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Cochlear implant imaging

1. Pre-operative imaging such as HRCT and MRI are important for cochlear implantation to evaluate anatomical variations and identify any contraindications. 2. Key factors assessed on imaging include the size of the internal auditory meatus, status of the cochlear nerve, and presence of any neurovascular anomalies which could increase surgical risk. 3. Congenital anomalies of the bony labyrinth or membranous structures detected on pre-operative imaging may influence the surgical approach and expectations of device insertion and outcome.

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BMCH, Chitradurga Imaging Requirements for Cochlear Implantation Dr. Prahlada N.B MBBS, MS, MBA, MHA ENT, HEAD – NECK & SKULL BASE SURGERY Basaveshwara Medical College & Hospital Chitradurga
10-04-2017 210-04-2017 2BMCH, Chitradurga • Determine patients with Contraindications for CI • Determine the approach • As a guide during surgery Why Imaging? Objectives
10-04-2017 310-04-2017 3BMCH, Chitradurga • HRCT temporal bone. • MRI What type of Imaging Protocol
10-04-2017 410-04-2017 4BMCH, Chitradurga • Evaluates the status of – Mastoid pneumatisation – Thickness of the cortical bone – Middle ear aeration – The round window niche Role of HRCT Protocol
10-04-2017 510-04-2017 5BMCH, Chitradurga • It may display anatomic middle ear variations of surgical importance such as: – Dehiscent facial nerve – Low lying dura – High jugular bulb and – Aberrant carotid artery Role of HRCT Protocol
10-04-2017 610-04-2017 6BMCH, Chitradurga • CT demonstrates anomalies of the bony labyrinth such as – Paget’s disease – Otosclerosis – Postmeningitis stenosis of the round window niche. Role of HRCT Protocol
10-04-2017 710-04-2017 7BMCH, Chitradurga • HRCT scans are performed on a 64- slice volume scanner in a straight axial plane: kV: 140, mA: 350, matrix: 512 × 512 • Slice thickness: 0.625 mm/10.63, 0.531:1 • Scan field of view (FOV): 32 cm, display FOV: 9.6 cm HRCT Protocol
10-04-2017 810-04-2017 8BMCH, Chitradurga • The original isometric volume data is used to obtain Coronal reformatted images. • The images are reviewed with a high- resolution bone algorithm, using a small FOV for separate right and left ear documentation. HRCT Protocol
10-04-2017 910-04-2017 9BMCH, Chitradurga • Coronal reformations along with 3D maximum intensity projection (MIP) reconstructions. HRCT Protocol
10-04-2017 1010-04-2017 10BMCH, Chitradurga • To identify active fibrosis • Identify cochlear fluid fibrosis • To depict cochlear nerve agenesis and cochlear anomalies • To detect an occult acoustic nerve tumour • To detect brainstem anomalies – Trauma, Congenital. Role of preoperative MRI Protocol
10-04-2017 1110-04-2017 11BMCH, Chitradurga • MRI scans are performed on 1.5-T MR with an 8-channel head coil. • Sedation is used in most patients. • A 3D-FIESTA (fast imaging enabling steady-state acquisition) axial sequence (TR: 5.5, TE: 1.7/Fr, FOV: 16 × 16, slice thickness: 1.0/−0.5, matrix: 320 × 320, NEX: 6.0) is performed MRI Protocol
10-04-2017 1210-04-2017 12BMCH, Chitradurga • A 3D-FIESTA sequence is also acquired in a DIRECT OBLIQUE SAGGITTAL PLANE (TR: 6.7, TE: 2.1/Fr, FOV: 12 × 12, slice thickness: 1.0/−0.5, matrix: 384 × 320, NEX: 6.0) perpendicular to the VII–VIII nerve complexes. MRI Protocol
BMCH, Chitradurga MRI Direct Oblique Saggittal View Cadaver Dissection showing Direct Oblique Sagittal View.
BMCH, Chitradurga MRI Direct Oblique Saggittal View
BMCH, Chitradurga MRI - Constructive Interference Steady State (CISS) Science Photo library Advantage : Combination of high signal levels and extremely high spatial resolution.
