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NMSP Exam 3 > [PATH] PNS and Skeletal Muscle [Martin] > Flashcards

[PATH] PNS and Skeletal Muscle [Martin] Flashcards

1
Q

Define:

Epineurium

A

Encloses entire nerve

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2
Q

Define:

Perineurium

A

Multilayered, concentric connective tissue sheath that encloses each fascicle

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3
Q

Define:

Endoneurium

A

Surrounds individual nerve fibers

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4
Q

With neuromuscular dz, what is the primary symtpom?

A

Weakness;

due to disorder of motor unit

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5
Q

What are the 2 main responses of peripheral nerve injury?

A

Segmental demeylination

Axonal degeneration

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6
Q

Segmental demeylination occurs with?

A

Schwann cell and loss of myelin

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7
Q

Axonal degeneration occurs with?

A

Neuron and axon failure

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8
Q

What is the LEFT vs RIGHT image showing?

A

LEFT = Segmental demyelination

RIGHT = Axonal degeneration

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9
Q

What are the two basic pathologic processes that occur in the muscle?

A

Denervation atrophy

Myopathy

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10
Q

When does segmental demyelination occur?

A

When dysfunction of SCHWANN CELLS occurs and damage to the myelin sheath occurs

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11
Q

What is the CLASSIC schwann cell disease?

A

Guillian Barre

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12
Q

Does segmental demyelination affect all schwann cells?

A

NO!

Only certain SEGMENTS

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13
Q

What is a length characteristic of a newly myelinated internode?

(This is following segmental demyelination)

A

Shorter than normal

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14
Q

What is a histologic characteristic of newly meylinated internodes following segmental demyelination?

A

Onion bulbs: concentric layers

of schwann cytoplasm

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15
Q

What is a traumatic neuroma?

A

Following a trauma;

A failure of the outgrowing axons to find their distal target, can produce a “pseudotumor”

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16
Q

What are myelin ovoids?

A

Schwann cells catabolize myelin and later engulf axon fragments which produces small oval compartments

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17
Q

What is a hallmark feature of axonal degeneration?

A

Denervation atrophy

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18
Q

What do the atrophic fibers following axonal degeneration look like?

A

Triangular shape

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19
Q

What determines the fiber type that will be regenerated?

A

The motor neuron determines the fiber type

*All muscle fibers of a single unit witll become the same type

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20
Q

Where is the normal nuclei distribution in a motor unit?

A

PERIPHERAL nuclei

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21
Q

Where will nuclei be in a motor unit undergoing regeneration?

A

CENTER

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22
Q

What will be the pattern of reinnervation muscle fibers?

A

Uniform;

*it is NOT like the normal checkerboard pattern seen in healthy motor units

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23
Q

Quick review of type1 vs type2 muscle fibers

General overview of Type 1?

A

Sustained force

Weiht bearing

Slow-twitch

Red

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24
Q

Quick review of type1 vs type2 muscle fibers

General overview of Type 2?

A

Sudden movements

Fast-twitch

White

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25
Q

When do type 2 fibers typically undergo atrophy?

A

Inactivity/disuse

Neurodegenerative disease

Glucocorticoid therapy

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26
Q

Segmental necrosis:

When there is a loss of muscle fiber, it can lead to?

A

Deposition of collagen and fat

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27
Q

What stain do you use to identify regeneration of muscle fibers?

A

Trichrome stain

*Cytoplasm is laden with RNA

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28
Q

What is a histologic feature of hypertrophy?

A

Muscle fiber splitting:

Large fibgers may divide longitudinally

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29
Q

What is the common description of pain in patients with peripheral neuropathies?

A

Tingling, stabbing, burning or “pins and needles”

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30
Q

What is the typical distrubution of a polyneuropathy?

A

Stocking and glove distribution

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31
Q

Mononeuritis multiplex is commonly associated with?

A

Vasculitis

(Polyarteritis nodosum = PAM)

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32
Q

How are the nerves damaged in mononeuritis multiplex?

