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NMSP Exam 2 > Peripheral Nervous System and Skeletal Muscle Path > Flashcards

Peripheral Nervous System and Skeletal Muscle Path Flashcards

1
Q

segmental demyelination

A

schwann cell dysfunction secondary to damage of the myelin sheath

no primary abnormality of axons

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2
Q

what is a histo sign of demyelination?

A

onion bulbs = concentric layers of schwann cytoplasm and redundant basement membrane surrounding thinly myelinated axon

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3
Q

traumatic neuroma

A

failure of the outgrowing axons to find their distal target can produce a pseudo-tumor

painful nodule

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4
Q

axonal degeneration

A

primary destruction of axon with secondary disintegration of myelin sheath

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5
Q

axon damage

A

focal or generalized trauma or ischemia affecting the whole neuron body or its axon

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6
Q

describe the process of axonal degeneration

A
  1. myelin ovoids form due to engulfed axon fragments
  2. macrophages clean up
  3. proximal stump of severed nerve shows degenerative changes in distal 2-3 internodes
  4. axon undergoes regeneration
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7
Q

what happens to muscle fibers during axon degeneration?

A

lose neural input and undergo denervation atrophy resulting in angulated and target fibers

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8
Q

what reactions occur within the muscle fiber with damage?

A

segmental necrosis
vacuolization
regeneration
hypertrophy

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9
Q

what are the different anatomical patterns of peripheral neuropathies?

A

mononeuropathy - single nerve

polyneuropathy - multiple nerves

mononeuritis multiplex - multiple nerves in a haphazard fashion

polyradiculopathy - nerve roots + peripheral nerves

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10
Q

Bell’s palsy

A

mononeuropathy of CN VII causing facial muscle paralysis

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11
Q

what is the clinical presentation of bell’s palsy?

A

one sided facial droop
associated with URI or DM
facial tingling
headache

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12
Q

what is the ddx for facial droop?

A 
Bell's palsy
stroke
brain tumor
Ramsay hunt syndrome
Lyme dz
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13
Q

what are the causes of neurogenic bladder?

A

nerve damage secondary to MS, Parkinsons or DM

infection of the brain or spinal cord

heavy metal poisoning

stroke

spinal cord injury

spina bifida

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14
Q

Guillain-Barre

A

acute inflammatory demyelinating polyneuropathy

ascending paralysis

inflammation of demyelination of spinal nerve roots and peripheral nerves

immune-mediated

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15
Q

what organisms can cause GB?

A

C. jejuni
CMV
Ebstein Barr
Mycoplasma pneumoniae

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16
Q

what is the etiology of GB?

A

inflammation of peripheral nerves by lymphocytes, macrophages and plasma cells

macrophages penetrate Schwann cells at the nodes of Ravier and strip myelin away from axon

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17
Q

what lab results can support GB?

A

increased CSF protein

anti-myelin antibodies

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18
Q

treatment of GB

A

plasmapheresis and IV Ig

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19
Q

chronic inflammatory demyelinating polyradiculopathy

A

most common acquired inflammatory peripheral neuropathy

symmetrical mixed sensorimotor polyneuropathy > 2 months

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20
Q

what distinguishes chronic inflammatory demyelinating polyradiculopathy from GB?

A

time of course

response to steroids

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21
Q

chronic inflammatory demyelinating polyradiculopathy diagnostic tools

A

sural nerve biopsy showing onion bulbs

complement-fixing IgG and IgM on myelin sheath

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22
Q

Leprosy/Hansen disease

A

schwann cells invaded by mycobacterium leprae

bacteria proliferates and infects other cells

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23
Q

what is the pathology underlying the symptomatology of leprosy

A

segmental demyelination
endoneurial fibrosis and thickened perineural sheaths
symmetric polyneuropathy affecting cool ext

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24
Q

what is the presentation of leprosy?

A

loss of sensation

large traumatic ulcers

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25
Q

diptheria neuropathy

A

Diptheria exotoxin damage to peripheral nerves

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26
Q

what is the presentation of Diptheria neuropathy?

A 
paraesthesias
weakness
loss of vibratory sense
loss of proprioception
loss of respiratory muscle function if untreated
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27
Q

what is the most common viral infection of the PNS?