10-04-2017 1610-04-2017 16BMCH, Chitradurga • Provides better resolution than with reformations from an axial sequence; Provides better delineation of the nerves . • A routine T2W axial sequence through the brain is obtained in all patients. MRI Protocol
10-04-2017 1710-04-2017 17BMCH, Chitradurga • Advantages of MRI over CT: – Distinguish between cochlear fibrosis and ossification – Diagnose cochlear nerve agenesis. – MRI may depict unsuspected acoustic nerve or central acoustic pathway anomalies including acoustic nerve tumours. HRCT Vs MRI Protocol
10-04-2017 1810-04-2017 18BMCH, Chitradurga • Disadvantages of MRI – Additive cost as MRI does not replace CT. – Good quality MR images in deaf patients are more difficult to obtain, as difficulties of communication may lead to movement artefacts. – Sedation is needed in children. HRCT Vs MRI Protocol
BMCH, Chitradurga NORMAL ANATOMY - HRCT Imaging requirements for Cochlear Implantation
BMCH, Chitradurga Frontal Medial Occipital Lateral 1. Temporomandibular joint (glenoid roof and articular disc) 2. Pharyngotympanic tube (auditory tube) 3. Internal carotid artery 4. External acoustic meatus 5. Facial canal 6. Internal jugular vein 7. Mastoid process 8. Sigmoid sinus 9 Carotid canal 10. Malleus (handle) 11. Tensor tympani muscle (canal) 12. Middle ear 13. Incus (long limb) 14. Cochlea (basal turn) 15 Sinus tympani 16 Vestibular aqueduct 17 Round window
BMCH, Chitradurga Frontal Medial Occipital Lateral 1. Temporomandibular joint (glenoid roof and articular disc) 2. Pharyngotympanic tube (auditory tube) 3. Internal carotid artery 4. External acoustic meatus 5. Facial canal 6. Internal jugular vein 7. Mastoid process 8. Sigmoid sinus 9 Carotid canal 10. Malleus (handle) 11. Tensor tympani muscle (canal) 12. Middle ear 13. Incus (long limb) 14. Cochlea (basal turn) 15 Sinus tympani 16 Vestibular aqueduct 17 Round window
BMCH, Chitradurga 2 Malleus (handle) 3 Incus (long limb) 4 Cochlea 5 Stapes 6 Oval window 7 Sinus tympani 8 Facial canal 9 Internal jugular vein (bulb) 10 Mastoid 11 Epitympanic recess 12 Malleus (head) 13 Incus (short limb) 14 Internal acoustic meatus 15 Aditus to mastoid antrum 16 Vestibule 17 Posterior semicircular canal 18 Mastoid antrum 19 Lateral semicircular canal Frontal Medial Occipital Lateral
BMCH, Chitradurga 2 Malleus (handle) 3 Incus (long limb) 4 Cochlea 5 Stapes 6 Oval window 7 Sinus tympani 8 Facial canal 9 Internal jugular vein (bulb) 10 Mastoid 11 Epitympanic recess 12 Malleus (head) 13 Incus (short limb) 14 Internal acoustic meatus 15 Aditus to mastoid antrum 16 Vestibule 17 Posterior semicircular canal 18 Mastoid antrum 19 Lateral semicircular canal Frontal Medial Occipital Lateral
BMCH, Chitradurga 1 Geniculate ganglion 2 Facial nerve (first part) 3 Facial nerve (second part) 4 Internal acoustic meatus 5 Tympanic cavity 6 Vestibule 7 Posterior semicircular canal 8 Mastoid antrum 9 Lateral semicircular canal 10Sigmoid sinus 11 Anterior (superior) semicircular canal 12 Mastoid cells Frontal Medial Occipital Lateral
BMCH, Chitradurga Frontal Medial Occipital Lateral 1 Geniculate ganglion 2 Facial nerve (first part) 3 Facial nerve (second part) 4 Internal acoustic meatus 5 Tympanic cavity 6 Vestibule 7 Posterior semicircular canal 8 Mastoid antrum 9 Lateral semicircular canal 10 Sigmoid sinus 11 Anterior (superior) semicircular canal 12 Mastoid cells
BMCH, Chitradurga NORMAL ANATOMY - MRI Imaging requirements for Cochlear Implantation.
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BMCH, Chitradurga Inferior view of 3D maximum intensity projection (MIP) reconstructed from 3T MR. Note the cochlear nerve anteriorly and both saccular and posterior branches of the inferior vestibular nerves posteriorly. John I. Lane Robert J. Witte: The Temporal Bone, An Imaging Atlas
BMCH, Chitradurga Superior view of 3D MIP reconstructed from 3T MR. Note the facial nerve anteriorly and the superior vestibular nerve posteriorly John I. Lane Robert J. Witte: The Temporal Bone, An Imaging Atlas
BMCH, Chitradurga PRE-SURGICAL EVALUATION Imaging requirements for Cochlear Implantation
10-04-2017 3710-04-2017 37BMCH, Chitradurga • An IAM less than 2 mm in diameter increases the risk of a congenital absence or of severe hypoplasia of the acoustic nerve. • An absent or narrow modiolus (diameter less than 3 mm in CT, or a modiolar surface less than 4 mm2 in MR) are at risk of absence of cochlear nerve. • The modiolus is a bone area of low signal intensity in T2WI, located at the base of the cochlea. It represents the exit of the cochlear nerve. 1. Size of the IAM KeyPoints
10-04-2017 3810-04-2017 38BMCH, Chitradurga • Exploration of the IAM by MR with CISS sequence and sagittal reconstructions allows the measurement of the diameter of the cochlear nerve. • Cochlear nerve diameter is measured in relation to the facial nerve taken as reference. • Normally, the cochlear nerve lays on the inferior part of the IAM and • Cochlear nerve is larger than the facial nerve. • Its diameter is approximately of 0.4 mm. 3. Cochlear nerve status KeyPoints
BMCH, Chitradurga Modiolus The modiolus is a conical shaped central axis in the cochlea. It consists of spongy bone and the cochlea turns approximately 2.5 times around it. The spiral ganglion is situated inside it. Basic human anatomy - O'rahilly, Müller, Carpenter & Swenson
BMCH, Chitradurga Cochlear nerve deficiency C. Isolated Cochlea. D. Absent Cochlear Nerve. Christine M. Imaging Findings of Cochlear Nerve Deficiency. AJNR 2002 23: 635-643
BMCH, Chitradurga Absent Modiolus Axial section of the cochlea of a 4-year-old boy with Cornelia de Lange syndrome. Note the diminished width and height of cochlear upper turns with an absent modiolus in the section from the patient with Cornelia de Lange syndrome (A) as compared with a 2-year- old control with normal hearing (B). J. Kima: Temporal Bone CT Findings in Cornelia de Lange Syndrome. AJNR March 2008 29: 569-573
10-04-2017 4210-04-2017 42BMCH, Chitradurga • Anomaly of the course of the: • Facial nerve • The carotid artery • The sigmoid sinus • Venous variants such mastoid emissary veins 2. Neurovascular Anomaly KeyPoints
10-04-2017 4310-04-2017 43BMCH, Chitradurga • Facial nerve with an abnormal course through the mastoid cells is at significant risk during implantation. • Facial nerve injury can occur during – Facial recess approach. – Insertion of electrodes. • Facial nerve monitoring is an option. 2. Neurovascular Anomaly KeyPoints
10-04-2017 4410-04-2017 44BMCH, Chitradurga • Study: – The number of cochlear turns – Symmetry of scala chambers – Status of the modiolus – Status of the posterior membranous labyrinth. mbranous labyrinth anomaly KeyPoints
