Cortical motor overactivation in parkinsonian patients with L-dopa-induced peak-dose dyskinesia.
We have studied the regional cerebral blood flow (rCBF) changes induced by the execution of a finger-to-thumb opposition motor task in the supplementary and primary motor cortex of two groups of parkinsonian patients on L-dopa medication, the first one without L-dopa induced dyskinesia (n = 23) and the other with moderate peak-dose dyskinesia (n = 15), and of a group of 14 normal subjects. Single photon emission tomography with i.v. 133Xe was used to measure the rCBF changes. The dyskinetic parkinsonian patients exhibited a pattern of response which was markedly different from those of the normal subjects and non-dyskinetic parkinsonian patients, with a significant overactivation in the supplementary motor area and the ipsi- and contralateral primary motor areas. These results are compatible with the hypothesis that an hyperkinetic abnormal involuntary movement, like L-dopa-induced peak dose dyskinesia, is due to a disinhibition of the primary and associated motor cortex secondary to an excessive outflow of the pallidothalamocortical motor loop.
Rascol
O
O
INSERM U455, University Hospital of Toulouse, France.
Sabatini
U
U
Brefel
C
C
Fabre
N
N
Rai
S
S
Senard
J M
JM
Celsis
P
P
Viallard
G
G
Montastruc
J L
JL
Chollet
F
F
D000368:Aged; D000704:Analysis of Variance; D002560:Cerebrovascular Circulation / Q000502:physiology; D004409:Dyskinesia, Drug-Induced / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007980:Levodopa / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015999:Multivariate Analysis; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology*; D012016:Reference Values; D015899:Tomography, Emission-Computed, Single-Photon
D007980:Levodopa