53. Cervical Swellings 356 Section 8: RECENT ADVANCES 54. Radiology and Imaging in ENT 367 Abhilash Kapila 55. AIDS/HIV: Clinical Manifestations with Special Reference to ENT 381 Jagjit Singh Tuli 56. Radiotherapy in Head and Neck Cancer 388 Harjot Kaur 57. Chemotherapy of Head and Neck Cancers 393 Harjot Kaur 58. Cryosurgery 397 BS Sohal 59. Lasers in ENT 400 BS Sohal 60. Computer Applications in ENT 404 Sanjay Arora Section 9: MISCELLANEOUS DISORDERS 61. Proptosis 409 Navneet Kaur 62. Cavernous Sinus Thrombosis 411 Navneet Kaur 63. CSF Rhinorrhoea 414 64. Cleft Lip and Cleft Palate 417 65. Sleep Apnoea Syndrome and Snoring 420 66. Signs and Tests in ENT 422 67. Syndromes in ENT 428 68. Spaces and Triangles of ENT 433 Contents xxi
  17. 17. xxii Textbook of Ear, Nose and Throat 69. Stalwarts of ENT 437 70. Anaesthesia in ENT 441 71. Sterilisation 446 72. Medicolegal Aspects in Relation to ENT 451 RK Gorea, Amandeep Singh 73. Histopathological Diagnosis in ENT 457 74. Yoga in Relation to ENT 469 PK Bhardwaj Section 10: OPERATIVE SURGERY Vikas Kakkar, GPS Gill, Sukhbir Singh, Prasun Chattopadhaya 75. Myringotomy 479 76. Mastoidectomy 481 77. Myringoplasty and Tympanoplasty 488 78. Nasal Packing 493 79. Antral Wash and Intranasal Antrostomy 495 80. Radical Operations on Maxillary Sinus 498 81. Operations for Polypi Nose 501 82. Functional Endoscopic Sinus Surgery (FESS) 504 83. Operations of Nasal Septum 507 84. Adenoidectomy 511 85. Tonsillectomy 514 86. Tracheostomy 520 87. Direct Laryngoscopy 525 88. Bronchoscopy 528 89. Oesophagoscopy 531 Section 11: INSTRUMENTS 90. Instruments for ENT Examination 537 91. Ear Instruments 542 92. Nose Instruments 546 93. Throat Instruments 551 94. Endoscopic Instruments 555 95. Tracheostomy Instruments 558
  18. 18. Contents xxiii APPENDICES Appendix 1 How to Present a Long Case 563 Appendix 2 ENT Diseases in Relation to Age and Sex 568 Appendix 3 Commonly Used Antibiotics, their Doses and Side Effects 569 Appendix 4 Laboratory Values of Clinical Importance 571 Appendix 5 Head and Neck Cancer 572 Index 575
  19. 19. Surgical Anatomy of Ear 3 Section1 Surgical Anatomy of Ear DEVELOPMENT a) External ear: The pinna develops from a series of 6 ectodermal tubercles that appear on 1st and 2nd pharyngeal arches in the 6th week of intrauterine life (IUL) and it is well formed by 20 weeks. Preauricular sinus results from failure of fusion of these tubercles of first and second branchial arches. External auditory meatus is formed by about 16th week from 1st branchial cleft by the process of canalisation and is well formed by 28 weeks. b) Middle ear: It develops from entoderm of tubotympanic recess arising mainly from the first and second pharyngeal pouches in the 3rd week of IUL and development is complete by 30 weeks. At birth antrum approximates that of an adult. Malleus and incus develop from mesoderm of 1st arch (Meckel’s cartilage), while stapes along with styloid process and hyoid bone are formed from 2nd arch cartilage. Ossicular chain appears at 4th week and by 15 weeks attains the adult size. c) Inner ear: Bony labyrinth develops from mesoderm around otocyst while membra- nous labyrinth develops from ectoderm around otocyst. It starts in the 3rd week of foetal life and is complete by 16th week. Cochlea is well developed by 20 weeks of gestation. ANATOMY OF EAR Ear can be divided into three parts: a. External ear b. Middle ear c. Inner ear. External Ear It consists of pinna and external auditory meatus. Pinna It consists of fibroelastic cartilage covered by skin and connected to the surrounding parts by ligaments and muscles. The cartilage of pinna is continuous with the cartilage of external auditory meatus. Various landmarks on the pinna are helix, antihelix, lobule, tragus, concha, scaphoid fossa and triangular fossa (Fig. 1.1). CHAPTER 1
  20. 20. 4 Textbook of Ear, Nose and Throat Section1 Ligaments and muscles of pinna: There are both extrinsic and intrinsic ligaments and muscles. Extrinsic muscles are anterior, posterior and superior auricularis, while intrinsic muscles are helicis major and helicis minor, tragicus and antitragicus. Both groups are supplied by branches of facial nerve. Sensory nerve supply of pinna: Cranial surface—upper third by lesser occipital nerve (C2) and lower two-thirds by greater auricular nerve (C2, C3) (Figs 1.2A and B). Lateral surface by greater auricular nerve (lower part) and rest by auriculotemporal nerve and auricular branch of vagus nerve. Blood supply of pinna: Posterior auricular branch of external carotid, anterior auricular branch of superficial temporal and a branch of occipital artery. Veins corresponding to the arteries drain into external jugular and common facial vein. Lymphatics: They drain into parotid group, upper deep cervical and mastoid lymph nodes (Fig. 1.3). External Acoustic Meatus It is 24 mm in length, outer one-third (8 mm) being cartilaginous and inner two-thirds (16 mm) bony. Fissures of Santorini are Fig. 1.1: Various landmarks on the lateral surface of pinna Figs 1.2A and B: Cutaneous innervation of pinna (A) lateral surface (B) cranial surface
  21. 21. Surgical Anatomy of Ear 5 Section1 deficiencies seen in cartilaginous portion of external auditory canal (EAC). It forms a mild S-shaped curve directed medially, upwards and forwards and then medially, backwards and downwards. There are present two constrictions in the EAC; one, near the medial end of cartilaginous part and the other 5 mm short of tympanic memb- rane in the osseous part called isthmus. Floor and anterior wall of meatus are longer than the roof and posterior part. Anterior, inferior and posterior bony wall is formed by tympanic part of temporal bone, while roof and part of posterior wall is formed by squamous part of temporal bone. Meatal recess is present in relation to the inferior wall of the meatus. Skin is very thin and firmly attached to the bone and cartilage of meatus, that is why inflammation here is very painful due to increased tension in these tissues. Ceruminous glands and hair are present mostly in the subcutaneous tissue of cartilaginous part. Condyloid process of mandible is in close relation to anterior wall. Middle cranial fossa lies above the osseous meatus and mastoid air cells are posterior to it. Nerve supply of anterior and superior wall comes through auriculotemporal branch of mandibular nerve, while posterior and inferior wall is supplied by auricular branch of vagus. Middle Ear (Tympanum) It is a biconcave irregular space contained in the petrous part of temporal bone. It has three parts—mesotympanum, epitympanum and hypotympanum. It measures 15 mm each both vertically and anteroposteriorly, while transverse diameter will be 6 mm above, 4 mm below and 2 mm opposite umbo. Contents of middle ear are air, ossicles and tendons of stapedius and tensor tympani. It communicates with nasopharynx through and mastoid antrum posteriorly through aditus opening. Walls of Tympanic Cavity (Fig. 1.4) Roof: It is formed by tegmen tympani, part of petrous and squamous bone forming petrosquamous suture through which veins communicate with the meninges or superior petrosal sinus. Floor: It is a thin convex plate of bone which separates the floor from superior bulb of internal jugular vein. An aperture for the passage of Jacobson’s nerve (tympanic branch of glossopharyngeal nerve) exists close to the medial wall of tympanic cavity. Lateral wall: Tympanic membrane which forms the lateral wall of middle ear separates it from external acoustic meatus (Figs 1.5A and B). It is semitransparent, pearly grey in colour weighing nearly 12 to 14 mg, thick- ness varies from 0.1 mm to 0.15 mm. Tympanic membrane (TM) of an infant is thicker than that of an adult. It is placed at an angle of 55o with the floor. Antero- posteriorly it is 8 to 9 mm and vertically it is 9 to 10 mm.Total surface area is 85 sq mm while vibrating surface area is nearly 55 sq mm. Peripheral part of tympanic membrane is thickened to form fibrocartilaginous ring attached to tympanic sulcus which is Fig. 1.3: Lymphatic drainage of pinna
  22. 22. 6 Textbook of Ear, Nose and Throat Section1 deficient superiorly. The membrane is convex towards the middle ear cavity and the tense part is called pars tensa and the flaccid part above the malleolar folds is called pars flaccida (Sharpnell’s membrane) which is approximately 2 to 3 mm only. It allows free movements to the head of malleus. The tympanic membrane has three layers; outer cuticular, middle fibrous layer of inner circular and outer radiating fibres and finally the inner mucosal layer. Blood supply of tympanic membrane comes through deep auricular branch of maxillary artery to cuticular layer, stylomas- toid branch of occipital or posterior auricular artery, tympanic branch of maxillary artery to middle and mucosal layer. Veins drain to external jugular vein and transverse sinus. Nerve supply is by auriculotemporal branch of mandibular nerve, auricular branch of vagus (Arnold’s nerve) and tympa- Fig. 1.4: Showing walls of middle ear cavity with lateral wall opened up Figs 1.5A and B: Various landmarks of normal tympanic membrane (A) right tympanic membrane (B) left tympanic membrane
