Electrodiagnostic studies (NCS/EMG)

Findings: Reduced amplitude of the left ulnar compound muscle action potential (CMAP). The left median, tibial and peroneal CMAPs are normal. The left sural, median and ulnar sensory nerve action potentials (SNAPs) are normal. Needle EMG shows fibrillation potentials, positive sharp waves, and fasciculations in bilateral leg, left arm, and thoracic paraspinal muscles. Motor units were generally large and long in the same areas.

Impression: Abnormal study. There is electrodiagnostic evidence of acute denervation and chronic reinnervation in three spinal regions.