A clinical and electrophysiological study of patients with polychlorinated biphenyl poisoning

Neurological examination of 28 patients, 4 years after serious poisoning by polychlorinated biphenyl contaminated cooking oil, are compared with similar examinations of the same patients two years earlier (in 1980). Clinical peripheral sensory neuropathy was found in 54%, headache in 36% and dizziness in 46% of the patients; these findings did not differ (p greater than 0.1) from those in 1980. Although the mean blood polychlorinated biphenyl concentration (19.2 ppb) in the patients was lower (p less than 0.001) than that in 1980 (35.9 ppb), it was still higher than the normal value (less than 4 ppb). There was no difference in the blood polychlorinated biphenyl concentration of patients with neurological manifestation from those without. Although the mean motor and sensory nerve conduction velocities (MNCV and SNCV) were still slower (p less than 0.06) than the mean normal NCV, the mean MNCV of tibial nerve and SNCV of sural nerve were improved (p less than 0.06) as compared with those in 1980. EEGs were normal except in two cases showing nonspecific slow wave changes. In addition, evoked potentials (somatosensory, visual and brain-stem auditory) were measured in this study and found to be normal in all 12 cases examined.