PNS Flashcards
myasthenia gravis
NMJ disorder. antibodies block and distort achR. 2 peaks: 20-30- w>M, 60-80s- M>W. Sx: flucturating sc of M weakness- ocular, bulbar, neck. ptosis, fatigable chewing, weak neck extensor- dropped head syndrome. better in morning. double vision bc many achR in M of eye. dysphagia, bilateral ptosis
dx: EMG-decremental response to repetitive stimulation, then give trial of edrophonium, send ab against AchR- pos in 85% .
after confirm dx, screen for tumor of thymus
other dx: MuSK ab- in generalized MG searing for anti-AChR ab- tend to only have ocular findings.
single fiber EMG- jitter
edrophonium
readily reversible acetylcholinesterase inhibitor. Tensilon test. not specific for MG. eyelid M respond first.
ice pack test
for MG pt, put icepack on forehead of min- temporary reversal of ptosis.
myasthenic crisis
respiratory insufficiency out of proportion to M weakness. or incr generalized weakness to bulbar M needing intubation. emergency! panting like a dog, have freq PFT and NIF to ck for decline. if mild- IVIG or plasmapheresis immediate to dear ab load in blood- provide relief (wks). if severe -intubate. though some prefer proactive intubation. if has thymoma- do thymectomy
lambert eaton myasthenic syndrome
paraneoplastic D. ab against presynaptic ca-ch. can be in small cell carcinoma of lung. slowly progressive. spares eyes unlike MG. brief improvement in strength with exercise.
EMG- incremental response to repetitive stimulation.
pyridostigmine
mestinon. maintanence tx for MG>
azathioprine
steroid immunosuppressant for MG.
guillain barre syndrome
AI. often following GI illness. progressive ascending weakness with min sensory sx. sx dec over hr to days. sig back pain due to info nerve roots. loss of reflexes! LP: normal WBC, RBC, protein high= albuminocytologic dissociation, takes a wk to dev so CSF may be normal acutely. often proceed by campylobacter jejune infection.
autonomic dysfunction (BP changes and arrhythmias)
miller fisher syndrome- triad of ophthmaloplegia (weakness of eye M), areflexia, ataxia. present with descending sx and associated with anti-GQ1b ab.
MRI: enhanced nerve roots
LP- albuminocytologic dissocation
Tx: IVIG and plasmapharesis. former is easier with less SE. no steroids. supportive care bc 30% dev NM respiratory failure- need mechanical ventilation. DVT pox, bowel and bladder care, PT/OT, pain ctrl, psych support
conduction studies
conduction block, decr v- demyelinating. decr amplitude- axonal process
GBS RF
AI, 20-50yo, presided by respiratory or intestinal infection
ulnar N injruy
travel around posterior aspect of medial epicondyle. so if strike that, may injure. parathesiae in 4th and 5th digit or claw hand
radial N
extend wrist. sensation on dorsal hand
carpal tunnel syndrome
compression of median N in wrist. C6, 7, 8, T1 roots. pain and paresthesias in digit 1-3, half of 4, thinner eminence atrophy. clumsiness while hold obj, difficulty opening door knobs and jar lids. can awaken pt from sleep and feels better when shake hand. pain may radiate in arm or forearm.
tinel test
elecit pain by gently banging on wrist. for carpel tunnel
phalen’s test
elect pain by prolong wrist flexion. for carpel tunnel
in carpel tunnel pt, evaluate for
preg, endocrinopathies- diabetes, thyroid and GH. acromegaly
carpel tunnel tx
splints at night and avoidance of repetitive mvt. release of transve carpal ligament
drop wrist
radial N injury
extensor problem
radial nerve via triceps
preacher’s hand
weakness of middle, index, thumb from median N injury