10-04-2017 4510-04-2017 45BMCH, Chitradurga • Congenital anomalies discovered during preoperative imaging studies can be the cause of the sensorineural hearing loss. • Can increase the surgical risk to have a `Gusher-ear' during the electrode insertion within the round window 4. Membranous labyrinth anomaly KeyPoints
10-04-2017 4610-04-2017 46BMCH, Chitradurga • Cochlear ossification or fibrosis may: – Limit the full insertion of the electrode array or – Modify the choice of the cochlear implant – Modify the way of Electrode insertion. ndo- and perilymphatic fluid Status KeyPoints
10-04-2017 4710-04-2017 47BMCH, Chitradurga • Stenosis of the round window niche may occur in bone remodelling lesions such as: – Paget’s disease – Otosclerosis – Lobstein disease – Post-meningitis labyrinthitis. Status of Bony Labyrinth & Round Window Niche KeyPoints
BMCH, Chitradurga Paget’s Disease Axial CT scan demonstrates diffuse expansion and sclerosis of the bones of the skull base, characteristic of Paget disease. S. Vattotha, et al. A Compartment-Based Approach for the Imaging Evaluation of Tinnitus. AJNR 2010 31: 211-218
BMCH, Chitradurga Otosclerosis Fenestral otosclerosis showing a fissula ad fenestram. Medical Observer. Australia
BMCH, Chitradurga Osteogenesis Imperfecta The labyrinthine segment, the geniculate ganglion (arrowheads), and the proximal tympanic segment of the facial nerve canal are severely involved and have indistinct, irregular margins. Progression of demineralization is also demonstrated in pericochlear areas Osteogenesis Imperfecta of the Temporal Bone: CT and MR Imaging in Van der Hoeve-de Kleyn Syndrome Hatem Alkadhi . AJNR 2004 25: 1106-1109
BMCH, Chitradurga Post-meningitis labyrinthitis. Axial CT scan showing advanced labyrinthitis ossificans in both ears. Vanessa Y.J. Tan et al: Acoustic brainstem implant in a post-meningitis deafened child—Lessons learned. International Journal of Pediatric Otorhinolaryngology Volume 76, Issue 2, February 2012, Pages 300–302
BMCH, Chitradurga CONGENITAL ANOMALIES Imaging requirements for Cochlear Implantation
10-04-2017 5310-04-2017 53BMCH, Chitradurga • Cochlear • Vestibular • Semicircular canal, • Internal auditory canal (IAC) • Vestibular and • Cochlear aqueduct malformations. Types of anomalies Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
10-04-2017 5410-04-2017 54BMCH, Chitradurga • Michel deformity • Common cavity deformity • Cochlear aplasia • Hypoplastic cochlea • Incomplete partition types – I (IP-I) and – II (IP-II) (Mondini deformity). Cochlear anomalies Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
10-04-2017 5510-04-2017 55BMCH, Chitradurga • Incomplete partition type I or Cystic cochleovestibular malformation: – Cochlea lacks the entire modiolus and cribriform area, resulting in a cystic appearance, and there is an accompanying large cystic vestibule. mplete partition of Cochlea Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
BMCH, Chitradurga Incomplete partition type I or Cystic cochleovestibular malformation Axial Section showing Cystic appearing Cochlear and Large cystic Vestibule. University of Washington Department of Radiology.
BMCH, Chitradurga Common cystic cavity University of Washington Department of Radiology.
BMCH, Chitradurga Incomplete partition - II Classic Mondini malformation University of Washington Department of Radiology.
BMCH, Chitradurga Incomplete partition - II Classic Mondini malformation University of Washington Department of Radiology.
BMCH, Chitradurga Incomplete partition variant Normal basal turn of the Cochlear and Round Window University of Washington Department of Radiology.
BMCH, Chitradurga Incomplete partition variant 1.5 Turns of Cochlear with Confluence of the middle and apex resulting in Cystic apex. Enlarged vestibule with nomral Vestibular aqueduct are seen. University of Washington Department of Radiology.
10-04-2017 6210-04-2017 62BMCH, Chitradurga • Incompelete Partition Type II or the Mondini deformity: – A cochlea consisting of 1.5 turns (in which the middle and apical turns coalesce to form a cystic apex accompanied by a dilated vestibule and enlarged vestibular aqueduct. mplete partition of Cochlea Classification
10-04-2017 6310-04-2017 63BMCH, Chitradurga • Michel deformity • Cochlear aplasia • Common cavity • Cochlear hypoplasia • IP-I (Cystic cochleovestibular malformation), • IP-II (Mondini deformity) Clinical Classification Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
10-04-2017 6410-04-2017 64BMCH, Chitradurga • Absent Cochlear nerve – Diameter of IAM (mid-part) <3 mm • Absent Cochlear • Absent Modiulus Contraindications for CI NotoCI
10-04-2017 6510-04-2017 65BMCH, Chitradurga • Cochlear ossification (partial or total; length in basal turn) • Hyperostosis of the round window niche • Persistent membranous labyrinth inflammation • Inner ear at risk of `Gusher': endolymphatic sac dilatation. Alternate Surgical Technique/Implant Device NotoCI
10-04-2017 6610-04-2017 66BMCH, Chitradurga • Abnormal cochlear segmentation. • Deficient modiolus. • Semicircular canal or vestibular dilatation. • Stenosis of the basal turn. • Otosclerosis foci. • Paget’s disease. Alternate Surgical Technique/Implant Device NotoCI
BMCH, Chitradurga Deficient Modiolus Axial T2-weighted FSE MR image of the right inner ear : The cochlear outline is distorted, and the normal notch between the middle and apical turns laterally (white arrow) is blunted. Note that the modiolus is deficient (black arrow). H. Christian Davidson: MR Evaluation of Vestibulocochlear Anomalies Associated with Large Endolymphatic Duct and Sac. AJNR 1999 20: 1435-1441 ,
BMCH, Chitradurga Deficient Modiolus Axial T2-weighted FSE MR image in another patient shows severe dysplasia. The cochlea (C) appears as a common cavity, the internal architecture is lost, and the modiolus is absent. The vestibule also shows severe dysplastic changes, including gross vestibular enlargement (V) and hypoplasia of the lateral semicircular canal (arrowhead). A portion of the enlarged endolymphatic duct is also apparent (asterisk). H. Christian Davidson: MR Evaluation of Vestibulocochlear Anomalies Associated with Large Endolymphatic Duct and Sac. AJNR 1999 20: 1435-1441 ,
BMCH, Chitradurga Otosclerosis of the Cochlea During surgery it was noted that otosclerosis had filled the basal turn of the cochlea and obliterated the round window. Eric W. Sargent M.D., OTOSCLEROSIS: A Review for Audiologists
BMCH, Chitradurga Stenosis of the Basal Turn of the Cochlear Small calcification in basal turn of cochlea as a result of labyrinthitis ossificans. Eric Beek and Frank Pameijer: Temporal Bone Pathology.
