Anti-spastic effect of contralesional dorsal premotor cortex stimulation in stroke patients with moderate-to-severe spastic paresis: a randomized, controlled pilot trial

Objective This study aimed at investigating the effect of a single-session repetitive transcranial magnetic stimulation (rTMS) of the contralesional dorsal premotor cortex on poststroke upper-limb spasticity. Material and methods The study consisted of the following three independent parallel arms: inhibitory rTMS ( n = 12), excitatory rTMS ( n = 12), and sham stimulation ( n = 13). The primary and secondary outcome measures were the Modified Ashworth Scale (MAS) and F/M amplitude ratio, respectively. A clinically meaningful difference was defined as a reduction in at least one MAS score. Results There was a statistically significant change in MAS score within only the excitatory rTMS group over time [median (interquartile range) of − 1.0 (− 1.0 to − 0.5), p = 0.004]. However, groups were comparable in terms of median changes in MAS scores ( p > 0.05). The proportions of patients achieving at least one MAS score reduction (9/12 in the excitatory rTMS group, 5/12 in the inhibitory rTMS group, and 5/13 in the control group) were also comparable ( p = 0.135). For the F/M amplitude ratio, main time effect, main intervention effect, and time–intervention interaction effect were not statistically significant ( p > 0.05). Conclusions Modulation of the contralesional dorsal premotor cortex with a single-session of excitatory or inhibitory rTMS does not appear to have an immediate anti-spastic effect beyond sham/placebo. The implication of this small study remains unclear and further studies into excitatory rTMS for the treatment of moderate-to-severe spastic paresis in poststroke patients should be undertaken. Clinical trial registration no NCT04063995 (clinicaltrials.gov).