cranial nerve exam.pptx cranial nerve exam.

cranial nerve exam.

1. “ EXAMINATION OF CRANIAL NERVES ”

2. CRANIAL NERVES EXAMINATION FUNCTIONS OF CRANIAL NERVES TESTING OF CRANIAL NERVES POSSIBLE ABNORMAL FINDINGS ASSOCIATED WITH EACH CRANIAL NERVE LECTURES CONTENTS

3. At the end of the lecture students will be able to; To give brief overview of cranial nerves examination Identify the function of each cranial nerve Describe special tests to examine each cranial nerve To give possible abnormal findings associated with each cranial nerve LECTURES OBJECTIVES

4. CRANIAL NERVE EXAMINATION The cranial nerve exam is part of the neurological examination. It is used to identify problems with the cranial nerves. Cranial nerves are specialized nerves that originate in the brain & connect to specialized structures such as the nose, eyes, muscles in the face, scalp, ear, and tongue. Knowledge of the location and course of the cranial nerves is important in localizing lesions, particularly those within the brainstem from which the majority of cranial nerves originate and emerge.

5. Function: Sense of smell Test: Place a strong smelling item (non irritating odor) under each nostril, close off other nostril & ask the pt to identify it Use non irritating odor such as tobacco, orange, vanilla, coffee etc Possible Abnormal Findings: Anosmia, seen in frontal lobe lesions CN-I OLFACTORY

6. Function: Vision Test Visual Acuity : Using a standard Snellen eye chart Test each eye separately (covering other eye); test at a distance of 20 ft or 6 meter wall chart Possible Abnormal findings: Blindness, Myopia (nearsightedness), Presbyopia (farsightedness ) CN II: OPTIC NERVE

7. Test visual acuity by using a pocket visual acuity chart Hold the chart 14 inches from the patient's face, & ask the patient to cover one of his eyes completely with his hand & read the lowest line on the chart possible. Repeat the test with other eye Perform the test in a well lit room & make certain that if the patient wears glasses, wearing them during the exam. If the patient has difficulty reading a selected line, ask them to read the one above. Note the visual acuity for each eye. CN II: OPTIC NERVE

8. Test Peripheral Vision (Visual Fields) by confrontation: Ask the pt to cover one eye Fix his gaze between your eyes Move your arm out & away, A raised index finger should be just outside pt’s field of vision. The examiner will then conduct finger movements, bringing his or her hands into your visual field from the sides. Possible Abnormal Findings: Field Defects: Homonymous Hemianopsia CN II: OPTIC NERVE

9. Test Visual Fields (central) Get your head at the pt’s eye level Cover your own eye opposite to the pt’s covered eye Ask the pt to fix his gaze between your eyes Tell pt, you will move finger across his field of vision Holding a finger midway between your heads & slowly bring it across pt’s field of vision. Possible Abnormal Findings: Field Defects: Homonymous Hemianopsia CN II: OPTIC NERVE

10. Function: Pupillary Reflexes Test: Ask the pt to look straight ahead Quickly swing a torch beam from the side to illuminate the ratina Look for constriction of that pupil…direct response Repeat the action & look for the constriction in the pupil of opposite eye…consensual response Possible Abnormal Findings: Absence of pupillary constriction CNII & III:OCULOMOTOR (visual reflexes test)

11. Examine pupillary size/shape Look at the pupil; are they round & equal size Possible Abnormal Findings : Anisocoria (unequal pupils) Horner’s syndrome CNII &III:OCULOMOTOR

12. Function: Extraocular movements Test: Test Saccadic & Test Pursuit eye movements TESTING OF OCULOMOTOR,TROCHLEAR & ABDUCENS

13. Test: Examiner hold up his hands about three feet apart & instruct the patient to look at the finger that is wiggling, keeping pt’s head steady. The patient's eyes should be able to quickly, smoothly and accurately jump from target to target. Possible Abnormal Findings: Strabismus, impaired eye movement, double vision TESTING OF SACCADIC EYE MOVEMENTS