  23. 23. Surgical Anatomy of Ear 7 Section1 nic branch of glossopharyngeal nerve (Jacobson’s nerve). Medial wall: The main features on medial wall are (Fig. 1.6): • Promontory formed by basal turn of cochlea. • Fenestra vestibuli (oval window) lies posterosuperior to the promontory and opens into scala vestibuli. It measures 3.25 × 1.75 mm. It is occupied by foot plate of stapes fixed by annular ligament. • Fenestra cochleae (round window) lies posteroinferior, opens into scala tympani of cochlea, measures 1.5 × 1.3 mm and is closed by secondary tympanic membrane. The round window is closest to ampulla of posterior semicircular canal. • Prominence of facial nerve canal lies above the fenestra vestibuli curving downwards into posterior wall of middle ear (Fig. 1.7). • Anterior to oval window lies a hook-like projection called the processus cochleari- formis for tendon of tensor tympani. Posterior wall: It has the following main features: • Aditus is an irregular aperture leading back from epitympanic recess into upper part of mastoid antrum. • Pyramidal eminence lies just behind fenestra vestibuli and contains stapedius muscle. Fig. 1.6: Various structures on the medial wall of middle ear Fig. 1.7: Left tympanic cavity in relation to the facial nerve
  24. 24. 8 Textbook of Ear, Nose and Throat Section1 • Fossa incudis lies in epitympanic recess and contains short process of incus. • An opening for exit of chorda tympani nerve. Facial recess also called suprapyramidal recess is a collection of air cells lying lateral to facial nerve. It is bounded medially by external genu of facial nerve, laterally by chorda tympani, superiorly by fossa incudis and anterolaterally by tympanic membrane. Importance of this recess is that one can approach the middle ear without disturbing posterior meatal wall. Ear may continue discharging if this area is not cleaned during mastoid surgery. Anterior wall: It has the following openings (Fig. 1.8). • Above is the canal for tensor tympani extending to medial wall to form a pulley called processus cochleariformis. • Below is osseous opening of E. tube. • Opening of carotid canal (Glasserian fissure) through which pass superior and inferior caroticotympanic nerves and tympanic branch of internal carotid artery. • Canal of Huguier for passage of chorda tympani nerve. Surgical Anatomy of Mastoid Antrum It is an air sinus in the petrous temporal bone. It is of the same size (10 mm) in adults and children and it is always present. Its upper anterior wall has the opening of aditus, while medial wall is related to poste- rior semicircular canal (SCC). Posteriorly lies the sigmoid sinus. The roof is formed by tegmen antri separating it from middle cranial fossa and temporal lobe of brain. Anteroinferior is the descending part of facial nerve canal (or fallopian canal). Lateral wall is formed by squamous temporal bone and its thickness in adult is 12 to 15 mm. • Macewen’s triangle or suprameatal triangle: It is bounded above by supramastoid crest, anteroinferiorly by posterosuperior margin of external auditory canal and posteriorly by a tangent drawn from zygomatic arch (Fig. 1.9). Spine of Henle lies in the triangle. Mastoid antrum lies 15 mm deep which is clinically palpated in the cymba conchae of Fig. 1.8: Anterior wall and floor of middle ear cavity
  25. 25. Surgical Anatomy of Ear 9 Section1 the pinna. Korner’s septum is persistence of petrosquamous suture forming a false bottom of mastoid antrum. • Trautmann’s triangle: It is bounded by sigmoid sinus posteriorly, bony labyrinth anteriorly and superior petrosal sinus superiorly. Infection into the posterior cranial fossa can spread through this triangle and can be approached by removing the bone in between the triangle. Types of mastoid antrum: i. Pneumatised (80%) — there are present many groups of cells like tip cells, dural cells, perisinus cells, sinodural angle cells, retrofacial cells and zygomatic cells. ii. Sclerotic (20%) — there are present few or no cells. In this type, cells are absent and are replaced by dense bone. iii. Mixed (Diploeic)—there are small air cells and bone marrow spaces (Fig. 1.10). Extent of pneumatisation depends on E. tube function (Tumarkin’s theory), envi- ronment, heredity (Diamant) or infantile otitis media (Wittmark). Pneumatisation begins in first year and is complete by 4 to 6 years of age. Eustachian Tube It is also called pharyngotympanic tube and helps to equalise pressure on both sides of tympanic membrane (Fig. 1.11). It is about 36 mm long and descends at an angle of 45o with sagittal plane and 30o with horizontal plane. In resting state tubal end in nasopharynx lies collapsed, opening during yawning and deglutition. Osseous part (12 mm) starts from anterior tympanic wall which narrows to end at squamous and petrous part of temporal bone to attach with cartilaginous part which is 24 mm long and opens into the nasopharynx between the petrous part of temporal bone and greater wing of sphenoid bone. In infants the auditory tube is short and wide and is placed horizontally. Fig. 1.9: Boundaries of Macewen’s triangle Fig. 1.10: Various groups of air cells in the temporal bone Fig. 1.11: Right eustachian tube
  26. 26. 10 Textbook of Ear, Nose and Throat Section1 • Muscles of E. tube are tensor palati (dilator tube is a part of it) supplied by branch of mandibular nerve and levator palati supplied by pharyngeal plexus through XIth cranial nerve. Tensor palati separates the E. tube from otic ganglion, mandibular nerve, chorda tympani nerve and middle meningeal artery (Fig. 1.12). • Arterial supply is through branches from ascending pharyngeal, middle meningeal and artery of pterygoid canal (both branches of maxillary artery). • Venous drainage is to the pterygoid venous plexus. • Nerve supply is by tympanic plexus and pharyngeal branches of pterygopalatine ganglion. Auditory Ossicles These are malleus, incus and stapes (Fig. 1.13). Malleus: It is shaped like a mallet, is 8 to 9 mm long, weighs 23 to 25 mg and is the largest of the three ossicles. It has head, neck, manubrium (handle), anterior and lateral processes. Head lies in epitympanic recess and articulates with the incus. Incus: It is shaped like an anvil, weighs 25 to 30 mg, has a body and two processes, long process (lenticular) and a short process which lies in the fossa incudis of epitym- panic recess. Stapes: It is the shortest bone of the body and weighs 2.5 to 3 mg. It has a head, neck, Fig. 1.12: Tensor palati and eustachian tube Fig. 1.13: Ear ossicles and their parts
  27. 27. Surgical Anatomy of Ear 11 Section1 two cruras and a base which fits into the oval window. All these ossicles are supplied by bran- ches of anterior, inferior and posterior tympanic arteries. Muscles of the Tympanic Cavity Tensor tympani: It arises from cartilaginous part of the E. tube and adjoining region of greater wing of sphenoid and its tendon is attached to the handle of malleus near its root. It is supplied by a branch of mandibular nerve. Stapedius: It arises from pyramidal eminence and after it emerges from its apex is attached to the neck of stapes. It is supplied by branch of facial nerve. Actions: Both muscles contract in response to loud sounds exerting a protective, dampening effect before vibrations reach the internal ear. Paralysis of stapedius results in hyperacusis. Compartments and Spaces of Middle Ear Epitympanum (3 mm) communicates with mesotympanum (7-8 mm) through isthmus tympani anticus and posticus. Upper part of mesotympanum has three compart- ments— inferior incudal space, anterior and posterior pouch of Von Troltsch (Fig. 1.14). Prussak’s space: It lies between neck of mal- leus (internally) and pars flaccida (exter- nally). Fig. 1.14: Middle ear spaces (diagrammatic view) Figs 1.15A and B: (A) Facial recess and sinus tympani (B) Diagrammatic view of sinus tympani in relation to oval and round windows Bounded above by fibres of lateral malleolar fold and below by short process of malleus. Importance of this space is that the cholesteatoma may extend to posterior mesotympanum under lateral incudal fold and infection here does not drain easily and causes attic pathology. Facial recess and sinus tympani: Facial recess, also called suprapyramidal recess, is bounded by facial nerve (medially), chorda tympani (laterally) and fossa incudis (above) (Figs 1.15A and B). Sinus tympani also called infrapyramidal recess or medial facial recess is a triangular space between ponticulus and subiculum process. It starts at oval window and occu- pies a space deep to descending part of VIIth nerve and pyramid, passes behind round window niche to hypotympanum.
