Trial at the Cleveland Clinic (USA) on 12 patients with moderate-to-severe hemiparesis. Thin electrodes inserted into the cerebellum made it possible to improve the effects of rehabilitation.
Deep brain stimulation (known by its acronym, DBS), already used to treat Parkinson's disease and other neurological disorders, could find a new application in a field that, until now, has only been explored using animal models: hemiparesis and, in general, the damage arising from ischaemic stroke.
A trial (the first of its kind), conducted on human volunteers by neurologists and bioengineers from the Cleveland Clinic (one of the most highly-regarded hospitals in the United States), has, in fact, shown that electrical stimulation of a specific part of the brain called the dentate cerebellar nucleus can significantly improve limb movement and function and increase chances of recovery. The results of the study have appeared in the scientific journal Nature Medicine.
DBS, as you may recall, involves the insertion of thin electrodes into the brain, all the way into the specific areas identified by the experts (the procedure is performed by neurosurgeons). The electrodes are then connected to a device called a brain pacemaker, which emits mild electric pulses, providing controlled stimulation to the “target” regions.
Eight months of testing
During this phase I (first stage) trial, called EDEN (Electrical Stimulation of the DEntate Nucleus), 12 subjects, all of whom had suffered a stroke between one and three years prior and exhibited moderate-to-severe upper-extremity hemiparesis, underwent a procedure to implant micro-electrodes in their brains (the dentate nucleus is located in the cerebellum, the part of the brain beneath the brain hemispheres, which plays an important role in controlling the body’s motor function). The 12 patients then underwent normal rehabilitation, with the devices switched off, for several weeks.
After that, they switched on the devices and kept them connected for 4 to 8 months, so as to be able to compare the two situations. As it happens, the difference was clear to see. Once the DBS was initiated, there was a noticeable improvement in motor function, with 9 of the 12 volunteers achieving progress viewed as statistically significant on the scales used to assess the consequences of strokes and subsequent recovery.
Specifically, those who had retained a minimum of motor function tripled their initial scores, an extremely positive statistic.
What's more, none of the subjects suffered harmful complications or side effects. Given its ability to improve movement and balance and boost the effectiveness of rehabilitation treatment, deep (in this case) brain stimulation, a method patented by the physicians at the Cleveland Clinic (the hospital is controlled by a non-profit foundation) could thus be a valuable tool for helping people who have to cope with stroke-related disability.
"Phase two" is already on the way
Naturally, however, further trials, conducted on larger sample groups, will be required in order to confirm the results seen at Cleveland Clinic and to develop specific protocols for administering DBS to patients with varying degrees of post-stroke disability. We must also consider the fact that, in any event, DBS is still a delicate procedure, to be reserved for carefully chosen subjects. Be that as it may, the Cleveland Clinic has already launched a phase II trial (there are a total of three trial phases), with the financial support of the BRAIN Initiative (an important project involving numerous U.S.-based research institutions) and the National Institutes of Health.