Therapeutic effect of repetitive transcranial magnetic stimulation in Parkinson's disease:: Analysis of [11C] raclopride PET study

Repetitive transcranial magnetic stimulation (rTMS) has been used as a potential therapeutic tool in Parkinson's disease (PD). However, the therapeutic value and/or the placebo effect of rTMS on PD remain to be elucidated. To investigate the therapeutic value and/or placebo effect of rTMS in PD, we compared the motor section of unified PD rating scale (UPDRS III) and the amount of extracellular dopamine concentration using [C-11] raclopride PET before and after two sessions of rTMS in 9 PD patients. During a consecutive 2 days while off-medication, two series of 15 trains of 5 Hz-frequency rTMS (intensity, 90% of the resting motor threshold) were applied to the hand area of more severely symptomatic motor cortex (MC). After unilateral rTMS of MC, mean raclopride binding potentials (BPs) were reduced not only in putaminal and caudate areas on the stimulated side (-4.9% and -6.5%, respectively) (P > 0.05) but also in putaminal and caudate areas of nonstimulated hemispheres (-6.6%, P > 0.05 and -12.1%, P = 0.049, respectively). UPDRS III scores were significantly decreased (35.0 +/- 14.1 to 32.0 +/- 13.4, P = 0.049). A reduction of raclopride BP in nonstimulated ventral striatum by unilateral rTMS supports the placebo response during rTMS. (C) 2007 Movement Disorder Society.