Low-frequency repetitive TMS of premotor cortex can reduce painful axial spasms in generalized secondary dystonia: a pilot study of three patients.

Dystonia is associated with excessive corticospinal motor output. Motor cortex excitability may be reduced by low-frequency repetitive transcranial magnetic stimulation (rTMS) of premotor cortical areas. We report the effects of 1 Hz rTMS applied at 90% of resting motor threshold over the left premotor cortex in an open pilot study of three patients with severe, generalized, secondary dystonia including painful spasms in the proximal and axial musculature. A 20-min session of premotor rTMS was daily performed during 5 consecutive days. The series of rTMS sessions dramatically reduced the painful spasms, for 3-8 days after the last session, without any other significant beneficial effects. However, a slight reduction of the Movement score of the Burke, Fahn and Marsden rating scale was observed for two patients, and of the Disability score for the third one. Low-frequency rTMS of the premotor cortex may improve some specific motor symptoms in severe, generalized dystonia. These results should prompt confirmation in a larger placebo-controlled study.