Cranial nerve examination


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Cranial nerve examination

  1. 1. Cranial nerve examination
  2. 2. Cranial nerves I. II. III. IV. V. VI. VII. VIII. IX. X. XI. XII. Olfactory Optic Occulomotor Trochlear Trigeminal Abducent Facial Auditory Glossopharyngeal Vagus Spinal accessory Hypoglosseal
  3. 3. Summary of funCtion of Cranial nerveS
  4. 4. FUNCTIONAL TYPES Pure sensory    Pure motor Olfactory Optic  Auditory    Trochlear Abducent Accessory Hypoglosseal Mixed nerves      Trigeminal Facial Glossopharyngeal Vagus Occulomotor
  5. 5. Cranial Nerve I: Olfactory
  6. 6. Function  Carries the sensation of smell from nasal mucosa to olfactory bulb
  7. 7. Purpose of the test  To determine any impairment of smell is unilateral or bilateral  Whether impairment is due to any local nasal disease or neural lesion
  8. 8. Method of testing  Small bottles containing essences of very familiar odour are required • Coffee • Lemon • Chocolate • Asafetida etc
  9. 9. PROCEDURE Compress 1 nostril & sniff the taste odour twice Ask whether he can smell or identify odour Repeat test on other nostril & ask if smell is similar in both nostril Allow odour to disperse & repeat test with other 2 test odour, ask he can distinguish smell
  10. 10. Interpretation of result    Who can recognize & name odours quickly (females) Who can recognize but difficult in naming (males) Who can smell & know difference but neither recognize nor naming •    The above 3 should be accepted as normal Who feel each odour is similar but is distorted & unpleasant (parosmia) Those who cant smell anything or is much reduced compared to the other (anosmia) Those whose responses are vague & variable
  11. 11. Common causes of anosmia  Acute/chronic inflammatory nasal disease  Heavy smoking  Head injury  Intra cranial tumour compressing the olfactory bulb  Atrophy of olfactory bulb  Chronic meningeal inflammation  Parkinson’s disease
  12. 12. Cranial Nerve II: Optic
  13. 13. Function  Carries the visual impulses from the retina to the optic chiasma & in the optic tract to the lateral geniculate body  The impulse acts as an afferent pathway for the pupillary light reflex
  14. 14. Purpose of the test  To measure aquity of vision & determine if any disease is due to local occular disease or neural impairment  To chart the visual field
  15. 15. Method of testing  Visual acuity • The standard snellen’s chart can be used for vision & the Jaegar type card can be used for near vision [the commonest causes of visual error lies in the eye only]
  16. 16. Visual field  Purpose: • To chart periphery of visual field • To detect position, size & shape of the blind spot
  17. 17. Confrontation test Pt & examiner sit face to face Pt covers left eye & examiner right PT moves the test object from outside the visual field towards midline Instruct Pt to indicate appearance of the object
  18. 18. Common causes  Total unilateral loss of vision: optic nerve lesion  Homonymous hemianopia: lesion between optic tract to occipital cortex  Bitemporal hemianopia: lesion of optic chiasma
  19. 19. Occulomotor, Trochlear, Abducent
  20. 20. Function  Controls the external occular muscles & elevators of the lids  Also regulates the pupillary muscles
  21. 21. Purpose of the test  Inspect pupils to rule out a local disease, peripheral lesion or a nuclear involvement  Examine eye movement & determine if defects is muscular origin or neural involvement  To detect nystagmus
  22. 22. Method of testing  Observation • Presence & absence of ptosis & squint • Whether unilateral or bilateral • Constant or variable • Size, shape, equality & regularity of the pupils
  23. 23. Reaction to light  Reduce illumination of room & vision should focus on a far object  A bright beam of light is shone from the side of one eye  Repeat on the other side [the pupil should constrict briskly]  Shield one eye & perform test on the other & see for consensual reaction
  24. 24. Reaction to convergence & accommodation for near vision  Fix vision on a distant object & instruct to look in a near object  Place finger tip in front of the bridge of the nose (22 cm)  Then return to the far object  Observe pupillary reaction in both
  25. 25. Examination of occular movement  Observe lagging of one or both eye • Observe nystagmus
  26. 26. Analysis of diplopia  Shield one eye with a transparent red shield  Object is moved from left to right, up & down  Ask if - • He sees 1 or 2 object • Object lies one above the other or side by side
