Peripheral Nerve Disorders Flashcards
Wallerian degeneration occurs (proximal/distal) to the site of injury.
distal
What are the Bands of Bungner?
proliferation of Schwann cells under the old basal lamina of a nerve with axons growing inside
What is segmental demyelination?
Scattered demyelination with replacement by thinner myelin and shorter variable internodes (normally the nodes of Ranvier have a set internodal length)
relative axonal sparing
What kind of demyelination is seen with diptheria?
segmental
Porphyria causes what type of neuropathy?
Rapid, severe, symmetric, motor > sensory loss, bilateral brachial weakness
Uremia causes what type of neuropathy?
painless, symmetric, sensorimotor, lower > upper limbs
In GBS, pathologic examination reveals _____.
perivascular mononuclear infiltrates and segmental demyelination
When is the protein peak seen in GBS on CSF?
5 weeks
What do nerve conduction studies show in GBS?
decreased velocity and amplitude
What percent of GBS patients have severe/permanent weakness?
10%
Experimental allergic neuritis is caused by _____.
T cell mediated attack of P2 protein
What is the inheritance of Dejerine Sottas? What type of disease is it?
AR
hereditary/hypertrophic (onion bulb) neuropathy
What is the inheritance of Refsum’s disease?
AR
What is Refsum’s disease?
a type of hereditary/hypertrophic (onion bulb) neuropathy
deficiency in phytanic acid oxidase
What is neuropraxia?
functional but no structural damage (nerve concussion) with temporary loss of function that may last 6–8 weeks
What is axonotemesis?
interruption of axons and myelin with intact perineurium and epineurium
spontaneous regeneration may occur at 1–2 mm/day
What is neurotemesis?
transection of the nerve and nerve sheath
axonal regeneration may lead to neuroma formation
Acute ophthalmoplegia can be seen in what metabolic disease? What is the mechanism?
diabetes
ischemia of the vaso nervosum
What is a Morton neuroma?
traumatic neuroma that forms on the digital nerve between the toes
What is Brachial Plexitis?
Idiopathic onset of upper limb pain and weakness that usually resolves in 6 to 12 weeks; there is no fever, leukocytosis, or elevated ESR
In carpal tunnel syndrome, what causes the compression?
transverse carpal ligament
What causes cubital tunnel syndrome?
caused by compression of the ulnar nerve under the two heads of the flexor carpi ulnaris
What is posterior interosseous syndrome?
Causes weakness of the radial-innervated forearm and hand muscles (supinator, extensor digitorum, extensor carpi ulnaris, and abductor pollicis longus). No sensory loss. It causes a finger drop without a wrist drop because of sparing of the extensor carpi radialis longus
What is anterior interosseous syndrome?
Pure weakness without sensory loss caused by compression of the anterior interosseous branch of the median nerve in the deep forearm. It involves the pronator quadratus, flexor pollicis longus, and flexor digitorum profundus 2 and 3 (FDP 4 and 5 are innervated by the ulnar nerve). Patients are unable to form the “okay” sign and demonstrate the “pinched” sign
