This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
What suggests segmental demyelination on NCV 
Select and explain. 
A. Decreased CAMP amplitudes, B. Uniform slowing of nerve conduction, C. Decreased area under CAMP curve, D. No evidence of distal conduction
A: Decreased CAMP amplitudes
Answer: A: Decreased CAMP amplitudes 
Explanation: Answer- A. Decreased CAMP amplitudesSegmental Demyelination : Because there is variable slowing or different nerve fibers withing the nerve, conduction velocity will be slowed and distal latencies will be prolonged in segmentally demyelinatiing injuries.CMAP amplitudes may be decreased because of temporal dispersion, not because of axonal damage. Therefore, the CMAP may be longer in duration. However, the area under the CAMP will be normal.