the patient presented himself to us at the age of 54 yr with a history of intermittent attacks of dizziness and mild sense of disequilibrium lasting minutes to a whole day for years . the laboratory tests were included serum profiles of liver and kidney functions ; complete blood counts ; serum level of vitamin e , b12 , and folic acid ; and studies of thyroid function , which showed normal results . a search for occult malignancy and 5 years of follow revealed no evidence of malignancy . the first brain magnetic resonance imaging ( mri ) and brain magnetic resonance angiography ( mra ) showed no specific abnormality ( figure 1 ) . the first neuropsychological tests showed normal cognitive function and evaluation for metabolic derangement were normal . over the subsequent years , the episodic symptoms slowly progressed in the frequency , severity , and duration . and the symptoms responded poorly to levodopa therapy . when he visited our hospital again at the age of 56 yr he showed severe ataxic gait , intention tremor , dysarthria , as well as urinary incontinence and orthostatic hypotension . the neurologic examination showed scanning slurred speech , wide based ataxic gait , impaired tandem gait , swing both in eye - open and closure on the romberg test . follow up brain mri showed cerebellar atrophy of moderate degree and mild frontal atrophy ( figure 1 ) . there was diffusely decreased metabolism on both cerebellar hemisphere , prominence of cerebellar cortical area , vermis , cerebellar peduncle and middle pons , relatively sparing of deep cerebellar nuclei ( figure 2 ) . third brain mri done at the age of 58 yr showed hot cross bun sign , indicating degeneration of transverse pontine fibers as well as bilateral putaminal atrophy . extensive genetic tests for spinocerebellar ataxia type 1 , 2 , 3 , 6 , 7 , 8 and point mutation of 47 exons of cacna1a gene revealed no abnormalities . he also has glucose hypometabolism of cerebellum and pons as well as severe atrophy of these areas . the hot cross bun sign and putaminal atrophy appeared apparently at 3rd mri , indicating that it might not appear in the first several years with clinical symptoms . all the five patients showed asymmetric irregular hypometabolic areas and four of them showed cerebellar cortical involvement . visual analysis of the fdg - pet of our patient shows very clear discrimination of hypometabolic area of cerebellum.3 it is characteristic that deep cerebellar nuclei were relatively spared and the hypometabolic areas are quite symmetric ( figure 2 ) . the cerebellar cortex , containing purkinje cells , showed most prominent hypometabolic area and cerebellar white matter showed relatively lesser hypometabolism . the reason why does the cerebellar cortex is vulnerable to the mechanism of the disease could be explained by glutamate excitotoxicity.4 glutamate dehydrogenase , an enzyme central to glutamate metabolism , is significantly reduced in patients with heterogenous neurological disorders characterized by msa and predominant involvement of the cerebellum and its connections.4 moreover , there are relative deficiencies in aldolase c and excitatory amino acid transporter ( eaat4 ) that are localized extrasynaptically on purkinje cell spines than other areas of brain.5 the enzymes work as glutamate transporters and play a critical role in the maintenance of low extracellular concentrations of glutamate . in case of global brain ischemia or other excitotoxic injuries , the relative deficiency of the enzymes is related to severe damage of purkinje cells than other areas of cerebellum.6 secondly , the deep cerebellar nuclei may have benefit of being proximity from brainstem and could have more blood supply for survival.7 our report , as we know , shows the first case of preserved metabolism of deep cerebellar nuclei relative to cerebellar cortical area .
the cerebellar glucose metabolism of multiple system atrophy with predominant cerebellar ataxia ( msa - c ) is known to be decreased but is not defined among areas of cerebellum . 
 we encountered a 54-year - old man who developed dizziness and progressive ataxia followed by urinary incontinence and orthostatic hypotension , all of those symptoms progressed relentlessly and the symptoms responded poorly to levodopa therapy . visual analysis and statistical parametric mapping analysis of f-18 fluorodeoxyglucose positron emission tomography showed hypometabolism of both cerebellar hemisphere , severe at cortical area , and pons . 
 there was clear sparing of deep cerebellar nuclei . 
 our report , as we know , shows the first case of preserved glucose metabolism of deep cerebellar nuclei relative to cerebellar cortex in an msa - c patient .