CN Palsies Part II Flashcards
Where do abducens nerve nucleus originate from? where do they exit?
- pons
- at junction of pons and medulla; ascends along cluivus of occipital bone and enters orbit via superior orbital fissure through annulus of zinn
CN VI is _____ to the floor of the fourth ventricle and is closely related to PPRF. The fasciculus of CN ___ curves around nucleus.
ventral
Nuclear lesions of CN VI will cause:
- ipsilateral LR palsy
- ipsilateral gaze deficits (bc affects PPRF too
- ipsilateral CN VII palsy
What does a fascicular lesion of CN VI cause?
- ipsilateral facial numbness ( near CN V)
- ipsilateral CN VII palsy
- Descending sympathetic fibers: ipsilateral Horners
- cerebral peduncles: contraleral hemiplegia
5: vestibular nuclei: nystagmus
what are causes of fascicular CN VII lesions
- stroke (older patients)
- MS (younger patients)
- Tumor (kids)
_______ angle and ___ lesions are due to subarachnoid CN VI palsy
cerebellopontine; clivus
CN VI, VII, and VIII as well as ataxia is involved in ________ angle, due to acoustic neuroma
cerebellopontine
Neoplasms (like meningioma), meningitis, and bilateral CN VI palsy is due to ____ lesions
clivus
Since CN VI travels through the ____ of the the cavernous sinus, adjacent to the ICA, a cavernous sinus CN VI palsy may involve which nerves/fibers? What is this caused by?
body; CN III, IV, V1, V1, and sympathetic fibers (Horner’s)
- inflammation
- mass effect
- infection
What is due to acquired isolated CN VI palsy in children?
- trauma
- neoplasm (brainstem glioma)
- infection
- inflammation
What is due to acquired CN VI Palsy in young adults?
- trauma
- idiopathic
- infectious
- demylinating
- Elevated ICP
What is due to acquired CN VI palsy in older adults?
- Ischemia
- Neoplasm
- Infection
- Elevated ICP
Any neurologic events in young adults make you think ____ lesions
demylinating
A CN VI palsy results in ____ diplopia, and its at ____
horizontal; distance
How do you manage isolated CN VI in children
- obtain neurologic consultation
- Monitor every 2-6 weeks for progression
- MRI if no improvement in 3 months
How do you manage isolated CN VI palsy in young adults
- MRI
- Blood work
- Lyme
- Symphilis
- Collagen vascular disease
- MS
How do you manage isolated CN VI palsy in older adults
- Rule out cardiovascular disease
- ESR and CRP to rule out GCA (very elevated ESR rate)
- normal value for men: half their age
- normal value for women: half their age + 10 - MRI if no resolution within 3 months
anything ischemic should resolve within ____ months
3
How do you rule out brainstem and cerebellopontine angle signs
- contralateral hemiparesis: nicking cerebral peduncles
- Horners: nicking descending sympathetic tract
- facial palsy: nicking CN VII fascicles around nucleus
- Facial analgesia: trigeminal nerve - also in pons
- hearing loss (lesion in cerebellar pontine angle)
- ataxia: cerebellum
- nystagmus: cerebellum
- rule out bilaterality and/or papilledema: clivus lesion
- rule out facial pain:
- rule out cavernous sinus syndrome:
______ retraction syndrome is another cause of CN VI palsy which is a CONGENITAL disorder causing:
Duane’s’; agenesis of CN VI nucleus and nerve
-lateral rectus becomes innervated by CN III.
What are features of CN VI palsy
- patients are asymptomatic (learn to compensate for it)
- globe retraction and narrowing of palpebral fissure on adduction
- head turn toward the side with the deficit
Describe Duane’s Syndrome Type 1
- abduction impaired
- adduction normal or slightly defective
- most patients are orthophoric in primary gaze
Describe Duane’s syndrome Type 2
- Abduction normal
2. Adduction impaired due to improper contraction of LR on adduction
Describe Duane’s syndrome Type 3
- impaired adduction and abduction.
2. absent VI nuclei
Other causes of CN VI palsy include _____ disease, the MR becomes inflamed, which causes mechanical restriction out. _____ also can cause CN VI palsy, as well as spasm of the near reflex (pseudo CN VI palsy)
Graves; MG
multiple nerve palsies include: ____ ____ syndrome or ____ ___ syndrome.
cavernous sinus; orbital apex
orbital apex syndrome includes CN:
II, IV, VI, and V1
what are signs of carotid cavernous fistula
- swelling
- engorgement of vessels
- injection
_____ syndrome is actually a mechanical problem, not an IO palsy. It is caused by the ____ being stuck in the pulley. It will have a positive forced duction test and normal alignment in primary gaze. Features include an audible pop on attempted up gaze, usually congenital, but may be caused by trauma, inflammation or infection
Brown; SO;
restriction of elevation in adduction , normal elevation in abduction.
ischemic CN III palsy is usually 60+, and have to have at least one ____ risk factor. NO history of cancer, vasculitis, or autoimmune disease. COMPLETE CN III palsy (eye must be down and out) with _____ sparing. There should not be additional symptoms such as pain, weakness or numbness. There should not be any orbital signs. Spontaneous recovery by ____ months
vasculopathic (HTN, DM, smoking)
pupil
3
______ CN IV palsy can affect any age group, medical history is usually unremarkable. Diplopia make develop suddenly or gradually. Its usually compensated in younger patients. There will be evidence of longstanding ____ tilt. Vertical fusional amplitude > ____ degrees and less than 10 degree torsion on double Maddox rod test.
Congenital; head; 8
Diabetic opthalmoplegia is usually ____ cranial nerve, but could be III or IV. Caveats are if pupil are involved then its compressive, not ischemic. Multiple simultaneous cranial nerve palsies means it is NOT ______. Pt must be in 40s or older and NO signs of _____
6th; microvascular; GCA –> superficial temporal artery; systemic inflammatory condition, ischemia because the lumen is now very small.
what are brainstem signs of a CN Palsy
- nystagmus
- vertical gaze is limited
- ipsilateral horners
- contralateral hemiplegia
what are cavernous signs of a CN palsy
- multiple CN’s are involved
- horner’s
- decreased facial sensation
what are orbital signs of a CN palsy
- multiple CN’s are involved
- proptosis
- positive forced duction test
what would be considered an emergent workup
- compressive: MRI
- inflammatory: ESR to tell you how much inflammation is in body, CRP, platelets, temporal artery biopsy (want to rule out GCA)
what would be considered urgent workup
- Bloodwork (high yield)
- Hgb A1c
- Electrolytes
- CBC, ESR, CRP
- Acetylcholine receptor antibodies
- Antibody to MuSK - Bloodwork (low yield)
- ANA
- RF
- Cholesterol
- Clotting factors
