Changes in Hemodynamic Response Following Transcranial Electrical Stimulation in Sroke Individuals

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.

Inclusion criteria

• Unilateral stroke individuals aged 18-80 years.
• A first-ever stroke.
• Stroke onset from at least 2 weeks-5 years.
• Able to walk independently with or without gait aids (modified Rankin scale (mRS) 1-3)
• Montreal cognitive Assessment-Thai version (MoCA-T) greater than or equal to 20 scores.
• Ability to read, communicate, follow and understand instructions.

Exclusion criteria

• Presence of any psychological or neurological antecedent, unstable medical conditions or condition that may increase risk of stimulation such as epilepsy, seizure, and history of brain injury
• Having unstable cardiovascular disease or respiratory disease, and uncontrolled chronic disease such as diabetes mellitus (DM), hypertension (HT) and chronic kidney disease (CKD)
• Receiving other non-invasive brain stimulation or additional intervention such as TMS, PMS or acupuncture
• Presence of metal implantation, intracranial shunt, cochlear implantation, or cardiac pacemakers.
• Presence of an opened wound, infectious wound around scalp or craniectomy with unreplaced bone flap
• Moderate pain (numeric pain rating score > 4/10) in any joint of the upper or lower limb, whether paretic or non-paretic
• Presence of color blindness
• Presence of any substance use including cannabis and kratom