A 30 year-old woman comes to the physician for evaluation of double vision for 2 days. She states that she had a tingling sensation and paraesthesia in her hand last month. MRI of the brain demonstrates a lesion in several areas of T2 hyperintensity consistent with axonal demyelination and a diagnosis of multiple sclerosis is made.
Last summer she had an episode of weakness in her right leg that resolved without any intervention.
Which of the following neuronal properties is most likely to decrease as a direct result of demyelination?

Question

Quizplus · Accepted Answer

Eductional Objective: The speed of conduction down an axon depends on 2 constants: the length constant and the time constant (ie, velocity = length/time).  Myelination increases the length constant and decreases the time constant, both of which improve axonal conduction speed.  Demyelination thus impairs stimulus transmission.

A 30 Year-Old Woman Comes to the Physician for Evaluation