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Path II > Muscle/Nerve > Flashcards

Muscle/Nerve Flashcards

(49 cards)

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1
Q

What are the three groups of peripheral nerve pathology?

A

Wallerian Degeneration

Distal Axonopathy

Segmental demyelination/remyelination

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2
Q

What can skeletal muscle disease fall into?

A

Neurogenic: Primary problem is the motor neuron/axon

Myopathic: Primary problem is with the muscle

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3
Q

What are major types of myopathic disease?

A

Muscular dystrophy

Inflammatory myopahties

Metabolic myopathies

Congenital myopathies

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4
Q

How are muscle fibers distributed in a normal individual?

A

THe different motor units are intermixed with each other

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5
Q

How many muscle fibers are innervated by a single axon?

A

10-2000

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6
Q

What is the muscle findings in an individual who has demyelination and remyelination?

A

The motor units are multipled from a single motor unit

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7
Q

What are types of axonal degeneration

A

Peripheral neuropathy

  • Classic Wallerian Degeneration: Injury of vascular disease
  • Distal axonopathy: Systemic meta disease, toxins, some genetic disease

Starts distal because of how metabolic toxics hit the periphery first

Demyelination/Remyelination
-Inflammation, toxins, some genetic diseases

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8
Q

What are some Ischemic neuropathies?

A

Cause axonal degeneration

Vasculitis (PAN)
Collagen Vascular diseases
Paraneoplastic Microvasculitis
Diabetic symmetrical sensorimotor neuropathy

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9
Q

What are the steps of axonal degeneration in a crush injury?

A

Schwann cells distal to injury dye and demylinate

Macrophages come and clean up the debris

Proliferation of schwann cells back in to myelinate the axon

Regenerated axon

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10
Q

What is seen in vasculitis?

A

Fibrinoid necrosis of the vessel wall

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11
Q

In vasculitic neuropathy what occurs to the axons?

A

They are preferentially hit, due to the blood supply some of the neurons may be spared

-Fascile to Fascicle variation in degree of axon loss

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12
Q

What is diabetic neuropathy?

A

A axonal degeneration due to acquired metabolic/toxic neuropathy

Predominated by axonal degen with some regen

Often has ischemic componenet
Endoneural microvascular thickening: ischemia

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13
Q

How can you tell a loss of axon density?

A

The axonal loss is seen as less dark areas in an LFB stain

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14
Q

What is a demyelinating neuropathy?

A

Pattern is segmental demyelination

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15
Q

What is the etiology of demyelinating neuropathy?

A

Inflammatory (immune-mediated)
- Guillain-Barre Syndrome or Acute inflammatory demyelinating polyradiculoneuropathy

Toxins

Some genetic diseases, CHARCOT TOOTH DISEASE

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16
Q

What is the clinical presentation of GBS?

A

Ascending paralysis

Involve resp muscles sometimes

Slowed conduction velocity

Elevated CSF protein

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17
Q

What type of inflammation is seen in GBS?

A

Endoneurial and perineurial
Lymphs, Macros»»> plasmas

Segmental demyelination

Some dmg to axons, in severe disease

Remyelination is seen: THINNER SHEATH

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18
Q

How do you see segmental demyelination?

A

Teased fiber preparation

Variation in myelin sheath thickness and internodal length

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19
Q

What is seen around a naked neuron?

A

Myelin Debris surrounding a naked axon

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20
Q

What is Charcot-Marie-Tooth Disease

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A

Most common hereditary periphearl neuropathy

Progressive muscular atrophy of CALVES; weak

Genetically heterogeneous

Demyelinating neuropathy: Repetitive demyelination and remyelination

Pathy:
Thin myelinated axons
Hypertrophic ONION BULB neuropathy

21
Q

What causes onion bulb neuropathy?

Study These Flashcards
A

Chronic demyelination and remyelination

Concentric rings of Schwann cell processes

22
Q

What is seen in normal muscle biopsy?

Study These Flashcards
A

Frozen section shows peripheral nuclei

23
Q

What is seen in normal muscle biopsy?

Study These Flashcards
A

Frozen section shows peripheral nuclei

24
Q

What is the content of a type 1 muscle fiber?

