Study of Hemodynamic Markers of Upper Extremity Motor Dysfunction in Stroke Patients Using Functional Near Infrared Spectroscopy (fNIRS)

Stroke, Stroke, Ischemic, Stroke with Hemiparesis

stroke, hemiparesis, hemodynamics, fNIRS, restoration of motor function, Neurovascular coupling

The aim of the study was to explore potential pathways for recovery and adaptation of the motor cortex by examining cerebral blood flow characteristics and hemodynamic markers analyzed by functional near-infrared spectroscopy (fNIRS) in patients with hemiparesis after stroke. Participants in the study performed a simple stimulus-response task several times with one healthy and one paralyzed limb at different stages of basic rehabilitation. A group of healthy, age-matched volunteers participated in the same experiment to verify the stroke-related changes. The researchers recorded fNIRS signals, muscle activity using electromyography, and heart activity using electrocardiography.

The study included 40 participants, divided into two groups: individuals with a history of stroke-related hemiparesis and a matched healthy control group.Participants were instructed to perform a stimulus-response task designed to assess reaction speed.During the task, they positioned their hands within a designated box equipped with two buttons corresponding to left and right responses. A visual stimulus, presented via LEDs located above the buttons, served as the response target. A flash of a stimulus required participants to respond by extending their fingers to press the corresponding button. If limb paresis prevented a full button press, participants were instructed to form an intention to move and attempt the task to the best of their ability. Neurophysiological data acquisition. Functional near-infrared spectroscopy (fNIRS) data were acquired using a combined NIRSport 16x16 and NIRSport 8x8 system (NIRx Medizintechnik GmbH, Berlin, Germany).Twenty-four sources and 24 detectors were placed over the sensorimotor area and adjacent regions, forming 76 source-detector pairs to ensure comprehensive cortical coverage. The light sources were activated synchronously, resulting in a sampling rate of 13.56 Hz. In addition, surface electromyography (EMG), electrocardiography (ECG), and scalp electroencephalography (EEG) were recorded using the NVX-36 electroencephalograph (ISS, Zelenograd, Russia). EMG activity was recorded from the extensor digitorum communis muscle of both hands using a bipolar belly-tendon montage. ECG was recorded by 1st standard bipolar montage with electrode placed on both wrists. EEG was recorded with 6 electrodes placed at 'FCC3', 'FCC4', 'CCP3', 'CCP4', 'FCC5', 'A1', 'FCC6', 'A2' according to the standard 10-05 montage. The experimental protocol was completed within two weeks for each participant. There were six sessions (3 at the beginning of rehabilitation and 3 before discharge). Each session lasted a maximum of one hour. Before the experimental session, each patient's motor abilities were tested using the Action Research Arm Test (ARAT) and the Fugl-Meyer Assessment (FMA) scale.

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