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MSK > NMJ Electrophys and Nerve growth > Flashcards

NMJ Electrophys and Nerve growth Flashcards

1
Q

describe a growth cone in 2 sentences

A

expansion on the tip of axon that senses environment. dictates growth via cytoskeletal remodeling in response to trophic factors.

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2
Q

ensure survival of neuron once proper synapse has been made

A

neurotrophins

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3
Q

3 things trophic interactions are responsible for

A

1) matching neurons to available target space 2) regulating the degree of innervation of individual afferents and their postsynaptic partners 3) modulating growth and shape of axon and dendritic branches

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4
Q

explain the neural response to botox administration (once vesicle fusion is blocked resulting in denervation); use trophic and muscle in your answer

A

in response to trophic factors produced by now denervated muscles, nerves try to re-inervate the muscle therefore they sprout terminal branches

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5
Q

flexing all toes in response to …..

A

stroking of lateral aspect of plantar foot

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6
Q

babinski reflex:

A

dorsiflexion of big toe and slight fanning of the toes upon plantar stroking of foot.

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7
Q

babinski normal in ages

A

normal up to 2 yrs old

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8
Q

in adults babinski indicates (less than sentence)

A

UMN lesion

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9
Q

describe wallerian degeneration in terms of response to …., and what part of …. is affected

A

response to cut or crush, distal parts of PNS axon degenerate

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10
Q

what two cell types cause breaking down of axon and myelin

A

proliferating schwann cells, and macrophages

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11
Q

describe retrograde degeneration using terms: weeks, cell body, and schwann cells

A

within 1-2 weeks of injury, proximal to cut, cell body swells and nissl bodies disperse, dendrites may be replaced by schwann cells

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12
Q

what are two (either or) requirements for regeneration?

A

endoneurial sheath intact OR severed nerves <2mm away

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13
Q

saturday night palsy is example of … type of injury via mechanism of ….

A

neuropraxia via temporary interference with fxn but no degen (e.g transient sustained pressure)

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14
Q

axonotmesis and mechanism

A

nerve injury where axon damaged but endoneurial sheath and schwann cells are fine; crush/ischemia

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15
Q

neurotmesis

A

nerve injury where axon and sheath and myelin are severed

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16
Q

what is first sign of regeneration of neuron

A

the cell body’s nissl bodies structure recovers

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17
Q

explain role of schwann cells in neuron regeneration use words such as bridge, trophic, and surround

A

schwann cells proliferate and lose their myelin. they then surround the basal lamina of endoneurium and act as a bridge. They provide trophic support as well.

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18
Q

explain axon sprouting in context of regeneration of nerve contrast this with botox poisoning

A

axon makes numerous sprouts on proximal end of cut, that all advance. only one sprout ends up innervating the end organ botox the neuron isnt regenerating strictly, but is merely sprouting in response to the denervated muscle trophic factors

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19
Q

when more than one axon is injured, and if multiple axons enter an endoneurial tube during regeneration, what can happen?

A

the wrong neuron type can pair with the wrong end organ.

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20
Q

why is recovery better in nerves that all all sensory or all motor?

A

if things get scrambled, at least same type of neuron

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21
Q

what is a mechanism by which a neuroma can form?

A

during regeneration if some of the terminal sprouts escape the epineurial sheath they can get tangled up and form neuroma.

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22
Q

what surrounds individual nerve fascicles?

A

perineurium

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23
Q

what surrounds groups of fascicles?

A

epineurium

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24
Q

when is myelin put on the axon in terms of the regeneration process?

A

when it reaches target organ

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25
Q

axonal loss results in … on NCS

A

decreased amplitude

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26
Q

demyelination loss results in …. on NCS

A

longer latency and slower velocity. also temporal dispersion for acquired demyelinating

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27
Q

vasculitic neuropathy is classified as a

A

multiple mononeuropathy

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28
Q

diabetes and etoh neuropathy are classified as a

A

polyneuropathy

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29
Q

distal muscle pain and weakness are more characteristic of ….; name an exception

A

neuropathies more so than myopathies; exception is inclusion body myositis

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30
Q

name 4 signs and sxs consistent with myopathy

A

muscle weakness (esp proximal); muscle atrophy; early fatigue; myotonia

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31
Q

what is a test to order to assess muscle damage?

