Neurophysiological and psychological picture of solvent poisoning

Neurophysiological and psychological tests were administered to 107 patients--48 men and 59 women--with a diagnosis of solvent poisoning after longstanding (mean 9.6 years for males and mean 7.6 years for females) occupational exposure. Electroencephalography (EEG) and a wide psychological test battery were applied in all cases, and electroneurographic measurements were performed in 77 subjects. Sixty-five percent of the patients showed an abnormal EEG, and excessive beta activity, not induced by drugs, was found in 54% of patients. At least one abnormally slow nerve conduction velocity (CV) was found in 48 out of 77 patients. The scores of Wechsler Adult Intelligence Scale (WAIS) subtests Digit Span (DSp) and Digit Symbol (DSy) among the men and scores of Similarities (Sim), Digit Symbol (DSy), Picture Completion (PC), and Block Design (BD) among the women were statistically significantly lower than in the Finnish standardization sample. Long duration of exposure was related to poor performance in the Santa Ana Dexterity test in both sexes, to poor visual memory among the men and to poor visuoconstructive intellectual tasks among the women. The background frequency in the EEG showed a correlation to the DSp test of WAIS and some relationship emerged also between the former and the BD, the Symmetry Drawing test, the Santa Ana Dexterity test, and the Mira test. Focal slow wave abnormalities were related to inaccurate hand movements in the psychomotor Mira test. Neurophysiological and psychological tests seem to reflect partly different aspects of neurologic effects and their combined use helps in the evaluation of hazards of solvent exposure.