  28. 28. 12 Textbook of Ear, Nose and Throat Section1 Antrum threshold angle: Bounded above by horizontal semicircular canal (HSCC) and fossa incudis, medially by descending part of VIIth nerve, and laterally by chorda tympani nerve. Solid angle: Formed by solid bone in the angle formed by three SCC’s. Sinodural angle: The angle between tegmen antri and sigmoid sinus. Mucous Membrane of Middle Ear Tympanic mucosa is pale, thin and slightly vascular ciliated columnar epithelium except on posterior wall where it is nonciliated like that of the mastoid antrum. Blood supply of tympanic cavity: Anterior tympanic branch of maxillary, posterior tympanic branch of stylomastoid (which is a branch of posterior auricular), superior tympanic branch of middle meningeal artery, inferior tympanic branch of ascending pharyngeal and deep auricular branch of maxillary. Veins: drain into pterygoid venous plexus and superior petrosal sinus. Lymphatics: drain to parotid and upper deep cervical lymph nodes. Nerves: middle ear is supplied by tympanic plexus formed by union of tympanic branch of glossopharyngeal nerve and carotico- tympanic nerves of sympathetic origin. Mastoid antrum is supplied by meningeal branch of mandibular nerve. Internal Ear It consists of a bony labyrinth contained with in the petrous temporal bone along with the membranous labyrinth (Figs 1.16A and B). It serves the most important function of hearing and equilibrium. Bony Labyrinth It consists of (Fig. 1.16A): 1. Vestibule 2. Semicircular canals 3. Cochlea. Vestibule: Ovoid in shape measuring 5 mm × 3 mm forming the central part of bony labyrinth. Lateral wall has the fenestra vestibuli. It has a spherical recess containing saccule, cochlear recess for cochlear duct and an elliptical recess for utricle. Opening of vestibular aqueduct lies below elliptical recess. Posterior part of vestibule has 5 openings of 3 semicircular canals. Its medial wall is related to internal acoustic meatus. Semicircular canals: There are 3 SCC’s, i.e. anterior, posterior and lateral. These are all about 0.8 mm in diameter and have a terminal swelling called ampulla and open into vestibule by 5 openings, one common between anterior and posterior is called the crus commune. The 3 canals lie at 90o to each other. Posterior SCC is 18 to 22 mm long while anterior SCC is 15 to 20 mm and lateral SCC is 12 to 15 mm long. Anterior SCC is placed transverse to the long axis of petrous temporal and its upward convexity forms the arcuate eminence. Posterior SCC runs parallel to posterior surface of petrous bone, while lateral SCC lies at 30o to the horizontal plane; and hence, after 30o flexion of head, the lateral canal becomes horizontal. Remember that the two horizontal SCC’s lie in the same plane, while anterior SCC of one side is parallel with the posterior SCC of other side. Cochlea: It is shaped like a conical snail shell, measures 35 mm (long) × 5 mm (base to apex) and 9 mm across its base. Apex of cochlea points towards anterosuperior part of medial wall of middle ear cavity and its
  29. 29. Surgical Anatomy of Ear 13 Section1 base towards the fundus of internal acoustic meatus. Cochlea has a central conical axis called modiolus with a spiral canal of 2 and 3 quarter turns around it. An osseous spiral lamina projects from the modiolus and divides the cochlear canal into upper scala vestibuli and lower scala tympani. Both the scalae are continuous with each other through helicotrema at the apex of cochlea. Cochlea at its base has three openings, i.e., fenestra vestibuli, fenestra cochleae and cochlear canaliculus which transmits a small vein to inferior petrosal sinus. Bony labyrinth contains perilymph which resembles cerebrospinal fluid (CSF) in its composition. Membranous Labyrinth It lies within the osseous labyrinth and is filled with endolymphatic fluid (Fig. 1.16B). Vestibulocochlear nerve fibres are distributed in the walls of membranous labyrinth. The Figs 1.16A and B: (A) View of bony labyrinth (B) Membranous labyrinth
  30. 30. 14 Textbook of Ear, Nose and Throat Section1 membranous labyrinth is separated from the bony labyrinth by perilymphatic fluid. It has the following parts. Utricle: It is an irregular oblong structure 2 to 5 mm in diameter which occupies ellipti- cal recess of the vestibule. Lateral wall and adjoining floor have a thickened area of 3 mm × 2 mm called utricular macula which is innervated by utricular fibres of vestibular nerve. Semicircular ducts open into the utricle through 5 ampullary ends. Saccule: It is globular in shape of 1 to 1.5 mm in diameter and occupies the spherical recess near the opening of scala vestibuli. Its anterior wall has the macula set at right angle to the utricular macula. Saccule is connected to the utricle through a Y-shaped tube, to the endolymphatic duct and sac which lies under the dura mater on posterior surface of petrous bone. Ductus reuniens passes inferior from lower part of saccule into the basal end of cochlear duct. Semicircular ducts: These open into the utricle by 5 orifices, one being common to the medial end of anterior and posterior duct. In the ampullary end of each duct, there is a transverse elevation shaped like an hour glass called septum transversum and its most prominent part being ampullary cristae which are the sensitive organs to the movements of endolymph. These cristae respond to pressure changes of endolymph while maculae respond to gravitational changes. Structure of utricle, saccule and semicircular ducts: Each has three layers. External layer is fibrous and vascular, middle layer is vascular connective tissue and internal layer is simple epithelium varying from squamous to cuboidal with a basement membrane having light and dark cells. In ampullary crests, the epithelium contains sensory hair cells of type I and type II and supporting cells of Hensen (Fig. 1.17). Type I cell is pyriform in shape and type II cell is cylindrical. Apical surface of both these cells carry 40 to 100 stereocilia or modified microvilli. A long kinocilium is also attached to each cell. These stereocilia and kinocilium are inserted into a gelatinous mass-like membrane called otolithic memb- rane containing many otoliths or statoconia (Fig. 1.18). Macula is the organ for static balance, while ampullary crest is the organ for kinetic balance (or responds to angular acceleration). Endolymph resembles intracellular fluid being rich in potassium and poor in sodium ions. Cochlear duct: It lies within the bony cochlea. Basilar membrane stretches from the osseous spiral lamina to spiral ligament and has the sensory area of cochlea called organ of Corti. Vestibular membrane also called Reissner’s membrane lies well over the basilar memb- rane below the scala vestibuli. The canal thus enclosed between scala vestibuli and scala tympani is the cochlear duct (or scala media). It is triangular in cross-section (Fig. 1.19). Fig. 1.17: Sensory hair cells of vestibular organ
  31. 31. Surgical Anatomy of Ear 15 Section1Basilar membrane consists of two zones, i.e. zona arcuata which supports organ of Corti and zona pectinata. Its total length is 35 mm and width is between 0.21 mm and 0.36 mm. Organ of Corti consists of two rows of cells. External rod cells (4000) and internal rod cells (6000). Inner-to-inner rods are inner hair cells (3500) in one row while external-to-outer rods are 3 to 4 layers of outer hair cells (12000). Organ of Corti is covered by tectorial membrane. Supporting cells of Deiters are Fig. 1.18: Structure of macula Fig. 1.19: Section of the cochlea to show scala media situated between the outer hair cells. Cells of Hensen lie outside the Deiters’ cells. In addition to tunnel of Corti (between outer and inner rod cells), there is also an outer tunnel and space of Nuel (medial tunnel). These spaces are filled with cortilymph which resembles perilymph. Vestibulocochlear Nerve The VIIIth nerve divides deep in the internal acoustic meatus into anterior cochlear and posterior vestibular nerve.
  32. 32. 16 Textbook of Ear, Nose and Throat Section1 Cochlear nerve: After dividing into many filaments at the modiolar base ultimately it ends in inner hair cells (95%) and outer hair cells (5%). A vestibular branch of cochlear nerve supplies the vestibular end of cochlear duct. Vestibular nerve: It supplies maculae of utricle, saccule and ampulla of SC ducts. Scarpa’s ganglion from where these fibres arise lies in the internal meatus. Distal to the ganglion, it divides into superior, inferior and posterior vestibular branches. • Superior branch supplies utricular macula and ampullary crest of anterior and lateral SC ducts. • Inferior branch supplies saccular macula. • Posterior supplies ampulla of posterior SC duct. Arteries of Labyrinth Internal auditory artery is a branch of anterior inferior cerebellar artery which itself arises from basilar artery. Internal auditory artery (labyrinthine artery) divides into a cochlear and a vestibular branch. Stylomas- toid branch of occipital artery and posterior auricular artery also contribute. Veins: Cochlear vein and vestibular vein join to form the labyrinthine vein which ends in superior petrosal sinus or in transverse sinus. A small vein from basal turn of cochlea also joins the internal jugular vein. Remember, the organ of Corti has no direct blood supply and depends for its metabolic activity from diffusion of oxygen from stria vascularis. This arrangement provides acoustic insulation of hair cells. KEY POINTS 1. Preauricular sinus results due to failure of fusion of tubercles of 1st and 2nd branchial arches. 2. Measurements Name In mm Name In mm EAC 24 (8C+16B) Length of HSCC 12-15 Middle ear 15×15×6-2-4 Length of ant. SCC 15-20 Tymp. membrane 10×9×0.1 Length of post. SCC 18-22 E. tube 36 (24C+12B) Cochlea 5×9×35 Fenestra cochleae 1.5×1.3 Basilar membrane 35×0.3 Fenestra vestibuli 3.25×1.75 Pars flaccida 2-3 Mastoid antrum 15×12 Utricular macula 3×2 Vestibule 5×3 Saccular macula 1-1.5 SCC dia. 0.8 Vibrating surface 55 (in sq mm) 3. Boundaries of facial recess are facial nerve (medially), chorda tympani (laterally) and fossa incudis (above). 4. Sinus tympani or infrapyramidal recess lies between oval and round window, below ponticulus and above subiculum process of bone on medial wall. 5. Trautmann’s triangle is bounded by superior petrosal sinus (superiorly), sigmoid sinus (posteriorly) and bony labyrinth (anteriorly). 6. Eddy currents in the external auditory meatus do not allow water to reach TM while swimming. 7. Glasserian fissure in the middle ear transmits anterior tympanic branch of maxillary artery, anterior ligament of malleus and chorda tympani nerve through canal of Huguier.
