A new brain-controlled muscle stimulation technique for restoring arm movement in a tetraplegic patient was tested. The patient had a brain-computer interface (BCI) device implanted into the area of his brain which controls hand movement.
In spinal cord injuries, the connections between the brain and the nerves controlling the limbs are cut, which means that the brain can no longer control and move the limbs. High-level neck spinal cord injuries can cause tetraplegia (paralysis of all limbs), preventing an individual from performing even basic movements such as reaching and grasping. This has a huge impact on their daily lives.
Several techniques have been tested to try and restore some movement and function in paralyzed limbs. Functional electrical stimulation (FES) of limb nerves and muscles has been used successfully to restore grasping in patients who still have some shoulder or elbow movements following their injuries. However, this technique has been less effective in patients with more severe injuries who do not have any remaining limb movement.
Devices called brain-computer interfaces (BCIs) implanted into the brain area that controls limb movement can directly link electrical activity in the brain to a desired movement. These devices have been tried successfully in experimental animal models and in humans to control robotic arms.
Furthermore, in one experiment, combining an implanted BCI with FES of limb nerves was used in a patient with a low-level neck injury and some remaining upper arm movement to partially restore reaching and grasping movements.
Researchers in Cleveland, Ohio, USA developed this technique in an effort to further restore reaching and grasping function in a chronic tetraplegic patient who had no limb movement following his injury. The patient had a BCI implanted into the area of his brain which controls hand movement. Following implantation, the patient was able to use the BCI to control movements of a virtual 3-D arm on a computer.
At 4 and 9 months after BCI implantation, the patient had electrodes implanted into his right upper and lower arm to electrically stimulate his hand, elbow and shoulder muscles. The patient was also fitted with a motorised mobile arm support to help strengthen arm movement under BCI control.
The experimental procedure was tested to assess the patient’s ability to use his brain to command his paralysed arm to perform simple single-joint arm & hand and more complex multi-joint movements which could be used to perform everyday tasks.
The BCI was implanted in Dec 2014 and the progress of the patient is still being monitored. To date, the patient has successfully used the BCI + FES system to coordinate single joint and coordinated multi-joint arm movements accurately, at first using a virtual 3-D arm on the computer and then his own paralysed arm stimulated by FES. Using this system, the patient can reach and grasp for a mug of coffee and drink it using a straw, as well as feed himself.
This first report of a combined implanted BCI & FES system to restore both reaching and grasping movements in a patient with chronic tetraplegia due to a spinal cord injury is an important advance. The researchers hope that the technique can be further developed to provide a method of restoring limb movement and function in tetraplegic patients.
Written By: Julie McShane