Can rTMS Enhance Somatosensory Recovery After Stroke?

Stroke affects over 795,000 Americans every year and has an enormous impact on the well-being of American Veterans with 6,000 new stroke admissions every year. Many of these stroke survivors are living with disabilities that limit their everyday function. One of the major consequences of stroke is loss of sensation which manifests as inability to perceive touch, temperature, pain or limb movement. Lack of sensation hinders full functional recovery. Current treatments for sensory loss produce only limited improvements and do not achieve full recovery. Therefore, it is critical to develop new therapies to re-train sensory function. The investigators propose to evaluate a novel non-invasive brain stimulation treatment called repetitive Transcranial Magnetic Stimulation (rTMS). The effects of this technique on motor deficits following stroke have been studied, however rTMS for the treatment of sensory loss has not been examined to date. The investigators' study will examine for the first time if rTMS of a sensory brain region can improve sensory function in chronic stroke survivors.

Sensory deficits are present in the majority of stroke survivors. Inability to feel movement, touch or pain impairs the investigators' 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. This pilot study will measure an immediate effect of different repetitive Transcranial Magnetic Stimulation (rTMS) paradigms in a crossover single session design. The effect of intervention is measured with clinical measures of sensory and motor function and with neurophysiological assessment of sensory pathways. 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-term multi-session intervention of combined rTMS and peripherally directed therapy.

Eligibility Criteria:
Inclusion Criteria:

* Medically stable at least 6 months after first ever stroke.
* Sufficient endurance to participate in the study.
* Cognition sufficiently intact to give valid informed consent to participate.
* Age \> 18years.
* Ability to follow 2 stage commands.
* Impaired but not absent ability to feel touch, vibration and movement of the affected arm.

Exclusion Criteria:

* Acute or progressive cardiac, renal, respiratory, neurological disorders or malignancy.
* Any psychiatric diagnosis or active psychological condition.
* History of substance abuse within the last 6 months
* More than one ischemic stroke or stroke affecting both sides.
* Claustrophobia, or inability to operate the MRI patient call button.
* Pregnancy or pregnancy planning during the study period.
* Lower motor neuron damage or radiculopathy
* Contraindications for rTMS according to the TMS-use guidelines (Rossi et al 2009).
* Inability to understand English.
* Significant neglect for those with left-sided deficits.