PATTERNS OF CEREBRAL GLUCOSE-METABOLISM DETECTED WITH POSITION EMISSION TOMOGRAPHY DIFFER IN MULTIPLE SYSTEM ATROPHY AND OLIVOPONTOCEREBELLAR ATROPHY

We used positron emission tomography with [F-18]fluorodeoxyglucose to study local cerebral metabolic rates for glucose (1CMRglc) in patients with multiple system atrophy (MSA), sporadic olivopontocerebellar atr ophy (sOPCA), and dominantly inherited olivopontocerebellar atrophy (d OPCA) in comparison with normal control subjects. In MSA, absolute 1CM Rglc was significantly decreased in the brainstem, cerebellum, putamen , thalamus, and cerebral cortex. In sOPCA, absolute 1CMRglc was signif icantly decreased in the brainstem, cerebellum, putamen, thalamus, and cerebral cortex. In sOPCA, absolute 1CMRglc was significantly decreas ed in the brainstem and cerebellum but not in the other structures. Ex amination of 1CMRglc normalized to the cerebral cortex in comparison w ith normal controls revealed in MSA significant decreases in the brain stem, cerebellum, and putamen but, in both sOPCA and dOPCA, significan t decreases only in the brainstem and cerebellum. The findings indicat e that these three disorders all show a marked decrease of 1CMRglc in the brainstem and cerebellum but differ in the degree of hypometabolis m in forebrain and cerebral cortical structures. The results are consi stent with the possibility that, in many cases, sOPCA will evolve into MSA. Moreover, positron emission tomography may provide helpful diagn ostic information in these neurodegenerative diseases.