BMCH, Chitradurga Semicircular Canal dilatation There is a widening and shortening of the lateral semicircular canal. Eric Beek and Frank Pameijer: Temporal Bone Pathology.
BMCH, Chitradurga Vestibular dilatation The vestibule is relatively large (arrow). Eric Beek and Frank Pameijer: Temporal Bone Pathology.
10-04-2017 7310-04-2017 73BMCH, Chitradurga • Hypoplastic mastoid process • Inflammed middle ear • Dehiscent or aberrant facial nerve • Mastoid emissary vein • Deep sigmoid sinus • Exposed jugular bulb • Aberrant carotid artery • Persistent stapedial artery Increased Surgical Risk NotoCI
BMCH, Chitradurga Hypoplastic Mastoid Process Right side, the mastoid air cells are under pneumatized. There is no identifiable external auditory canal. American College of Radiology
BMCH, Chitradurga Normal Vs Sclerosed Mastoid First: Normal pneumatized mastoid with aerated cells. The mastoid is completely sclerotic - no air cells are present.
BMCH, Chitradurga Chronic Otitis Media The eardrum is thickened. A small amount of soft tissue (arrow) is visible between the scutum and the ossicular chain but no erosion is present. This favors the diagnosis of chronic otitis media.
BMCH, Chitradurga Dehiscent Facial Nerve Robert J. Witte, MD: Pediatric and Adult Cochlear Implantation: RadioGraphics 2003; 23:1185–1200
BMCH, Chitradurga Dehiscent Facial Nerve Patient also has signs of Chronic Otitis Media NIRA A. GOLDSTEIN, MD et al., Intratemporal complications of acute otitis media in infants and children. Otolaryngology - Head and Neck Surgery Volume 119, Issue 5, November 1998, Pages 444–454.
BMCH, Chitradurga Mastoid Emissary Vein H Alsherhri1, B Alqahtani2, M Alqahtani3: Year : 2011 | Volume : 17 | Issue : 3 | Page : 123-126
BMCH, Chitradurga Anterior Bulging Sigmoid Sinus The sigmoid sinus can protrude into the posterior mastoid. It can be accidentally lacerated during a mastoidectomy . Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga High Jugular Bulb The jugular bulb is often asymmetric, with the right jugular bulb usually being larger than the left. If it reaches above the posterior semicircular canal it is called a high jugular bulb. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga Jugular Bulb Diverticulum Rarely an out-pouching is seen &#8211; this is known as a jugular bulb diverticulum. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga Dehiscent jugular bulb On the left a dehiscent jugular bulb (blue arrow). This can be dangerous during myringotomy. Note also the bulging sigmoid sinus (yellow arrow). Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga Persistent Stapedial Artery www.neuroangio.org
BMCH, Chitradurga Aberrant internal carotid artery In patients with an aberrant internal carotid artery the cervical part of the internal carotid artery is absent. It is replaced by the ascending pharyngeal artery which connects with the horizontal part of the internal carotid artery. It courses through the middle ear. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga Aberrant internal carotid artery On the left coronal images of the same patient. On the right side the internal carotid artery is separated from the middle ear (blue arrow). On the left side the internal carotid artery courses through the middle ear (red arrow) Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
BMCH, Chitradurga Thank you

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Cochlear implant imaging

  • 1.
    BMCH, Chitradurga Imaging Requirementsfor Cochlear Implantation Dr. Prahlada N.B MBBS, MS, MBA, MHA ENT, HEAD – NECK & SKULL BASE SURGERY Basaveshwara Medical College & Hospital Chitradurga
  • 2.
    10-04-2017 210-04-2017 2BMCH,Chitradurga • Determine patients with Contraindications for CI • Determine the approach • As a guide during surgery Why Imaging? Objectives
  • 3.
    10-04-2017 310-04-2017 3BMCH,Chitradurga • HRCT temporal bone. • MRI What type of Imaging Protocol
  • 4.
    10-04-2017 410-04-2017 4BMCH,Chitradurga • Evaluates the status of – Mastoid pneumatisation – Thickness of the cortical bone – Middle ear aeration – The round window niche Role of HRCT Protocol
  • 5.
    10-04-2017 510-04-2017 5BMCH,Chitradurga • It may display anatomic middle ear variations of surgical importance such as: – Dehiscent facial nerve – Low lying dura – High jugular bulb and – Aberrant carotid artery Role of HRCT Protocol
  • 6.