A

CK

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32
Q

clinical criteria for rhabdo

A

myoglobinuria or elevated CK

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33
Q

what is acute complication of rhabdo?

A

ARF

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34
Q

can you have muscle atrophy without a primary myopathy?

A

yes, in denervation atrophy

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35
Q

do steroids cause nerve damage?

A

no just type II muscle fiber atrophy

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36
Q

do mitochondrial myopathies cause nerve damage?

A

no

37
Q

list some diseases that are neuropathic but can cause muscle atrophy

A

ALS, SMA, poliomyelitis, motor neuron disease

38
Q

grouped atrophy is a result of ….. (acute or chronic) denervation?

A

chronic

39
Q

fiber type grouping is a result of ….. following acute denervation

A

re-innervation

40
Q

example etiologies of fiber type grouping

A

CMT disease compression neuropathy poliomyelitis nerve transection w/surgical repair

41
Q

normal muscle biopsy in these conditions

A

botulinum toxin, myasthenia gravis, lambert eaton

42
Q

grouped atrophy often seen in

A

ALS, SMA, motor neuron disease

43
Q

larger amplitude and fewer peaks (Reduced recruitment), longer duration

A

neurogenic diseases

44
Q

smaller amplitude and more peaks (early recruitment), shorter duration

A

myopathic disease

45
Q

early and reduced recruitment examples of (..APs)

A

MUAPs

46
Q

diminished amplitude of muscle action potential upon repeated stimulation is consistent with

A

myasthenia gravis

47
Q

increased amplitude of muscle action potential upon repeated stimulation is consistent with

A

lambert eaton

48
Q

explain cause of myasthenia gravis and lambert eaton

A

mg: abs to post synaptic ach receptor le: abs to presynaptic calcium channels

49
Q

only two nerve fiber types that are not myelinated:

A

c and IV

50
Q

ice pack test for myasthenia gravis

A

cold enough on eyes to stop ach esterase therefore improving ptosis after ice applied

51
Q

get stronger after admin of ach esterase indicates this disease

A

myasthenia gravis

52
Q

thymectomy, plasmapheresis, and immune suppression are all ways to treat ….

A

myasthenia gravis

53
Q

what is dystrophin?

A

protein that holds actin cytoskeleton with the sarcolemmal membrane/ECM.

54
Q

inheritance pattern for DMD and BMD

A

x linked recessive

55
Q

explain gowers sign

A

pt must push on floor or on own legs to get up 2/2 proximal thigh weakness.

56
Q

additional complications of DMD

A

cardiac and pulm

57
Q

list 3 histopathological findings in DMD and less so in BMD

A
  1. endomysial fibrosis 2. internalized nuclei 3. necrosis and fat buildup
58
Q

duchenne age of onset and course

A

onset 1-5 yrs old proximal muscle weakness; delayed motor skills; 10-12 y/o wheelchair dependent; death 20-40 y/o

59
Q

can you essentially live normal life span with becker? when is onset?

A

yes onset: late childhood or early adolescence

60
Q

most common adult muscular dystrophy

A

myotonic muscular dystrophy

61
Q

myotonic muscular dystrophy pathophys and muscles most affected

A

trinucleotide repeat in myotonin; anticipation; demonstrates myotonia; cataracts; progressive weakness and muscle degeneration; facial and sternomastoid

62
Q

hallmark histopath of myotonic dystrophy

A

many internal nuclei and ring fibers

63
Q

McCardle’s disease clinical presentation (3 facts) +inheritance and enzyme deficiency +histopath

A

fatigue after brief intense exercise; second wind; <15 y/o male predominant; AR inheritance; glycogen phosphorylase enzyme glycogen in subsarcolemma

