Recovery of upper-limb function six years after chronic severe hemiplegia using BCI-controlled FEST: a case report
Jovanovic, Lazar 1; Desai, Naaz 2; Lo, Lorna 2; Zivanovic, Vera 2; Popovic, Milos 1, 2; Marquez-Chin, Cesar 2
1. Institute of Biomaterial and Biomedical Engineering, University of Toronto; 2. Toronto Rehabilitation Institute - University Health Network
As of 2013, there are more than 400,000 stroke survivors in Canada. More than half of them are living with moderate or severe motor impairments decreasing their quality of life. Standard strategies for motor rehabilitation include physical or occupational therapies and these are essential tools for recovery after stroke. On the other hand, technological advancements and new discoveries in neurophysiology has brought about enhancing rehabilitation strategies. One example is Functional Electrical Stimulation Therapy (FEST) and it is a combination of conventional therapy and Functional Electrical Stimulation – a technique that uses electrical pulses to produce muscle contractions that facilitate functional movements (e.g., reaching or grasping).
During FEST, a patient is asked to attempt the movement, and after observing signs of effort, a therapist triggers the stimulation.
Multiple studies have examined the effects of FEST on functional recovery of upper extremities after stroke and showed promising results. However, the FEST approach was not as successful in cases with severe chronic hemiplegia. An explanation for decreased efficacy may be the greater uncertainty therapists experience in patients with severely paralyzed limbs. This problem might be solved by merging a brain-computer interface (BCI) and FEST. A BCI is a system that converts brain activity (e.g. metabolic or electrical) into a control signal.
Here, I report a case study on implementing a BCI-triggered FEST for improving upper-limb function following severe stroke. Our main objective was to evaluate the efficacy of the integrated BCI-FEST intervention using the measurements of function and independence.
The subject was a 57-year old man who had a severe chronic left hemiplegia due to as stroke 6 years before the intervention. It is important to mention here that the subject had previously underwent several treatments, including standard FEST, but did not experience significant improvement. Intervention included two blocks of 40 one-hour sessions, conducted three times per week. During the session, the patient would attempt the movement and BCI would trigger the stimulation upon successful detection. The BCI signal was recorded using one electroencephalographic (EEG) channel, and the control signal was based on the EEG pattern known as event-related desynchronization – frequency-specific decrease of power commonly present before the movement exaction.
After 80 hours of treatment, the subject improved 5 points on the Functional Independence Measure total score, with the highlighted progress in eating, ambulation and stairs management. On the Spinal Cord Independence Measure, the subject scored 100, making a 10-point difference from the baseline. Furthermore, the tests of function showed gradual improvements in patients grasp, pinch as well as object manipulation, after 40 and after 80 hours of treatment.