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The ipsilateral cerebellar hemisphere is overactive during hand movements in akinetic parkinsonian patients.

O Rascol, U Sabatini, N Fabre, C Brefel, I Loubinoux, P Celsis, J M Senard, J L Montastruc, F Chollet
DOI: http://dx.doi.org/10.1093/brain/120.1.103 103-110 First published online: 1 January 1997

Summary

We compared the rCBF changes induced by the execution of a finger-to-thumb opposition motor task in the cerebellar hemispheres of 12 normal subjects, 12 parkinsonian patients whose medication had been withheld for at least 18 h and 16 parkinsonian patients on medication using single photon emission tomography and i.v. 133Xe. The normal subjects and parkinsonian patients on medication exhibited the same pattern of response, with a significant increase in rCBF in the contralateral primary motor cortex and in the supplementary motor areas. No significant rCBF change was detected in the cerebellum of these two groups; this finding was expected since our technique cannot detect cerebellar activation when the motor task is executed at a relatively low rate and small amplitude as it was in this study. The parkinsonian patients off medication exhibited a markedly different pattern of activation characterized by a significant overactivation in the ipsilateral cerebellar hemisphere and a significant underactivation in the supplementary motor areas. These results suggest that parkinsonian patients off medication may try to compensate for their basal ganglia-cortical loop's dysfunction using other motor pathways involving cerebellar relays.