    10-04-2017 610-04-2017 6BMCH,Chitradurga • CT demonstrates anomalies of the bony labyrinth such as – Paget’s disease – Otosclerosis – Postmeningitis stenosis of the round window niche. Role of HRCT Protocol
  • 7.
    10-04-2017 710-04-2017 7BMCH,Chitradurga • HRCT scans are performed on a 64- slice volume scanner in a straight axial plane: kV: 140, mA: 350, matrix: 512 × 512 • Slice thickness: 0.625 mm/10.63, 0.531:1 • Scan field of view (FOV): 32 cm, display FOV: 9.6 cm HRCT Protocol
  • 8.
    10-04-2017 810-04-2017 8BMCH,Chitradurga • The original isometric volume data is used to obtain Coronal reformatted images. • The images are reviewed with a high- resolution bone algorithm, using a small FOV for separate right and left ear documentation. HRCT Protocol
  • 9.
    10-04-2017 910-04-2017 9BMCH,Chitradurga • Coronal reformations along with 3D maximum intensity projection (MIP) reconstructions. HRCT Protocol
  • 10.
    10-04-2017 1010-04-2017 10BMCH,Chitradurga • To identify active fibrosis • Identify cochlear fluid fibrosis • To depict cochlear nerve agenesis and cochlear anomalies • To detect an occult acoustic nerve tumour • To detect brainstem anomalies – Trauma, Congenital. Role of preoperative MRI Protocol
  • 11.
    10-04-2017 1110-04-2017 11BMCH,Chitradurga • MRI scans are performed on 1.5-T MR with an 8-channel head coil. • Sedation is used in most patients. • A 3D-FIESTA (fast imaging enabling steady-state acquisition) axial sequence (TR: 5.5, TE: 1.7/Fr, FOV: 16 × 16, slice thickness: 1.0/−0.5, matrix: 320 × 320, NEX: 6.0) is performed MRI Protocol
  • 12.
    10-04-2017 1210-04-2017 12BMCH,Chitradurga • A 3D-FIESTA sequence is also acquired in a DIRECT OBLIQUE SAGGITTAL PLANE (TR: 6.7, TE: 2.1/Fr, FOV: 12 × 12, slice thickness: 1.0/−0.5, matrix: 384 × 320, NEX: 6.0) perpendicular to the VII–VIII nerve complexes. MRI Protocol
  • 13.
    BMCH, Chitradurga MRI DirectOblique Saggittal View Cadaver Dissection showing Direct Oblique Sagittal View.
  • 14.
    BMCH, Chitradurga MRI DirectOblique Saggittal View
  • 15.
    BMCH, Chitradurga MRI -Constructive Interference Steady State (CISS) Science Photo library Advantage : Combination of high signal levels and extremely high spatial resolution.
  • 16.
    10-04-2017 1610-04-2017 16BMCH,Chitradurga • Provides better resolution than with reformations from an axial sequence; Provides better delineation of the nerves . • A routine T2W axial sequence through the brain is obtained in all patients. MRI Protocol
  • 17.
    10-04-2017 1710-04-2017 17BMCH,Chitradurga • Advantages of MRI over CT: – Distinguish between cochlear fibrosis and ossification – Diagnose cochlear nerve agenesis. – MRI may depict unsuspected acoustic nerve or central acoustic pathway anomalies including acoustic nerve tumours. HRCT Vs MRI Protocol
  • 18.
    10-04-2017 1810-04-2017 18BMCH,Chitradurga • Disadvantages of MRI – Additive cost as MRI does not replace CT. – Good quality MR images in deaf patients are more difficult to obtain, as difficulties of communication may lead to movement artefacts. – Sedation is needed in children. HRCT Vs MRI Protocol
  • 19.
    BMCH, Chitradurga NORMAL ANATOMY- HRCT Imaging requirements for Cochlear Implantation
  • 20.
    BMCH, Chitradurga Frontal Medial Occipital Lateral 1. Temporomandibularjoint (glenoid roof and articular disc) 2. Pharyngotympanic tube (auditory tube) 3. Internal carotid artery 4. External acoustic meatus 5. Facial canal 6. Internal jugular vein 7. Mastoid process 8. Sigmoid sinus 9 Carotid canal 10. Malleus (handle) 11. Tensor tympani muscle (canal) 12. Middle ear 13. Incus (long limb) 14. Cochlea (basal turn) 15 Sinus tympani 16 Vestibular aqueduct 17 Round window
  • 21.
    BMCH, Chitradurga Frontal Medial Occipital Lateral 1. Temporomandibularjoint (glenoid roof and articular disc) 2. Pharyngotympanic tube (auditory tube) 3. Internal carotid artery 4. External acoustic meatus 5. Facial canal 6. Internal jugular vein 7. Mastoid process 8. Sigmoid sinus 9 Carotid canal 10. Malleus (handle) 11. Tensor tympani muscle (canal) 12. Middle ear 13. Incus (long limb) 14. Cochlea (basal turn) 15 Sinus tympani 16 Vestibular aqueduct 17 Round window
  • 22.
    BMCH, Chitradurga 2 Malleus(handle) 3 Incus (long limb) 4 Cochlea 5 Stapes 6 Oval window 7 Sinus tympani 8 Facial canal 9 Internal jugular vein (bulb) 10 Mastoid 11 Epitympanic recess 12 Malleus (head) 13 Incus (short limb) 14 Internal acoustic meatus 15 Aditus to mastoid antrum 16 Vestibule 17 Posterior semicircular canal 18 Mastoid antrum 19 Lateral semicircular canal Frontal Medial Occipital Lateral
  • 23.
    BMCH, Chitradurga 2 Malleus(handle) 3 Incus (long limb) 4 Cochlea 5 Stapes 6 Oval window 7 Sinus tympani 8 Facial canal 9 Internal jugular vein (bulb) 10 Mastoid 11 Epitympanic recess 12 Malleus (head) 13 Incus (short limb) 14 Internal acoustic meatus 15 Aditus to mastoid antrum 16 Vestibule 17 Posterior semicircular canal 18 Mastoid antrum 19 Lateral semicircular canal Frontal Medial Occipital Lateral
  • 24.
