NCS Neurologic Pathophysiology 2

Question 1

Uhthoff's phenomenon in multiple sclerosis is best explained by which pathophysiologic mechanism?

Accepted Answer

Heat-induced conduction failure in demyelinated axons

Answer

Demyelinated axons have reduced safety factor for conduction, and even small rises in temperature further impair sodium channel function, causing transient neurologic deficits.

Question 2

Lewy bodies in Parkinson's disease are primarily composed of which misfolded protein?

Accepted Answer

Alpha-synuclein

Answer

Lewy bodies are intraneuronal inclusions predominantly composed of aggregated alpha-synuclein, a presynaptic protein implicated in dopaminergic neuron death.

Question 3

In Guillain-Barré syndrome (AIDP subtype), nerve conduction studies most characteristically show:

Accepted Answer

Prolonged distal latencies and slowed conduction velocity indicating demyelination

Answer

AIDP is an acute inflammatory demyelinating polyneuropathy, so NCS demonstrates slowed conduction velocity, prolonged distal latencies, conduction block, and temporal dispersion.

Question 4

A patient with ALS demonstrates both upper and lower motor neuron signs. The hallmark LMN finding that most strongly supports ALS over a structural lesion is:

Accepted Answer

Fasciculations at rest in multiple body regions

Answer

Widespread fasciculations at rest across multiple myotomal distributions indicate diffuse anterior horn cell involvement, a key LMN signature of ALS not explained by a focal structural lesion.

Question 5

The amyloid cascade hypothesis of Alzheimer's disease proposes that the initiating pathological event is:

Accepted Answer

Abnormal processing of APP leading to Aβ42 accumulation

Answer

The amyloid cascade hypothesis holds that accumulation of Aβ42 peptide from abnormal APP cleavage by beta- and gamma-secretases is the upstream trigger for downstream tau pathology and neurodegeneration.

(NCS) Neurologic Clinical Specialist Practice Test

(NCS) Neurologic Clinical Specialist Practice Test

NCS Neurologic Pathophysiology 2