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Reduced pre-movement facilitation of motor evoked potentials in spinocerebellar degeneration
T Nomura1, T Takeshima, K Nakashima
1Department of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, 36-1 Nishimachi, Yonago 683-8504, Japan. ntnomura@grape.med.tottori-u.ac.jp
Objectives:
The aim of this study was to clarify the cerebellar effects on the motor area of the cerebral cortex and abnormal control mechanisms of voluntary movement in spinocerebellar degeneration (SCD). We used transcranial magnetic stimulation (TMS) to study the change in the motor evoked potentials (MEPs) before voluntary movement (pre-movement facilitation) in patients with SCD.
Subjects And Methods:
Pre-movement facilitation of MEPs in subjects' muscles was observed during their thumb movement intention. Patients with SCD, who showed cerebellar signs, without pyramidal or extrapyramidal signs, were examined. TMS was applied randomly during the interval between the "go" signal and the onset of voluntary EMG. The MEPs were recorded from the abductor brevis pollicis muscle.
Results:
Patients with SCD showed a delay of task performance. In control subjects, the amplitude of MEPs was significantly facilitated (increased) prior to voluntary movement. In patients with SCD, pre-movement facilitation of the amplitude of MEPs was significantly decreased in the study with subthreshold TMS.
Conclusions:
Disturbance of pre-movement facilitation in SCD may indicate incomplete cerebellar regulation of voluntary movements.