Researchers at the Ohio State University Wexner Medical Center are attempting to improve arm movement in stroke patients by using a transcranial magnetic stimulator (TMS) device. By using TMS to reduce brain activity on the uninjured side of the brain, researchers hope that the injured side may have a better chance of recovering.
When one side of the brain is damaged by a stroke, the healthy side tends to increase its activity to compensate. However, that may actually prevent the injured side from recovering, according to principal investigator Marcia Bockbrader, assistant professor of physical medicine and rehabilitation at Ohio State.
Ohio State is one of 12 rehabilitation sites nationwide participating in the multicentre clinical trial that will enrol up to 200 patients during the next two years. Nexstim has launched the double-blinded, randomised, and sham-controlled trial to determine the therapeutic effects of navigated repetitive transcranial magnetic stimulation (rTMS) for stroke rehabilitation. This stroke therapy combines occupational therapy with navigated repetitive transcranial magnetic stimulation (n-rTMS).
“Nexstim is a way to specifically stimulate a brain area of interest,” says Bockbrader. “In our study, we are stimulating the motor areas that are sometimes injured in a stroke. This device targets the overactive side, quieting it down enough, so that through therapies, the injured side can learn to express itself again.”
To qualify for the study, participants must have had a stroke 3-12 months before, and continue to experience weakness in the arm and hand on one side. All participants also receive six weeks of hand and arm therapy free of charge. An occupational therapist focuses on improving movement, flexibility, strength and use of the weak arm and hand. The study lasts for up to eight months and will involve up to 29 visits.
“In this particular study, we are looking at people who are 3-12 months after stroke who have not recovered all the way and are trying to use this technology to boost their recovery process to restore the brain balance,” Bockbrader explains.
Researchers are using stereotactic MRI-guided rTMS to non-invasively modulate precise areas of the motor cortex. The system’s targeting tool allows the therapist to accurately locate the patient’s exact stimulation target using technology similar to mapping the globe with a GPS. The n-rTMS is used to stimulate the patient´s non-injured brain hemisphere at a low frequency, said co-investigator Stephen Page, associate professor of health and rehabilitation sciences at Ohio State.
This results in down-regulation of the excitability of the healthy side and restoration of the balance between the lesioned and healthy sides, allowing the lesioned side to regain function. Adding navigation to TMS is the key to finding the exact location and orientation of the motor area that should be inhibited by stimulation. The stimulation is then accurately repeated in every session, assuring the dose is applied to the correct place, said co-investigator Lise Worthen-Chaudhari, assistant professor of physical medicine and rehabilitation at Ohio State.
“What we are doing is allowing the brain to be ready and more receptive for therapies,” comments Bockbrader. “It is not a technology limited to just motor recovery after stroke, it seems to be something that has a potential to affect many of the brain circuits that are injured in stroke.” Other sites in the clinical trial are Mayo Clinic in Arizona; Ranchos Los Amigos National Rehabilitation Institute in California; Shepherd Center in Georgia; Rehabilitation Institute of Chicago; Indiana University; Spaulding Rehabilitation Hospital in Massachusetts; Columbia University; Burke Rehabilitation Center in New York; Duke University, University of Cincinnati; and TIRR Memorial Hermann Hospital in Texas.