CN Palsies Part I Flashcards
Components of the _____ nerve include the nucleus, whose cell bodies are in the midbrain, at the level of the SC. Fascicles, which are axons that are portions of the nerve still traveling through brain tissue, basilar components, intracavernous, and infraorbital. You can have a lesion at any one of these points.
oculomotor
The ____ nucleus is responsible for maintaining stability in limbs. It coordinates muscle tone, body position, and gait. Not same as ataxia, where its uncoordinated movement. Tremor is at rest.
red
superior Cerebellar_____ are responsible for coordination of movement. Cerebral peduncles are descending _____ and sensory tracts
peduncles; motor
Fascicular lesions include _____ CN III palsy, and ataxia, _____ tremor and motor weakness
ipsilateral; contralateral
whatever affects your cerebellum is always on the ___ side
same
____ Syndrome is a red nucleus lesion which causes ipsilateral CN III palsy and contralateral _____/involuntary movements
Benedikt; hemitremor; localized to midbrain
______ Syndrome is cerebral peduncle lesion which causes ipsilateral CN III palsy and contralateral ______/motor weakness
Weber; hemiplegia
_____ CN III palsy starts as a series of rootlets that leave the midbrain _____ and pass between posterior cerebral and superior cerebellar arteries. It runs laterally to the _____ ____ arteries. Causes of this type of palsy is due to an aneurysm of the _____ or head trauma.
Basilar; ventrally; posterior communicating, PCA
Which nerves are located in the wall of the cavernous sinus?
V1, V2, CN III, and CN IV
Which nerves are located in the body of the cavernous sinus
CN VI
any compressive disease, NOT ischemic, affects the ____ first. A single lesion that affects CN III and IV is probably in the _____ ____
pupil; cavernous sinus
What can an intracavernous CN III palsy include?
- CN III
- CN IV
- CN VI
- Horners syndrome
- Facial pain, numbness
Why would you get Horners syndrome with an intracavernous CN III palsy?
Horner’s is part of your sympathetic chain, which is wrapped around your ICA. If its an isolated Horner’s, the lesion won’t be in the cavernous sinus, but if its a complicated Horner’s (III, IV, VI) we can localize it to the cavernous sinus
cavernous sinus is a _____ sinus which drains blood.
venous; drains through the jugular veins. All the venous blood that the cavernous sinus is collecting from the front part of your eye is trying to drain back, but it gets stuck and stays in the front part of your eye. This will be seen as engorgement of blood vessels in the conj. Pts can also develop glaucoma bc of elevated episcleral venous pressure.
what are causes of intracavernous CN III palsy
- DM (pupil will be spared)
- pituitary apoplexy
- aneurysm
- meningioma
- carotid cavernous fistula
- inflammation (tolosa hunt syndrome) –>idiopathic, very painful
vortex veins drain into _____ veins which drain into cavernous sinus
ophthalmic (superior and inferior)
Intra orbital CN III palsy deals with superior division of CN III which includes _____ and _____. Inferior division includes IR, IO, MR, and _____ ganglion. Etiologies include it being traumatic, vascular or compressive.
SR; LPS; ciliary;
_____ apex is where everything leaves the orbit. Orbital apex syndrome is a compressive disorder affecting CN _____, ____, _____or _____. Common causes include tumor, infection or inflammation
orbital; III; IV, V1, VI
what are signs of mechanical compression that involve the Pupillary motor fibers
- Aneurysm
- Trauma
- Tumor
- Uncal herniation
what are signs of CN III palsy
- LPS weakness: ptosis
- eye abducted in primary gaze due to unopposed action of LR
- abnormal adduction
- abnormal subraduction
- abnormal infraction
- dilated pupil
- normal abduction
- intorsion due to intact SO innervation by CN IV
_____ regeneration is caused by a misdirection of regenerating axons which re-inervate the wrong EOM’s, and it is ALWAYS _______
Aberrant; compressive
Primary: no preceding history of acute CN III palsy
-hallmark of slow-growing compressive lesion of CN III (meningioma)
Secondary: follows an acute CN III palsy
-trauma, aneurysm, congenital
what are signs of aberrant regeneration
- eyelid retraction on downgaze
- eyelid retraction on adduction
- pupil constriction on adduction with poor light response
- globe retraction on upgaze
what are causes of CN III palsy in adults
- idiopathic
- ischemic - if pupil is spared resolves in 3 months
- compressive: aneurysm of PCA, trauma, or neoplastic
what are causes of CN III palsy in children
- congenital
- traumatic
- neoplasm
- aneurysm
How do you manage a CN III palsy if there is incomplete palsy and pupil is involved. what if its an complete palsy without pupil involvement?
Think PCA aneurysm, STAT ER referall for neuroimaging;
Think ischemic; monitor carefully for pupil involvement, monitor for aberrant regeneration, MRI/MRI/CTA if unresolved after 90 days.
In 65+ year olds: rule out GCA
whats GCA
Giant cell arteritis; pain, hurts when they chew, scalp hurts when they brush hair, weight loss, appetitie decreased, fevers, cold chills at night
CN IV is the only CN to leave from dorsal midbrain.Its very long and slender, and vulnerable to trauma. It is is the midbrain at the level of the ____ colliculus
inferior
what are symptoms of CN IV palsy
- acute onset of vertical diplopia
- head tilt away from paretic side
- overreaction of ipsilateral IO muscle (upshoot in adduction and abduction of eye in elevation)
- bilateral involvement:
- >10 degrees of cyclodeviation on double Maddox rod test.
- V- pattern due to overreaction of both IO muscles
a nuclear CN IV palsy will cause ____ SO palsy and _____ horners syndrome due to adjacent descending sympathetic fibers
contralateral; ipsilateral
a dorsal midbrain disease in CN IV will cause ____ CN IV palsy, LND (light near dissociation) pupil, loss of vertical gaze, papilledema, and convergence retraction nystagmus
ipsilateral
A CN IV palsy due to cavernous sinus will present with ____ CN IV palsy, ipsilateral CN III palsy, V1, V2, and ipsilateral ______ syndrome
ipsilateral; horners
what are causes of CN IV palsy
- undetermined
- traumatic; usually bilateral
- vasculopathic; must be isolated (no horner’s or orbital signs)
- neoplastic
young adults: trauma, idiopathic, congenital
elderly: idiopathic, congenital (head tilt + vertical vergence ranges (>2)) or vasculopathic
how do you manage an isolated CN IV palsy
- congenital: manage with prism: BD prism in front of hypertropic eye
- vasculopathic: blood work to rule out DM, HTN, GCA
- young patients without vasculopathic: MRI
