Repetitive transcranial magnetic stimulation to SMA worsens complex movements in Parkinson's disease.
OBJECTIVE
To evaluate the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS) for Parkinson's disease (PD) by delivering stimulation at higher intensity and frequency over longer time than in previous research. Promising beneficial effects on movement during or after rTMS have been reported.


METHODS
Ten patients with idiopathic PD were enrolled in a randomized crossover study comparing active versus sham rTMS to the supplementary motor area (SMA). Assessments included reaction and movement times (RT/MT), quantitative spiral analysis, timed motor performance tests, United Parkinson's Disease Rating Scale (UPDRS), patient self-report and guess as to stimulation condition.


RESULTS
Two of 10 patients could not tolerate the protocol. Thirty to 45 min following stimulation, active rTMS as compared with sham stimulation worsened spiral drawing (P=0.001) and prolonged RT in the most affected limb (P=0.030). No other significant differences were detected.


CONCLUSIONS
We sought clinically promising improvement in PD but found subclinical worsening of complex and preparatory movement following rTMS to SMA. These results raise safety concerns regarding the persistence of dysfunction induced by rTMS while supporting the value of rTMS as a research tool. Studies aimed at understanding basic mechanisms and timing of rTMS effects are needed.
Boylan
L S
LS
Department of Neurology, New York University School of Medicine, NY, New York, USA. laura.boylan@med.nyu.edu
Pullman
S L
SL
Lisanby
S H
SH
Spicknall
K E
KE
Sackeim
H A
HA
D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006236:Handwriting; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D010300:Parkinson Disease / Q000503:physiopathology*; D010812:Physical Stimulation; D011930:Reaction Time; D012720:Severity of Illness Index; D050781:Transcranial Magnetic Stimulation; D016138:Walking