Using a novel stroke rehabilitation device that converts an individual’s thoughts to electrical impulses to move upper extremities has reported improvements in stroke patients’ motor function and ability to perform day-to-day activities. Results of the study were presented at the annual meeting of the Radiological Society of North America (RSNA; 1–6 December, Chicago, USA).
“Each year, nearly 800,000 people suffer a new or recurrent stroke in the USA, and 50% of those have some degree of upper extremity disability,” said Vivek Prabhakaran, director of functional neuroimaging in radiology at the University of Wisconsin-Madison, Madison, USA. “Rehabilitation sessions with our device allow patients to achieve an additional level of recovery and a better quality of life.”
Prabhakaran, along with co-principal investigator Justin Williams and a multidisciplinary team, built the new rehabilitation device by pairing a functional electrical stimulation system, which is currently being used to help stroke patients recover limb function, and a brain control interface, which provides a direct communication pathway between the brain and this peripheral-stimulation device.
In a functional electrical stimulation system, electrical currents are used to activate nerves in paralysed extremities. Using a computer and an electrode cap placed on the head, the new brain control interface functional electrical stimulation (BCI-FES) device (called the closed-loop neural activity-triggered stroke rehabilitation device) interprets electrical impulses from the brain and transmits the information to the functional electrical stimulation.
“Functional electrical stimulation is a passive technique in that the electrical impulses move the patients’ extremities for them,” Prabhakaran says. “When a patient using our device is asked to imagine or attempt to move his or her hand, the brain control interface translates that brain activity to a signal that triggers the functional electrical stimulation. Our system adds an active component to the rehabilitation by linking brain activity to the peripheral- stimulation device, which gives the patients direct control over their movement.”
The Wisconsin team conducted a small clinical trial of their rehabilitation device, enlisting eight patients with one hand affected by stroke. The patients were also able to serve as a control group by using their normal, unaffected hand. Patients in the study represented a wide range of stroke severity and amount of time elapsed since the stroke occurred. Despite having received standard rehabilitative care, the patients had varying degrees of residual motor deficits in their upper extremities. Each underwent nine to 15 rehabilitation sessions of two to three hours with the new device over a period of three to six weeks.
The patients also underwent functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) before, at the midpoint of, at the end of, and at one month following the rehabilitation period. fMRI is able to show which areas of the brain are activated while the patient performs a task, and DTI reveals the integrity of fibres in the white matter that connects the brain’s functional areas.
Patients who suffered a stroke of moderate severity experienced the greatest improvements in motor function following the rehabilitation session, according to the study results. Patients diagnosed with mild and severe strokes reported improved ability to complete activities of daily living following rehabilitation.
Prabhakaran says that the results captured throughout the rehabilitation process—specifically the ratio of hemispheric involvement of motor areas—related well to the behavioural changes observed in patients. A comparison of pre-rehabilitation and post-rehabilitation fMRI results revealed reorganisation in the regions of the brain responsible for motor function. DTI results over the course of the rehabilitation period revealed a gradual strengthening of the integrity of the fibre tracts.
“Our hope is that this device not only shortens rehabilitation time for stroke patients, but also that it brings a higher level of recovery than is achievable with the current standard of care,” Prabhakaran states. “We believe brain imaging will be helpful in both planning and tracking a stroke patient’s therapy, as well as learning more about neuroplastic changes during recovery.”