Repetitive transcranial magnetic stimulation to SMA worsens complex movements in Parkinson's disease

Transcranial Magnetic Stimulation Treatment for Motor Symptoms in Parkinson’s Disease: A Review of Two Decades of Studies

“…Overall, there is growing evidence of potential beneficial effects of rTMS treatment for motor symptoms in PD: of the 40 studies reviewed, only 12 [31,32,36,43,45,47,54,60,[61][62][63]68] did not find any improvement and one of these reported a symptoms worsening after stimulation [54]. Nevertheless, the magnitude of effects varied significantly across studies, probably due to the heterogeneity between stimulation protocols (in terms of frequency, intensity, duration) and targeted regions.…”

“…Nine studies [32][33][34]39,45,52,54,55,63] tested the effects of only one rTMS session, while the remaining administered a higher number of sessions, ranging from 2 to 20. Most studies, especially those targeting M1, SMA and DLPFC, administered high-frequency stimulation (24 of 40 studies) [29][30][31][32][33][34][37][38][40][41][42][43][44][49][50][51][53][54][55][57][58][60][61][62], while lowfrequency stimulation was employed primarily in studies targeting other regions. The intensity of stimulation ranged from 20% of motor threshold to 120%.…”

“…Sample sizes were generally under 30 subjects, except for five studies [36,40,57,58,64]. In regard to outcome measures, the Unified Parkinson's Disease Rating Scale -Section III (UPDRS-III) was the most employed measure (33 of 40 studies) [32][33][34][36][37][38][39][40][41][42][43][44][47][48][49][50][51][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68], yet some studies employed other motor function measures such as movement and reaction time [29,30,35], Grooved Pegboard test for fine movement [31], pointing, pronation supination, Purdue Pegboard Test [45], movement frequency [46] and gait kinematics [52].…”

“…rTMS studies targeting SMA rTMS treatment has been administered over the SMA by 6 studies [54][55][56][57][58][59] (Table 2): two employed high-frequency stimulation [54,57], two employed low-frequency [56,59] and the remaining two employed both high-and low-frequency stimulation [55,58]. The number of pulses was between 900 and 1800 pulses/session and the treatment duration involved more than one session except for two studies [54,55]. SMA trials yielded mixed results: the first study on this target area [54] reported a worsening in complex movements after one session of high-frequency rTMS, while all the other five found some degree of improvement.…”

“…The number of pulses was between 900 and 1800 pulses/session and the treatment duration involved more than one session except for two studies [54,55]. SMA trials yielded mixed results: the first study on this target area [54] reported a worsening in complex movements after one session of high-frequency rTMS, while all the other five found some degree of improvement. Koch et al [55] reported that low-frequency stimulation markedly reduced dyskinesias, while high-frequency stimulation determined a slight, but not significant increase in dyskinetic behavior.…”