Motor Imagery Brain-Computer Interface in Rehabilitation of Upper Limb Motor Dysfunction After Stroke

This study focuses on the clinical application of MIBCI in stroke patients with moderate to severe upper limb motor dysfunction. And it provides ideas and references for the standardized clinical operation and mechanism research by demonstrating the operation process and intervention effect of MIBCI. MIBCI has present a positive effect on improving motor dysfunction in stroke patients.

However, more clinical researches of this field should be done in the future to extend more appropriate treatment protocols for this different level of research function in stroke patients. In this study, functional near-infrared spectroscopy, fNIRS, was used to monitor the concentration changes of hemoglobin and the oxygenated hemoglobin in the cerebral cortex in real time under different stimulation tasks. Thus providing imagining evidence for the clinical effect of MIBCI.

We present a protocol to use MIBCI training on stroke patients for upper limb motor rehabilitation. The scores of Fugl-Meyer assessment of upper extremity and Wolf Motor Function Test was both improved after MIBCI treatment. Meanwhile, the fNIRS assessment also showed more activation of dorsolateral prefrontal cortex, primary motor cortex, and primary sensory cortex.

The findings suggest potential improvement in motor and cognitive function in stroke patients upon MIBCI intervention. Original upper limb rehabilitation intervention methods are either peripheral intervention or central intervention, whereas MIBCI is based on the code loop principle of center, peripheral center, or combine central motor imagery with peripheral motor feedback. The code loop principle is more fit for the characteristic of central nervous system disease.

Begin by explaining the training purpose and method to the patient. Put the MIBCI EEG cap on the patient ensuring that the CZ point of the cap coincides with that of the patient's head. Confirm the position of the EEG cap by checking the intersection point of the ear bead line and the human median line passing through the nose and eyebrow center.

Keep the ears exposed from the ear seam of the head cap and adjust the chin strap to fix the head cap. Insert 24 electrodes dipped in normal saline into the groove of the EEG cap and clip two reference electrodes into the two ear lobes. Put the manipulator on the patient and adjust it to a comfortable training position to prevent upper limb forearm pain.

Then open the training software MIBCI upper limb hand function rehabilitation robot. Click the user list and enter the patient information, including name, disease name, date of birth, date of illness, and location of the affected side. Adjust the stability of the EEG signal to no obvious clutter.

And click the resting EEG button. Let the patient complete the resting EEG acquisition process according to the voice and text prompts. Click the task setting button and according to the situation of the patient, set the initial training difficulty upward, or downward from level nine.

Also set the training duration to 30 minutes. Click the task EEG button to start the formal training. Ask the patient to follow the onscreen text that asks them to close their eyes and relax for five seconds.

After five seconds, ask the patient to open their eyes and follow the onscreen commands. The screen on the patient's side displays the gripping, or opening video to assist the patient to imagine the actions. Ask the patient to perform the motion imagination task for five seconds.

After another four seconds, check the motor intention. If the intention is less than 60 points, the system determines that the patient cannot perform the movement. During the training, the MIBCI system will automatically adjust the task difficulty according to the patient's performance.

For course movements, the task difficulty is simple, making it easier for the patient to complete. Conversely, for fine movements, the task becomes more difficult, making it challenging for the patient to complete. If the patient has pain, or discomfort during the training, stop the training and record the reason for termination.

During the training, observe the EEG waveform in real time. If there is a small range of EEG disturbances, check the corresponding electrode for dryness. Stop the training and EEG acquisition immediately and properly wet the electrode before continuing.

If the EEG signal has an extensive range of disturbance, check whether the reference electrode has fallen off. Stop the training immediately and clamp the reference electrode at the ear lobe again. After the test, evaluate the motor function by Fugl-Meyer assessment of upper extremity out of a total score of 66.

Also evaluate the Wolf Motor Function Test out of a total score of 85. Perform cognitive function assessment by mini mental state examination on stroke subjects and divide the score according to the educational level. Also, evaluate the emotional function on patients using Hamilton Anxiety Scale and calculate the scores during the assessment process.

Then evaluate the emotion function using the Hamilton Depression Scale. MIBCI intervention was performed on a 36-year-old male stroke patient diagnosed with left limb motor dysfunction. Brain function, and clinical function assessment before in 10 days after treatment showed improvement in FMA-UE and WMFT scores.

Perform fNIRS Motor Task assessment by selecting the motor test paradigm in the fNIRS system. Place the patient's upper limb on the test table and ask the patient to rest for 10 seconds before the experiment. Ask the patient to follow the exercise rhythm, to grasp the affected hand in three blocks during the experiment.

Each block includes 30 seconds task and 30 seconds rest. Each task consists of 15 trials. Each trial includes one second gripping and one second opening of the grasp.

During each rest, ask the patients to close their eyes and rest. After all three blocks are complete, end the task, save the data, and import it to the self-built database. To perform cognitive task assessment by Stroop Task, run behavioral research software and choose the cognitive task paradigm.

Select the patient treatment files and then select congruence test. Ask the patient to place their healthy hand on the button of the keyboard. Then ask the patient to rest for 10 seconds before the trial starts.

Perform three blocks of the congruence test. Each block includes 60 seconds task and 30 seconds rest. Each task consists of 10 trials, each consisting of 2, 000 millisecond fixation, and 4, 000 millisecond stimulus response.

When the left symbol is displayed on the left of the field font, press the left arrow button on the keyboard as soon as possible. Similarly, press the right arrow button when the right symbol is displayed on the field font. Next, select the incongruence test.

When the right symbol is displayed on the left of the field font, ask the patient to ignore the character meaning, and press the left arrow button on the keyboard. Similarly, press right arrow button when left symbol is displayed on the screen. Complete the task, save the data and export it to the self-created database.

In a 36-year-old male stroke patient diagnosed with left limb motor dysfunction, fNIRS evaluation showed that for the motor task paradigm, the beta value of RM1 was higher after MIBCI treatment. Similarly, the beta value of bilateral DLPFC for the congruence test was higher for the post-treatment than that for the pre-treatment. Also, the beta value of all ROIs for the incongruence test was higher after treatment with MIBCI.

The Stroop Cognitive paradigm assessment results showed that for the congruence test, the accuracy rate remained unchanged and the response time became shorter after treatment. For the incongruence test, the accuracy rate remained unchanged and the response time was shorter after treatment.