Pallidotomy
Increases Cortical Inhibition in Parkinson's Disease
A.
Strafella, P. Ashby, A. Lozano and A.E. Lang
Abstract:
Background: Pallidotomy helps parkinsonian symptoms.
We tested the hypothesis that this might be due to changes
in inhibition in the motor cortex. Methods: We
examined 15 patients with parkinsonism before and after posteroventral
pallidotomy. Magnetic stimuli were delivered over the motor
cortex, while subjects maintained a 30% maximum voluntary
contraction of the contralateral first dorsal interosseus
(FDI). Results: Weak stimuli inhibited voluntary
muscle activity, while slightly stronger stimuli caused short
latency facilitation from activation of the corticospinal
neurons. After pallidotomy magnetic stimulation, at the threshold
for the short latency facilitation, resulted in more inhibition
than before. Conclusion: Pallidotomy increases
cortical inhibition. This may be associated with improved
control of movements.