14. Test: Ask the patient to keep watching the target without moving their head. Then move the target slowly from side to side and up and down. The eyes should be able to follow the target smoothly without lagging behind or jerking to catch up with the target. Possible Abnormal Findings: Strabismus, impaired eye movement, double vision TESTING OF SMOOTH PURSUIT EYE MOVEMENTS

15. CN-III Palsy : Ptosis , eye deviated down & out , large fixed pupil CN-IV Palsy : Diplopia when the affected eye looks down & slightly inward CN-VI Palsy : Pt can not abduct eye,diplopia when looking to the side of lesion If the pt sees double in all directions , consider CN-III palsy POSSIBLE ABNORMAL FINDINGS

16. Function : Medial, superior, inferior rectus & inferior oblique; turns eye up, down, in. elevates eyelid Testing: The patient is positioned in sitting & asked to follow an object such as writing utensils with his or her eyes as it is moved vertically, horizontally and diagonally. The patient should not rotate his or her head during the testing. Inspect the patient eye for asymmetry or ptosis. CN-III OCULOMOTOR NERVE

17. Function: Superior oblique: turns eye down when adducted Test: The patient is positioned in sitting and is asked to follow an object such as writing utensil with his or her eyes as it is moved in a inferior direction. Make sure that the patient does not move his or her head upward. Possible Abnormal Findings: Eye can not look down when eye is adducted. CN-IV TROCHLEAR NERVE

18. Function: Lateral rectus: turns eye out Test: The patient is positioned in sitting. Examiner asked the patient to abduct his or her eyes without rotating the head. Possible Abnormal Findings: Eye can not look out. Esotropia (eye pulled inward) CN VI: ABDUCENT NERVE

19. 3 Divitions Ophthalmic Maxillary & Mandibular Mixed Nerve Sensory Motor CN V-TRIGEMINAL NERVE

20. Function: Sensory: face Test: The patient is positioned in sitting and is asked to close his or her eyes . Use a piece of cotton and a safety pin to test pain & light touch sensations on forehead, cheeks, and jaw Possible Abnormal Findings: Loss of facial sensations , numbness with CN V lesion CN-V TRIGEMINAL NERVE (SENSORY)

21. Function: Sensory: corneal reflex Test: Touch the end of cornea lightly with a wisp of cotton. The patient is asked if he feel the touch as well as the examiner will observe the reflex blink. CN-V TRIGEMINAL NERVE (CORNEAL REFLEX)

22. Function: Motor: muscles of mastication Test: Palpate temporal & masseter muscles . Ask the pt to open mouth against resistance. Mouth should open in the midline. Ask the pt to clench his teeth. Feel for the contraction of masseter & temporalis muscle. If the jaw protrudes to one side on opening, indicates weakness of pterygoids on the same side. CN-V TRIGEMINAL NERVE (MOTOR)

23. Function: Taste to anterior two thirds of tongue Test: The patient is positioned in sitting. Ask the patient to distinguish between sweet and salty substance apply on to one side then the other side of the anterior portion of the tongue using a cotton swab Possible Abnormal findings: Incorrectly identifies solution CN-VII FACIAL NERVE (SENSORY)

24. Function: Facial expression Test: Ask the pt to raise eyebrows, frown, close eyes tightly, show teeth, whistle, smile & puff out both cheeks Possible Abnormal Findings: Paralysis: Inability to close eye, Drooping corner of mouth, Difficulty with speech articulation Unilateral LMN: Bell’s palsy Unilateral UMN: Stroke CN-VII FACIAL NERVE (MOTOR)

25. Function: Vestibular function Test: The vestibular division of CN 8 can be tested by using the vestibulo-ocular reflex Ask the patient to visually fixate on an object straight ahead, then rapidly turning the patient's head form side to side and up and down. The eyes should stay fixed on the object and turn in the opposite direction of the head movement Possible Abnormal Findings: Gaze instability with head rotations, nystagmus CN-VIII:VESTIBULOCOCHLEAR

