The ipsilateral cerebellar hemisphere is overactive during hand movements in akinetic parkinsonian patients.
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.
Rascol
O
O
Department of Medical and Clinical Pharmacology, University Hospital, Toulouse, France.
Sabatini
U
U
Fabre
N
N
Brefel
C
C
Loubinoux
I
I
Celsis
P
P
Senard
J M
JM
Montastruc
J L
JL
Chollet
F
F
D001931:Brain Mapping; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D006225:Hand; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon
D007980:Levodopa