Cranial nerve examination.pptx

cranial nerve examination

1. Cranial Nerves Examination By AKLILU G (MD) 1

2. Outline Instrument Requirement for cranial nerve examination. Functional anatomy of cranial nerve. Examination of function of cranial nerve. Techniques of examining cranial nerve. 2

3. Material Required before examination Tuning fork Torch light Snell chart Ishiahara chart Cotton Pin Piece of soap, fruit 3

4. Cranial nerve exam… A. Cranial Nerve I (Olfactory nerve) Anatomy :- Direct extension of Brain - Its nuclei Located in Cerebral Cortex. Function : - it mediates the sense of smell (Mainly Sensory Function). - Examination of Cranial I Function - By testing the sense of smell. 4

5. CN- I (olfactory) exam…. Technique of Examination. -test the sense of smell using substance with familiar and non irritating odor. Use piece of soap, fruit or other sbs….. - First be sure that each nasal passage is open by compressing one side of the nose & asking the patient to sniff through the other. -The patient should then close both eyes. - Occlude one nostril and test smell in the other with familiar substance. 5

6. CN- I (olfactory) exam… Interpretation of examination Finding. Normal – Cranial nerve I is Intact . Abnormal – Loss of sense of smell (Ansomia) Some causes of Ansomia (DDX) - Nasal obstruction due to common cold. - tumors of olfactory groove (meningoma, frontal glioma) - Head injury 6

7. Cranial nerve exam… II. Cranial Nerve II (Optic nerve) Anatomy :- Direct extension of Brain - Its nuclei Located in Cerebral Cortex. - group of optic nerves forms optic tract, ends in optic lobe of cerebral cortex. Some of optic nerve fibers synapse with occlumotor nerve at Edinger westphal nucleus in midbrain . Function : it takes visual sensory in put to midbrain and optic cortex for interpretation of visual impulse. 7

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9. Examination of Cranial II Examination of Cranial II Function - Using the following tests Testing Visual Acuity Technique :- using - Pocket Visual Acuity card – 14 inches away from the eye. - Snell chart (E chart) - 6metres away. b/c 6meter is the minimum distance at which light rays coming to eye would be parallel - Pin hole test - Examine one eye at a time by closing the other with palms. 9

10. Visual Acuity 10

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12. Examination of Cranial II Interpretation of examination Finding On the Snellen chart each line of letters is designated by a number that corresponds to the distance at which those letters can be read by someone with 'normal' distance vision. Visual acuity is expressed as a ratio, such as 20/20. The first number is the distance at which the patient reads the chart. The second number is the distance at which a person with normal vision can read the same line of the chart. 12

13. Interpretation of examination Finding On the Snellen chart each line of letters is designated by a number that corresponds to the distance at which those letters can be read by someone with 'normal' distance vision. Visual acuity is expressed as a ratio, such as 6/60. The first number is the distance at which the patient reads the chart. The second number is the distance at which a person with normal vision can read the same line of the chart. The normal person can read the line designated 6 at 6m, i.e. 6/6 (20/20) vision. 13

14. Interpretation of examination Finding If vision is below 1/60,make the patient to detect motion of hand in front of eye (HM) If patient can’t see HM the final test is to shine alight in to his eye , - if the patient can perceive light – record as LP. - if the patient can’t perceive light – record as NLP. In pin hole test -only the central rays of light pass through to the retina, so if V/A improves it is due to lens refractive error. If it doesn’t improve, it is due to other ocular disease. 14

15. Interpretation of examination Visual acuity defects are recorded in ratio using abbreviation (OD- oculus dexter or Rt Eye ,OS -oculus sinister or Lt eye),& OU- oculus Unita (Both Eyes). V/A of < 3/60 in the better eye with the best possible correction – is Legally Blind. DDx for causes of Visual acuity defects - i . Ocular Causes :- Refractive errors, glaucoma,Cataract,diabetic retenopathy …. - ii.Lesion of Visual Pathway:- Lesion of optic nerve , Optic tract ,visual cortex…. 15

16. Examination of CII Testing Visual Fields Technique - By confrontation method :- I.e - Sit 1meter apart from the patient on same level . - Make patient to look straight to your Eyes. - Examine both eyes or one at a time by wiggling fingers in imaginary field of vision for both the patient & physician and compare it with yourself. 16

