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George E. Carvell, PhD, PT   University of Pittsburgh
PERIPHERAL NERVE CONDUCTION:Sensory Nerve Conduction Slowing
Slow Sensory Nerve Conduction
Slowing of nerve conduction may result from an acute ischemia, demyelination, or as a result of regeneration (conduction in immature axons with reduced diameter and immature myelination). Conduction time is longer than normal and the compound action potential waveforms tend to be temporally dispersed (less uniformity in conduction of  involved axons). Peripheral neuropathies often show slow nerve conduction in distal segments of upper and lower extremity peripheral nerves. Both sensory and motor axons are commonly involved. If the neuropathy is restricted to small fibers, NCV should be normal.
GMOMM  2001
  Antidromic Sensory Nerve Conduction Studies record responses from digital nerves or superficial cutaneous nerves. Stimuli are delivered at several locations along the course of the nerve. Brief (0.1 msec monophasic DC pulses at 1/sec) but strong (supramaximal strength) stimuli are used. Responses are recorded as simulated digital oscilloscope traces in these animations. A ground electrode is placed over non-contractile tissue (not shown). The example shown here is antidromic sensory nerve conduction for the Median Nerve. Ring recording electrodes are placed around the proximal and middle phalanges of the index finger. Proximal and distal stimuli & stimulation sites are the same as for median motor nerve conduction. Sensory compound action potentials are small (mV range) and high amplifier gain is required. If peripheral nerve disease is present the signal to noise ratio may require waveform averaging to reveal tiny responses buried within the background noise (note calibration scale on scope).