SPECT abnormalities with unilateral arm dystonia in a young mentally retarded apprentice cook: contralateral thalamo-cortical dysfunction.

We report a young, mentally retarded apprentice cook with a 2-month history of right upper extremity dystonia, for whom diazepam therapy was efficacious. We evaluated brain perfusion by single photon emission tomography (SPECT) before and after diazepam treatment. The abnormal hyperperfusion in the left thalamus and hypoperfusion in the left frontal cortex were normalized on the second SPECT under the successful diazepam treatment. These findings were indicative of functional changes in the left thalamus and left frontal cortex.