Study These Flashcards
A

Sustained force, SLOW TWITCH

Color: Red

Lipids: Abundant

Glycogen: Scant

Enzyme content: NADH Dark, ATPase light (ph 9.4)

25
What is the content of a type 2 muscle fiber?
Action: sudden movement, purposeful Enzymes: NADH (light), ATPase (Dark) different stain than type 1, how to distinguish Lipids: Scant Glycogen: Abundant Physiology: Fast-twitch Color: White
26
What color are type two muscle fibers in ATPase stain (9.4)
Dark
27
What color are type 1 muscle fibers in ATPase stain (9.4)
Light
28
What are neurogic muscle diseases?
Motor neuron disease: - ALS - Spinal muscular atrophy Peripheral neuropathy NMJ -Myasthenia gravis
29
What are myopathic muscle diseases?
Dystrophy -Duchennes Inflammatory -Polymyositis Metabolic -Storage diseases Congenital -Centronuclear myopathy
30
What are clinical features of a neurogenic muscle disease?
Site: DISTAL Pain/tender: NONE Fasciculations: Present Serum Enzymes: Normal EMG: Fibrillations potential Nerve conduction: Variable
31
What are clinical features of myogenic muscle disease?
Site: Proximal Pain/tender: Variable Fasciculations: Absent Serum Enzymes: Elevated (CK) EMG: Polyphasic potential Nerve conduction: NOrmal
32
What are the histological differences between neuropathy and myopathy?
Atrophy - Neuropathy: Angular fibers, Grouped - Myopathy: Rounded fibers, scattered Neuropathy: Target fibers Myopathy: Fiber necrosis, inflammation, internal nuclei, endomysial fibrosis
33
Where are angulated fibers seen in neuopathy?
Grouped
34
What happens after regeneration in neuropathy?
The muscle fibers are in large groups
35
What causes duchennes muscular dystrophy?
A mutation in the dystrophin gene Cytoplasmic protein that anchors to the extracellular action
36
What is seen in early muscular dystrophy?
Myocyte necrosis Atrophy and hypertrophy of next muscle fiber
37
What happens in late muscular dystrophy?
There is endomysial fiboris and fatty replacement Atrophy and hypertrophy still seen
38
What is seen in myotonic dystrophy?
Autosomal Dominatn disease Trinucleotide repeat disease Path: Myopathic features with INTERNAL NUCLEI, occasional ring fibers NEED GENETIC TESTING
39
What are some inflammatory myopathies?
Primary - Polymyositis - Inclusion body myositis - Dermatomyositis Secondary -Other CT diseases,, immune processes, or infections
40
What are some inflammatory myopathies?
Primary - Polymyositis - Inclusion body myositis - Dermatomyositis Secondary -Other CT diseases,, immune processes, or infections
41
What is seen in early polymyositis?
Inflammation (endomysial) and muscle fiber necrosis
42
What is seen in late polymyositis?
Regnerating muscle Scarring fibrosis Inflammation
43
What is seen in inclusion body myositis?
Gradual onset/progression Male predominance Proximal and distal weakness Dysphagia in some Lymphocytic inflammation, angular annd round atrophy Autophagic "rimmed" vacuoles
44
What is the main histo feature to look for inclusion bodymyositis?
Rimmed Vacuoles Abnormal filaments
45
What are some metabolic myopathies?
Glycogen storage diseases - Type II (pompe disease): Def a1,4-glucosidase (acid maltase) -Type V (McArdle disease): Def myophosphorylase (not lysosomal) Lipid storage myopathy: (carnitine def) MIto myopathy: Ragged Red fibers
46
What is seen on PAS of Pompe disease?
Lots of glycogen seen in vacuoles
47
What are some characteristics of mitochondrial DNA?
Maternally inherited Circular Heteroplasmy
48
What is mitochondrial heteroplasmy?
Each cell has hundreds of mitos Each mitochondrion has 2-10 copies of mtDNA Each cell has thousands of mtDNA MItosis, mitos are randomly distributed If abnormal mtDNA it will be different in each cell
49
What is the hallmark of mito myopathy?
Ragged red fibers Paracrystalline inclusions

Path II (11 decks)

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