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The severity of parkinsonism and response to levodopa vary in patients with multiple system atrophy (MSA) because of the heterogeneity of nigrostriatal neuropathology. To investigate the difference in clinical features between MSA patients with predominantly pre-synaptic nigrostriatal dysfunction and those with trans-synaptic nigrostriatal dysfunction. We retrospectively analyzed clinical data of 61 patients with MSA who underwent both [18F]FP-CIT-PET and [18F]FDG-PET within 3 months of clinical evaluation, and who had ≤3 years of disease duration. Tracer uptake of the striatum on [18F]FP-CIT-PET and glucose metabolism of the striatum on [18F]FDG-PET were analyzed using eight striatal subregional volumes-of-interest templates. The patients were classified into two subgroups according to the predominant pre-synaptic tracer uptake loss of the posterior putamen on [18F]FP-CIT-PET (MSA-SNpc, n = 21) and trans-synaptic dopaminergic dysfunction reflected by both [18F]FP-CIT-PET and [18F]FDG-PET (MSA-STR, n = 40). Parkinsonian features were significantly more severe in the MSA-STR group than in the MSA-SNpc group (P =.005) and cerebellar ataxia was significantly more severe in the MSA-SNpc group (P =.036). The cerebellar type of MSA was significantly more common in the MSA-SNpc group (P =.001). There was no difference in age at onset, disease duration at the time of study, or Mini-Mental Status Examination scores between the groups. Patients with MSA showed distinct clinical features depending on whether the pattern of nigrostriatal dysfunction was predominantly pre-synaptic or trans-synaptic. • Brain [18F]FP-CIT- and [18F]FDG-PET is useful to understanding the features of MSA. • Parkinsonism is more severe in MSA with trans-synaptic nigrostriatal dysfunction. • Cerebellar ataxia is more severe in MSA with presynaptic nigrostriatal dysfunction. • MSA shows distinct features depending on the pattern of nigrostriatal dysfunction. [ABSTRACT FROM AUTHOR]

We evaluated cerebellar subregional metabolic alterations in patients with cerebellar ataxia, a representative disease involving the spinocerebellum. We retrospectively analyzed 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) images in 44 patients with multiple system atrophy of the cerebellar type (MSA-C), 9 patients with spinocerebellar ataxia (SCA) type 2, and 14 patients with SCA type 6 and compared with 15 patients with crossed cerebellar diaschisis (CCD) and 89 normal controls. Cerebellar subregional metabolism was assessed using 13 cerebellar subregions (bilateral anterior lobes [ANT], superior/mid/inferior posterior lobes [SUPP/MIDP/INFP], dentate nucleus [DN], anterior vermis [ANTV], and superior/inferior posterior vermis [SUPV/INFV]) to determine FDG uptake ratios. MSA-C and SCA type 2 showed severely decreased metabolic ratios in all cerebellar subregions compared to normal controls (ANT, 0.58 ± 0.08 and 0.50 ± 0.06 vs. 0.82 ± 0.07, respectively, p < 0.001). SCA type 6 showed lower metabolic ratios in almost all cerebellar subregions (ANT, 0.57 ± 0.06, p < 0.001) except INFV. Anterior-posterior lobe ratio measurements revealed that SCA type 2 (Right, 0.81 ± 0.05 vs. 0.88 ± 0.04, p < 0.001; Left, 0.83 ± 0.05 vs. 0.88 ± 0.04, p = 0.003) and SCA type 6 (Right, 0.72 ± 0.05 vs. 0.88 ± 0.04, p < 0.001; Left, 0.72 ± 0.05 vs. 0.88 ± 0.04, p < 0.001) showed preferential hypometabolism in the anterior lobe compared to normal controls, which was not observed in CCD and MSA-C. Asymmetric indices were higher in CCD and MSA-C than in normal controls (p < 0.001), whereas such differences were not found in SCA types 2 and 6. In summary, quantitative analysis of cerebellar subregional metabolism ratios revealed preferential involvement of the anterior lobe, corresponding to the spinocerebellum, in patients with cerebellar ataxia, whereas patients with CCD and MSA-C exhibited more asymmetric hypometabolism in the posterior lobe. [ABSTRACT FROM AUTHOR]

Background: Although cognitive impairment is not a consistent feature of multiple system atrophy (MSA), increasing evidence suggests that cognitive impairment is common in MSA with predominant parkinsonism (MSA-P). It is assumed that the cognitive impairment in MSA-P is caused by the striatal dysfunction and disruption of striatofrontal connections. The aim of this study was to evaluate the relationship between regional glucose metabolism in the frontal cortex and striatum in patients with MSA-P using [18F]FDG brain PET. Methods: Twenty-nine patients with MSA-P and 28 healthy controls underwent [18F]FDG brain PET scan. The [18F]FDG brain PET images were semiquantitatively analyzed on the basis of a template in standard space. The regional glucose metabolism of the cerebral cortex and striatum were compared between MSA-P and healthy control groups. The correlations between age, symptom duration, H&Y stage, UPDRS III score, MMSE score, and glucose metabolism in the cerebellum and striatum to glucose metabolism in the frontal cortex were evaluated by multivariate analysis. Results: The glucose metabolism in the frontal cortex and striatum in MSA-P patients were significantly lower than those in healthy controls. Glucose metabolism in the striatum was the most powerful determinant of glucose metabolism in the frontal cortex in MSA-P. Only age and glucose metabolism in the cerebellum were independent variables affecting the glucose metabolism in the frontal cortex in healthy controls. Conclusion: The decrease in frontal glucose metabolism in MSA-P is related to the decrease in striatal glucose metabolism. This result provided evidence of striatofrontal deafferentiation in patients with MSA-P. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate whether striatal dopamine transporter (DAT) loss as measured by F-fluorinated- N-3-fluoropropyl-2-b-carboxymethoxy-3-b-(4-iodophenyl) nortropane ([F]FP-CIT) PET differs according to the metabolic subtype of multiple system atrophy (MSA) as assessed by [F]FDG PET. Methods: This retrospective study included 50 patients with clinically diagnosed MSA who underwent [F]FP-CIT and [F]FDG brain PET scans. The PET images were analysed using 12 striatal subregional volume-of-interest templates (bilateral ventral striatum, anterior caudate, posterior caudate, anterior putamen, posterior putamen, and ventral putamen). The patients were classified into three metabolic subtypes according to the [F]FDG PET findings: MSA-P (striatal hypometabolism only), MSA-mixed (both striatal and cerebellar hypometabolism), and MSA-C (cerebellar hypometabolism only). The subregional glucose metabolic ratio (MR), subregional DAT binding ratio (BR), and intersubregional ratio (ISR; defined as the BR ratio of one striatal subregion to that of another striatal subregion) were compared according to metabolic subtype. Results: Of the 50 patients, 13 presented with MSA-P, 16 presented with MSA-mixed, and 21 presented with MSA-C. The BR of all striatal subregions in the MSA-P and MSA-mixed groups were significantly lower than those in the MSA-C group. The posterior putamen/anterior putamen ISR and anterior putamen/ventral striatum ISR in the MSA-P and MSA-mixed groups were significantly lower than those in the MSA-C group. Conclusion: Patients with MSA-P and MSA-mixed showed more severe DAT loss in the striatum than patients with MSA-C. Patients with MSA-C had more diffuse DAT loss than patients with MSA-P and MSA-mixed. [ABSTRACT FROM AUTHOR]