Preliminary Study of Transcranial Magnetic Stimulation for Stroke Rehabilitation

Overview

This is a preliminary study to evaluate the possible use of transcranial magnetic stimulation (TMS), together with exercise, for rehabilitation of chronic stroke patients. It will identify the optimum stimulation settings (within the limits of current safety guidelines) to be used in a later rehabilitation study and confirm the safety of the procedure at these settings. Some previous studies using TMS to treat movement disorders such as Parkinson's disease have shown improvement in motor function; others have not. The results of this study may provide information to help researchers design better rehabilitation treatments after stroke. Stroke patients with residual arm function and no history of seizures may be eligible for this study. The stroke must have occurred at least 6 months before entry into the study and must have affected only one side of the brain. For the TMS procedure, subjects are seated in a comfortable chair with their hands placed on a pillow on their lap. An insulated wire coil is placed on the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the outer part of the brain, called the cortex. This may cause muscle, hand or arm twitching if the coil is near the part of the brain that controls movement, or it may affect movements or reflexes. Subjects are asked to make movements, do simple tasks, or tense muscles. Metal electrodes are taped to the skin over the muscle for computer recording of the electrical activity of the hand and arm muscles activated by the stimulation. The testing lasts 2-3 hours.

Stroke survivors are often left with permanent physical and mental disabilities that create a major social and economic burden. Many of these patients receive different therapies in an attempt to improve their independence and quality of life. However, most of the current strategies are focused on the acute stage after stroke and are of limited influence in improving stroke outcome. One of the main problems of patients who have suffered a stroke is the difficulty in appropriately using the hand contralateral to the lesioned hemisphere; to date we have no successful means to improve the hand function in chronic stages of stroke. This protocol attempts to address this problem. A promising technique is repetitive transcranial magnetic stimulation (rTMS) that, so far, has produced some effects on motor function on other movement disorders like Parkinson's disease (PD). We hypothesize that rTMS will have a beneficial effect on motor function in chronic stroke patients. Specifically, we propose to look at the effect of 20 and 25 Hz stimulation since these types of stimulation have been shown to increase the excitability of the cerebral cortex. The purpose of this protocol is to investigate the effect of repetitive transcranial stimulation (rTMS) on the motor cortex of chronic stroke patients and motor function. Four different stimulation parameters within the limits of current safety guidelines will be used. We plan to determine; 1) which rTMS stimulation parameters induce more cortex excitability, 2) whether there is any improvement of hand motor function after rTMS, and 3) if the applied stimulation parameters are safe in chronic stroke patients. The optimal parameters will be subsequently proposed for use in an experimental protocol for rehabilitation.