  33. 33. Applied Physiology of Hearing and Equilibrium 17 Section1 Applied Physiology of Hearing and Equilibrium Ear performs two important functions of hearing and equilibrium. VARIOUS AUDIOLOGICAL TERMS • Sound — is a subjective sensation produced by vibrating objects. • Sound waves—are produced due to vibration of air molecules in an alternate phase of condensation and rarefaction and when these molecules strike the tympanic membrane (TM), sound is heard. • Frequency—is the number of cycles or vibrations per second and is described in Hertz (Hz) after the name of a German scientist, Heinrich Rudolph Hertz. • Amplitude—of the sound waves deter- mines the intensity of the sound, hence the loudness. • Pitch—of the sound is determined by fre- quency of sound waves. • Loudness—of sound depends upon fre- quency of sound waves. • Intensity—of sound is denoted in decibels (1 /10 of a bel). Bel is a log of the ratio of intensity of that sound and standard sound. 1 Bel Intensity of sound (Alexander = Log of ____________________________________________________ Graham Bel) Intensity of standard sound • Noise — is defined as an unwanted super- fluous or random sound energy. It may be white noise, narrow band noise or speech noise (between 500 and 3000 Hz). • Sounds levels: — Whisper at 4 feet = 20 dB — Office noise = 40 dB — Noisy street = 60-80 dB — Loud motor horn = 100 dB — Thunder = 120 dB — Jet engine = 140 dB Since actual scale is logarithmic, therefore: — 1 bel = 101 , i.e. 10 times of 0 level — 2 bel = 102 ,i.e. 100 times of 0 level — 3 bel = 103 , i.e. 1000 times of 0 level. Audible range of frequencies—it lies between 20 Hz and 20000 Hz. Above 20000 Hz (super- sonic) are heard by dogs and below 20 Hz (subsonic) are heard by bats. TRANSMISSION OF SOUND WAVES Effective vibratory area of tympanic memb- rane is nearly 45 to 55 sq mm and when sound CHAPTER 2
  34. 34. 18 Textbook of Ear, Nose and Throat Section1 waves fall on it, part of sound energy is transmitted to the inner ear through middle ear ossicular chain. Total effective vibratory area of TM is 14 times greater than the foot plate of stapes called hydraulic ratio. Handle of malleus is longer than the incus by 1.3 times, so the pressure exerted at oval window works out to be 14 × 1.3 times = 18.3 times. This is called middle ear transformer mechanism (Fig. 2.1). Another method of sound conduction to cochlear fluid is by bone conduction through transmission of vibration of bones of skull. Movements of foot plate, and hence, cochlear fluid brings travelling waves and osscilations of basilar membrane, and hence, stimulation of hair cells setting in neural impulses which takes place because of shearing action between tectorial membrane and reticular lamina (Fig. 2.2). Theories of Hearing Helmholtz’s Resonance theory (Place theory) According to this theory, sound waves enter- ing the internal ear set up vibrations of particular fibres of basilar membrane depending upon the tones. Lower tones stimulate longer fibres at the apex of cochlea and higher tones stimulate smaller fibres at the base of cochlea. Rutherford’s Telephone Theory This theory says that cochlea acts like a telephone transmitter, and hence, basilar membrane gets stimulated by every frequency of sound. Von Bekesy’s Travelling Wave Theory It is a combination of above two theories and is most widely accepted as it explains the response of whole cochlea to low frequencies Fig. 2.2: Physiology of ear Fig. 2.1: Transformer action of the middle ear
  35. 35. Applied Physiology of Hearing and Equilibrium 19 Section1 and also explains the cochlear analysis of higher frequencies above 5000 Hz at the basal turn of cochlea. Electrical Potentials of Cochlea It is because of these potential differences that acoustic impulses are transmitted as neural impulses. These potentials are as follows. Cochlear Microphonic Potentials (CMP) Tasaki (1954) recorded these potentials which originate in cochlea and spread to the neighbouring structures and are produed due to acoustic stimulation. These, potentials CM1 and CM2, can be recorded by placing an electrode in the scala media and another in the scala tympani. These potentials are highly resistant to drugs, anaesthesia, cold and fatigue and can even be recorded in recently died animal. Summating Potential There are two negative and positive poten- tials due to acoustic stimulation of inner and outer hair cells and are recorded due to changes in endolymphatic potentials. Endolymphatic Potential These originate in the scala media (endo- lymph) where there is steady + 80 mV potential and depends upon oxygen supply. The potential increases when basilar membrane moves towards scala tympani due to inward movement of stapes. Cortilymph Potential It is recorded in the organ of Corti where a potential of –20 mV to –80 mV is recorded. Action Potential Tasaki recorded action potentials of auditory nerve fibres proportionate to the loudness of sound stimuli. Auditory nerve has 25000 fibres subserving 17000 hair cells (Table 2.1). PHYSIOLOGY OF EQUILIBRIUM Equilibrium of body is maintained by the coordination of reflexes from vestibular apparatus (also called gyroscope of head), eyes and proprioceptive reflexes from skin, muscles joints and tendons (Fig. 2.3). Maculae (otolithic organ) of utricle and saccule and cristae in the ampullae of 3 Fig. 2.3: Physiology of equilibrium
  36. 36. 20 Textbook of Ear, Nose and Throat Section1 Table 2.1: Pathways of auditory impulse Hair cells (organs of Corti) Cochlear nerve (1st order neurons) Dorsal ventral Ventral cochlear nucleus nucleus (2nd order neurons) Acoustic striae Corpus trapezoideum Superior Lateral fillet of Superior olivary nucleus and olivary nucleus opposite side trapezoid nucleus of same side of the same side Lateral fillet Lateral fillet Lateral fillet of of same side of same side opposite side Pons and midbrain Interior colliculus Medial geniculate body (3rd order neurons) Auditory radiations (internal capsule) Auditory centre (Heschl’s gyrus-temporal lobe)
  37. 37. Applied Physiology of Hearing and Equilibrium 21 Section1 Fig. 2.4: Structure of ampullary end of semicircular duct semicircular (SC) ducts are the sensory organs concerned with the equilibrium of body. The discharge rate of impulses from nerve endings which supply the maculae changes with the gravitational pull on otolith organs. Remember, linear acceleration (gravity) stimulates the maculae, while angular accele- ration (rotation) stimulates the cristae in SC ducts. It is due to lagging behind of perilymph and endolymph thereby deflecting the cupula and stimulating the hair cells (Fig. 2.4). Functions of Vestibular Apparatus 1. It helps in the maintainence of the muscle tone, posture and equilibrium. 2. It also maintains the erect position of head to that of trunk and limbs. 3. Sends impulses to cortex giving infor- mation about the position and rotation of head through otolithic organs. How These Functions are Performed? Cristae ampullaris: It is a ridge of neuroepi- thelium which has type I (flask shaped) and type II (cylindrical) cells. When movements of endolymph occur towards kinocilium, the discharge increases, while when it occurs towards stereocilia, the discharge decreases. Because of this, sensory nerve endings are stimulated and send impulses upwards to the brain giving information about the move- ments of head. If the person is rotated to the left, both his eyes move slowly to the right due to vestibular activity and this is further followed by quick movement of eyes to the left due to central correcting mechanism. During rest with normal vestibular apparatus the eyes remain in the centre due to cancellation effect of right and left vestibular apparatus. Now, if left vestibular apparatus is destroyed, the normal tone exerted by right vestibular apparatus pushes the eyes to the left side. This is corrected to the central position with a quick movement and nystagmus to right side appears. Thus, semicircular canals give information about the direction, degree and plane of movements of head. These canals are stimulated by angular acceleration which can be given by Barany’s chair or by caloric test. Coriolis effect is the specific type of angular acceleration that causes motion sickness in spacecraft due to rotation of earth. Otolithic organs of maculae and saccule: They act as stretch receptors and gravity acts as the stimulus. Macular epithelium resembles that of cristae with additional feature of presence of otoconia or calcareous granules embedded in otolithic membrane. When the otolith rests
  38. 38. 22 Textbook of Ear, Nose and Throat Section1 Table 2.2: Pathways of vestibular impulses Cristae Maculae Scarpa’s ganglion (1st order neurons) Vestibular nerve Pons Cerebellar nuclei Cerebellum Inferior vestibular Superior Median vestibular Lateral nerve vestibular nerve nerve vestibular nerve (Bechterew’s nucleus) (4th ventricle) (or Deiters’ nerve) 2nd order neurons Vestibulospinal tract Vestibulocortical Inferior cerebellar Red fibres end in thalamus peduncle nucleus 3rd order Vestibulo-ocular neurons Vestibulocerebellar tract, ending in IIIth, IVth tract, ends in and VIth nerve nuclei Lateral - outer flocculonodular lobe horn cells of Temporal lobe and fastigial nucleus grey matter or brain in cerebellum Medial Vestibuloreticular tract, ends in bulbar reticular formation Anterior funiculus (responsible for nausea, vomiting, palpitation, perspiration, pallor, eye and neck movements)
  39. 39. Applied Physiology of Hearing and Equilibrium 23 Section1 on the hair cells, the stimulation is minimal; while when these hang down vertically, these exert a pulling action on hair cells thus producing maximal stimulation. These organs give information about the static position of head and not of movements. Saccule gives information about the position of head in a lateral plane while utricle in anteroposterior plane (Table 2.2). KEY POINTS 1. Decibel (1/10 of a bel) is a log of the ratio of intensity of that sound and standard sound. 2. Pressure exerted at oval window is Hydraulic ratio (14 times) × 1.3 HOM v/s incus—(Length of handle of malleus/length of long process of incus) = 18.3 times (Middle ear transformer mechanism) 3. It is because of electrical potentials that acoustic impulses are transmitted as neural impulses. 4. Macula of utricle and saccule, and cristae in ampullae of SCC’s are concerned with equilibrium of the body. 5. Linear acceleration (gravity) stimulates maculae while angular acceleration (rotation) stimulates cristae. 6. Ewald’s law states that the slow component of nystagmus is always towards flow of endolymph. 7. Cone of light is seen in the anteroinferior quadrant of the TM, because it lies at right angle to the meatus, and hence, the light is reflected back.
