Can rTMS enhance somatosensory recovery after stroke?

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 DESCRIPTION (provided by applicant): Problem: Stroke is a leading cause of disability in the United States. Sensory deficits are present in the majority of stroke survivors. Inability to feel movement, touch or pain impairs our ability to interact with environment and diminished the quality of life. These sensory deficits significantly impair functional activity and slow down recovery during rehabilitation. Currently available sensory rehabilitation techniques can only partially restore sensory function. The main objective of this study is to test a novel approach to improve sensory function after stroke using non-invasive brain stimulation. Rationale: Sensory deficits can be partially recovered with peripheral manipulation of skin, muscles and joints using sensory re-education-based rehabilitation. Sensory re-education is associated with adaptive functional and structural alterations in the brain, called neuroplasticity. Despite reorganization, sensory recovery is usually slow and incomplete. There is a non-invasive method of brain modulation, called repetitive Transcranial Magnetic Stimulation (rTMS) that can potentially drive the adaptive functional and structural brain changes that lead to functional improvements. Although rTMS of motor control regions has been shown to enhance motor rehabilitation after stroke, evidence in support of rTMS to improve sensory function is lacking. In our preliminary studies, we discovered that rTMS of the contralesional primary sensory region (S1) is feasible and promising as an intervention for sensory treatment. The proposed study will test this novel approach. Study Design: We will enroll 30 individuals with sensory deficits after first ever stroke (stroke onset > 6 months prior). There will be two baseline sessions followed by three different rTMS interventions targeting contralesional S1 (facilitatory 5Hz, inhibitory 1 Hz and sham) randomly ordered and administered at least one week apart. Hypothesis 1a: Facilitatory rTMS of contralesional S1 produces a greater response versus sham rTMS, according to a measure of tactile discrimination. Hypothesis 1b Facilitatory rTMS of contralesional S1 produces a greater response versus inhibitory rTMS in improving tactile discrimination. We will test these hypotheses by comparing response to rTMS interventions according to 2-point discrimination (primary outcome measure). Secondary outcome measures will include grating orientation test, proprioception, monofilament discrimination, vibratory perception and Jebsen Taylor test. Hypothesis 2: Facilitatory rTMS at contralesional S1 can increase excitability of bilateral sensory networks and enhance sensory motor connectivity. We will test this hypothesis by measuring functional brain changes using somatosensory evoked potential (SSEP) induced by median nerve stimulation (primary outcome measure) and short-latency afferent inhibition (secondary outcome measure). Significance: This study will provide information about a novel brain stimulation approach for sensory rehabilitation, characterize the functional role of the contralesional S1 regions in sensory processing after stroke and open opportunities for development of new interventions for sensory rehabilitation. This study will be a first step in determining if rTMS stimulation of contralesional S1 can improve sensory function of a stroke-affected limb. If the concept is demonstrated in this pilot study, then following the lead of other investigations of this type, this pilot will provide the foundation to test the efficacy of a long-erm multi-session intervention of combined rTMS and peripherally directed therapy.