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2 examples of causes ov NMJ dysfunctions
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pt has myopathy.
What's still normal?
What's involved?
- sensation & the motor nerve (only muscle is affected)
- muscle fibers
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basic diff of presentation in myopathies vs neuropathy
- myopathy - starts prox
- neuropathy - start distal
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temporal dispersion
slower conduction, signal is spread out -- a sign of demyelination
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moter NCVs are measured w what unit?
milivolts or 1/1000 volts
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amplifier's job
amplify the electrical diff btwn active and reference electrode
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conduction velocity revelas
- velocity of the fastest conducting fibers (it's not an averaging thing, it's looking at the fastest fibers)
- amount of demyelination
- MU innervation
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amplitude reveals
- number of fibers conducting the AP
- if axons are blocked or there's degen the amp will decrease
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median nerve, wrist --> APB,
ulnar nerve, W --> ADM
normal, borderline, prolonged latencies?
- median:
- normal < 4.0 ms
- bord 4-4.2
- prol >4.2
- ulnar:
- norm <3.4
- bord 3.4-3.6
- prol >3.6
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velocity norm, borderline, and low for median, ulnar, and radial nerves
- norm >50m/s
- bord 47.5-50 m/s
- low <47.5
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radial n. latency
- not done bc of variety of locations
- but he has the value 40m/s in that box, tho the vel should be >50 m/sec
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temp's affect on NCV
cold gives slower conduction vel
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which muscle for median nerve testing?
APB
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APB attachments
transverse carpal ligament, the scaphoid and trapezium --> radial base of proximal phalanx of thumb
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elecrode placements for median and ulnar n testing
- active: over belly of muscle
- reference: distal to muscle belly
- ground: back of hand
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1st site of stim for median nerve / APB
wrist, btwn FCR and PL
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rule on cathode (-) and anode (+) placement
cathode is always closest to the electrode
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2nd site of stim for median nerve / APB
prox to the first -- ant and just med tothe biceps tendon
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3rd site of stim for median nerve / APB
- more pros still
- belly of bicep and a bit medial, over the nerve
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physical response when you hit the median nerve
thumb jump, writs flex and pronate
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muscle for ulnar nerve test
ADM
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ADM attachments
pisiform -->base of the proximal phalanx of the 5th digit on the ulnar or medial side
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1st site of stim for ulnar n
med or lat to flexor carpi ulnaris
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2nd and 3rd site of stim for ulnar n
- (must be done with elbow flexted 70-90 degrees to take the nerve off slack)
- just distal to med condyle
- just prox to it (bc the ulnar groove is such a common site for nerve compression, got to go right above)
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4th site of stim for ulnar n
medial upper arm
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main problems for median, ulnar, radial nerves
- median: carpal tunnel, pronator teres
- ulnar: ulnar groove in elbow
- radial: compression in forearm, soft tissue damage, upper arm by spiral groove -- most common spot
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tinnel's sign when nerve is regenerating?
positive
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radial nerve's test muscle?
extensor indicis
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1st site of stim for radial n
prox forearm lat to extensor carpi ulnaris (this is vague, so we don't have a latency time norm)
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2nd site of stim for radial n
upper amr distal to spiral groove btwn brachioradialis and biceps
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3rd site of stim for radial n
axilla
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