    BMCH, Chitradurga 1 Geniculateganglion 2 Facial nerve (first part) 3 Facial nerve (second part) 4 Internal acoustic meatus 5 Tympanic cavity 6 Vestibule 7 Posterior semicircular canal 8 Mastoid antrum 9 Lateral semicircular canal 10Sigmoid sinus 11 Anterior (superior) semicircular canal 12 Mastoid cells Frontal Medial Occipital Lateral
  • 25.
    BMCH, Chitradurga Frontal Medial Occipital Lateral 1 Geniculateganglion 2 Facial nerve (first part) 3 Facial nerve (second part) 4 Internal acoustic meatus 5 Tympanic cavity 6 Vestibule 7 Posterior semicircular canal 8 Mastoid antrum 9 Lateral semicircular canal 10 Sigmoid sinus 11 Anterior (superior) semicircular canal 12 Mastoid cells
  • 26.
    BMCH, Chitradurga NORMAL ANATOMY- MRI Imaging requirements for Cochlear Implantation.
  • 27.
  • 28.
  • 29.
  • 30.
  • 31.
  • 32.
  • 33.
  • 34.
    BMCH, Chitradurga Inferior viewof 3D maximum intensity projection (MIP) reconstructed from 3T MR. Note the cochlear nerve anteriorly and both saccular and posterior branches of the inferior vestibular nerves posteriorly. John I. Lane Robert J. Witte: The Temporal Bone, An Imaging Atlas
  • 35.
    BMCH, Chitradurga Superior viewof 3D MIP reconstructed from 3T MR. Note the facial nerve anteriorly and the superior vestibular nerve posteriorly John I. Lane Robert J. Witte: The Temporal Bone, An Imaging Atlas
  • 36.
    BMCH, Chitradurga PRE-SURGICAL EVALUATION Imagingrequirements for Cochlear Implantation
  • 37.
    10-04-2017 3710-04-2017 37BMCH,Chitradurga • An IAM less than 2 mm in diameter increases the risk of a congenital absence or of severe hypoplasia of the acoustic nerve. • An absent or narrow modiolus (diameter less than 3 mm in CT, or a modiolar surface less than 4 mm2 in MR) are at risk of absence of cochlear nerve. • The modiolus is a bone area of low signal intensity in T2WI, located at the base of the cochlea. It represents the exit of the cochlear nerve. 1. Size of the IAM KeyPoints
  • 38.
    10-04-2017 3810-04-2017 38BMCH,Chitradurga • Exploration of the IAM by MR with CISS sequence and sagittal reconstructions allows the measurement of the diameter of the cochlear nerve. • Cochlear nerve diameter is measured in relation to the facial nerve taken as reference. • Normally, the cochlear nerve lays on the inferior part of the IAM and • Cochlear nerve is larger than the facial nerve. • Its diameter is approximately of 0.4 mm. 3. Cochlear nerve status KeyPoints
  • 39.
    BMCH, Chitradurga Modiolus The modiolusis a conical shaped central axis in the cochlea. It consists of spongy bone and the cochlea turns approximately 2.5 times around it. The spiral ganglion is situated inside it. Basic human anatomy - O'rahilly, Müller, Carpenter & Swenson
  • 40.
    BMCH, Chitradurga Cochlear nervedeficiency C. Isolated Cochlea. D. Absent Cochlear Nerve. Christine M. Imaging Findings of Cochlear Nerve Deficiency. AJNR 2002 23: 635-643
  • 41.
    BMCH, Chitradurga Absent Modiolus Axialsection of the cochlea of a 4-year-old boy with Cornelia de Lange syndrome. Note the diminished width and height of cochlear upper turns with an absent modiolus in the section from the patient with Cornelia de Lange syndrome (A) as compared with a 2-year- old control with normal hearing (B). J. Kima: Temporal Bone CT Findings in Cornelia de Lange Syndrome. AJNR March 2008 29: 569-573
  • 42.
    10-04-2017 4210-04-2017 42BMCH,Chitradurga • Anomaly of the course of the: • Facial nerve • The carotid artery • The sigmoid sinus • Venous variants such mastoid emissary veins 2. Neurovascular Anomaly KeyPoints
  • 43.
    10-04-2017 4310-04-2017 43BMCH,Chitradurga • Facial nerve with an abnormal course through the mastoid cells is at significant risk during implantation. • Facial nerve injury can occur during – Facial recess approach. – Insertion of electrodes. • Facial nerve monitoring is an option. 2. Neurovascular Anomaly KeyPoints
  • 44.
    10-04-2017 4410-04-2017 44BMCH,Chitradurga • Study: – The number of cochlear turns – Symmetry of scala chambers – Status of the modiolus – Status of the posterior membranous labyrinth. mbranous labyrinth anomaly KeyPoints
  • 45.
    10-04-2017 4510-04-2017 45BMCH,Chitradurga • Congenital anomalies discovered during preoperative imaging studies can be the cause of the sensorineural hearing loss. • Can increase the surgical risk to have a `Gusher-ear' during the electrode insertion within the round window 4. Membranous labyrinth anomaly KeyPoints
  • 46.
    10-04-2017 4610-04-2017 46BMCH,Chitradurga • Cochlear ossification or fibrosis may: – Limit the full insertion of the electrode array or – Modify the choice of the cochlear implant – Modify the way of Electrode insertion. ndo- and perilymphatic fluid Status KeyPoints
  • 47.
