Safety and behavioral effects of high-frequency repetitive transcranial magnetic stimulation in stroke

Abstract

Background and purpose: Electromagnetic brain stimulation might have value to reduce motor deficits after stroke. Safety and behavioral effects of higher frequencies of repetitive transcranial magnetic stimulation (rTMS) require detailed assessment.

Methods: Using an active treatment-only, unblinded, 2-center study design, patients with chronic stroke received 20 minutes of 20 Hz rTMS to the ipsilesional primary motor cortex hand area. Patients were assessed before, during the hour after, and 1 week after rTMS.

Results: The 12 patients were 4.7+/-4.9 years poststroke (mean+/-SD) with moderate-severe arm motor deficits. In terms of safety, rTMS was well tolerated and did not cause new symptoms; systolic blood pressure increased from pre- to immediately post-rTMS by 7 mm Hg (P=0.043); and none of the behavioral measures showed a decrement. In terms of behavioral effects, modest improvements were seen, for example, in grip strength, range of motion, and pegboard performance, up to 1 week after rTMS. The strongest predictor of these motor gains was lower patient age.

Conclusions: A single session of high-frequency rTMS to the motor cortex was safe. These results require verification with addition of a placebo group and thus blinded assessments across a wide spectrum of poststroke deficits and with larger doses of 20 Hz rTMS.

Figure 1

On a representative slice from the T1-weighted anatomic image from each of the 12 study patients, an arrow indicates stroke location. Stroke was subcortical in 11 (although directly abutting the cortex in 5 of 11) and cortical in one.

Figure 2

A, Number of pegs placed in the 9-hole pegboard over 60 seconds by the affected hand. B, Grip strength is the maximum force of squeezing by the affected hand on a Jamar dynamometer in pounds. For both A and B, the pre-rTMS baseline was stable, showing no significant change over time. The arrow indicates timing of rTMS application. Values are mean±SEM *P<0.05 versus immediately pre-rTMS, paired testing.