26. Dix-Hallpike Maneuver: Test vestibular function. Test: The pt is long sitting on a plinth with eyes open. The head is turn 45 degree to the side that is being tested. The pt is brought quickly into a lying position with the head in 30 degree extension by the examiner. This position is maintained for 30 sec & the presence, duration & direction of nystagmus are noted. If no nys t agmus is observed after 15 seconds, repeat the maneuver in the contralateral direction. The absence of nystagmus suggests normal vestibular nerve function. CN-VIII:VESTIBULOCOCHLEAR

27. Function: Cochlear function Test Auditory acuity: Auditory acuity (hearing) is checked either by ticking watch or lightly rubbing fingers together Possible Abnormal Findings: Deafness, impaired hearing, tinnitus CN-VIII:VESTIBULOCOCHLEAR

28. Weber Test: Place vibrating tuning fork on top of head, mid position; check if sound heard in one ear, or equally in both. Possible Abnormal Finding: Unilateral conductive loss: sound laterized to impaired ear Sensorineural loss: sound heard in good ear. CN-VIII:VESTIBULOCOCHLEAR (Cochlear Function)

29. Rinne Test: Compare air & bone conducting Place vibrating tuning fork on mastoid bone, then close to ear canal; sound heard longer through air than bone Possible Abnormal Findings: Conductive loss: Sound heard through bone is equal to or longer than air Sensorineural loss: Sound heard longer through air CN-VIII:VESTIBULOCOCHLEAR (Cochlear Function)

30. Function: Sensory to posterior one third of tongue, pharynx, middle ear Test: Apply saline & sugar solution on the posterior one third of tongue with a cotton swab & ask the pt to distinguish it Possible abnormal findings: Incorrectly identifies solution CN-IX GLOSSOPHARYNGEAL (SENSORY)

31. Function: Gag reflex Test: Patient is positioned in sitting. Stroke the back of throat or pharynx with a cotton swab or tongue depressor. Possible Abnormal Findings: Absence of gag reflex indicates lesions of CN-IX & possibly CN.X CN-IX GLOSSOPHARYNGEAL (GAG REFLEX)

32. Function: Phonation Swallowing Test: Listen to voice quality. Examine for difficulty in swallowing glass of water. Possible Abnormal Findings: Dysphonia: hoarseness denotes vocal cord weakness; nasal quality denotes palatal weaknes Dysphagia CN-X VAGUS NERVE

33. Function: Palatal, pharynx control Test: Ask the pt to say “ah”; observe motion of soft palate (elevates) & position of uvula (remains midline) Possible Abnormal Findings: Paralysis: palate fails to elevate; asymmetrical elevation with unilateral paralysis Test for gag reflex is also done to rule out CN-X palsy CN-X VAGUS NERVE

34. Function: Motor function Test: Examine bulk & strength Possible Abnormal findings: LMN: atrophy, fasciculations, ipsilateral weakness CN-XI SPINAL ACCESSORY

35. Test for Trapezius Muscle: Ask the patient to shrug both shoulders upward against resistance Possible Abnormal Findings: Inability to shrug ipsilateral shoulder; shoulder droops CN-XI SPINAL ACCESSORY

36. Test For Sternocleidomastoid Muscle Ask the patient to turn head each side against resistance Possible Abnormal Findings: Inability to turn head to opposite side UMN: weakness of ipsilateral sternocleidomastoid & contralateral trapezius CN-XI SPINAL ACCESSORY

37. FUNCTION: Tongue movements Test: Listen to patient’s articulation Possible abnormal Findings: Dysarthria CN-XII HYPOGLOSSAL

38. Test: Examine resting position of tongue Possible Abnormal Findings: Atrophy or fasciculations of tongue (LMN, ALS) CN-XII HYPOGLOSSAL

39. Test: Examine tongue movements Ask the patient to protrude tongue , move side to side Possible Abnormal Findings: Impaired movements, deviation to weak side UMN lesion: tongue deviates away from side of cortical lesion CN-XII HYPOGLOSSAL

40. O’Sullivan SB, Schmitz TJ, Physical Rehabilitation, Fifth Edition, F.A. Davis Company, 2007; Ch.8; 239-242 http://library.med.utah.edu/neurologicexam/html/cranialnerve_normal.html REFERENCES