Cranial Nerve Exam Flashcards
What would a lesion look like in CN I?
Loss of smell (decreased appetite, complete loss unlikely), more obvious in working/police dogs
What would a lesion look like in CN II?
Blind (unilateral, bilateral)
What would a lesion look like in CN III?
Strabismus - lateral deviation of the eye (because lateral rectus is still intact)
Ptosis - drooping of upper eyelid
No constriction of pupils (Myonasis)
What would a lesion look like in CN IV?
Strabismus
Lateral rotation of dorsal aspect of pupil (because ventral oblique still has tone)
What would a lesion look like in Ophthalmic br of CN V?
No corneal reflex (No sensation to the cornea)
No palpebral reflex (no sensation to upper eyelid and medial canthus)
What would a lesion look like in Maxillary br of CN V?
No palpebral reflex (No sensation from lower eyelid and lateral canthus)
No response to pinch of upper lip
What would a lesion look like in Mandibular br of CN V?
No response to pinch of lower lip
Not able to close the mouth/poor jaw tone –> atrophy of these muscles
What would a lesion look like in CN VI?
Medial strabismus
Not able to retract the globe - no 3rd eyelid moving across
What would a lesion look like in CN VII?
No palpebral reflex
No menace response
No response to pinching or upper/lower lip
Deviation of philtrum to normal side
Drooping of face/lack of facial expressions on affected side
What would a lesion look like in CN VIII?
Head tilt/turn
No hearing
Circling, leaning, ataxia
Nystagmus - fast AWAY from lesion
What would a lesion look like in CN IX?
History of trouble eating/swallowing
Dysphagia (difficulty swallowing: cough, gag, choke)
Decreased/absent gag reflex
What would a lesion look like in CN X?
Dyphagia
Decreased/absent gag reflex
Loss of PSNS –> Decreased HR, Decreased gut sounds
What would a lesion look like in CN XI?
Possible gait changes and altered head/neck movement
Laryngeal paralysis - Roarers in equine (Stridor - inspiratory noise)
What would a lesion look like in CN XII?
Difficulty eating/drinking
Tongue set off to UNAFFECTED side
Decreased tone tone (atrophy)
If bilateral, complete paralysis of tongue
Tests for CN I?
Smelly treat without visualization (don’t use noxious substances)
Tests for CN II?
Pupillary Light Reflex - Dilated (mydriatic) pupil becomes constricted (miotic) with light - Should be consenual (both R and L constrict at same time) CN II in, CN III out
Menace Response - response to threatening gesture - close eyes - CN II in and CN VII out
Visual placement reaction
Obstacle Course
Tracking an object
Tests for CN III?
Look for normal eye position and movement when tracking an object (CN II in, III out)
Look for normal upper eyelid position
PLR - no constriction
Tests for CN IV?
Look for abnormal rotation of pupil
Look for normal congruent eye movement
Tests for Ophthalmic br of CN V?
Corneal Reflex (CN V in, CN VI out) - touch cornea Palpebral Reflex (CN V in CN VII out) - touch medial canthus, dog should blink
Tests for Maxillary br of CN V?
Palpebral Reflex (V in VII out) Pinch upper lip (V in VII out)
Tests for Mandibular br of CN V?
Pinch lower lip
Look at jaw tone, ability to close mouth
Tests for CN VI?
Look for normal eye movement and position Corneal Reflex (V in VI out) - eye should be pulled back and 3rd eyelid should sweep across when cornea is touched
Tests for CN VII?
Look for facial symmetry
Could stimulate CN V and observe for efferent response via facial
Schirmer Tear Test - but not definitive (for PSNS function)
Can test taste, but rarely done
Tests for CN VIII?
Test hearing and balance separately
Tests for CN IX?
Give treat/water - watch for normal swallowing
Gag reflex
Tests for CN X?
Gag reflex
Observations
Tests for CN XI?
Gait change
Stridor?
Tests for CN XII?
Observations about tongue
Difficulty eating/drinking
