Peripheral Neuropathies Flashcards

1
Q

Define peripheral neuropathy

A

damage/disease involving nerves of the PNS which may affect sensation, movement, gland, organ function

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2
Q

What are large myelinated axons responsible for

A

motor and sensory info
- light touch, movement, vibration, proprioception

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3
Q

What are small myelinated axons responsible for

A

autonomic fibers and sensory axons
- light touch, pain, temp

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4
Q

What are small unmyelinated axons responsible for

A

autonomic
- sensory and enhancement of pain and temp

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5
Q

Describe the inputs of the cervical, brachial, lumbar, sacral, and coccygeal plexuses

A
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6
Q

What are some of the most common causes of peripheral neuropathy

A
  • DM
  • Alcoholism
  • carpal tunnel syndrome
  • post herpetic neuralgia
  • spinal radiculopathy
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7
Q

What is the most common pattern of peripheral neuropathy

A

generalized sensorimotor polyneuropathy with axonal degeneration - diabetes

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8
Q

What are the 3 types of peripheral neuropathies

A
  • mononeuropathies: 1 nerve)
  • polyneuropathies: multiple symmetric nerves
  • mononeuritis multiplex: multiple non-symmetric nerves
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9
Q

What are the 4 causes of peripheral neuropathies

A
  • traumatic
  • systemic
  • infectious/autoimmune
  • hereditary
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10
Q

Describe some systemic causes of PN

A
  • vitamin deficiencies
  • medications
  • toxins/poisons
  • systemic diseases
  • cancer
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11
Q

What are some of the major autoimmune causes of PN

A
  • DM
  • RA
  • Guillan Barre
  • Sjogren’s
  • Celiac
  • SLE
  • necrotizing vasculitis
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12
Q

What is one of the major hereditary causes of PN

A

Charcot Marie Tooth Disease
- flaw in gene responsible for making neurons/myelin sheath
- extreme weakness, wasting of muscles in lower legs
- pes cavus foot deformity

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13
Q

Describe the pathophys of Wallerian Degeneration

A
  • axon degenerates distal to focal
  • often caused by carpal tunnel or direct trauma
  • can regenerate
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14
Q

Describe segmental demyelination

A

segments of myelin coating break down but axon is spared (Charcot Marie, GBS, SLE, RA, Sjogren’s)

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15
Q

Describe Axonal Degeneration

A
  • most common neuronal response to injury (DM, toxins, meds, nutritional deficiencies)
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16
Q

Which type of demyelination or degeneration is associated with better recovery outcomes

A

segmental demyelination because only the myelin needs to be restored rather than the axon as well

17
Q

What is the typical symptomatic presentation of PN

A
  • onset with numbness
  • burning/tingling
  • weakness
18
Q

Describe some of the physical exam findings for PN

A
  • cranial nerve exam
  • fundoscopic exam may show optic pallor
  • strength testing may show mild weakness
  • motor exam may show fasciculations or atrophy, changes in muscle tone
  • reduced tendon reflex
  • foot drop
  • proximal weakness
19
Q

What labs should be explored in PN

A
  • fasting serum glucose
  • Hgb A1C
  • BUN
  • Cr
  • CBC
  • ESR
  • UA
  • B12, folate
  • TSH
  • serology (viral, autoimmune)
20
Q

What is often the most useful initial lab study for PN

A

electromyography: detects electrical potential generated by muscle

nerve conduction study: measures speed of transmission along a nerve from pt A to pt B

21
Q

What is the pathophys of EtOH neuropathy

A
  • direct poisoning of nerve by alcohol and effects of poor nutrition associated with alcoholism
  • generalized sensorimotor polyneuropathy with features of axonal degeneration
22
Q

Describe the pathophys of diabetic neuropathy

A
  • distal to proximal sensorimotor symmetric polyneuropathy
  • stocking and glove distribution: lower extremities then upper extremities
  • sharp, burning, tingling, temp, numbness
  • charcot arthropathy
23
Q

Describe charcot arthropathy

A

complication of diabetic neuropathy
- bones become weakened and fractured
- little pain as result of neuropathy
- ulceration and infection can result

24
Q

Describe the pathophys of entrapment neuropathy

A
  • mild/intermittent pressure damaging myelin sheath
  • will slow nerve conduction
  • conditions can increase risk (pregnancy, hyperthyroidism, DM)
  • can improve if pressure relieved
25
Q

Describe the pathophys of Bell’s Palsy

A
  • lesion/inflammation in Facial nerve (CN VII)
  • unilateral
  • syx at ear then evolving over a few hours/days
  • numbness, hyperacusis
    - skin changes could indicate ramsey hunt syndrome
26
Q

How is Bell’s Palsy managed

A

usually spontaneous recovery within 12 weeks
- oral prednisone for a week
- acyclovir

27
Q

How would you differentiate Bell’s palsy from a CVA

A
  • stroke = drooping only in lower face, can still raise forehead
  • palsy = drooping of whole side of face including forehead
28
Q

General treatment of PN

A
  • treat the cause if acquired
  • ASMs, SNRIs, TCAs, lidoderm patch, topical capsaicin, gabapentin
  • rehab with PT/OT/TENS
  • acupuncture, injections, nerve blocks
29
Q

What type of inheritance is involved in charcot marie tooth

A

autosomal dominant (common in diabetic neuropathy)