17. Interpretation of examination Finding - Normally Intact Visual Fields - Visual Field defect – Called Hemanopsia Types of Hemanopsia Cause - 1. Blind Rt Eye - Rt. Optic nerve Lesion - 2. Left homonymous - Rt. Optic tract He hemianopsia lesion - 3. Bitemporal - Optic Chiasma heminaopsia Lesion 17

18. Light reflex – sensory input is carried by optic nerve and, motor response to pupilary constrictor muscle is brought by Occlumotor nerve. Technique of examination - shining torch light on one eye at a time and looking for pupillary constriction in both eyes. Interpretation of examination Finding. - Normally :- - Constriction of pupil on the side of light – Direct light reflex. - Constriction of pupil on the other side of light – Consensual light reflex. Abnormality of Light Reflexes - Absence of Direct light reflex. - Lesion of Optic N. - Absence of Consensual light reflex- Lesion of CNIII. 18

19. Examination of CII iv. Color Vision - Tested using a chart called Ishihara Chart. - Ask the patient to differentiate green from red by reading the number. Normal Person Could Read No 74 Person with Red – green blindness couldn’t identify the number inside. 19

20. Cranial Nerves III, IV and VI. Anatomy :- CN III (Occulomotor) and CN IV (Trochlear) nuclei located in mid Brain Function – Mainly motor supply to extraoccular muscles of Eye .( 4 recti &2 Oblique mm) CN III – supplies ,both Superior Oblique mm,Superior,inferior medial recti mm. And levator palpebrae superioris . CNIV - supplies inferior Oblique mm Anatomy :- CN VI (Abducent n) nuclei located in pons . Function – Mainly motor supply to Lateral rectus m. 20

21. Cranial Nerves III, IV and VI. Function of CN III,IV and VI , responsible for extraoccular movement of the eye ball in 6 Cardinal directions (gaze). 21

22. Cranial Nerves III, IV and IV. Examination of function of CN III,IV & VI Technique :- - ask the patient to follow your finger or pencil as you sweep through the six cardinal directions of gaze . 22

23. Examination of function of CN III,IV & VI Interpretation of examination Finding Normal – Intact all extra ocular movement. Abnormal :-Deviation of the eyes from their normally conjugate position is termed strabismus or squint. Strabismus ( Esotropia / Exotropia )may be classified into two groups: (1) non paralytic , in which the deviation is constant in all directions of gaze, and (2) paralytic, in which the deviation varies depending on the direction of gaze. 23

24. Examination of function of CN III,IV & VI Examples of strabismus a. paralytic strabismus b. Non Paralytic 24

25. Esotropia Exotropia 25

26. Examination of function of CN III,IV & VI Other Interpretation of CNIII examination Finding Normal – Symmetrical upper eye lid movement due to intact levator palpebrae superioris . Abnormal :- Drooping of upper lid .( Ptosis ) 26

27. Cranial Nerve V( Trigeminal Nerve) Anatomy :- Nuclei Located in Pons Function :- Mainly sensory innervations to face via its three main division (Ophthalmic, maxillary,& Mandibular branches) :- sensory innervations to cornea with motor response via facial nerve. :- Motor supply to muscles of mastication (temporal and masseter Muscles) 27

28. Examination of function of CNV Techniques of examination 1. Motor examination :- While palpating the temporal and masseter muscles in turn, ask the patient to clench his or her teeth. Note the strength of muscle. 28

29. . II. Sensory Examination a. Sensation over face:-test sense of touch and pain over forehead, cheeks and jaw after the patient closes his/her eye. b . Corneal sensation :- test using piece of cotton and try to touch cornea slightly. 29

30. Examination of function of CNV Interpretation of examination Finding - loss of sensation ( paresthesia ) - exaggerated sensory perception ( Hypersthesia ) Diminished corneal reflex Deviation of jaw to side of lesion when mouth opens. Some of causes for abnormal finding (DDX) Brain stem lesion Pontine lesion Infection of trigeminal ganglion Trigeminal neuralgia. 30

31. Cranial Nerve VII (Facial Nerve) Anatomy :- Upper nuclei located in cerebral cortex and Lower nuclei located in Pons Function :- mainly motor innervations of facial nerves. - Upper face :- has dual innervations from both cortex. - Lower face:-- has innervations only from contra lateral cortex.. 31

32. Examination of function of CN VII Technique of examination - Ask the patient to do the following Smile Frown iii. Puff out both cheeks. Iv . Close both eyes tightly & try to open them and look for strength of muscles. 32

