Stroke Recovery may be Rebooted through Magnetic Pulses
10 January 2015, Nirapad News : According to the World Health Organization, 15 million people suffer stroke worldwide each year. Of these, 5 million die and another 5 million are permanently disabled.
Stroke survivors face a range of potential side effects, including vision problems, memory loss and impairments in speech. The most prevalent side effect, however, is paralysis on either side of the body, which can cause loss of movement and diminished range of motion in the arms and legs. When one side of the brain is damaged by stroke, the healthy side tends to generate much more activity to compensate for the immobile side. This overcompensation can actually prevent the injured side from recovering.
In an effort to help patients regain movement on the side of their body affected by stroke, Dr. Marcia Bockbrader an assistant professor of physical medicine and rehabilitation at the Ohio State University Wexner Medical Center along with few of her colleagues have taken part in a double-blind, randomized, placebo-controlled, Phase III trial to determine the effectiveness of repetitive transcranial magnetic stimulation (rTMS) using a device developed by NexStim, which funded the study.
After a stroke hits, often, stroke patients can have a rapid partial recovery in the first few months after a stroke, then the spontaneous healing process slows down after about three to six months, and then slows even further after a year. This can be frustrating for patients who have a stroke that leaves one side of their body weak, making it difficult for them to do their usual everyday activities, like dressing and eating, or leisure activities like golfing.
Often, when those impairments have persisted even after completing 3 to 6 months of outpatient therapies, many patients lose hope of regaining the ability to use their weaker side.
Up to this point, doctors have not known how to reset the brain back into the state of rapid recovery that we see in the initial months after a stroke. They have been looking for a way to boost the benefits of physical and occupational therapy for motor recovery after stroke, and they think that using a powerful magnet to enhance brain plasticity prior to therapies may be the solution.
Doctors think that part of the problem is that the healthy and injured sides of brains of some stroke patients develop an imbalance over time, either as a direct result of the tissue injury from stroke or through lack of use of the weaker side of the body. The result appears to be overactivity on the healthy side of the brain that may actually prevent the injured side from recovering. The rTMS device helps even out this imbalance by reducing activity on the side of the brain that was not injured by stroke and giving the other side a more likely chance to recover and express itself once more. They use the navigated rTMS to essentially map the participant’s brain like a GPS system would, and then repeatedly stimulate specific areas of the motor cortex in a non-invasive manner. The rTMS device is a flat, water bottle-sized magnet that can be hold against the patient’s scalp while they are reclining comfortably in a chair. The process is painless, though participants may feel the snap of the magnet pulse against their scalp or the twitch of a muscle in their arm as the device works.
The critical advance of this technology is the navigation tool, which allows to more easily find the area of the brain that needs to be stimulated, which speeds up a patient’s recovery and restores the brain balance. Adding navigation to TMS is the key to finding the exact location and orientation of the motor area in each person that needs inhibition, via the stimulation. The stimulation is then accurately repeated in every session, assuring the exact dose is applied to the correct place, within a tolerance of 2 millimeters.
The process helps improve the brain’s receptiveness to activity-based therapy. The technology isn’t limited solely to motor recovery after stroke — in fact, it seems to have the potential to affect many of the brain circuits that are injured in stroke.
As a Phase III clinical trial, this technology is in the last phase of testing needed to obtain U.S. Food and Drug Administration (FDA) approval for use in clinical settings. In development since 2000, NexStim’s non-invasive Navigated Brain Stimulation System is currently available for investigational use only.
Patients in the trial undergo occupational therapy rehab after each use of the device to improve flexibility, strength and use of weak arms or hands. They hypothesize that pretreatment with carefully dosed magnetic pulses to the motor cortex will predispose participants to make bigger gains with therapy than they would have with 6 weeks of therapy alone. The trial continues for 8 months so it can be determined whether initial improvements in motor function persist 6 months after completing treatment.
Since the study is double-blind, patients are not sure if they’re actually getting a stimulation dose from the device, but already some have been encountered who say everyday tasks like opening the refrigerator and getting around the house are much easier. Although it still can’t be known for sure if these individuals have received the stimulation or placebo treatment, but these indications gives hope that the trial will be successful and the device will be approved for general use in the near future.
The technology also has implications outside of post-stroke motor recovery. The rTMS treatment is a highly precise, yet non-specific, way of preparing the brain for all types of therapies, and depending on where the magnet is aimed, can potentially affect many of the brain circuits that are impaired during stroke or other types of brain injuries. Instead of targeting the motor cortex to promote recovery of arm movement, we can vary the location of magnetic stimulation to target the brain regions associated with other neurologic impairments, e.g., language areas, attention areas, chronic pain areas. Thus, rTMS treatment could be potentially improve aphasia, hemispatial neglect or pain perception resulting from stroke or brain injury. This bodes well for neurorehabilitation programs in the future, shedding light on the possibility that this technology might not be limited to stroke recovery alone.