NMJ and Muscle Diseases Flashcards

1
Q

presentation of lmn

A

fasciculations (spontaneous discharges)

fibrillations (1 single muscle discharge, unsynchronized)

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2
Q

most common type of childhood disease

A

duchenne muscular dysthrophy

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3
Q

disease progression of duchenne muscular dystrophy

A

ascending pattern
3-5: difficulty running, jumping, hopping, gower maneuver
6-8: toe walking
8-10: need braches, joint contractures
12-16: wheelchair-dependent or bed bound, contractures, scoliosis
16-18: systemic manifestations, dec pulmo fn

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4
Q

lab findings in dmd

A

increased ck 20-100x
muscle biopsy is standard of diagnosis
immunoperoxidase stain: absent dystrophic in sarcolemma (absent stain)

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5
Q

treatment for dmd

A

supportive
prednisone
eteplirsen

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6
Q

presentation of beckers muscular dystrophy

A

ambulatory beyond 15 yo
cardiomyopathy
myalgias
myoglobinuria

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7
Q

lab findings in beckers muscular dystrophy

A

similar to dmd but less severe

REDUCED amount of dystrophin (not absent)

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8
Q

presentation of central core myopathy

A

generalized weakness or hypotonia
delayed motor milestones
affects proximal muscles (legs > arms)
minimal facial/neck flexor/ bulbar symtptoms

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9
Q

lab findings in central core myopathy

A

normal cks
myopathic pattern in emg
muscle biopsy with structural alteration within the center of the muscle fiber

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10
Q

forms of nemaline myopathy

A

mutation in tropomyosin, nebulin, troponin t, and actin

severe infantile form, static/slowly progressive form, adult onset form

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11
Q

lab findings in nemaline myopathy

A

type 1 fiber predominance and hypotrophy

nemaline rods on sarcomela

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12
Q

clinical features of myotonic dystrophy 1

A
distal limb weakness
progressing proximally
neck flexor involvement sometimes bulbar muscle
dysarthria
myotonia
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13
Q

specific features in myotonic dystrophy 1

A
cataracts
frontal balding
testicular atrophy
impotence
hyperinsulinemia
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14
Q

lab tests for myotonic dystrophy 1

A

normal ck
muscle biopsy: pyknotic nuclear clumps, agulated fibers
emg: fibrillating, pws, myopathic mups, myotonic discharges

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15
Q

types of myotonia

A

percussion myotonia: thenar muscle delayed relaxation
grip release myotonia: delayed release of grip
tongue myotonia

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16
Q

hypokalemic vs hyperkalemic periodic paralysis

A

table 6

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17
Q

largest group of aceuqired and treatable cause of skeletal muscle weakness

A

inflammatory myopathies

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18
Q

types of inflammatory myopathies

A

polymyositis, dermatomyositis, inclusion body myositis

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19
Q

pathogenesis of inflammatory myopathies

A

triggering events causing autoimmune or t-cell mediated reaction

complement mediated microangiopathy and muscle ischemia –> necrosis, degeneration, phagocytosis of muscle fibers

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20
Q

pathogenesis of dm vs pm

A

table 7

derma: perifascicular atrophy
poly: cd8 or mhc-1 lesion

21
Q

clinical presenation of inflammatory myopathies

A

progressive, symmetric proximal muscle weakness
skin manifestations in dm
systemic symptoms
associated malignancies

22
Q

inflammatory myopathy with poor outcome

A

inclusion body myositis

23
Q

skin manifestations of dm

A
heliotrope rash (eyes)
v sign and shawl sign
gottron's papules
mechanic hands
periungual telangiectasia
24
Q

treatment for inflammatroy myopathies

A

glucocorticoids
methotrexate, azathioprine, mycophenolate
immunomodulation (IV Ig)

25
Q

acquired myopathies with endocrine or systemic disease

A

thyrotoxic myopathy (proximal muscle weakness, myalgia, bulbar and respi muscles
hypothyroid myopathy: proximal arm/leg weakness, fatigue, cramps, pain, stiffness, 10x ck
hyperparathyroid myopathy: muscle weakness in osteomalacia

26
Q

often performed to diagnose a myopathy

A
ck levels
thyrotropin, electrolytes, renal and liver function, cbc, esr, serum protein electrophoresis/immunofixation
genetic testing
ncs/emg
muscle biopsy = GOLD STANDARD
27
Q

presenatations in nmj diseases

A

weakness

no sensory loss

28
Q

first thing to do when evaluating nmj diseases

A

rule out umn lesion first
rule out sensory problems

fluctuating pain in ocular or proximal muscles = nmj

29
Q

autoimmune disease of postsynaptic ach receptors

A

myasthenia gravis

30
Q

treatment of mg

A

acetylcholinesterase inhibitors

immunosuppressors

31
Q

clinical features of mg

A

fluctuating weakenss, diurnal pattern
eye muscles are involved first (weakness, diplopia, ptosis)
progression to other areas

32
Q

PE of mg

A

ocular weakness/ptosis with no pupillary dysfunction
bifacial weakness
poor gag, palatal elevation, dysarthria, dysphonia
elicited by upward gaze or forward arm abduction

33
Q

simpson’s test (upward gaze test)

A

fatigued eyelid when looking upwards (asymmetrical)

34
Q

gorelick’s test

A

passive opening of the left eyelid leads to a decrease in the right eyes

35
Q

ice pack test

A

slows down the enzyme breakdown of ach = improved nmj transmission

36
Q

clinical features of lambert-eaton myasthenic syndrome

A

weakness, fatigability of proximal limb muscles, eom and bulbar sparing
facilitation in sustained contraction
autonomic symptoms, myalgias

37
Q

treatment for mg

A

mestinon, prednisone, azathioprine, plasma exchange or ivig

thymectomy

38
Q

treatment for l-e ms

A

mestinon, plasma exchange or ivig or steroids, tumor treatment

39
Q

clinical findings in botulism

A
descending paralysis (eye head, neck, trunk, limbs)
12-72 hrs after ingestion and progresses for several days
no sensory or tendon reflex abnormalities
40
Q

pathogenesis of botulism

A

c. botulinum toxin prevents release of ach at nmj and autonomic synapses
inhibit synaptobrevin

41
Q

treatment for botulism

A

ventilator assistance
supportive care
trivalent antitoxin
guanidine hcl

42
Q

rns response in mg

A

slow rns, not enough ach, epp does not reach threshold

normal at first then reduced amplitude

43
Q

rns response in mg

A

rapid rns
epp above threshold
incremental response, gradual increase in amplitude

44
Q

edrophonium test

A

block ach degradation = more free ach

45
Q

serologic tests for nmj diseases

A

achr modulating antibodies
achr blocking antibodies
strational antibodies
anti-muscle specific receptor tk antibodies

46
Q

treatments for nmj disorders

A
cholinesterase inhibitors (pyridostigmine)
plasma exchange or ivig or steroids
thymectomy (gold standard)
47
Q

moa of cholinesterase inhibitors

A

prevents ache in degrading ach

48
Q

indications for plasma exchange ivig steroids

A

accutely ill patient (myasthenic crisis)
improve symptoms prior to elective surgery
non-response to other forms of therapy