High frequency repetitive transcranial magnetic stimulation decreases cerebral vasomotor reactivity

Objective: Repetitive Transcranial Magnetic Stimulation (rTMS) has been recently employed as a therapeutic strategy for stroke, although its effects on cerebral hemodynamics has been poorly investigated. This study aims to examine the impact of high frequency rTMS on cerebral vasomotor reactivity (VMR). Methods: Twenty-nine healthy subjects were randomly assigned to real (19) or sham 17-Hz rTMS, applied on primary motor cortex (M1) of the dominant hemisphere. All subjects underwent Transcranial Doppler of the middle cerebral arteries to evaluate mean flow velocity and VMR before (T0) and within 10 min (T1) following rTMS. Four subjects underwent further VMR evaluations at 2 (T2), 5 (T3) and 24 h (T4) after rTMS. As a control condition, 10 subjects underwent real (5) or sham rTMS on calcarine cortex. In addition, five acute stroke patients underwent five daily rTMS sessions on the affected hemisphere mimicking a therapeutic trial. Results: Following real rTMS on M1 (p = 0.002) and calcarine cortex (p < 0.001) VMR decreased with respect to T0 in both hemispheres, while no change was observed after sham rTMS (p > 0.6). VMR tended to remain lower than T0 until T3. Cerebral VMR decreased independently of the stimulated side also in the patients' group. Conclusions: High frequency rTMS reduces cerebral VMR, possibly as a secondary effect on autonomic control of cerebral hemodynamics. Significance: The effect of rTMS on cerebral hemodynamics should be carefully considered before proceeding toward a therapeutic application in stroke patients. © 2009 International Federation of Clinical Neurophysiology.