Diseases of the PNS (finished)

Question 1

Describe the cause, histologic findings, and clinical course of Guillian-Barre syndrome.

Answer 1

Life-threatening disease of the PNS
Flu-like illness, then acute ascending paralysis
Immune-mediated demyelination
Usually resolves with time (Remyelination follows
)
“Acute inflammatory demyelinating polyradiculoneuropathy”
T cells and macrophages cause segmental demyelination; antibodies also present

Question 2

Describe the clinical findings in peripheral nerves in Leprosy

Answer 2

Slowly progressive infection of skin and nerves
Caused by Mycobacterium leprae
Transmitted through respiratory droplet
Endemic in poor tropical countries
Causes disabling deformities
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

Question 3

Describe the clinical findings in peripheral nerves in varicella-zoster virus

Answer 3

Common viral infection of the PNS!
After chickenpox, virus remains dormant in sensory ganglia of cord, brainstem
Reactivation: painful, vesicular, dermatomal rash, dangerous if it gets in the eyes
Histology: neuronal destruction

characteristic finding:
multinucleated giant cells

Question 4

Describe the three main patterns of peripheral nerve disease in adult-onset diabetes mellitus

Answer 4

Most common manifestation: symmetric sensory and motor neuropathy involving distal nerves
Decreased pain sensation in distal extremities
Some patients also have autonomic neuropathy and/or asymmetric neuropathy

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

Question 5

Guillain-Barré Morphology

Answer 5

Inflammation around venules, nerves
Lymphocytes, macrophages, plasma cells
Widely distributed throughout PNS
Most intense in spinal and cranial nerve motor roots and adjacent nerves

Question 6

Guillain-Barré Clinical Course

Answer 6

Symmetric, ascending paralysis
Rapid-onset weakness, loss of deep tendon reflexes
Some loss of sensation too
Elevated CSF protein (no lymphocytes though)
2-5% mortality (respiratory paralysis, autonomic instability, cardiac arrest, complications of treatment)

Question 7

Two Forms of Leprosy

Answer 7

Tuberculoid leprosy

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

Lepromatous leprosy

• More severe, widespread
• Skin, nerves, eye, mouth, testes, hands, feet
• Patient’s immune system doesn’t respond

Question 8

Hereditary Neuropathies

Answer 8

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

Question 9

Hereditary Motor and Sensory Neuropathy Type 1

Answer 9

Also called Charcot-Marie-Tooth disease, demyelinating type
Repetitive demyelination and remyelination: onion bulb formation
Muscle loss, loss of sensation but pain intact
Childhood or early adulthood
High arches, hammer toes, muscle atrophy
Normal life span