  27. 27. Rules governing analysis of diplopia  Separation of image is greatest in the direction in which the weak muscle has its purest action  False image is displaced farthest in the direction in which the weak muscle should move the eye
  28. 28. Analyzing nystagmus  Watch the patients eye while talking  Ask to look at a definite point & move the point from left to right & up to down  Hold each end position for 5 sec & assess nystagmus (direction, rate amplitude)
  29. 29. Common causes of paralysis Pontine lesions  Neoplasms  Vascular accidents  Demyelinating disease  Meningeal inflammation  Tumour of base of skull  Increased intra cranial pressure  Head injury [Total paralysis of III, IV & VI nerve indicates a lesion in cavernous sinus (carotid aneurism)] 
  30. 30. Cranial Nerve V: Trigeminal
  31. 31. Function  Carries all forms of sensation from the face, anterior scalp,eye & the anterior 3rd of the tongue  Also supplies the muscles of mastication
  32. 32. Purpose of the test  To determine any sensory impairment  To determine unilateral or bilateral motor weakness & determine UMN from LMN
  33. 33. Method of examination  Superficial sensory asst from mainly 6 areas (mainly light touch & pain) • Forehead & upper part of the side of nose (ophthalmic) • Malar & upper lip region (maxillary) • Chin & anterior part of tongue (mandibular)
  34. 34. Interpretation  Total loss of sensation: lesion of ganglion or sensory root  Total sensory loss over 1 division: partial lesion of ganglion or root  Touch only lost: pontine lesion affecting sensory nucleus  Pain & temp lost: dissociate anesthesia (seringobulbia)
  35. 35. Corneal reflex  Using a cotton piece the cornea is teased  Normal response is a bilateral blink (facial nerve forms the efferent loop of the reflex arc)
  36. 36. Interpretation  No closure: ophthalmic division of the facial nerve  No response in either lid when abn. is tested & bilateral blink when normal is tested: V nerve lesion  No response of the affected side whichever side is tested: VII nerve lesion
  37. 37. Motor assessment Muscles of mastication  Have Pt bite against resistance  Have Pt protrude mandible against resistance  Have Pt go into lateral excursive movts against resistance  Jaw jerk 
  38. 38. Common causes  Tumours of base of skull  Chronic meningeal lesion  Trigeminal sensory neuropathy  Acoustic neuroma  Syringomyelia  Multiple sclerosis
  39. 39. Cranial Nerve VII: Facial
  40. 40. Function  Supplies the muscles of facial expression including platysma & stapedius muscle  Secretomotor fibers to the lacrimal gland & the salivary gland  Carries sensation of taste from anterior 2/3 of tongue & general sensation from external acoustic meatus
  41. 41. Purpose of the test  To detect any unilateral or bilateral weakness of facial muscles (UMN or LMN)  Detect impairment of taste
  42. 42. Method of testing  Observation • Symmetry and asymmetry of • face Nasolabial fold & wrinkle on forehead  Ask the Pt to close the eyes, raise the eyebrows, blow out the cheek, whistle etc
  43. 43. Examination of taste  The four primary taste (sweet, salt, sour, bitter) can be carried out by using sugar, salt, vinegar & quinine  The side of the tongue is moistened by the test substance  Ask the Pt to indicate taste by pointing
  44. 44. Secretomotor function  The flow of tears of two side can be compared by giving ammonia to inhale which will result in tearing of eye  The flow of saliva can be tasted by keeping a spicy substance in the tongue & the tip is raised to observe the sub maxillary salivary flow
  45. 45. Reflexes  Corneal reflex  Nasopalpebral reflex: tap on the nasopalpebral ridge will produce closure of both eyes. In bells palsy there is failure to close on the affected side
  46. 46. Common causes of facial paralysis  Neoplasm affecting thalamus: unilateral emotional paralysis  Parkinsonism : bilateral emotional paralysis  CVA neoplasm, MND: bilateral UMN palsy  Bell’s palsy  GBS
  47. 47. Cranial Nerve VIII: Vestibulocochlear
  48. 48. Function  Carries the impulses of sound from the hair cell of organ of corti to cochlear nucleus in pons  Control balance through vestibular nerve
  49. 49. Purpose of the test  To determine any deafness is bilateral or unilateral  Whether deafness is due disease of middle ear or cochlear nerve  To determine the disturbance of vestibular functions
  50. 50. Test of hearing  Observe if the patient turns one ear towards you  Evaluate hearing using a ticking watch, rub fingers together, whisper.
