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Abnormalities of finger representations in the somatosensory cortex have been identified in patients with focal hand dystonia. Measuring blood flow with positron emission tomography (PET) can be use to demonstrate functional localization of receptive fields.
A vibratory stimulus was applied to the right thumb and little finger of six healthy volunteers and six patients with focal hand dystonia to map their receptive fields using H215O PET.
The cortical finger representations in the primary somatosensory cortex were closer to each other in patients than in normal subjects. No abnormalities were found in secondary somatosensory cortex, but the somatotopy there is less well distinguished.
These data confirm prior electrophysiological and functional neuroimaging observations showing abnormalities of finger representations in somatosensory cortex of patients with focal hand dystonia.
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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.
To investigate the relationship between presenting clinical manifestations and imaging features of multisystem neuronal dysfunction in MSA patients, using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET).
We studied 50 consecutive MSA patients with characteristic brain MRI findings of MSA, including 34 patients with early MSA-parkinsonian (MSA-P) and 16 with early MSA-cerebellar (MSA-C). The cerebral glucose metabolism of all MSA patients was evaluated in comparison with 25 age-matched controls. 18F-FDG PET results were assessed by the Statistic Parametric Mapping (SPM) analysis and the regions of interest (ROI) method.
The mean time from disease onset to 18F-FDG PET was 25.9±13.0 months in 34 MSA-P patients and 20.1±11.1 months in 16 MSA-C patients. Glucose metabolism of the putamen showed a greater decrease in possible MSA-P than in probable MSA-P (
Our results may suggest that the early neuropathological pattern of possible MSA with a predilection for the striatonigral or olivopontocerebellar system differs from that of probable MSA, which has prominent involvement of the autonomic nervous system in addition to the striatonigral or olivopontocerebellar system.
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About two thirds of the patients with multiple system atrophy (MSA) do not respond to levodopa treatment. Postmortem pathological studies and one retrospective [18F]-deoxyglucose positron emission tomography (FDGPET) study attributed such poor response to the striatal degeneration. We prospectively investigated the relationship between levodopa responsiveness and the metabolic activities of the striatum and cerebellum in MSA patients.
In 39 patients with MSA, the UPDRS motor score was assessed and two sets of timed motor tests were perform ed before and after the levodopa treatment. After quantitative FDG PET and baseline evaluation, treatment w as started with 3 tablets of Sinemet® 25/250 mg a day. Clinical assessments were performed monthly for three months. Metabolic activities of the caudate, anterior putamen, posterior putamen, cerebellar cortex and cerebellar vermis were measured. We compared the measurements with mean percentage changes of motor function. Also, using statistical parametric mapping (SPM) analysis, we tried to find brain areas in which metabolism correlated with the clinical changes.
Mean percentage improvements of UPDRS motor scores w ere correlated with glucose metabolism in the posterior putamen and cerebellar vermis. The mean percentage improvements of performance in Purdue peg board test correlated with the glucose metabolism in the cerebellar cortex and vermis. In SPM analysis, cerebellar glucose metabolism correlated with the improvement of UPDRS motor score and the performance of two timed motor tests.
The integrity of cerebellum, as well as posterior putamen, may be an important factor for showing the response to levodopa.