Improvement of motor performance and modulation of cortical excitability by repetitive transcranial magnetic stimulation of the motor cortex in Parkinson's disease.
OBJECTIVE
To assess the effects of focal motor cortex stimulation on motor performance and cortical excitability in patients with Parkinson's disease (PD).


METHODS
Repetitive transcranial magnetic stimulation (rTMS) was performed on the left motor cortical area corresponding to the right hand in 12 'off-drug' patients with PD. The effects of subthreshold rTMS applied at 0.5 Hz (600 pulses) or at 10 Hz (2000 pulses) using a 'real' or a 'sham' coil were compared to those obtained by a single dose of l-dopa. The assessment included a clinical evaluation by the Unified Parkinson's Disease Rating Scale and timed motor tasks, and a neurophysiological evaluation of cortical excitability by single- and paired-pulse TMS techniques.


RESULTS
'Real' rTMS at 10 or 0.5 Hz, but not 'sham' stimulation, improved motor performance. High-frequency rTMS decreased rigidity and bradykinesia in the upper limb contralateral to the stimulation, while low-frequency rTMS reduced upper limb rigidity bilaterally and improved walking. Concomitantly, 10 Hz rTMS increased intracortical facilitation, while 0.5 Hz rTMS restored intracortical inhibition.


CONCLUSIONS
Low- and high-frequency rTMS of the primary motor cortex lead to significant but differential changes in patients with PD both on clinical and electrophysiological grounds. The effects on cortical excitability were opposite to previous observations made in healthy subjects, suggesting a reversed balance of cortical excitability in patients with 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.


CONCLUSIONS
The present study gives some clues to appraise the role of the primary motor cortex in PD. Clinical improvement induced by rTMS was too short-lasting to consider therapeutic application, but these results support the perspective of the primary motor cortex as a possible target for neuromodulation in PD.
Service de Physiologie-Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, 51 avenue de Lattre de Tassigny, 94010 Créteil, France. jean-pascal.lefaucheur@hmn.ap-hop-paris.fr
Jean-Pascal
JP
Lefaucheur
Xavier
X
Drouot
Florian
F
Von Raison
Isabelle
I
Ménard-Lefaucheur
Pierre
P
Cesaro
Jean-Paul
JP
Nguyen
D000368:Aged; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy*; D010812:Physical Stimulation / Q000379:methods; D012720:Severity of Illness Index; D050781:Transcranial Magnetic Stimulation; D016896:Treatment Outcome