Neuro of the PNS Flashcards
Axonal Neuropathies are due to _______ and ______ insults
toxic, metabolic
During Axonal Neuropathies, the axons often degenerate in a __________, resulting in a __________ pattern
length-dependent fashion, “dying-back”
Which types of axons in Axonal Neuropathies are most susceptible?
Longest axons
What is the Axonal Neuropathy Electrophysiologic hallmark ?
reduction in signal amplitude owing to the dropout of axons from affected peripheral nerves with relative preservation of conduction velocity.
In Demyelinating Neuropathies, what are the primary targets of the damage?
Schwann cells with their myelin sheaths
T/F are axons relatively preserved during Demyelinating Neuropathies?
True
During Demyelinating Neuropathies, individual myelin sheaths degenerate in a __________ resulting in _______ damage of myelin segments
seemingly random pattern, discontinuous
During Demyelinating Neuropathies, in response, ________ proliferate and initiate repair through the formation of new myelin sheaths, but now _____ and _______ than the original ones
Schwann cells
shorter
thinner
What is the electrophysiologic Demyelinating Neuropathy hallmark?
is slowed nerve conduction velocity, reflective of the loss of myelin.
What do Neuronopathies result from and what do they lead to?
destruction of neurons, leading to secondary degeneration of axonal processes.
What are examples of neuronopathy insults ?
Infections like herpes zoster and toxins like platinum compounds
In neuronopathies, because the damage is at the level of the neuronal cell body, the peripheral nerve dysfunction is equally likely to affect the ________ and ________ parts of the body
proximal, distal
In peripheral axonopathies, it ONLY affects the __________ extremities
distal
What are Mononeuropathies?
single nerve and result in deficits in a restricted distribution dictated by nerve anatomy ex: Trauma, entrapment, and infections
Polyneuropathies affect ________ nerves and is usually __________
multiple nerves, usually symmetric
What are Polyneuropathies?
axons are affected in a length-dependent fashion leading to deficits that start in the feet and ascend with disease progression. The hands start when deficits at knee, resulting in a characteristic “stocking and glove” distribution of sensory deficits.
What are Mononeuritis multiplex?
individual nerves in a haphazard fashion. right wrist drop from involvement of the right radial nerve and a left foot drop from peroneal nerve damage. Vasculitis is a common cause.
What are Polyradiculoneuropathies
nerve roots as well as peripheral nerves, leading to diffuse symmetric symptoms in proximal and distal parts of the body.
Guillain-Barré Syndrome is an acute inflammatory__________
Demyelinating Polyneuropathy
In Guillain-Barré Syndrome, where does the weakness begin?
in the distal limbs that rapidly advances to affect proximal muscle function (“ascending paralysis”)- respiratory compromise
What are the histologic features of Guillain-Barré Syndrome
inflammation and demyelination of spinal nerve roots and peripheral nerves (radiculoneuropathy)
What are 2/3 of causes of Guillain-Barré Syndrome preceeded?
by an acute, influenza-like illness convalescing by the time the neuropathy becomes symptomatic
What are the inciting agents of Guillain-Barré Syndrome ?
Campylobacter jejuni,CMV, EBV, andMycoplasma pneumoniaeas well as prior vaccination
What are Guillain-Barré Syndrome’s main clinical feature?
Ascending paralysis and areflexia
