Analysis of MEP parameters in patients with post stroke spasticity in relation with rTMS therapy

BACKGORUND: Spasticity is a common complication of stroke limiting patient’s daily activities. Management of spasticity in chronic stroke patients may be necessary to improve their quality of life. Transcranial magnetic stimulation is a painless and non-invasive method that can potentially reduce post-stroke spasticity. In this study we evaluated the effectiveness of 3 sessions of low Hz rTMS therapy by analysing the changes in MEP parameters. METHODS: Patients with upper limb spasticity after stroke of 3 months duration were randomised into active and sham groups. In the active group three sessions of 1000 pulses, 1 Hz rTMS at an intensity of 90% of resting motor threshold were applied to the primary motor area of the contra-lesional hemisphere over three consecutive days. Sham rTMS intensity was 0% but with a similar sound and scalp sensation. MEP was measured pre and post therapy in each group. RESULTS: 106 patients were screened of which 50 patients were selected. 25 patients allotted to active group and 25 to sham group. Mean amplitude of MEP on stimulation of normal side was 1.98±1.70 mV before versus 1.53±1.16 mV after therapy showing significant reduction p=0.001 (95% CI-.135 - -.630). Similarly, there was significant increase in latency after therapy [22.92±2.25 ms vs 24.26±2.62 ms, p=0.001 (95% CI-2.0 - -.96)]. There was no significant change in amplitude (1.05±.69 mV vs 1.17±1.01 mV) or latency (23.66±2.45 ms vs 24.05±2.58 ms) after therapy in sham group. CONCLUSION: MEP parameters revealed even three sessions of therapy can be helpful in supressing normal hemisphere. We found reduction in amplitude and increase in latency of MEP after low Hz rTMS therapy in contra-lesional hemisphere suggesting its suppression after therapy. Spasticity across each joint reduced after the therapy in active group.