Repetitive deep transcranial magnetic stimulation for motor symptoms in Parkinson's disease: A feasibility study

Repetitive transcranial magnetic stimulation (rTMS), using standard coils, provided modest symptomatic benefits in patients with Parkinson's disease (PD). In our previous exploratory studies, using the newly developed Hesed coil (providing deeper rTMS; rDTMS) high frequency (HF), excitatory rDTMS over the primary motor cortex (M1), did not achieve sufficient beneficial effect for PD symptoms, while low frequency (LF) inhibitory stimulation, was mildly beneficial. To further investigate the optimal rDTMS stimulation parameters for PD patients, and to assess whether there is an added value for dual stimulation, consisting of HF rDTMS over the prefrontal cortex (PFC) along with LF M1 rDTMS. The rational for the selection of the current stimulation parameters and sites lies on the previous studies that demonstrated an inhibitory effect of 1Hz rTMS on the increased cortical activity in PD as well as dopamine release by PFC stimulation.

An open comparative active study of one month duration (12 sessions) of LF rDTMS over M1 alone (n=9) or combined with HF PFC rDTMS (M1-PFC, n=10). Outcome measures included the total and motor Unified Parkinson's Disease Rating Scale scores (T-UPDRS and M-UPDRS) and other variables, were collected at baseline and on days 30 and 60.

For the M1+PFC group, T-UPDRS score improved from baseline to day 30, by 15% (median: 52 points, decreased to 44, p=0.02, effect size: 0.51) and M-UPDRS score improved by 24% (median: 37 points decreased to 28, p=0.04, effect size: 0.47). The corresponding results for the M1 group were insignificant. Additionally, the between groups comparison, was insignificant.

rDTMS, consisting of M1 excitation with PFC inhibition improved PD motor symptoms but was not significantly superior to M1 rDTMS alone. rDTMS stimulation protocols for M1 should be further evaluated in larger scale controlled studies.