64
Q

Pompe’s disease clinical presentation of two main types + histopath +inheritance + enzyme deficiency

A

infantile/severe: weakness hypotonia, death <1 yr adult/child/moderate: proximal muscle weakness histopath: glycogen in membrane bound vacuole enzyme: acid maltase /lysosome trafficking

65
Q

CPTII disease enzyme

A

lipid storage myopathy from carnitine palmitoyl transferase II

66
Q

CPTII clinical presentation and inheritance + 3 more sxs

A

infants: often fatal adults: myopathy and myoglobinuria after exercise AR inheritance + cardiomyopathy, liver failure, seizures

67
Q

presents in young adulthood with proximal muscle weakness and sometimes with EO muscle involvement

A

mitochondrial myopathies

68
Q

parking lot inclusions and ragged red fibers are

A

mitochondrial myopathies

69
Q

systemic weakness and facial muscles also ptosis and sometimes diplopia

A

myasthenia gravis

70
Q

Kearns Sayre syndrome manifestations (5)

A

external opthalmoplegia that is progressive over years. + pigmentary retinopathy, cardiac conduction, ataxia, high protein csf (cf cidp)

71
Q

dermatomyositis: clinical presentation age of onset responsive to steroids? histopathologic findings

A

proximal symmetric muscle weakness heliotrope rash gottron papules juvenile and adult yes perifascicular atrophy and sometimes perimysial inflammation (CD4)

72
Q

polymyositis: clinical presentation age of onset responsive to steroids? histopathologic findings

A

Insidious onset w/ pelvic and pectoral girdle muscle weakness > 1 month adult (45-60 y/o F>M) yes endomysial cd8 infiltrate

73
Q

inclusion body myositis clinical presentation age of onset responsive to steroids? histopathologic findings

A

distal muscle weakness; forearm atrophy common inflammatory myopathy affecting adults >50 year old M>>F NO steroids. rimmed vacuoles and amyloid containing lesions; endomysial infiltrates

74
Q

steroids cause atrophy of ….

A

type II muscle fiber

75
Q

onion bulb sign found in

A

cidp and hereditary neuropathies (eg CMT)

76
Q

clinical presentation of GBS

A

paresthesias and pain with symmetric weakness, decreased DTRs; starts distally and spreads proximally (ascending); sxs onset within 4 weeks; 1/3 require intubation; molecular mimicry esp/ w/ campy?

77
Q

tx of GBS:

A

IvIG or plasma exchange

78
Q

epi of GBS:

A

young adults and >55 y/o most commonly

79
Q

differentiate onset of CIDP from GBS and degree of sensory findings

A

weeks to months for CIDP with progression or relapse beyond 8 weeks; prominent sensory findings in CIDP

80
Q

distal sensory polyneuropathy

A

diabetic neuropathy

81
Q

diabetic neuropathy affects (size, myelinization status)

A

small unmyelinated or myelinated

82
Q

3 histo hallmarks of diabetic neuropathy

A

axonal loss; axonal regeneration; thickened/hyalinated capillary walls

83
Q

3 risk factors for vitamin b12 def

A

elderly, hiv, impaired intrinsic factor secretion

84
Q

sxs of vitamin b12 neuropathy (myelin sheath destruction)

A

symmetric paresthesia, gait problems, LE>UE

85
Q

CMT1a disease gene lesion

A

duplication of PMP22 gene on chromosome 17 (a myelin protein)

86
Q

clinical presentation of CMT1a + cmt Histo buzzword

A

progressive weakness and loss of sensation; peroneal atrophy; pes cavus; reduced DTRs; onion bulb on histo

87
Q

differentiating factors clinically b/w MG and LEMS

A

MG: more ptosis and face LEMS: often legs. PRECEDES CANCER

88
Q

cardiomyopathy in

A

duschennes, pompe’s, CPTII, and (AV block for Kearns Sayer)

MSK (9 decks)

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