EFFECT OF HIGH FREQUENCY REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION OF THE CONTRALESIONAL MOTOR CORTEX ON RECOVERY FROM POST-STROKE SEVERE MOTOR IMPAIRMENT

Abstract

Background: The traditional inhibition of contralesional primary motor area (cM1) with low frequency repetitive transcranial magnetic stimulation (rTMS) fails to improve post-stroke severe motor impairment. The role of contralesional motor areas in post-stroke motor recovery is still questionable. While the previous data suggested that cM1 exerts transcallosal inhibitory effect on ipsilesional M1 (iM1) following stroke, there isan evidence that contralesional motor areas, particularly the contralesional dorsal premotor area (cPMd), have compensatory roles in severely impaired patients who have extensive ipsilesional damage. Objectives: To study whether facilitating cPMd with high frequency rTMS as a novel approach, instead of conventionally suppressing cM1, has beneficial effect on motor recovery of post-stroke severely impaired upper extremity (UE) or not. Patients and Methods: Forty right handed, first ever stroke patients (3 months post event) with severe stroke symptoms, severe motor deficit, and radio logically evident massive right cerebral infarctions at baseline were randomly assigned to two equal groups, to receive, as adjunct to ordinary rehabilitation techniques, ten consecutive sessions of either: (1) High frequency rTMS at 5 Hz on cPMd; or (2) Sham rTMS. The Medical Research Council (MRC) for muscle strength and UE- Fugl Meyer Assessment (UE-FMA) were assessed before and after the intervention. Results: By using the one way analysis of covariance (ANCOVA), we found significant improvements in grand means of MRC in the active rTMS group in relation to the sham group. The improvements included in particular the mean proximal MRC, whereas no significant improvement in the mean distal MRC. Similarly, we found that the UE-FMA totals were markedly improved in the active group in relation to the sham group, mainly in the proximal UE-FMA. Stepwise regression showed that lower baseline MRC of the affected UE muscles is an independent predictor of better response to the novel rTMS approach. Conclusion: Applying high frequency rTMS to cPMd can improve motor functions of the disabled UE, mainly proximal functions, in more severely impaired stroke patients.