    10-04-2017 4710-04-2017 47BMCH,Chitradurga • Stenosis of the round window niche may occur in bone remodelling lesions such as: – Paget’s disease – Otosclerosis – Lobstein disease – Post-meningitis labyrinthitis. Status of Bony Labyrinth & Round Window Niche KeyPoints
  • 48.
    BMCH, Chitradurga Paget’s Disease AxialCT scan demonstrates diffuse expansion and sclerosis of the bones of the skull base, characteristic of Paget disease. S. Vattotha, et al. A Compartment-Based Approach for the Imaging Evaluation of Tinnitus. AJNR 2010 31: 211-218
  • 49.
    BMCH, Chitradurga Otosclerosis Fenestral otosclerosisshowing a fissula ad fenestram. Medical Observer. Australia
  • 50.
    BMCH, Chitradurga Osteogenesis Imperfecta Thelabyrinthine segment, the geniculate ganglion (arrowheads), and the proximal tympanic segment of the facial nerve canal are severely involved and have indistinct, irregular margins. Progression of demineralization is also demonstrated in pericochlear areas Osteogenesis Imperfecta of the Temporal Bone: CT and MR Imaging in Van der Hoeve-de Kleyn Syndrome Hatem Alkadhi . AJNR 2004 25: 1106-1109
  • 51.
    BMCH, Chitradurga Post-meningitis labyrinthitis. AxialCT scan showing advanced labyrinthitis ossificans in both ears. Vanessa Y.J. Tan et al: Acoustic brainstem implant in a post-meningitis deafened child—Lessons learned. International Journal of Pediatric Otorhinolaryngology Volume 76, Issue 2, February 2012, Pages 300–302
  • 52.
    BMCH, Chitradurga CONGENITAL ANOMALIES Imagingrequirements for Cochlear Implantation
  • 53.
    10-04-2017 5310-04-2017 53BMCH,Chitradurga • Cochlear • Vestibular • Semicircular canal, • Internal auditory canal (IAC) • Vestibular and • Cochlear aqueduct malformations. Types of anomalies Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
  • 54.
    10-04-2017 5410-04-2017 54BMCH,Chitradurga • Michel deformity • Common cavity deformity • Cochlear aplasia • Hypoplastic cochlea • Incomplete partition types – I (IP-I) and – II (IP-II) (Mondini deformity). Cochlear anomalies Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
  • 55.
    10-04-2017 5510-04-2017 55BMCH,Chitradurga • Incomplete partition type I or Cystic cochleovestibular malformation: – Cochlea lacks the entire modiolus and cribriform area, resulting in a cystic appearance, and there is an accompanying large cystic vestibule. mplete partition of Cochlea Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
  • 56.
    BMCH, Chitradurga Incomplete partitiontype I or Cystic cochleovestibular malformation Axial Section showing Cystic appearing Cochlear and Large cystic Vestibule. University of Washington Department of Radiology.
  • 57.
    BMCH, Chitradurga Common cysticcavity University of Washington Department of Radiology.
  • 58.
    BMCH, Chitradurga Incomplete partition- II Classic Mondini malformation University of Washington Department of Radiology.
  • 59.
    BMCH, Chitradurga Incomplete partition- II Classic Mondini malformation University of Washington Department of Radiology.
  • 60.
    BMCH, Chitradurga Incomplete partitionvariant Normal basal turn of the Cochlear and Round Window University of Washington Department of Radiology.
  • 61.
    BMCH, Chitradurga Incomplete partitionvariant 1.5 Turns of Cochlear with Confluence of the middle and apex resulting in Cystic apex. Enlarged vestibule with nomral Vestibular aqueduct are seen. University of Washington Department of Radiology.
  • 62.
    10-04-2017 6210-04-2017 62BMCH,Chitradurga • Incompelete Partition Type II or the Mondini deformity: – A cochlea consisting of 1.5 turns (in which the middle and apical turns coalesce to form a cystic apex accompanied by a dilated vestibule and enlarged vestibular aqueduct. mplete partition of Cochlea Classification
  • 63.
    10-04-2017 6310-04-2017 63BMCH,Chitradurga • Michel deformity • Cochlear aplasia • Common cavity • Cochlear hypoplasia • IP-I (Cystic cochleovestibular malformation), • IP-II (Mondini deformity) Clinical Classification Classification Sennaroglu L, Saatci I. Laryngoscope. 2002;112:2230–41.
  • 64.
    10-04-2017 6410-04-2017 64BMCH,Chitradurga • Absent Cochlear nerve – Diameter of IAM (mid-part) <3 mm • Absent Cochlear • Absent Modiulus Contraindications for CI NotoCI
  • 65.
    10-04-2017 6510-04-2017 65BMCH,Chitradurga • Cochlear ossification (partial or total; length in basal turn) • Hyperostosis of the round window niche • Persistent membranous labyrinth inflammation • Inner ear at risk of `Gusher': endolymphatic sac dilatation. Alternate Surgical Technique/Implant Device NotoCI
  • 66.
    10-04-2017 6610-04-2017 66BMCH,Chitradurga • Abnormal cochlear segmentation. • Deficient modiolus. • Semicircular canal or vestibular dilatation. • Stenosis of the basal turn. • Otosclerosis foci. • Paget’s disease. Alternate Surgical Technique/Implant Device NotoCI
  • 67.
    BMCH, Chitradurga Deficient Modiolus AxialT2-weighted FSE MR image of the right inner ear : The cochlear outline is distorted, and the normal notch between the middle and apical turns laterally (white arrow) is blunted. Note that the modiolus is deficient (black arrow). H. Christian Davidson: MR Evaluation of Vestibulocochlear Anomalies Associated with Large Endolymphatic Duct and Sac. AJNR 1999 20: 1435-1441 ,
  • 68.