  40. 40. 24 Textbook of Ear, Nose and Throat Section1 History Taking and Physical Examination of Ear CHAPTER 3 HISTORY TAKING History taking of an ear patient is like history taking in any other discipline in of medicine. The scheme is similar such as chief comp- laints with duration, history of present illness, past history, personal history and family history. General physical examination including lymph nodes of neck, cardiovas- cular system (CVS), central nervous system (CNS) with cranial nerves (especially VIIth and VIIIth ), and examination of respiratory system is done. Chief Complaints Main chief complaints of ear disease are as follows: • Discharge from ear: Enquire whether dis- charge is continuous or intermittent, serous, mucopurulent, purulent, blood stained, foul smelling, any aggravating factors and effects of treatment taken for the discharge. • Hearing loss: Onset and duration, prog- ress, whether mild, moderate or severe in degree, autophony, fluctuating. Any aggravation because of drugs, trauma, viral fever or discharge. • Vertigo: Onset and duration of attack, nau- sea, vomiting, effect of posture, frequency of attack, feeling of rotation, or incoordi- nation of movements. • Noises in the ear: Character, unilateral or bilateral, continuous or intermittent, high pitched or low pitched, any association with trauma, drugs or tensions. • Earache: Unilateral or bilateral, duration, aggravating factors, history of trauma, any orodental problem, severity, charac- ter, or distribution of pain. • Other symptoms of complications: Headache, fever, facial deformity or swelling behind the ear, or aphasia. METHOD OF LOCAL EXAMINATION OF EAR It starts with the following: • Pinna: On inspection and palpation both the pinna is examined for any deformity, scar mark, sinus opening, swelling, tenderness, painful movement, tragus sign, and circumduction sign (Fig. 3.1). • Preauricular and postauricular region: Look for any swelling, sinus, scar mark, tender- ness or oedema.
  41. 41. History Taking and Physical Examination of Ear 25 Section1 • External auditory meatus: It is examined for any wax, fungus, foreign body, debris, discharge, polyp, swelling and most importantly for sagging of posterosupe- rior wall of meatus. Sagging of posterosuperior meatal wall indicates periosteitis due to choles- teatoma in the mastoid antrum. • Tympanic membrane: It is pearly grey in colour and all the standard landmarks on it have to be identified such as HOM (handle of malleus), short process of malleus, anterior and posterior malleolar folds, umbo, and cone of light (Fig. 3.2). Then describe any perforation by starting with the following (Figs 3.3A and B): — Site, size and shape of perforation. — Dry and wet, single or multiple. — Margins of perforation. — Condition of rest of the tympanic membrane for the presence of any retraction, bulge, congestion, or tymp- anosclerotic patches. Fig. 3.1: Examination of ear without speculum Fig. 3.2: Examination of ear with speculum Fig. 3.3A: Different sites and types of central perforations Fig. 3.3B: Different types of unsafe perfo- rations: i) marginal ii) attic perforation
  42. 42. 26 Textbook of Ear, Nose and Throat Section1 Fig. 3.4: Examination of ear with Siegle’s speculum — Granulation tissue, cholesteatoma flakes or polypi. — Condition of ossicles, promontory, E. tube opening and round window niche if seen through a large perforation. — Mobility with Siegle’s speculum (in case of large perforation, there is no mobility of TM) (Fig. 3.4). • Examination of E. tube patency: Besides a bedside test of putting some ear drops, such as chloromycetin in the ear and feeling its bitter taste in the mouth or some dye likewise, other tests are: 1. Valsalva’s manoeuvre 2. E. tube catheterisation 3. Politzer’s method. Politzer’s bag with nozzle is inserted into one nostril and both nostrils are compressed. The patient takes a sip of water in his mouth and is asked to swallow. As he swallows, the bag is pressed and air enters the middle ear with a feeling of propping up sensation. • Examination of facial nerve: It is also important. If it is involved, describe the various effects on face, such as wrinkling of forehead, closure of eyes, creases on the nose, deviation of angle of mouth, blowing or whistling from the mouth and watering from eyes, and taste sensation of anterior two-thirds of the tongue. INVESTIGATIONS IN EAR CASE 1. Blood for Hb, BT, and CT. 2. Urine for sugar, albumin and pus cells. 3. Culture and sensitivity of ear discharge. 4. Pure tone audiometry (PTA). 5. Radiological assessment: — X-ray paranasal sinus (PNS) occipito- mental view. — X-ray both mastoids lateral oblique view. — CT scan in case of suspected compli- cations. X-ray PNS: To rule out any causative factor for chronic suppurative otitis media (CSOM) (safe or unsafe type). X-ray both mastoids: It is taken to compare the cellularity pattern of diseased and undiseased mastoid with each other. It also indicates any sclerosis, cavitation, erosion and position of sigmoid sinus and dura mater for keeping in mind while doing surgical exploration. CT scan: If facility is available, it will confirm the findings of simple X-ray. Besides, any complication of CSOM, such as sinus thrombosis, brain abscess, facial nerve involvement, condition of ossicles, etc. will be clearly demonstrated on CT scan.
  43. 43. History Taking and Physical Examination of Ear 27 Section1 KEY POINTS 1. Blood-stained discharge may be due to granulations, polypoidal masses, macerations during cleaning, in malignancy or in malignant otitis externa. 2. Foul-smelling discharge is due to saprophytic bacteria and osteitis caused by cholesteatoma, indicating unsafe pathology. 3. Constant pain, swelling, vertigo, and facial nerve palsy always point towards complications following atticoantral pathology. 4. Remember, there is no perforation in secretory or adhesive otitis media. Perforation indicates CSOM. 5. X-ray both mastoids (lateral oblique view) is done in CSOM to see and compare cellularity pattern of both mastoids. It also gives information about the presence of sclerosis, cavitation, erosion of bone and position of sigmoid sinus and dura which are important during mastoid exploration. 6. CT scan is important in cases with complications following CSOM. It tells us about the extent of cholesteatoma, bony erosion, condition of ossicles, facial nerve, sigmoid sinus and dura.
  44. 44. 28 Textbook of Ear, Nose and Throat Section1 Functional Assessment of Hearing and Vestibular Function Tests CHAPTER 4 TESTS OF HEARING It is important to measure the degree, type of hearing loss, site of hearing loss and its impact on speech development and rehabili- tation. The tests of hearing should be preferably done in a sound-proof room. Various tests are as follows: Whisper and Conversation Tests The drawback with this test is lack of standardisation. Normally, whisper should be heard up to 12 feet and conversational voice up to 20-40 feet. Whisper is given with the residual air after full expiration. If the patient has 30 dB loss, the whisper will be heard at 3’ distance; while if it is 60 dB loss, then conversation will be heard at 3’ only. Tuning Fork Tests These tests are qualitative tests as these indicate the type of hearing loss. Tests are done with various tuning forks, but 512 Hz is the most commonly used as it has longer tone decay and sound is quite distinct from ambient noise. The tuning fork should be held firmly by the stem and struck lightly against resilient surface such as elbow, heel of the hand, or the padded edge of a table. Forceful striking should be avoided as it produces the overtones. Air conduction (AC) is tested by placing the tuning fork 1 /2-1 inch in front of external acoustic meatus and this test indicates the integrity of tympano-ossicular chain. Bone conduction (BC) is tested by placing the base of tuning fork on mastoid bone or on the forehead. Bone conduction signifies sound conduction through cochlea, auditory nerve and its central connections and hence providing information about the integrity of inner ear. Sound through bone conduction is transmitted by vibration of skull bones or through one’s own voice or sound in the atmosphere (ambient noise). Types of Vibration Two different types of vibration occur, i.e. a. Inertial type (below 800) when skull vibrates as one unit and lagging behind of ossicles, mandible and cochlear fluid occurs due to inertia.