A

Haphazard fashion

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33
Q

Bell’s palsy is related to which CN?

A

CN VII

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34
Q

Signs of bells palsy?

A

One sided facial droop within 48-72 hours of initial symptoms

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35
Q

What is a neurogenic bladder?

A

A number of urinary conditions in people who lack bladder control due to a brain, spinal cord or nerve problem

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36
Q

What are some associated disease processes associated with neurogenic bladder?

A

Nerve damage

Infection

Spina bifida

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37
Q

Guillain-Barre

What is it?

How does it travel?

A

Acute inflammatory demyelinating polyneuropathy

Weakness begins in distal limbs, but rapidly advances to proximal muscles “ascending paralysis”

-DTRs disappear

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38
Q

Guillain-Barre

What is the biggest organism that can cause?

A

Campylobacter jejuni

39
Q

Guillain-Barre

What type of antibodies are formed?

A

Anti-myelin antibodies

40
Q

Guillain-Barre

Whta will the CSF look like?

A

Increased protein

That’s it!!! (The inflammatory cells remain confined to the roots, therefore, very little or no CSF infiltration will be seen)

41
Q

Guillain-Barre

Treatment?

A

Plasmapheresis; IVIg

42
Q

What are the three major infectious polyneuropathies?

A

Leprosy (Hansen disease)

Diptheria

Varicella zoster virus

43
Q

What is the path behind leprosy?

A

Schwann cells invaded by mycobacterium leprae

44
Q

What kind of demyelination occurs in leprosy?

A

Loss of BOTH myelinated and unmyelinated axons

45
Q

Leprosy primarily involves which parts of the body?

A

Cool extremities

(lower temp favors mycobacterium growth)

46
Q

What is one mechanism that contributes to leprosy injury?

A

Involvement of pain fibers that leads to loss of sensation

47
Q

What is the knee-jerk (+) stain pattern you should associate with leprosy?

A

AFB

48
Q

What is the path behind diptheria?

A

Diptheria exotoxin affects peripheral nerves and begins with paresthesias and weakness

49
Q

What is the most common viral infection of PNS?

A

Varicella-zoster virus

50
Q

Where does varicella zoster virus typically attack first?

A

Sensory ganglia of spinal cord and brainstem

51
Q

What does reactivation of varicella zoster virus lead to?

A

Shingles

52
Q

What is the most common cause of peripheral neruopathy?

A

Diabetes

53
Q

What fibers are typically affected in diabetic neuropathy?

A

Small myelinated fibers

Unmyelinated fibers

54
Q

What nerve is involved in carpel tunnel?

A

Median n.

55
Q

What nerve is involved in saturday night palsy?

A

Radial n.

56
Q

What is the most common inherited peripheral neuropathy?

A

Charcot-Marie-Tooth (CMT)

57
Q

What is the most common disease of neuromuscular junction?

A

Myasthenia Gravis

58
Q

What is the path of myasthenia gravis?

A

Immune mediated loss of acetylcholine receptors;

*Circulating autoantibodies to AChR

59
Q

What is a strong association for myasthenia gravis?

A

Thymic abnormalities

60
Q

What is the clincal description of a patient with myasthenia gravis?

A

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

Drooping eyelids, weakness in extraocular muscles

61
Q

What is the classic sign following examination that a patient has myasthenia gravis?

A

Diminished responses after repeated stimulation

62
Q

What is the path of lambert-eaton myasthenic syndrome?

A

Antibodies block acetylcholine release by inhibiting presynaptic Ca2+ channel

63
Q

Lambert-eaton is a ________ process, mostly derivative of ____________

A

Paraneoplastic

Small cell carcinoma of the lung

64
Q

What is the response in lambert-eaton syndrome that is the OPPOSITE of myasthenia gravis?

