Stroke Rehabilitation: A Case Study

With ~800,000 stroke cases every year in the United States, stroke is considered the major cause of disability in adults [1]. The ability of the brain to reorganize in response to pathological or environmental changes such as lesions is critically important to the recovery of motor function after stroke [2]. Re-establishment of ipsilesional cortical excitability has been associated with improved functional outcomes of the paretic limb following stroke [3,4]. Numerous approaches to modulate cortical excitability in stroke have been investigated. However, many involve the use of repetitive task practice with the affected hand which is not possible for severely impaired patients. Two promising approaches to modulate excitability of the ipsilesional hemisphere that do not require movement of the affected hand include paired associative stimulation (PAS) and mirror therapy. PAS is described as a peripheral nerve stimulation paired with transcranial magnetic stimulation (TMS) of primary motor cortex (M1) in a timing dependent manner to induce
In mirror therapy, the illusion that movement of one hand is occurring on the opposite side, has been shown to activate the contralateral motor cortex in a task specific manner. Importantly, mirror therapy for stroke rehabilitation is reliant only on movement of the healthy hand making it appropriate for the most severely impaired individual [5].
In this study we will examine the effectiveness of combining the PAS and mirror therapy to induce a higher level of cortical excitability and/or longer lasting plasticity changes than either therapy in isolation. Modulation of cortical excitability will be evaluated over a period of 60 minutes after the therapy. We hypothesize that combining PAS and mirror therapy in one protocol (Mirror-PAS) will induce higher excitation and longer lasting excitation in motor cortex in healthy and stroke