Neuromuscular

Demyelinating Neuropathy with anti-MAG Antibodies

Prolonged Distal Latency
Temporal Dispersion
Absent SNAPs


Prolonged Distal Latency

Sweep speed = 5 ms/div; Sensitivity = 5 mV/div
  • Distal latencies are long.
  • Nerve conduction velocities may be relatively spared
      early in the course of anti-MAG neuropathies.
from M. Al-Lozi

Temporal Dispersion of Compound Motor Action Potentials (CMAPs)

Sweep speed = 5 ms/div; Sensitivity = 5 mV/div
  • Amplitude of CMAPs is reduced with proximal nerve stimulation.
  • Duration of CMAPs is prolonged with proximal nerve stimulation.
  • Area of CMAPs is relatively spared.
  • There is no evidence of conduction block.
  • Also see: CIDP
from M. Al-Lozi

Absent Sensory Potentials

  • Sensory nerve action potentials (SNAPs) are reduced
      out of proportion to motor potentials.
from M. Al-Lozi


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6/14/00