Chapter 21 Flashcards

1
Q

Axonal neuropathy

A

• Direct injury to axon
Wallerian degeneration (destroy axon and myelin degrades)
↓ amplitude

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2
Q

Demyelinating neuropathy

A

• Damage to SCHWANN cells or myelin  SPARES AXON
random internode demyelination
slowed nerve conduction velocity

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3
Q

Mononeuropathy

A

asymmetric
• Entrapment: carpal tunnel syndrome = thenar atrophy
• Trauma: shoulder dislocation = axillary nerve palsy

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4
Q

Polyneuropathy

A

symmetric axonal loss
• ‘stocking and glove’ paresthesia/anesthesia
• Diabetics, alcoholism

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5
Q

Polyneuritis multiplex

A

randomly affects portions of individual nerves

• Autoimmune: RA wrist drop, polyarteritis nodosa

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6
Q

Guillain—Barre Syndrome

A
  • acute motor neuron demyelination –>ASCENDING paralysis; respiratory failure possible
  • Autoimmune: idiopathic –>viral
  • Males
  • Ages 15-35 or 50-57
  • Ventilation
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7
Q

Chronic Inflammatory Demyelinating Polyneuropathy

CIDP

A
•	Relapsing chronic GBS
onion-skin Schwann cells
•	associated with immune disorders: lupus, HIV
•	Males (2x)
•	40-60 (older)
•	MC some residual LOF
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8
Q

Diabetic Peripheral neuropathy

A

• #1 cause of peripheral neuropathy, 50% of DM

↓ sensation: distal, symmetric

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9
Q

what/how do environmental toxins injure peripheral nerves

A
  • Alter axonal transport or cytoskeletal damage
  • ADRs, lead, methyl-mercury
  • Longest neurons
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10
Q

what genetic condition injures peripheral nerves

A
  • PMP22 gene mutation
  • Charcot-Marie-Tooth disease
  • Axonal or demyelinating, motor & sensory
  • Pes cavus
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11
Q

Myasthenia gravis

A
NMJ disorder
degrade post-synaptic Ach receptors
•	Extraocular weakness
worse w e-stim
•	Females (MC): 20-30 years
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12
Q

Lambert-Eaton Syndrome

A
NMJ disorder
•	Auto-antibodies inhibit PRE-SYNAPTIC Ca++ channels
•	Repetitive e-stimulation improves
•	Females MC
•	60 years
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13
Q

Congenital myasthenic syndromes

A
  • Mutations alter NMJ proteins pre/post/synaptic

* Mimic MG or LES few respond to AChase inhibitors

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14
Q

what infections effect NMJs?

A
  • Clostridium tetani: ↑ACh release

* Clostridium botulinum: ↓ACh release; DESCENDING paralysis

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15
Q

what causes ascending paralysis?

descending paralysis?

A

ascending- GBS

descending- botulism

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16
Q

what determines myofiber type?

A

peripheral axons

17
Q

types of skeletal muscle disorders

A

o Neuropathic changes: altered innervation, grouped atrophy
o Disuse atrophy: primarily type II fibers, localized or generalized
o Glucocorticoid atrophy: primarily type II fibers, endogenous (cushings) or exogenous (MC)

18
Q

dystrophinopathies & features

A

inherited skeletal muscle disorders
MC cause of MD, dystrophin gene mutation: X chromosome
 Can’t “keep up”
 Pelvic girdle weakness (later shoulder)
 Pseudohypertrophy of calf muscles
 ↑ creatine kinase
 Death: cardiorespiratory insufficiency

19
Q

Duchenne MD

A
inherited skeletal muscle disorder
o	Dystrophin is ABSENT
o	More severe & more common than becker
o	Gower sign
•	males
•	Childhood onset 
Fatal by early adulthood
20
Q

Becker MD

A
inherited skeletal muscle disorder
o	ABNORMAL dystrophin
o	Variable severity—less severe than duchenne
•	Males
•	Onset in adolescence
Possible normal lifespan
21
Q

list of inflammatory myopathies

A

polymyositis, dermatomyositis, inclusion body myositis

22
Q

polymyositis

A

inflammatory myopathy
autoimmune
T-cell attack
males

23
Q

dermatomyositis

A

autoimmune
muscle & skin inflammation
MC inflammation myopathy in kids
Paraneoplastic syndrome in adults

24
Q

inclusion body myositis

A

Tau proteins in cytoplasm

MC inflammatory myopathy in elderly >60

25
list of toxic myopathies
thyrotoxic myopathy ethanol myopathy drug myopathy
26
thyrotoxic myopathy
overproduction of thyroxine | goiter/graves disease
27
ethanol myopathy
binge drinking | rhabdomyolysis -->acute renal failure
28
drug myopathy
no inflammation | statins MC
29
what age group are peripheral nerve sheath tumors MC in?
adults
30
schwannoma
benign MC sporadic CN VIII schwannomatosis: familial, NO vestibular schwannomas
31
neurofibromatosis type 2
benign brain --> bilateral vestibular schwannomas merlin gene no cutaneous lesions
32
neurofibromas
benign | cutaneous, subcutaneous & plexiform
33
neurofibramtosis type 1
benign cutaneous neurofibromas axillary freckling, Lisch nodules, Cafe au lait (california) inc risk of malignant peripheral nerve sheath tumors
34
malignant peripheral nerve sheath tumors
MC transformed plexiform neurofibroma | 50% of all cases arise in NF1 pts --> 3-10% of all NF1 pts
35
Traumatic neuroma
reactive lesion --> non-neoplastic post-neuronal injury (surgery) painful mass