A

varicella zoster virus

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28
Q

shingles

A

reactivation of latent infection causing painful vesicular skin eruption in the distribution of sensory dermatomes

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29
Q

what is the pathology of shingles?

A

neuronal destruction and loss of affected ganglia

regional necrosis and hemorrhage

axonal degeneration of peripheral nerves after death of sensory neurons

focal destruction of large motor neurons in anterior horns or cranial nerve motor nuclei

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30
Q

lyme dz neuropathy

A

unilateral or bilateral facial nerve palsies

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31
Q

HIV neuropathy

A

mononeuritis multiplex

demyelinating disorder resembling GB

later stages associated with distal sensory neuropathy

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32
Q

what is the most common cause of peripheral neuropathy?

A

DM

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33
Q

presentation of diabetic neuropathy

A

symmetric neuropathy involving distal sensory and motor nerves:

numbness
loss of pain sensation
difficulty with balance
diffuse vascular injury 
autonomic dysfunction
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34
Q

what is the etiology of diabetic neuropathy?

A

segmental demyelination

thickened endoneurial arterioles

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35
Q

what else can cause neuropathy?

A 
uremia
thyroid dysfunction
vitamin deficiency
EtOH
heavy metals
chemotherapy
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36
Q

what causes neuropathy associated with malignancy?

A

direct infiltration or compression of peripheral nerve

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37
Q

what are the signs of neuropathies associated with monoclonal gammopathies?

A 
POEMS:
polyneuropathy
organomegaly
endocrinopathy
monoclonal gammopathy
skin changes
38
Q

what are some examples of compression/entrapment neuropathy?

A

carpel tunnel - median nerve
saturday night palsy - radial nerve
morton neuroma - interdigital nerve

39
Q

what is the most common inherited PN?

A

Charcot-Marie-Tooth

40
Q

what are the subtypes of CMT?

A

CMT1
CMTX
CMT2

41
Q

CMT1

A

AD mutation on chrom 17 PMP22 gene
second decade of life
slowly progressive demyelinating motor and sensory

42
Q

CMTX

A

X-linked form of Charcot-Marie-Tooth

43
Q

CMT2

A

AD mutation on MDN2 gene

early childhood

44
Q

familial amyloid polyneuropathies

A

amyloid deposition within the peripheral nerves

45
Q

what inherited metabolic disorders can cause neuropathy?

A

leukodystrophies
porphyria
Refsum dz

46
Q

what toxins block ACh release from the neuromuscular junction?

A

Clostridium botulinum

Curare

47
Q

myasthenia gravis

A

autoantibodies to AChR at the neuromuscular junction

48
Q

what is frequently associated with MG?

A

thymoma

thymic hyperplasia

49
Q

what is the presentation of MG?

A

fluctuating generalized weakness that worsens with exertion and over the course of the day

diminished response after repeated stimulation

50
Q

what is usually the first sign of MG?

A

extraocular muscle weakness - ptosis and diplopia

51
Q

MG tx

A

AChE inhibitors
plasmapheresis
immunosuppressives
thymectomy

52
Q

Lambert Eaton Myasthenic Syndrome

A

antibodies block ACh release by inhibiting presynaptic calcium channel

50% paraneoplastic process due to small cell carcinoma of the lung

53
Q

what is the presentation of LEMS?

A

proximal muscle weakness and autonomic dysfunction

repetitive stimulation increases muscle response

54
Q

dermatomyositis

A

autoantibodies

anti-Mi2
anti-Jo1
anti-P155/P140

55
Q

what is the presentation of dermatomyositis?

A 
lilac or heliotrope rash with periorbital edema
telangiectasias
Grotton lesions
proximal muscle weakness
dysphasia
56
Q

dermatomyositis puts you at an increased risk to develop what?

A

visceral cancer

57
Q

what is seen on histo in dermatomyositis?

A

perifascicular atrophy

perimysial mononuclear infiltrates

58
Q

what is the common presentation of juvenile dermatomyositis?

A

onset at 7 y/o
involves GI tract
calcinosis and lipodystrophy

59
Q

polymyositis

A

adult-onset myalgia and weakness due to CD8 Tcells in endomysium

symmetrical proximal muscle involvement
No cutaneous involvement

60
Q

what is seen on histo with polymyositis?