  45. 45. Functional Assessment of Hearing and Vestibular Function Tests 29 Section1 b. Compression type (for frequency above 800) in this the vibrations act on the fluids of inner ear and cause its movements. VARIOUS TUNING FORK TESTS Rinne Test In this test, AC is compared with BC of the patient (Figs 4.1A and B). Tuning fork is struck and placed in front of external auditory meatus. When he stops hearing, move it on to the mastoid bone and ask the patient if he still hears and then reverse the process. The object is to find out whether the patient hears longer by air or bone conduction. Rinne test will be negative in conductive deafness of more than 15 dB (Figs 4.2A to C). Interpretation is as follows: — Normally, AC is 2 times better than BC (+ve Rinne). — Conductive deafness BC > AC (–ve Rinne). — Sensorineural (SN) deafness AC > BC [duration is reduced] (low +ve Rinne). — Severe unilateral SN deafness BC > AC [due to transcranial transmission of sounds to the normal ear] (false –ve Rinne) (Fig. 4.3). Weber’s Test In this test, the vibrating tuning fork is placed in the middle of forehead and the patient is asked about the lateralisation of sound to left or right ear or in which ear the sound is heard better (Fig. 4.4). It is a very sensitive test and even less than 5dB difference in 2 ears’ hearing level will be indicated by this test. Conductive deafness—the sound is laterali- sed to deaf ear and in bilateral conductive loss to the more deaf ear or it is centrally heard if both ears are equally deaf. It is because ambient noise does not disturb the diseased ear as much as the normal ear. In sensorineural hearing loss (SNHL), sound is lateralised to better hearing ear or is heard centrally if both ears are equally bad. In normal ear, no lateralisation of sound occurs. If the test is false -ve Rinne, then Weber’s is done and if lateralisation occurs to the healthy side, it indicates severe SNHL. Fig. 4.1B: Rinne’s tuning fork test— bone conduction Fig. 4.1A: Rinne’s tuning fork test— air conduction
  46. 46. 30 Textbook of Ear, Nose and Throat Section1 Absolute Bone Conduction (ABC) Test It is an improved version of Schwabach’s test which is not used much these days. In this test, bone conduction of the patient is tested after occluding the external auditory meatus and then compared with the BC of the examiner if he has a normal hearing. Conclusion If both the patient and examiner hear equally—ABC normal—normal or conduc- tive deafness. If patient ceases to hear before exami- ner—ABC is reduced—SNHL. Fig. 4.2A: Rinne’s test in a normal person Fig. 4.2B: Rinne’s test with conductive hearing loss Fig. 4.2C: Rinne’s test with perceptive hearing loss Fig. 4.3: Rinne’s test showing false negative Rinne Fig. 4.4: Weber’s test
  47. 47. Functional Assessment of Hearing and Vestibular Function Tests 31 Section1 Schwabach’s Test Bone conduction (BC) of the patient and examiner is compared, but the meatus is not occluded. Remember — Schwabach is shortened in SNHL (SSS). — Schwabach is lengthened in conductive hearing loss. Gelle’s Test This test is done to confirm the presence of otospongiosis. In this test, BC is tested and at the same time Siegle’s speculum comp- resses the air in the meatus. If hearing is reduced, it is normal; but in stapes fixation, bone conduction sound is not affected. Other Tuning Fork Tests They are: — Stenger’s test — Teel’s test — Lombard’s test These tests are done for those patients who feign deafness but actually are normal subjects. SPECIAL TESTS OF HEARING • Subjective where response depends upon the patients. • Objective where response is automatically recorded. Pure Tone Audiometry It is a reliable method of testing the hearing acuity and gives information about the quantity and quality of hearing loss (Fig. 4.5). In this test, pure tones are given at various frequencies by increasing the intensity at 5 dB steps; and when the patient just hears the sound, it is recorded. Hearing threshold at both air and bone are tested at different frequencies and a graph called audiogram is plotted (Figs 4.6A to D). Frequencies between 500 Hz and 3000 Hz are important as these are the speech frequencies. Signs used are: O AC right ear X AC left ear > BC right ear < BC left ear In normal persons, both hearing thre- shold values with air and bone remain between 0 and10 dB (graph A). Conductive deafness is shown by bone-air gap which means a patient can hear by bone under 10-20 dB; while with air, hearing is usually much below depending upon the severity (graph B). Bone dip at 2 kHz is seen in otospongiosis in some cases (33%) called Carhart’s notch and it may be because the middle ear contribution to bone conduction is reduced by the mass of focus on the footplate. In SNHL, both bone and air conduction values drop down and may even overlap each other (graph C). If these both values drop but air-bone gap still persists, it may be indicative of mixed hearing loss (graph D). In acoustic trauma, there is a sudden dip at 4000 Hz both in air and bone values. In Fig. 4.5: Photograph while performing audiometry
  48. 48. 32 Textbook of Ear, Nose and Throat Section1 Fig. 4.6A: Normal audiogram Fig. 4.6B: Audiogram showing conductive hearing loss Fig. 4.6C: Audiogram showing sensorineural hearing loss
  49. 49. Functional Assessment of Hearing and Vestibular Function Tests 33 Section1 normal persons, hearing threshold values both with bone and air remain between 0 and10 dB. Speech Audiometry In this audiometry, recorded spondee words are presented to the ear at various sound pressures. The patient is asked to write the words and which are then cross checked with the list. Speech Reception Threshold (SRT) SRT of a person is the minimum intensity level (in dB) at which 50% of the spondee words can be repeated correctly. Spondee words are 2 syllable words such as black night, football, daydream, sunlight or 5 × 2. Generally, SRT is ± 10 dB of average of 3 speech frequencies. Speech Discrimination Score (SDS) or Optimum Discrimination Score (ODS) It is the maximum percentage of correct score when phonetically balanced single syllable words such as pin, day, bus, fun, and rum are used. Results a. In normal subjects or conductive HL, SDS is 95 to 100%. b. In cochlear lesion, SDS is low. c. In retrocochlear lesions, SDS is very poor and roll over phenomenon is present (which means with increase of intensity, drop of score occurs). As poor discrimination score of less than 80% affects the ability to understand speech, hence this test is useful to find out if hearing aid will be useful or not. Békésy Audiometry It is a device in which the patient himself presses or releases the button depending upon hearing or ceasing to hear pulsed or continuous tone. It is not used these days. Various types of graphs are recorded (Figs 4.7A to D). In type I seen in normal persons, both C and I tracings overlap in all frequen- cies. In type II seen in cochlear lesions, I and C tracings overlap up to 1000 Hz after which C tracings drop down by about 15 to 20 dB. In type III seen in retrocochlear lesions, C tracings drop by more than 20 dB. In type IV, the two tracings never overlap and C tracings are weak. In type V seen in malin- gerers, two tracings are widely separated from each other and C tracings are better than I tracings. Tests for Recruitment Recruitment is an abnormally rapid increase in loudness with increasing sound intensity. Fig. 4.6D: Audiogram showing mixed hearing loss
  50. 50. 34 Textbook of Ear, Nose and Throat Section1 Type I tracing seen in normal persons Type II tracing seen in cochlear lesions Type III tracing seen in retrocochlear lesions Type IV tracing seen in acoustic nerve lesions Fig. 4.7: Various tracings in Bekesy audiometry Ear which does not hear low intensity sounds will hear greater intensity sounds as loud or even louder than normal ear. This phenomenon of recruitment is seen in cochlear type of SNHL, i.e. Ménière’s disease and presbycusis. In normal and
  51. 51. Functional Assessment of Hearing and Vestibular Function Tests 35 Section1 conductive hearing loss, the test is nega- tive. ABLB Test of Fowler It is also called alternate binaural loudness balance (ABLB) test (Fig. 4.8). In this test, a tone is played alternatively into normal and deaf ear, the intensity is gradually increased in the affected ear until the sound is heard equally in both ears. In positive recruitment, ladder pattern becomes horizontal at higher intensity. Short Increment Sensitivity Index (SISI) Test In this test, the ability to recognise short increase of 1 dB every 5 sec is recorded at 20 dB above threshold levels. A score above 60% indicates cochlear lesion. A score of 15% is seen in retrocochlear or conductive HL. Tone Decay Test (or nerve fatigue test) A continuous tone 5 dB above threshold in 500 and 2000 Hz is given to the ear and the person should be able to hear it for 60 sec. The result is expressed as dB by which intensity has to be increased so that the patient can hear the sound for 60 sec. If tone decay of more than 30 dB or more is seen, it points towards retrocochlear lesion, i.e. acoustic neuroma. Impedance Audiometry It consists of a probe fitted into external auditory meatus connected to an oscillator which gives sound at 220 Hz, an air pressure pump which is used to alter the pressure in the meatus and a microphone (Fig. 4.9). Thus, we can measure the resistance of TM and middle ear and also compliance of TM and ossicular chain to sound pressure transmission. Tympanogram is the graphic representation of compliance and impedance of tympano-ossicular system with air pressure changes. Besides, it also measures acoustic reflex. Four types of graphs are obtained (Fig. 4.10): Fig. 4.8: Alternate binaural loudness balance test (Fowler’s) Fig. 4.9: Principle of impedance audiometry
  52. 52. 36 Textbook of Ear, Nose and Throat Section1 A—Normal B—Flat or dome-shaped audiogram (middle ear fluid) C—Maximum compliance at -100mm of H2O (E. tube dysfunction) Ad—Increased compliance at ambient pressure (ossicular disruption) Fig. 4.10: Tympanograms • Type A: Normal graph with compliance of 1.6 cc while in otosclerosis compliance is less than normal (0.25 cc) (As type). • Type B: Flat or dome-shaped curve, no change in compliance with pres- sure changes. It is seen in secre- tory otitis media or thick TM.
