[Magnetic resonance imaging in chronic toluene abuse, and volitional hyperkinesia]

We described the central nervous system impairments and findings of magnetic resonance imaging (MRI) of the brain in three chronic toluene abusers. Patient 1 and 2 had a history of chronic toluene inhalation for 1 or 2 years and patient 3 has a history of it for 16 years. The patients were evaluated after an abstinence period of at least 4 weeks, to avoid neurologic effects of acute intoxication. Neurologic signs included cerebellar, cognitive and pyramidal dysfunctions in all 3 patients and hyperkinésie volitionnelle (HV; volitional hyperkinesia) in patient 3 who had a long history of toluene inhalation. This HV was found to be tremulous by surface electromyography. Appearance of HV in chronic toluene abuse seems to be related to a period or quantity of inhalation of toluene. T2-weighted MRI in the 3 patients revealed the following abnormalities: (1) increased signal intensity of middle cerebellar peduncle and cerebellar white matter, deep cerebral white matter, and posterior limb of internal capsule; and (2) decreased signal intensity of thalamus and basal ganglia. Proton-weighted MRI in patient 3 with HV showed decreased signal intensity of lateral portion of the thalamus and tegmentum of the brainstem. These MRI findings correlate remarkably well with the neurologic signs seen in the 3 patients. Cerebellar, cognitive, and pyramidal dysfunctions appear to be related to involvement of middle cerebellar peduncle (cerebellar white matter), deep cerebral white matter, and internal capsule, respectively, and HV seems to correlate with involvement of the thalamus or tegmentum of the brainstem, especially the latter.