Objective: To assess the effects of focal motor cortex stimulation on motor pe rformance and cortical excitability in patients with Parkinsons disease (PD). Methods: Repetitive transcranial magnetic stimulation (rTMS) was performed on th e left motor cortical area corresponding to the right hand in 12 offdrugpati ents with PD. The effects of subthreshold rTMS applied at 0.5 Hz (600 pulses) or at 10 Hz (2000 pulses) using a realor a shamcoil were compared to those obtained by a single dose of l dopa. The assessment included a clinical evalua tion by the Unified Parkinsons Disease Rating Scale and timed motor tasks, and a neurophysiological evaluation of cortical excitability by single and paired pulse TMS techniques. Results:RealrTMS at 10 or0.5 Hz, but notshamstim ulation, improved motor performance. High frequency rTMS decreased rigidity and bradykinesia in the upper limb contralateral to the stimulation, while low fre quency rTMS reduced upper limb rigidity bilaterally and improved walking. Concom itantly, 10 HzrTMS increased intracortical facilitation, while 0.5 HzrTMS restor ed intracortical inhibition. Conclusions: Low and highfrequency rTMS of the pri mary motor cortex lead to significant but differential changes in patients with PD both on clinical and electrophysiological grounds. The effect s on cortical excitability were opposite to previous observations made in health y subjects, suggesting a reversed balance of cortical excitability in patients w ith PD compared to normals. However, the underlying mechanisms of these changes remain to determine, as well as the relationship with clinical presentation and response to l dopa therapy. Significance: The present study gives some clues to appraise the role of the primary motor cortex in PD. Clinical improvement induc ed by rTMS was too short lasting to consider therapeutic application, but these results support the perspective of the primary motor cortex as a possible targe t for neuromodulation in PD.
展开▼