  53. 53. Functional Assessment of Hearing and Vestibular Function Tests 37 Section1 • Type C: Maximum compliance at –ve pressure and is seen in E. tube dysfunction or retracted TM. • Type D: There is increased compliance at normal pressure and is seen in ossicular chain disruption, lax or thin TM. Stapedial Reflex or Acoustic Reflex In impedance audiometry, if the other ear is presented with a sound of 80 to 90 dB above threshold level, acoustic reflex due to stimu- lation of stapedius muscle can be elicited because contraction of stapedius muscle causes stiffness of ossicular chain. The reflex is elicited due to integrity of VIIIth and VIIth nerve. Stapedial reflex helps in: — Estimation of hearing acuity. — Localisation of lesion of VIIth nerve and progress of recovery. — Demonstration of recruitment if stapedial reflex is elicited at 40 dB or so instead of 70 dB. — In malingerers. — Hearing acuity in infants and children. Evoked Response Audiometry It is the latest development in which the diagnosis of cochlear and retrocochlear pathology can be detected without the active cooperation of the patient since it is an objective test. It can be done in all age groups including infants and children. It has the following types: • Brainstem evoked response audiometry (BSERA) (Fig. 4.11): It records electrical responses originating from cochlear nuclei and its central connections in the brainstem. Five type of waves (I-V) can be recorded, Ist, IIIrd and Vth wave are prominent and important waves. Remember, ECOLI for origin of waves; Istwave arises from eighth nerve, IInd wave from cochlear nucleus, IIIrd wave from olivary nucleus, IVth from lateral leminiscus and Vth from inferior colliculus (Fig. 4.12). This audiometry is very useful in children, CP angle tumours and even malingerers. It is important to record latency, interwave latency and ampli- tude of waves. • Cortical evoked response audiometry (CERA): It records electrical responses arising from cerebral cortex. • Electrocochleography: In this, we place the electrode on the promontory through T. membrane and record coch- Fig. 4.11: Photograph while performing BERA Fig. 4.12: Various waves seen in brainstem evoked response audiometry (BSERA)
  54. 54. 38 Textbook of Ear, Nose and Throat Section1 lear, summating and action potentials of cochlea and its connections. • Psychogalvanic skin response audiometry: It is not used and so is not popular. VESTIBULAR FUNCTION TESTS Derangement of vestibular system is indica- ted by vertigo and nystagmus which is defined as involuntary, rhythmical, oscilla- tory movements of eyes away from the direction of gaze. Nystagmus of vestibular origin has 2 components, i.e. slow component and quick (fast) component and by convention nys- tagmus is named after quick component. Quick component of nystagmus is elimina- ted when the patient is put under anaes- thesia. Types of Nystagmus Central It is coarse, irregular and does not fatigue. Vertigo is usually not present. Symptoms and signs of intracranial disease are present. Ocular It is of congenital type and is pendular. Paralysis of external rectus may simulate nystagmus. Vestibular It is rhythmic, has a slow and fast compo- nent, fatigues easily, vertigo is present, duration is of less than 1 minute and latency is 2 to 20 sec. It can be spontaneous, posi- tional or induced. Spontaneous nystagmus It is either horizon- tal, rotatory or mixed type and does not last for more than 3 wk. and vertigo is also present. — First degree is a weak nystagmus and it is present when the patient looks in the direction of quick component. — Second degree nystagmus appears when the patient is looking straight ahead. — Third degree nystagmus (severe) appears when the patient is looking towards slow component. Positional nystagmus It appears and reappears when the head is put in the same position. Vertigo is not much and it may be because of vestibular or central causes. A nystagmus which is fatigueable and short lasting is usually of peripheral origin and the one not fatigueable and with changing direction is of central type. Induced nystagmus This type of nystagmus can be induced by rotation in a chair, thermal stimuli (caloric test) or by visual stimulation such as looking at a series of objects moving from one side to other. Table 4.1: D/D of peripheral and central vertigo Peripheral Central lesion lesion 1. Latency 2-20 seconds No latency 2. Duration Less than one More than minute one minute 3. Direction of Direction fixed Direction nystagmus towards the changing undermost ear and irregular and is regular 4. Fatigue Present Not fatigueable 5. Vertigo Severe degree None or slight degree 6. Eyes closure Not abolished Abolished by by eyes closure eyes closure
  55. 55. Functional Assessment of Hearing and Vestibular Function Tests 39 Section1 VARIOUS TESTS Galvanic Stimulation Test In this test a person stands with arms outstretched and feet together. Current of 1 mA is passed to one ear. A normal person sways to the side of current passed. This test helps to differentiate between end organ and vestibular nerve lesions. Barany’s Rotational Test Subject is rotated 10 times in 20 sec and postrotatory nystagmus is measured. Main objection of this test is excessive stimulation which may damage the cupula and, there- fore, cupulometry has been designed. Caloric Test Fitzgerald and Hallpike Technique The patient lies in a supine position looking at the roof with head flexed 30o forwards to make the lateral SCC vertical. External canal of ear is irrigated with 30o C or 44o C (7o above and below normal body temperature). In a healthy person, the patient has a feeling of vertigo and nystagmus appears. The res- ponse is measured in seconds between start of irrigation and cessation of nystagmus. About 5 minutes gap is given between cold and hot caloric test. Result is recorded in a calorigram (Fig. 4.13). Main advantage of caloric test is that each labyrinth can be tested separately. Frenzel’s glasses (+20 D) is used to high- light the nystagmus. Remember, COWS meaning cold to opposite and warm to the same side. Normal Nystagmus lasts for 2 to 3 minutes and response of cold is to the opposite side and warm to the same side (COWS). Canal paresis In this, the duration of nystagmus is reduced for both hot and cold left hot and left cold (Fig. 4.13) and is seen in peripheral vestibular lesions. Directional preponderance It is seen in both peripheral and central lesions, and in this, the response is greater in one direction both for hot and cold caloric testing (left hot and right cold). Dundas Grant Method of Cold Air Test If the drum is perforated or in mastoid operations or fenestration, normal caloric test cannot be done, hence, cold air jet is given by spraying ethyl chloride spray on the tube. If no nystagmus is seen in 30 to 60 sec, it indicates inactive labyrinth. Kobrak’s Cold Caloric Test It is a rough office test in which 5 ml of ice cold water is put for 30 sec in the ear canal. If no response, 10 ml or 20 ml of water is irrigated. If there is still no response, the labyrinth is considered dead. Fistula Test In this test, if air is compressed in external auditory canal by pressing the tragus or through Siegle’s speculum, it will produce stimulation of lateral SCC due to its erosion by some pathology. Fistula test is positive if there appears nystagmus to same side and a feeling of vertigo. • Positive fistula test indicates fistulous communication between middle ear and labyrinth. • False +ve fistula test also called Hennebert’s sign is a positive fistula test without any fistula in the labyrinth. It is seen in 20% patients in late congenital syphilis and is considered to be due to
  56. 56. 40 Textbook of Ear, Nose and Throat Section1 Fig. 4.13: Calorigram abnormally mobile footplate of stapes or erosion of bony labyrinth. • Negative fistula test indicates either there is no fistula or if fistula is present, then the labyrinth is dead (False –ve fistula). Romberg’s Test The patient is made to stand erect with eyes closed and direction of falling or swaying is noted. In this test, the patient tends to fall towards the direction of slow component of
  57. 57. Functional Assessment of Hearing and Vestibular Function Tests 41 Section1 nystagmus in peripheral lesions and towards the fast component of nystagmus in central lesions. In sharpened Romberg’s test, heel is in front of toes and arms are on the chest. Electronystagmography (ENG) In this test, the eye movements are graphi- cally recorded. Electrode is placed on the outer canthus of one eye and other electrode on the frontal region, potential difference is thus picked up between cornea and retina and thus the movements of eyes are recorded. In ENG, irrigation is done for 30 sec and eyes are closed or the room is darkened. The Fig. 4.14: Electronystagmography (ENG) graph is recorded and steeper the angle of slow phase greater is the nystagmus (Fig. 4.14). ENG shows: • Spontaneous nystagmus. • Whether the lesion is central or peri- pheral. In central lesion nystagmus is irregular and is abolished by eyes closure. In peripheral lesions nystagmus is regular and not abolished by eyes closure (Table 4.1). • It provides documentary evidence of nystagmus and also nystagmus of first degree is easily seen. Optokinetic Nystagmus In this test black strips pasted on white drum are rotated in both directions and nystagmus is recorded. A central lesion will show an asymmetrical response. KEY POINTS 1. 512 Hz Tuning Fork is preferred because it has a longer tone decay and the sound is quite distinct from ambient noise. 2. False –ve Rinne is seen in unilateral severe sensorineural deafness and Weber’s test decides the issue. 3. Carhart’s notch seen as a dip in bone conduction at 2 kHz is due to mass effect of focus on foot- plate of stapes thus reducing bone conduction. 4. Normal speech reception threshold is ± 10 dB of average of 3 speech frequencies while SDS (%) is 95 to 100%. 5. Recruitment is seen in cochlear type of deafness such as Ménière’s disease and presbycusis. 6. In retrocochlear lesions low SISI score (15%) and tone decay (positive) of more than 30 dB is seen. 7. Stapedial reflex is due to integrity of VIIIth nerve and VIIth nerve. 8. For origin of waves 1-5 in BERA remember ECOLI • E Wave I — Eighth nerve • C Wave II — Cochlear nucleus • O Wave III — Olivary nucleus • L Wave IV — Lateral leminiscus • I Wave V — Inferior colliculus
  58. 58. 42 Textbook of Ear, Nose and Throat Section1 9. In caloric test—lateral SCC is stimulated: — Canal paresis means reduced response both by hot and cold — Directional preponderance, in this the response is greater in one direction both for hot and cold (left hot and right cold). 10. Hennebert’s sign indicates false +ve fistula test seen in late congenital syphilis due to abnormal mobility of footplate of stapes.
