Low-frequency repetitive transcranial magnetic stimulation and off-phase motor symptoms in Parkinson's disease

Abstract

Repetitive transcranial magnetic stimulation (rTMS) can modulate cortical excitability and activation and consequently may affect clinical symptoms in neurological conditions characterized by altered motor cortex functions. There are conflicting reports whether low-frequency rTMS has any clinical effects in Parkinson's disease (PD). Ten patients with PD had rTMS (1800 stimuli at just below active motor threshold intensity) at 1 Hz rate delivered over the motor cortex for four consecutive days on two separate occasions. On one of these real rTMS was used and on the other sham rTMS (placebo) was used. Evaluations with UPDRS Part 3 (Motor Scale) were done in practically defined off-phase at the baseline and one day after the end of each of the treatment series. Neither total Motor Scale scores nor subscores for axial symptoms, rigidity, bradykinesia, and tremor showed any significant difference. The results do not confirm presence of residual beneficial clinical after-effects of consecutive daily applications of low-frequency rTMS on motor symptoms in PD, at least when 1800 stimuli at subthreshold intensity are applied for four days.