33. Interpretation of examination Finding Normal – Intact facial muscles Abnormal findings - Upper motor lesion (due to, stroke, tumor trauma…) results in Lower face muscle paralysis 33

34. Interpretation of examination Finding Lower motor lesion (due to, Viral infection of facial nerve, Parotid tumor …) results in all facial muscle paralysis. 34

35. Cranial nerve VII palsy 35

36. Cranial Nerve VIII (Vestibulochochlear n) Anatomy :- nuclei located in pons Function : - mainly sensory - Chochlear division – hearing. - Vestibular division- Balance. - Pathways of Hearing . Vibrations of sound pass through the air of the external ear & are transmitted through the eardrum and ossicles of the middle ear to the cochlea. -The first part of this pathway from the external ear through the middle ear is known as the conductive phase. - The cochlea senses &codes the vibrations, & nerve impulses are sent to the brain through the cochlear nerve.( sensorineural phase ) 36

37. Paths of Sound Conduction Air conduction describes the normal first phase in the hearing pathway. bone conduction , bypasses the external and the middle ear and is used for testing purposes. vibrating tuning fork, placed on the head, sets the bone of the skull into vibration and stimulates the cochlea directly. In a normal person, air conduction is more sensitive. 37

38. Cranial Nerve VIII Examination of function of CN VIII. By testing the following i . Auditory Acquity Technique :- Close both eyes and ,and examine one ear at a time by closing the other by whispering or tickling of watch from 30c.m away. II. Examine Air and Bone Conduction – if hearing is impaired to differentiate conductive or sensorineural hearing loss. Using the following tests 38

39. Cranial Nerve VIII A . Test for lateralization (Weber test ). Place the base of the lightly vibrating tuning fork firmly on top of the patient’s head or on the mid forehead. Ask where the patient hears it: on one or both sides. Normally the sound is heard in the midline or equally in both ears Interpretation of finding In unilateral Conductive Hearing loss :- Sound is heard (lateralize to) impaired ear. B/c Impaired won’t be distracted by environmental noise. 39

40. 40 Causes of Conductive Hearing loss - Acute ottits media, perforation of ear drum …. In unilateral Sensorineural Hearing loss :- Sound is heard (lateralize to) good ear. Causes of Sensorineural Hearing loss Occupational acoustic trauma , neurosyphilis , head injury….. Conductive Hearing loss VS Sensorineural loss

41. B. Compare air conduction (AC) and bone conduction (BC) ( Rinne test). Place the base of a lightly vibrating tuning fork on the mastoid bone, behind the ear and level with the canal. When the patient can no longer hear the sound, quickly place the fork close to the ear canal and ascertain whether the sound can be heard again.. Normally the sound is heard longer through air than through bone (AC > BC). 41

42. 42 Interpretation of finding - In unilateral Conductive Hearing loss :- BC is longer than Air conduction.(BC > AC),B/c bone conduction by passes conductive pathway. - In unilateral Sensorineural Hearing loss :-.(AC > B C), b/c it passes through less resistant than bone like normal

43. 43 Cranial IX

44. Cranial IX and X. Cranial IX and X. – Nuclei in Medulla - Functional Anatomy Gloss pharyngeal (CN-IX) - Motor—pharynx - Sensory—posterior portions of the eardrum and ear canal, the pharynx, and the posterior tongue, including taste (salty, sweet, sour, bitter) Vagus (CN X) - Motor—palate, pharynx, and larynx - Sensory—pharynx and larynx 44

45. Cranial nerves: X, and XI

46. Examination of function of CN IX &X Examination of function of CN IX &X - Technique:- examine the following - Palatal movement (tell the patient to say “Aha”) - Check gag reflex with spatula - Notice phonation Abnormal findings – Deviation of palatal movement, absent gag reflex. Causes : Head trauma, Medullary lesions 46

47. Spinal accessory (CN-XI) Function - Motor—the sternomastoid and upper portion of the trapizus. Examination of function of CN XI - Examine rotation of head & neck against resistant Loss of Resistance :- sternomastoid muscle weakness 47

48. Spinal accessory (CN-XI) - Examine Shrugging of shoulder against resistant. - Loss of Resistance :- trapizus muscle weakness 48

49. Hypoglossal Nerves: XII

50. Cranial nerve XII ( Hypoglossal nerve) nuclie located in medulla Function :- Motor to Tongue muscles Examination of function of CN XII - Examine - tongue protrusion ,look for fasciculation. - Symmetry - Strength - Wasting 50

51. Thank you very much!! 51