What suggests segmental demyelination on NCV
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.
Decreased CAMP amplitudes
Uniform slowing of nerve conduction
Decreased area under CAMP curve
No evidence of distal conduction