A

Repetitive stimulation increases muscle response

65
Q

Fascicles are associated with a ___________

A

Small pool of tissue stem cells = Satellite cells

66
Q

What disease of skeletal muscle is associated with perifascicular atrophy?

A

Dermatomyositis

67
Q

Dematomyositis

Describe the distinctive skin rash

A

Iilac or heliotrope discoloration of the eyelids

Telangiectasias (dilated capillary loops) in nail folds, eyelids and gums

Grotton lesions

68
Q

Dermatomyositis

Symptoms?

A

Proximal muscles first

Dysphagia

Difficulty rising from chair, climbing stairs

Cardiac involvement

69
Q

Dermatomyositis

Associated antibodies?

A

Anti-Mi2

Anti-Jo1

70
Q

Dermatomyositis

Histo?

A

Perifascicular atrophy

71
Q

Inclusion body myositis

Describe

A

Slowly progressive muscle weakness,

Most severe in quadriceps and distal upper extremities

72
Q

Inclusion body myositis

Histo?

A

Rimmed vacuoles

73
Q

What is the first line therapy for inflammatory myopathies?

A

Corticosteroids

74
Q

What drug categories are related to toxic myopathies?

A

Statins

Chloroquine & hydroxychloroquine

75
Q

X-linked muscular dystrophy

Which type is more common and more severe?

Which type is less common and less severe?

A

More common, more severe = Duchenne (DMD)

Less common, less severe = Becker (BMD)

76
Q

What gene is affected in x-linked muscular dystrophy?

What protein?

A

DMD gene:Xp21

Dystrophin

77
Q

What does the production level of dystrophin say about the severity of the muscular dystrophy?

A

DMD = NO dystrophin produced

BMD = Very little dystrophin made

78
Q

What is pseudohypertrophy?

A

Enlargement of muscles of lower leg associated with weakness; increased bulk and size occurs initially;

Later there is an increase in fat and connective tissue

79
Q

What is myotonic dystrophy?

A

Sustained involuntary contraction of a group of muscles;

can be elicited by percussion on thenar eminence

80
Q

What are the symtpoms of myotonic dystrophy?

A

Skeletal muscle weakness

Cataracts

Endocrinopathy

Cardiomyopathy

“Stiffness”, difficulty releasing grip

81
Q

Inheritance pattern of myotonic dystrophy?

A

Autosomal dominant

CTG trinucleotide repeat

82
Q

What is the appearance of someone with myotonic dystrophy?

A

“Hatchet face”

83
Q

What are the two general patterns of muscle dysfunction with lipid/glycogen metabolism?

A

1) Symtpoms with exercise or fasting
2) Slowly progressive muscle damage

84
Q

What are common symptoms associated with mitochondrial myopathies?

A

Sxs: Weakness, increase in serum CK or rhabdomyolysis

Extraocular muscle involvement

85
Q

What is the histo appearance of mitochondrial myopathies?

A

Ragged red fibers

86
Q

What are the symtpoms of spinal muscular atrophy (SMA)?

A

Generalized hypotonia

“Floppy infant”

87
Q

Malignant hyperthermia is a channelopathy with what mutation?

A

RYR1

88
Q

What are the characteristics of tuberous sclerosis?

A

AD

Hamartomas

Renal angiomyolipomas

Cardiac rhabdomyomas

Shagreen patches, Ash-leaf patches

89
Q

Characteristics of neurofibromatosis type 1

A

Common

Neurofibromas of peripheral nerves

Optic nerve gliomas

Lisch nodules

Cafe au lait spots

90
Q

Characteristics of neurofibromatosis type 2

A

Less common

Bilateral swannomas (CNVIII)

Increased meningiomas, ependymomas

91
Q

Schwannoma

Sxs?

A

CN VIII

tinnitus

hearing loss

92
Q

Schwannoma

Gene?

A

NF2: loss of merlin

93
Q

Neurofibroma

description?

A

Bag of worms

94
Q
A

NMSP Exam 3 (15 decks)

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