6-Hz Primed vs. Unprimed Low-Frequency rTMS in Chronic Stroke

Detailed Summary

The goal of stroke rehabilitation is to restore function to the weak side of the body. However, this is often a difficult task to accomplish due to not only to damage from the stroke, but from increased excitability in the non-stroke side of the brain that inhibits the stroke side from functioning optimally. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive form of brain stimulation that can enhance excitability in the stroke side when applied at a low-frequency on the non-stroke side. By "inhibiting the inhibition" (i.e. disinhibition), rTMS promotes adaptive brain reorganization following stroke. Previous research in healthy individuals demonstrates enhanced effects of low-frequency rTMS when it is preceded by high-frequency (excitatory) rTMS stimulation known as priming. Our lab previously demonstrated the safety of 6-Hz priming with low-frequency rTMS in both adults and children with chronic stroke. However, it is currently unknown whether or not the addition of priming stimulation to low-frequency rTMS enhances excitability in the stroke hemisphere. Our study will examine three rTMS interventions in twelve adults (at least 18 years): 1.) 10 minutes of real priming followed by 10 minutes of low-frequency rTMS, 2.) 10 minutes of fake priming followed by 10 minutes of low-frequency rTMS, 3.) 20 minutes of low-frequency rTMS only. Participants will receive all three interventions in randomized order. Each week, participants will complete two pretest and 3 posttest sessions consisting of behavioral measures of weak upper extremity function and cortical excitability in addition to receiving one rTMS intervention. Following each week of testing and treatment, subjects will take a one week rest break before crossing-over to receive another intervention. We hypothesize the following: 1.) Primed rTMS will result in significantly reduced inhibition and significantly increased excitation on the stroke side vs. fake primed rTMS or low-frequency rTMS given alone and 2.) Primed rTMS will result in greater improvements of paretic hand function. This study is innovative in that it intends to compare primed and unprimed rTMS in the stroke brain that could acknowledge a more effective delivery method of rTMS to potentially yield greater rehabilitative outcomes.

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