    BMCH, Chitradurga Deficient Modiolus AxialT2-weighted FSE MR image in another patient shows severe dysplasia. The cochlea (C) appears as a common cavity, the internal architecture is lost, and the modiolus is absent. The vestibule also shows severe dysplastic changes, including gross vestibular enlargement (V) and hypoplasia of the lateral semicircular canal (arrowhead). A portion of the enlarged endolymphatic duct is also apparent (asterisk). H. Christian Davidson: MR Evaluation of Vestibulocochlear Anomalies Associated with Large Endolymphatic Duct and Sac. AJNR 1999 20: 1435-1441 ,
  • 69.
    BMCH, Chitradurga Otosclerosis ofthe Cochlea During surgery it was noted that otosclerosis had filled the basal turn of the cochlea and obliterated the round window. Eric W. Sargent M.D., OTOSCLEROSIS: A Review for Audiologists
  • 70.
    BMCH, Chitradurga Stenosis ofthe Basal Turn of the Cochlear Small calcification in basal turn of cochlea as a result of labyrinthitis ossificans. Eric Beek and Frank Pameijer: Temporal Bone Pathology.
  • 71.
    BMCH, Chitradurga Semicircular Canaldilatation There is a widening and shortening of the lateral semicircular canal. Eric Beek and Frank Pameijer: Temporal Bone Pathology.
  • 72.
    BMCH, Chitradurga Vestibular dilatation Thevestibule is relatively large (arrow). Eric Beek and Frank Pameijer: Temporal Bone Pathology.
  • 73.
    10-04-2017 7310-04-2017 73BMCH,Chitradurga • Hypoplastic mastoid process • Inflammed middle ear • Dehiscent or aberrant facial nerve • Mastoid emissary vein • Deep sigmoid sinus • Exposed jugular bulb • Aberrant carotid artery • Persistent stapedial artery Increased Surgical Risk NotoCI
  • 74.
    BMCH, Chitradurga Hypoplastic MastoidProcess Right side, the mastoid air cells are under pneumatized. There is no identifiable external auditory canal. American College of Radiology
  • 75.
    BMCH, Chitradurga Normal VsSclerosed Mastoid First: Normal pneumatized mastoid with aerated cells. The mastoid is completely sclerotic - no air cells are present.
  • 76.
    BMCH, Chitradurga Chronic OtitisMedia The eardrum is thickened. A small amount of soft tissue (arrow) is visible between the scutum and the ossicular chain but no erosion is present. This favors the diagnosis of chronic otitis media.
  • 77.
    BMCH, Chitradurga Dehiscent FacialNerve Robert J. Witte, MD: Pediatric and Adult Cochlear Implantation: RadioGraphics 2003; 23:1185–1200
  • 78.
    BMCH, Chitradurga Dehiscent FacialNerve Patient also has signs of Chronic Otitis Media NIRA A. GOLDSTEIN, MD et al., Intratemporal complications of acute otitis media in infants and children. Otolaryngology - Head and Neck Surgery Volume 119, Issue 5, November 1998, Pages 444–454.
  • 79.
    BMCH, Chitradurga Mastoid EmissaryVein H Alsherhri1, B Alqahtani2, M Alqahtani3: Year : 2011 | Volume : 17 | Issue : 3 | Page : 123-126
  • 80.
    BMCH, Chitradurga Anterior BulgingSigmoid Sinus The sigmoid sinus can protrude into the posterior mastoid. It can be accidentally lacerated during a mastoidectomy . Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 81.
    BMCH, Chitradurga High JugularBulb The jugular bulb is often asymmetric, with the right jugular bulb usually being larger than the left. If it reaches above the posterior semicircular canal it is called a high jugular bulb. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 82.
    BMCH, Chitradurga Jugular BulbDiverticulum Rarely an out-pouching is seen &#8211; this is known as a jugular bulb diverticulum. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 83.
    BMCH, Chitradurga Dehiscent jugularbulb On the left a dehiscent jugular bulb (blue arrow). This can be dangerous during myringotomy. Note also the bulging sigmoid sinus (yellow arrow). Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 84.
    BMCH, Chitradurga Persistent StapedialArtery www.neuroangio.org
  • 85.
    BMCH, Chitradurga Aberrant internalcarotid artery In patients with an aberrant internal carotid artery the cervical part of the internal carotid artery is absent. It is replaced by the ascending pharyngeal artery which connects with the horizontal part of the internal carotid artery. It courses through the middle ear. Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 86.
    BMCH, Chitradurga Aberrant internalcarotid artery On the left coronal images of the same patient. On the right side the internal carotid artery is separated from the middle ear (blue arrow). On the left side the internal carotid artery courses through the middle ear (red arrow) Temporal bone – Pathology: Eric Beek and Frank Pameijer Radiology department of the University Medical Centre of Utrecht, the Netherlands
  • 87.

Editor's Notes

  • #2 Imaging Requirements for Cochlear Implantation. Dr. Prahlada N.B MBBS, MS, MBA, MHA ENT, HEAD - NECK SURGERY & SKULL BASE SURGERY Basaveshwara Medical College & Hospital Chitradurga
  • #41 Congenital absence of the cochlear nerve with an isolated cochlea. Axial and oblique sagittal T2-weighted fast spin-echo MR images of a 5-year-old girl with profound unilateral hearing loss (patient C8). A, Image of the normal left side shows the normal contours of the cochlea and other labyrinthine structures. B, IAC is of normal size and contains four nerves of comparative size. Cochlear nerve lies anteroinferiorly (arrow). C, Right side shows a deformed contour of the IAC (black arrow). Low-signal-intensity bar separates the fundus of the IAC from the modiolus (white arrow), which was confirmed to be bony at CT. We describe this as an isolated cochlea. The arrowhead indicates a singular canal containing the nerve of the posterior semicircular canal. D, Oblique sagittal image of the distal IAC shows a solitary nerve within the superior aspect of the small, deformed canal (arrow). The cochlear nerve is absent in this patient with normal facial nerve function.