[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention.
[Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions).
[Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels.
[Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out.
Dysfunction from upper extremity hemiparesis impairs performance of many activities of daily living (ADL)1) . Individuals affected by stroke will learn or relearn competencies necessary to perform ADL. Traditionally, the practice of skills provided in neurologic rehabilitation has focused on reducing motor impairment and minimizing physical disability2, 3) . Since 2000, various studies of upper extremity function recovery using interventions such as constraint-induced movement therapy, functional electric stimulation, robotic-assisted rehabilitation, and bilateral arm training have been carried out4) . Such interventions were effective in increasing upper extremity functions in patients with stroke and are continually utilized in the clinical field5–7) .
However, most of the treatment protocols for the paretic upper extremity are labor intensive and require one on one manual interaction with therapists for several weeks, which makes the provision of intensive treatment for all patients difficult8) . Hence, alternative strategies and therapies are needed to reduce the long-term disability and functional impairment from upper extremity hemiparesis9) .
Mirror therapy may be a suitable alternative because it is simple; inexpensive; and, most importantly, patient-directed treatment that may improve upper extremity function8, 10) . Emerging methods in mirror therapy aim to restore motor control through a change in brain function, i.e. motor relearning11, 12) . Voluntary movements of the paretic upper extremity and hand by referring to a mirror activate the bilateral cortex and cause reorganization for other areas around the damaged brain to replace its function, thereby affecting recovery in motor function13) .
Although such methods are promising, they have failed to restore functional motor control for many patients who have experienced stroke. It is important to explore new methods that may facilitate the recovery of brain function and the restoration of more normal motor control14) . Many studies have addressed the neurophysiological effects of mirror therapy. The EEG study gave diverse stimulations to the thumb with or without a mirror to examine which area of the cortex was activated. They observed common activation areas in the primary motor cortex (M1), cingulate, and prefrontal cortex15) . And the study with healthy adults used mirror therapy with functional MRI (fMRI) and showed no difference between the dominant and non-dominant hand. Excitability of M1 ipsilateral to a unilateral hand movement was facilitated by viewing a mirror reflection of the moving hand16) . This finding provides neurophysiological evidence supporting the application of mirror therapy in stroke rehabilitation. Even though, previous studies concerned healthy subjects and had no interventions, a diversity of studies have shown upper extremity functional improvement through mirror therapy8) .
Thus, the purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention.