Neuromuscular disorders in a new toxic syndrome: electrophysiological study--a preliminary report

The electrophysiological features in 145 patients with a new toxic syndrome related to ingestion of adulterated oil are described. Myalgia, joint limitation, weight loss, cramps, progressive weakness and wasting, sensory disturbances that can be asymmetrical or patchy, and scleroderma-like changes were the main clinical features. The electrophysiological findings suggest that the neuromuscular impairment in the new toxic syndrome is a slowly progressive mixed axonal neuropathy, which starts asymmetrically in some patients, with involvement of proximal and distal muscles as well as paraspinal and respiratory muscles. Muscle and nerve biopsies confirm the neuropathy, and show severe perineuritis and perineurial and perimysial fibrosis. The single fiber electromyography (SFEMG) study showed increased motor unit fiber density directly related to the time after onset of the illness. Unstable complex potentials were found after 6 months of evolution, which suggests that an effective collateral reinnervation was delayed following a long period of progressive denervation.