  59. 59. Diseases of External Ear 43 Section1 Diseases of External Ear CHAPTER 5 CLASSIFICATION Diseases of external ear may be classified into the following. Congenital Conditions These deformities occur because of genetic defect, from a virus or toxic effect of drugs during pregnancy. Since the time of deve- lopment of external, middle and inner ear vary, the deformities of one part may not be associated with congenital deformity of others. Preauricular Sinus These are blind tracks in front of ear lined by squamous epithelium and occur due to incomplete fusion of tubercles during deve- lopment of external ear (Fig. 5.1). These cause symptoms only when infected, i.e. pain, increase in temperature, swelling and dis- charge. Treatment: After treating the acute symptoms, the track is outlined by a dye and is excised. The healing is by secondary intention and scar formation. Congenital Swellings of Pinna Dermoid, haemangiomas and lymphangio- mas may occur in relation to pinna and treatment is by excision. Collaural Fistula It is an anomaly of first branchial cleft. In this, there is one opening in the floor of external auditory meatus and another behind the angle of mandible close to anterior border of sternocleidomastoid. Tract of fis- Fig. 5.1: Preauricular sinus
  60. 60. 44 Textbook of Ear, Nose and Throat Section1 tula passes through parotid in close proxi- mity to the facial nerve. Treatment is excision of the tract. Congenital Anomalies of Pinna • Anotia is complete absence of pinna and is treated by plastic reconstruction or prosthesis (Fig. 5.2A). • Microtia is very small deformed pinna and may be associated with other ano- malies of ear (Fig. 5.2B). • Melotia is displacement of pinna caudo- ventrally. • Polyotia means that there are multiple tags of skin and cartilage around the pinna and can be seen on a line drawn from tragus to the angle of mouth (Fig. 5.3A). • Bat ears are abnormal anteriorly placed pinna and are best treated by surgery at 6 years of age (Fig. 5.3B). • Lop ear is a severe variant of bat ear. • Wildermuth’s ear (Mozart’s ear)—here the antihelix is more prominent than helix, lobule may be absent or adherent to the skin of neck (Fig. 5.4). Fig. 5.2A: Anotia Fig. 5.2B: Microtia Fig. 5.3A: Accessory pinna (polyotia) Fig. 5.3B: Bat ear
  61. 61. Diseases of External Ear 45 Section1 • Darwin’s tubercle—it is a small elevation on the posterosuperior part of helix and is an inherited condition. Treacher-Collins Syndrome Also called mandibulofacial dysostosis. It is an autosomal dominant condition involving 1st and 2nd branchial arch. The following anomalies are presents: — Microtia with congenital atresia of external auditory canal. — Hypoplasia of mandible and middle third of face and malar prominence. — Antimongoloid palpebral fissures. — Notching of lower eyelid (coloboma) and atrophic lid margins. — Conductive type of deafness. Treatment is by plastic surgery recons- tructive procedures. Congenital Atresia of External Auditory Meatus The canal is canalised at 24th week of intra- uterine life and may be seen with normal middle and external ear because these develop in first trimester of pregnancy. It is due to the failure of canalisation of ectoder- mal core that fills the distal part of first branchial cleft. Outer meatus may be filled with fibrous tissue or bone (Fig. 5.6). Treatment is excision of the tissue and recanalisation with split skin graft. Congenital Tumours of External Auditory Meatus Such as haemangiomas or lymphangiomas may be seen although rarely. Treatment is excision of the tumour. Inflammatory Conditions of the Pinna Erysipelas Also called St. Anthony’s fire. It is a strep- tococcal haemolyticus infection of skin of pinna which produces raised red, oedema- Fig. 5.4: Absent lobule Fig. 5.5: Ornamental split ear Fig. 5.6: Stenosis of external auditory meatus
  62. 62. 46 Textbook of Ear, Nose and Throat Section1 tous eruptions with sharply defined edges associated with severe degree of malaise and temperature. It is treated by large doses of penicillin and anti-inflammatory drugs. Perichondritis It is inflammation of the perichondrium covering the cartilage of the pinna and may follow trauma leading to haematoma and infection or may also follow otitis externa or a furuncle of the pinna or follow operations such as cutting the cartilage in the presence of infection (Fig. 5.7). Signs/symptoms: There is uniform enlarge- ment of pinna, surface is red and shiny. There is severe pain along with constitutional disturbances such as fever, malaise, and body aches. Recurrent infection may result in cauliflower ear or Boxer’s ear. Treatment • Broad-spectrum antibiotics such as amoxycillin, ciprofloxacillin with or with- out tinidazole or inj. gentamicin 80 mg IM two times a day. • Anti-inflammatory drugs such as Brufen or Nimesulide. • Local application of magnesium sulphate dressing or ichthyol in glycerine. • Once abscess is formed I and D has to be done. Infective Conditions of External Auditory Meatus Furunculosis It is a staphylococcal infection of hair follicles which are present in cartilaginous part of the external auditory meatus. Clinical features • Severe pain spreading to jaw or head. • Swelling of canal. • Tragus sign +ve, i.e. tenderness on pres- sure of tragus. • Hearing is almost normal. • Examination shows swelling with a bursting point in the canal. • Tympanic membrane is normal. • Postauricular sulcus is obliterated if infection spreads posteriorly. • Regional lymph nodes are tender and enlarged. Treatment • In recurrent cases diabetes should be ruled out. • Antibiotics (broad spectrum). • Anti-inflammatory drugs. • Meatus is packed with a wick soaked in antibiotic steroid cream which acts as a splint and prevents movements of cartila- ginous part and also helps in relieving tension by counter pressure. • Hot fomentation locally is soothing. • Incision is usually not required. Otitis Externa It is a generalised infection of skin of the external auditory canal and may be acute or chronic (Fig. 5.8). Aetiology • Predisposing factors are hot and humid climate (Singapore ear). • Scratching with dirty nails or objects. Fig. 5.7: Perichondritis
  63. 63. Diseases of External Ear 47 Section1 • Bathing and swimming in dirty pools. • Allergic diathesis. • Excessive sweating changes pH of the canal from acid to alkaline which favours growth of organisms. Bacteriology • Staphylococci, Strept. haemolyticus, Ps. pyocyanea, B. proteus and E.coli. Clinical features • Pain or discomfort, tenderness, discharge which is serous with debris filled in canal. • No hearing loss usually. • Oedema, redness and tenderness on cir- cumduction sign, i.e. pinna when moved in all directions causes pain. Treatment Systemic antibiotics, anti-inflam- matory drugs, local treatment such as remo- val of debris and wick soaked in antibiotic steroid cream, avoidance of any predisposing factors. Malignant Otitis Externa or Necrotising Otitis Externa It was described by Meltzer and Kelemen in 1959. It is a fulminating severe form of otitis externa caused by pseudomonas seen in elderly diabetic patients. It may also be seen in those patients who are on immunosuppressive drugs like azathioprine, methotrexate, cyclophospha- mide and cyclosporine. Patients using steroids or having hypo- gammaglobulinaemia may also be affected by this disease. Clinical features It is called malignant as it behaves like a malignant process by causing destruction of tissues of canal, pre- and post- auricular region by various enzymes such as lecithinase and haemolysin. Facial nerve may also be paralysed. Severe pain is present (Fig. 5.9). Infection may spread to skull base and jugular foramen causing multiple cranial nerve palsies. Treatment • Heavy doses of antibiotics such as genta- micin/tobramycin/cefotaxime 1 gm I/V or I/M twice daily. • Local debridement of necrotic tissues and bone. • Control of diabetes is most important. Mortality is 67% in patients with facial Fig. 5.8: Otitis externa Fig. 5.9: Malignant otitis externa
  64. 64. 48 Textbook of Ear, Nose and Throat Section1 nerve palsy, while it is 80% in patients with multiple cranial nerve involvement. Otomycosis It is a fungal infection of external auditory canal usually caused by Aspergillus fumigatus, Asp. niger or Candida albicans. Wet blotting paper like debris in canal upon which myce- lia can be seen are the characteristics of otomycosis. Clinical features • Seen during hot and humid atmosphere. • Irritation, itching, dull pain and dis- charge. • Sense of blockade with mild conductive loss. Diagnosis It is confirmed by microscopic examination. Treatment • Keeping the ears dry. • Removal of fungal mass from canal. • Spirit cleaning 2 to 3 times. • Antifungal drops such as clotrimazole or 2% salicylic acid in alcohol. • Local application of gentian violet. • Use of amphotericin B is sometimes done in resistant cases. Viral Infections Herpes zoster oticus Also called Ramsay Hunt syndrome after it was described in 1907 by Hunt JR. In this disease, vesicles appear in or around the ear canal along with VIIth nerve weakness and pain in the area (Figs 5.10A and B). In its severe form, there may be SNHL and disturbed vestibular function and even signs and symptoms of viral encephalitis. Cranial nerves Vth, IXth and Xth may also be involved. It is caused by chickenpox virus Varicella which affects geniculate ganglion. Treatment: • Antibiotics to prevent secondary infec- tion. • Antiviral drugs such as acyclovir in the form of tablets (800 mg 4-5 times a day) and cream. • Anti-inflammatory drugs. • Corticosteroids in the form of tablets and local cream. Figs 5.10A and B: Ramsay Hunt syndrome (A) showing vesicles, and (B) showing facial palsy in the same patient
  65. 65. Diseases of External Ear 49 Section1 • Facial nerve palsy is managed in the usual way. Bullous myringitis haemorrhagica It is a viral infection seen during influenza epidemics and is characterised by severe earache with a few constitutional symptoms. On exami- nation, haemorrhagic blebs are seen on drum and sometimes in the canal wall. Mild conductive hearing loss may be seen. It should be differentiated from acute otitis media which shows marked systemic features. It is treated by analgesics, antibiotics and local steroids drops. Reactive Conditions Eczematous Otitis Externa It is allergic dermatitis of external ear which may be due to jewellery, cosmetics or use of antibiotics or chemicals. There is present lot of irritation, oedema, swelling and scaling and even stenosis of canal may be present. Treatment is by avoiding the irritating factors, use of antihistaminics with steroid cream and prophylactic antibiotics. Neurodermatitis It is compulsory itching due to psychological factors and is treated by psychotherapy and bandage to ear to avoid compulsive itching. Seborrhoeic Otitis Externa It is scaly dermatitis of external auditory canal which is associated with seborrhoeic capitis and is treated by treating the scalp condition. Traumatic Conditions Haematoma of Pinna It is usually seen in fights where due to trauma a fluctuant swelling appears under the skin. Usually, there are no constitutional symptoms unless infections supervenes. Its persistence deprives blood supply to perichondrium, leading to infection and necrosis. Treatment is by incision and drainage and with antibiotics to prevent secondary infection. Frost Bite It is commonly seen in extremely cold weather and best treatment is prevention besides the role of vasodilators, rewarming at 38o to 42o C, the application of 0.5% silver nitrate and systemic antibiotics. Pseudocyst Pinna A soft cystic swelling appears on the pinna beneath the skin and is usually because of trauma. Treatment is aspiration or incision and drainage under aseptic conditions. Tumours of External Ear Benign Exostosis These occur in bony meatus and are usually multiple, while osteomas are single and occur at the junction of bony and cartilaginous meatus. So exostosis is a bony outgrowth from bony meatus which may be single pedunculated or multiple of sessile type. It may be bilateral. Aetiology is not known but may be due to cold water bathing. Clinical features: Asymptomatic when small but if large may occlude the meatus causing irritation and deafness. Treatment: No treatment if asymptomatic but if large, electric drill is used to remove it avoiding injury to VIIth nerve.