Changes in Hemodynamic Response Following Transcranial Electrical Stimulation in Sroke Individuals

Overview

The present study will use transcranial electrical stimulation (tES) which are transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) combined with conventional physical therapy and cognitive-motor dualt ask gait training in sub-acute (at least 2 weeks after stroke onset) to chronic stroke (within 5 years post-stroke) to investigate changes in brain hemodynamics (oxy-hemoglobin and deoxy-hemoglobin concentration) as measured by functional near infrared spectroscopy (fNIRS). The findings may provides insights changes in combining tES with rehabilitation on improvements in brain hemodynamics in sub-acute to chronic stroke.

Stroke is a sudden neurological event which caused by an impaired blood flow and oxygen suppley, leading to neuronal cell death. An impaired in neuronal cell death and blood flow to the brain leads to imapirement in motor and cognitive function as well as disability in post-stroke individuals. To investigate changes in cerebral blood flow and oxygen comsumption, functional near-infrared spectroscpoy (fNIRS) which is a non-invasive neuroimaging can monitors alterations in blood flow and oxygenconsumption in the brain. Furthermore, fNIRS can be use as an outcome predictors and outcome measures for rehabilitation following stroke. Motor impairments following stroke affects activities of daily living (ADLs), moreover, cognitive impairments is commonly observed in post-stroke individuals that may limits and functional recovery and limites effectiveness of rehabilitation. These impairments affect both single- and duals-task activities, especially walking performance and increasing risk of falls in stroke individuals. In previous study laterations in cerebral blood flow was obsered during stroke individuals performing dual-task walking, indicating alterations in cortical activity during this activity. Furthermore, combining bottom-up and top-down approaches provide greater beneficial on improvement motor and cognitive function in stroke individuals. Transcranial electrical stimulation (tES), a non-invasive brain stimulation (NIBS) that can facilitates cortical activity and adjuncent intervention to combine with rehabilitation to facilitate greater rehabilitation outcome in stroke inidividuals. The most common tES technique are transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS). Both tDCS and tACS are different in their wave forms. tDCS delivers a weak direct current with polartiy-specific effects, while tACS enhance neural plasticity and endogenous brain wave with frequency-specific. A recent review demonstrated the effectiveness of tDCS in improvement of motor function, functional abilities and cognitive function. Furthermore, a previous study demonstrated an improvement in cognitive function and ADLs following combining 2mA of tDCS with CMDT training. However, the amount of evidence on the effects of tACS is much less than that for tDCS, as it has only recently started to gain interest. Furthermore, changes in brain hemodynamic responses remains unclear. To provide insights on changes in brain hemodynamic response following combining tES with conventional physical therapy and cognitive-motor dual task gait training in stroke individuals. This study will provide the combining of 12 sessions of tES with conventional physical therapy and cognitive motor-dual task gait training. Changes in brain hemodynamics response will be assessed using fNIRS. The oxy-hemoglobin and deoxy-hemoglobin will be recorded and analyze to represent changes of blood flow to the brain after intervention.