Time course of electrophysiological findings for patients with solvent poisoning. A descriptive study.

The time course of electroencephalographic (EEG) and electroneuromyographic (ENMG) findings was studied among 87 patients (40 men and 47 women) with a diagnosis of chronic solvent intoxication after occupational exposure. Neurophysiological studies were initially performed around the time of diagnosis, and all the patients were reexamined three to nine years later. No control group was available for the follow-up. Upon diagnosis 67% of the patients had an abnormal EEG, the majority with diffuse slow-wave abnormalities. The reexamination showed improvement in the EEGs of 47%, but the percentage of patients with paroxysmal abnormalities had increased from the initial 6 to 17. The percentage of patients with neuropathic findings was 62 for the first and 74 for the second ENMG. Upon reexamination fibrillations were seen in 46% (in 38% in the initial examination), and some loss of motor units was found for 61% (for 54% in the initial examination). Mild improvement in the neuropathic findings was noted for 60%, but the neuropathic findings of 25% showed slight deterioration during the follow-up period. The EEG findings showed a time course resembling that described after external head injuries. The ENMG findings resembled those described in hexa-carbon-induced or carbon disulfide-induced neuropathy. Controlled studies are recommended to examine the observed slight associations between electrophysiological findings and the type of chemical exposure.