Influence of Theta Burst Stimulation and Carbidopa-Levodopa on Motor Performance in Stroke Patients

This study will examine whether transcranial magnetic stimulation (TMS) of the brain used in combination with carbidopa-levodopa is more effective in temporarily improving the speed of hand movement in stoke patients than TMS alone. In TMS, a wire coil is held on the patient's scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. The effect of TMS on the muscles is detected with small metal disk electrodes taped to the skin of the arms or legs. Carbidopa-levodopa is a medication usually used to treat Parkinson's disease, but it may improve the effect of theta burst stimulation. Two kinds of TMS are used in this study. In single-pulse TMS one or two pulses are delivered at a time in order to measure brain activity at that moment. In repetitive TMS (rTMS), a series of pulses are given in short bursts, temporarily altering brain activity. The type of rTMS used in this study is called theta burst stimulation. Healthy normal volunteers and people who had a stroke 6 months or more before entering the study may be eligible to participate. All candidates must be between 18 and 90 years of age. Stroke patients must have had significant hand weakness and made a moderate or good recovery and must be able to move either the thumb or the wrist on the affected hand reasonably well. Normal volunteers must be right-handed. Participants complete the testing for this study in four main sessions scheduled at least a week apart and five short follow-up sessions. At each main session, participants take either a carbidopa-levodopa tablet or a placebo (a look-alike inactive substance). Stroke patients have their arm and hand function assessed using two tests. One requires them to insert pegs into holes; the other includes writing, lifting various objects, and performing activities like turning pages, feeding or stacking checkers. All subjects complete a questionnaire regarding their mood and alertness and then perform tests of thumb or wrist movement. For this test, a small electrical stimulus is applied to the side of the hand and the subject must respond to the stimulus as quickly as possible by making a thumb or wrist movement. This is repeated several times over about 3 minutes. A second test follows in which the subject moves the thumb or wrist in response to a beep from a speaker. This test is repeated several times over about 8 minutes. Some measurements are taken using single-pulse TMS during the beginning, middle and end of this test. In two of the four sessions, theta burst stimulation is applied after the single-pulse TMS and in the other two sessions, sham theta burst stimulation is applied. Five follow-up sessions are scheduled one day after each main session and one week following the final one. In these sessions, subjects perform an abbreviated form of the thumb movement tests.