  51. 51. Rinne’s test  Strike a tuning fork gently, hold it near one external meatus & ask the Pt if he can hear it  Place it on the mastoid, ask if he can still hear it & instruct him to say “NOW” when sound ceases, & keep it on the external meatus again (normally the note is still audible)
  52. 52. Interpretation  In middle ear deafness – the note is not heard  In nerve deafness – air & bone conduction are reduced but air remains better
  53. 53. Weber’s test  The fork is place on the vertex  Ask the Pt if he can hear the sound all over the head, in both ears or in one ear  In nerve deafness the sound appear to be heard on the normal ear  On chronic middle ear disease it is conducted to the abnormal ear
  54. 54. Common causes of deafness  Disease of external & middle ear & Eustachian tube  Prolonged exposure to loud noise  Old age  Meningitis  Demyelinating disease  Deafness due to drugs
  55. 55. Test of vestibular function  Observe equilibrium as patient walks or stands  Observe abnormal eye movts  Ask for - • Dizziness • Falling • Nausea and vomiting
  56. 56. Cranial Nerve IX: Glossopharyngeal
  57. 57. Function General Sensory: posterior 1/3 of tongue, tonsil, skin of external ear, tympanic membrane & pharynx Visceral Sensory: subconscious sensation from carotid body & sinus Visceral Motor: parasympathetic stimulation of parotid gland, & controls blood vessels in carotid body Special Sensory: carries taste from posterior 1/3 of tongue Branchial Motor: Supplies styolopharyngeus muscle
  58. 58. Cranial Nerve X: Vagus
  59. 59. Function General Sensory: posterior meninges, concha, skin at back of ear, external tympanic membrane, pharynx & larynx Visceral Motor: parasympathetic stimulation to smooth muscle & glands of pharynx, larynx; thoracic & abdominal viscera & cardiac muscle Visceral Sensory: from larynx, trachea, esophagus, & thoracic & abdominal viscera, stretch receptors & chemoreceptors Motor: superior, middle, inferior constrictors; levator palati, salpingopharyngeus, palatopharyngeus, palatoglossus
  60. 60. Purpose of the test  To test the elevation of palate & contraction of pharynx  To examine the movts of vocal cords [note: the IX & X nerve are tested together]
  61. 61. Method of testing  Notice the pitch & quality of voice, cough & difficulty in swallowing saliva  Ask the Pt to open his mouth wide after a few movts ask to say “AH” while breathing out & “UGH” while in  The palate should move symmetrically upwards & backwards, the uvula in mid line & two sides of pharynx contract symmetrically
  62. 62. Common causes of lesion  Poliomyelitis  Syringobulbia  Posterior fossa tumor  Advanced parkinsonism  Myasthenia gravis  Enlarged cervical glands  Surgical operation of the neck
  63. 63. Cranial Nerve XI: Accessory
  64. 64. Function Supplies sternocleidomastoid & trapezius muscles
  65. 65. Purpose of the test  To detect wasting & weakness, unilateral or bilateral of the muscles
  66. 66. Method of testing
  67. 67. Common causes of paralysis  MND  Poliomyelitis  Polyneuropathy  Trauma in the neck or base of skull  Tumour at jugular foramen  Syringomyelia
  68. 68. Cranial Nerve XII: Hypoglossal
  69. 69. Function  Control movts of the tongue, hyoid bone & larynx during & after deglutition Supplies 3 of 4 extrinsic muscles of tongue & all intrinsic muscles of tongue
  70. 70. Purpose of the test  To inspect the surface of the tongue  To detect wasting, weakness & involuntary movts  To examine voluntary muscle control
  71. 71. Method of testing  Ask the Pt to protrude the tongue & observe for • Reduction in size of affected side • Excessive ridging & wrinkling • Restricted protrusion • Deviation towards one side
  72. 72. Common lesions  Syringomyelia  Poliomyelitis  MND  Profound  ALS hemiplegia
  73. 73. 13th Cranial nerve  Known as cranial nerve zero or Terminal Nerve  It projects from nasal cavity, enters brain just a little bit ahead of other cranial nerves as a microscopic plexus of unmyelinated peripheral nerve fascicles
  74. 74. FunCtion  The nerve is vestigial or related to sensing of pheromones  Regulates sexual behavior in mammals