The brain has an amazing ability to respond and adapt to injury. A healthy region can take over the function that the damaged part was performing. “We are trying to promote conditions that are more favorable to functional reorganization of the remnant areas of the cortex,” says study author Kenneth Baker, a neuroscientist at the Cleveland Clinic.
A stroke reduces the excitability of neurons, their ability to send signals and connect with other parts of the body. In people who recover spontaneously from stroke, the excitability of these neurons is restored. Baker’s team hoped that the stimulation would make neurons near the injured area more excitable, increasing their ability to form new connections.
In the Cleveland Clinic study, all 12 patients had strokes in the cerebral cortex (the outermost layer of the brain). Previous studies have attempted to stimulate this area directly, but to no avail. Cleveland’s team instead targeted a part of the cerebellum at the back of the head called the dentate nucleus, a collection of neurons involved in fine-tuning voluntary movement and sensory functions. This area connects with other brain regions, including the cortex.
Surgeons implanted electrodes in each patient’s brain and a device under the skin in the chest that emitted electrical impulses. After the recovery period from surgery, the patient received physical therapy for 2 months. The researchers then turned on electrical stimulation and left it on for four to eight months while participants continued physical therapy.
The researchers measured each person’s progress by administering a common test that assesses hand and arm function after stroke. Physical therapy alone led to a modest improvement of about 3 points out of 66. After turning on stimulation, the median improvement increased by an additional 7 points.
Participants also became proficient at routine tasks such as using a comb, lifting a cup, and turning on a light. “Their movements and movements aren’t normal, but just being able to use their hands faster than before makes a big difference,” says Baker. His three patients who did not show significant improvement were initially more impaired than others.
After months of constant stimulation, Nicholas began noticing a change. He was able to raise his arm above his head and close his left hand, neither of which he could do before receiving the implant. Garden work and household chores around the house become easier. “I’m glad it’s benefited me,” he says.
The researchers removed the device when the study ended, but surprisingly the effects persisted throughout the 10-month follow-up period, so it may not be necessary to use DBS permanently, as it is in Parkinson’s disease. It was suggested that there is
