Movement disorders : official journal of the Movement Disorder Society
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The neural mechanisms underlying unintended mirror movements (MMs) of one hand during unimanual movements of the other hand in patients with Parkinson's disease (PD) are largely unexplored. Here we used surface electromyographic (EMG) analysis and focal transcranial magnetic stimulation (TMS) to investigate the pathophysiological substrate of MMs in four PD patients. Surface EMG was recorded from both abductor pollicis brevis (APB) and first dorsal interosseous (FDI) muscles. ⋯ During either mirror or voluntary finger tapping, 5 Hz repetitive TMS (rTMS) of the contralateral M1 disrupted EMG activity in the target FDI, whereas the effects of rTMS of the ipsilateral M1 were by far slighter. During either mirror or voluntary APB contraction, paired-pulse TMS showed a reduction of short-interval intracortical inhibition in the contralateral M1. These findings provide converging evidence that, in PD, MMs do not depend on unmasking of ipsilateral projections but are explained by motor output along the crossed corticospinal projection from the mirror M1.
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Randomized Controlled Trial
Blinded placebo crossover study of gabapentin in primary orthostatic tremor.
Primary orthostatic tremor (OT) is a rare but disabling condition characterized by leg tremor and feelings of instability during stance. Previous studies have reported a reduction in OT symptoms with gabapentin treatment. In this study, we report on the benefits of gabapentin treatment in a double-blind placebo-controlled crossover study of 6 OT patients. ⋯ Tremor amplitude was reduced to 79% +/- 11% and sway area to 71% +/- 11% of the placebo state. QOL improved in all patients, no adverse drug effects were noted, and symptomatic benefit was maintained at follow-up (mean = 19 months). The findings confirm that gabapentin is an effective treatment for OT, reducing both tremor and postural instability and improving quality of life, and support its use as add-on or first-line therapy for OT.