Residual electroneurographic modifications in subjects with n-hexane induced polyneuropathy: a follow-up study

A group of 90 subjects affected by n-hexane polyneuropathy were studied again after at least one year from cessation of occupational exposure to the neurotoxic agent. Neurological examinations, conduction velocities and distal latencies in sensory (sural and median) and motor (peroneal and ulnar) nerves were evaluated in order to study the evolution of the disease. The percentage of subjects with abnormal leg deep tendon reflexes, leg cutaneous sensitivity or vibration sensation was statistically higher in subjects who had ceased n-hexane exposure for less than 10 years than in the other subjects; however, no differences between these two groups were found for electrophysiological parameters. A complete recovery of motor nerve velocities was found. On the contrary, sensory nerve velocities, sensory nerve distal latencies, as well as ulnar nerve latency, were statistically different from controls, even if they were also statistically different from the values which had been recorded at the time of diagnosis. We conclude that in n-hexane polyneuropathy motor nerve components improve, while the sensory nerves are more seriously affected and do not completely recover, even after more than 10 years without exposure to the toxic agent.