Computed tomography and psychometric test performances in patients with solvent induced chronic toxic encephalopathy and healthy controls.

Patients with chronic toxic encephalopathy caused by occupational exposure to organic solvents and diagnosed between 1976 and 1981 have been re-examined during a follow up period of 21-88 months (median 48). Thirty two patients underwent computed brain tomography (CT), were retested psychometrically, and the results were compared with a group of age matched control subjects from the same socioeconomic level. The age of the patients was 33-69 (median 55) and they had been exposed to organic solvents for 7-50 years (median 26). The CT examinations were quantified by linear measurements on the films of the four largest sulci, the minimum width of the cella media and the third ventricle. Bifrontal horn, bicaudate, and third ventricle--Sylvian fissure distances were also measured; and measurements were adjusted for variation in skull diameter. No differences were found between the patients and controls. Most of the measures were correlated with age, to a somewhat higher degree in the patients. The patient-control differences did not increase with increasing age of the subjects. Psychometrically the patients performed worse than the controls despite adjustments for possible differences of intellectual level in the two groups. In the patients correlations were found between some of the CT measures and psychometric test performances suggesting slower psychomotor speed and attention difficulties among subjects with central and cortical brain substance reduction. No such correlation was found in the control group. It is concluded that patients with solvent induced chronic toxic encephalopathy have no severe loss of brain substance.