lesion to CN 4 causes:
CN4 lesion can be misdiagnosed as what?
Idiopathic torticollis
CN 4 is vulnerable to what?
DAMAGE D/T HEAD TRAUMA bc it wraps around the B.S
_________ is the most Common isolated CN palsy due to its long peripheral course.
Seen often in patients with:
1, subarachnoid hemorrhage,
2. late syphilis
3. trauma.
CN 6 (abducens)
CN 6 lesions result in:
laterality of nystagmus is based on what?
fast beating part of the nystagmus.
when do we see a nystagmus?
What kind are there?
when a person has an extreme deviation of gaze.
Hortizontal, vertical and rotary
What causes nystagmus?
Trigmeninal nerve does what?
CNS patterns of stroke –
in trigeminal lesion, what way will the jaw deviate?
to the weak side because of the unopposed action of the opposite lateral pterygoid
Corneal blink reflex tests the ____ component of CN 5 and _____ component of CN 7
afferent of CN 5
efferent of CN 6
loss of corneal blink reflex can be seen in
acoustic neuromas, brainstem (pontine)
lesions etc
Blinking is absent in both eyes in CN ____ lesions
Blinking is absent on the side of weakness for CN ___ lesions
5
7
facial N does what?
Inspect face during rest & conversation to note any asymmetry & observe any ticks or
other abnormalities
is testing what CN?
7
Bell’s Palsy (peripheral facial paralysis)
CN 7 lesion caused by unkown reasons in most cases.
affects BOTH upper & lower face causing widened palpebral fissure and increased nasolabial fold.
loss of taste,
hyperacusis (increases sensitivity to sound),
↑ or ↓ tearing
(supranuclear) central lesion
CN 7 lesion that affects mainly lower face muscles and is usually assx with hemiplegia (weakness on one side of the body).
This isimportant in determining if the weakness is central or peripheral in nature.
how to test CN 8
Cochlear: whisper test (if +, do webers and rhinne test)
vestibular: usually isnt done isolated. Usually tested with cerebellum
CN 8 (vestibular) lesions usually result in
2. nystagmus
CN 8 (cochlear) lesions can result in
• Destructive lesions => sensorineural hearing loss. Ex. acoustic neuroma
• Irritative lesions => tinnitus (ringing in ears). Ex. Medications (aspirin, some
antibiotics etc)
CN 9 does what
3 Afferent limb of the gag reflex
test CN 9
Afferent (sensory) part of gag reflex is CN ___.
efferent (motor) part is CN ____
9
10