Peripheral Nerve Diseases Flashcards

1
Q

What are the four type of peripheral nerve diseases?

A
  • Inflammatory neuropathies
  • Infectious polyneuropathies
  • Hereditary neuropathies
  • Acquired metabolic/toxic neuropathies
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2
Q

What is one type of inflammatory Neuropathy?

A

Guillain-Barre Syndrome

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3
Q

What is the pathogenesis/timeline of Guillain-Barre syndrome?

A

“Acute inflammatory demyelinating polyradiculoneuropathy”

  • 2/3 of cases preceded by acute flu-like illness (Campylobacter, CMV, EBV, Mycoplasma, influenza virus)
  • T cells and macrophages cause segmental demyelination; antibodies also present [patients get better when antibodies are taken out - plasmaphoresis]
  • Remyelination follows
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4
Q

Neuropathy

A

Problem with nerves

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5
Q

Guillain-Barre Syndrome

A
  • Immune mediated disease
  • Body starts attacking virus and then begins attacking myelin
  • Life-threatening disease of the PNS
  • Flu-like illness, then acute ascending paralysis (starts at feet)
  • Immune-mediated demyelination
  • Usually resolves with time
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6
Q

Where does Guillain-Barre target and what does it look like on a slide?

A
  • Inflammation around venules, nerves [look dark red/pink on H&E stain]
  • Lymphocytes, macrophages, plasma cells
  • Widely distributed through PNS
  • Most intense in spinal and cranial nerve motor roots and adjacent nerves
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7
Q

What does Guillain-Barre look like in the clinic?

A
  • Symmetric, ascending paralysis
  • Rapid-onset weakness, loss of deep tendon reflexes
  • Some loss of sensation
  • Elevated CSF protein (no lymphocytes though)
  • 2-5% mortality (respiratory paralysis, autonomic instability, cardiac arrest, complications of treatment)
  • Respiratory therapy may be needed
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8
Q

What type of demyelination happens in Guillain-Barre?

A

Segmental demyelination - some segments affected, some not

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9
Q

What are the two forms of Infectious polyneuropathies that we studied?

A

Leprosy & Varicella-Zoster

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10
Q

Describe Leprosy/Hansen Disease:

A
  • Slowly progressive infection of skin and nerves
  • Caused by myobacterium leprae
  • Transmitted through resp. droplets
  • Endemic in poor, tropical countries
  • Causes disabling deformities
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11
Q

What are the characteristics of Mycobacterium leprae?

A
  • Acid-fast, obligate intracellular bacterium
  • Grows poorly in culture
  • Cell wall doesn’t stain with gram stain!
  • Hard to kill in normal ways - body forms granulomas to attack and eat the bugs (LIKE TB)
  • Bacteria does not like to be too hot
  • Only grows at skin temperature
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12
Q

What are the two types of Leprosy?

A
  • Tuberculoid (less severe)

- Lepromatous (more severe)

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13
Q

Describe Tuberculoid Leprosy:

A
  • Less severe, localized
  • Dry, scaly skin lesions
  • Nerve degeneration (anaesthesia, ulcers, contractures)
  • Nice T-cell response to the bug, with nice granuloma formation
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14
Q

What does Tuberculoid leprosy look like?

A
  • Large, red circular lesions on back or other parts
  • Granuloma with lighter colored outer rim seen in H&E slides
  • Few bugs shown on H&E
  • Macrophages form the granuloma
  • Nerves may look inflamed with many lymphocytes on the H&E slides
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15
Q

Describe Lepromatous Leprosy:

A
  • More severe, widespread
  • Skin, nerves, eye, mouth, testes, hands, feet
  • Patient’s immune system doesn’t respond
  • Leonine facies <– lion face nodules
  • Autoamputation may occur at extremities
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16
Q

What does Lepromatous Leprosy look like on H&E?

A
  • Many macrophages are present making foam: FOAMY HISTIOCYTES
  • TONS OF PINK BUGS
17
Q

Describe Varicella-Zoster:

A
  • Common viral infection of the PNS
  • After chickenpox, virus remains dormant in sensory ganglia of cord, brainstem
  • Reactivation: painful, vesicular, dermatomal rash (shingles - herpes zoster)
  • Histology: neuronal destruction
18
Q

What does herpes zoster look like on H&E? (can be in any herpes disease)

A

Multinucleated Giant cell - large, irregular, pink cell

19
Q

What are hereditary neuropathies and what is an example of one?

A
  • Hereditary, progressive, disabling syndromes
  • May involve motor, sensory, and/or autonomic nerves
  • May be related to amyloid deposition or metabolic disorders
  • Most common: motor and sensory
  • Hereditary Motor and Sensory Neuropathy Type I = Charcot-Marie-Tooth disease
20
Q

What is Hereditary Motor and Sensory Neuropathy Type I?

A
  • Charcot-Marie-Tooth disease, demyelinating type
  • Repetitive demyelination and remyelination
  • Muscle loss, loss of sensation but pain intact
  • Childhood or early adulthood onset
  • High arches, hammer toes, muscle atrophy
  • Sometimes loss of muscle in lower leg - “bottle leg”
  • Normal life span
21
Q

What do nerves look like on a slide form a CMT patient?

A
  • Onion bulb formation/layers seen around the nerve

- Since nerves have been demyelinated and demyelinated so many times, they look onion-like

22
Q

What are the two types of acquired metabolic/toxic neuropathies we talked about?

A
  • Peripheral Neuropathy in Diabetes

- Neuropathies associated with malignancy

23
Q

Tell me about peripheral neuropathy in diabetes:

A
  • COMMON!
  • Most common manifestation: symmetric sensory and motor neuropathy involving distal nerves
  • Dec. pain sensation in distal extremities
  • Some patients also have autonomic neuropathy and/or asymmetric neuropathy
  • Diabetes - patients don’t heal well due to circulation
  • Usually Glove & Stocking distribution
  • Can develop deep ulcers!
24
Q

Autoamputation:

A

From multiple repeated infectious lesions that heal up in a way that causes odd shaped lesions

25
Q

What are common neuropathies associated with malignancy?

A
  • Common cause of mononeuropathy:
  • –Brachial plexopathy from lung neoplasms
  • –Obturator palsy from pelvic neoplasms
  • –Cranial nerve palsies from brain tumors
  • Polyneuropathy can occur as a paraneoplastic effect
  • –Small cell lung cancer
  • –Plasma cell malignancies