A

endomysial mononuclear infiltrates

random distribution of affected fibers

61
Q

inclusion body myositis

A

dz of late adulthood

slowly progressive muscle weakness most severe in quads and distal upper extremities

dysphagia common

62
Q

what is on histo in Inclusion Body Myositis?

A

rimmed vacuoles

63
Q

what is the treatment for inflammatory myopathies?

A

steroids

immunosuppressives if steroid-resistant

64
Q

what toxins can cause myopathy?

A 
statins
chloroquine/hydroxychloroquine
critical illness
thyrotoxic
alcohol
65
Q

Duchenne MD

A

X linked mutation in Xp21
NO dystrophin production

sx before 5 y/o
wheelchair by 10-12 y/o

66
Q

Becker MD

A

X linked mutation in Xp21

reduced dystrophin production

67
Q

what is pseudohypertrophy?

A

enlargement of muscles of LE associated with weakness

increased bulk due to increased size of muscle fibers

replaced by fat and CT as MD progresses

68
Q

what is seen on histo in both DMD and BMD?

A

variation in fiber size
increased internalized nuclei
degeneration, necrosis and phagocytosis of fibers
regeneration of fibers
proliferation of endomysium
fibers replaced by fat and CT (late stages)

69
Q

what is seen in DMD histo but not BMD?

A

enlarged, rounded hyaline fibers that have lost their cross striations

70
Q

myotonic dystrophy

A

AD mutation in DMPK gene due to CTG trinucleotide repeats

*anticipation

71
Q

what is the presentation of myotonic dystrophy?

A 
myotonia 
muscle weakness
"hatchet face"
cataracts
endocrinopathy
cardiomyopathy
72
Q

what is seen on histo with myotonic dystrophy?

A

ring fiber

sarcoplasmic mass

73
Q

Emery-Dreifuss MD

A

X linked EMD1 or AD EMD1 mutations in gene encoding lamina proteins

74
Q

EMD triad of symptoms

A

humeroperoneal weakness
cardiomyopathy
early contractures of Achilles, spine and elbow

75
Q

Limb-Girdle MD

A

AD or AR disease

muscle weakness that involves proximal muscle groups

76
Q

carnitine palmitoyltransferase II def

A

episodic muscle damage with exercise and fasting

77
Q

McArdle Dz/myophosphorylase def

A

episodic muscle damage with exercise

78
Q

Pompe dz/acid maltase def

A

infancy: generalized glycogenesis
adult: respiratory and trunk muscle weakness

79
Q

what are the mitochondrial myopathies?

A

Leber
Leigh
Barth
Kearns-Sayre

80
Q

Leber syndrome

A

point mutation in mtDNA

optic neuropathy

81
Q

Leigh syndrome

A

nuclear DNA gene mutation

subacute necrotizing encephalopathy

82
Q

Barth syndrome

A

nuclear DNA gene mutation

infantile x-linked cardioskeletal myopathy

83
Q

Kearns-Sayre syndrome

A

deletion of duplication in mtDNA

ophthalmoplegia
pigmentary degeneration of retina
complete heart block

84
Q

what can be seen in histo for mitochondrial myopathies?

A

ragged red fibers

85
Q

spinal muscular atrophy

A

AR mutation in SMN1 on Ch. 5 causing destruction of anterior horn cells

loss of motor neurons leading to muscle weakness and atrophy

86
Q

what is the presentation for SMA?

A

generalized hypotonia/”floppy infant”

87
Q

what is on the ddx for infantile hypotonia?

A 
congential masthenic syndrome
congenital myotonia
congenital myopathies
congenital MD
encephalopathy
neuronopathies (SMA)
88
Q

what is the most common type of SMA?

A

Wernig-Hoffman disease

onset at birth
death < 3 y/o

89
Q

what is the presentation of Wernig-Hoffman disease?

A

truncal and extremity weakness

chewing, swallowing and breathing difficulties

90
Q

malignant hyperthermia

A

AD mutation in RYR1 gene causing channelopathy

hypermetabolic state causing tachycardia, tachypnea, muscle spasm, and hyperreflexia

triggered by anesthetics

NMSP Exam 2 (14 decks)

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