NEUROLOGY & NEUROSURGERY

Exploring the Riddle of Brain Function to Revolutionize Stroke Recovery

Oct. 7, 2020

What do songbirds, stuttering and electromagnetic stimulation have in common? A revolutionary treatment for recovery after stroke — and potential treatments for many other neurological disorders.

It all started with the riddle of stuttering, explored by Houston Methodist neurologist David Rosenfield, MD, and neuroscientist Santosh Helekar, MD, PhD. They compared the brain structures of zebra finches learning songs to those of humans learning speech and asked: How can we identify and influence brain mechanisms that affect speech? It occurred to Helekar that the answer was to develop a way to apply electromagnetic stimuli to precise, localized points in the brain—by inventing a device small enough to stimulate a songbird's brain.

Helekar and Henning Voss, PhD, a physicist at Weill Cornell Medical College, worked together to invent a portable non-invasive device that uses powerful neodymium rare earth magnets, combined with tiny electric motors to produce high-speed oscillations: electromagnetic bursts that resemble the wave patterns that might occur in the brain during learning. Eventually, the researchers attached the motorized magnets, small enough to enclose in capsules, to a neoprene cap that fits snugly on the human head. Controlled by a smart phone app, the cap provides patients with an affordable and portable home-based therapy.

Called transcranial rotating permanent magnet stimulation, or TRPMS, the patented technology uses multi-focal stimulation to manipulate impulses at several points in the brain simultaneously, exciting or inhibiting areas responsible for specific functions. Following a stroke and its resulting lesions, the cap can stimulate nearby healthy tissue to take over functioning in damaged areas.

For example, healthy tissue surrounding lesions in the motor cortex may be stimulated to send instructions that induce muscle groups to continue functioning.

Results from a phase II clinical trial were presented as late-breaking science at the American Stroke Association International Stroke Conference 2020 in February. In the randomized, double-blind, sham-controlled clinical trial of 30 chronic ischemic stroke survivors, the new TRPMS cap produced significant increases in physiological brain activity in areas near the injured brain, as measured by functional MRI.

They found that treatment was well tolerated, and there were no device-related complications. Active treatment produced significantly greater increases in brain activity: nearly nine times higher than the sham treatment.

Although the study could not prove that the transcranial stimulator improved motor function, numerical improvements were demonstrated in five of six clinical scales of motor function, as measured by a functional MRI test. The scales measured gait velocity, grip strength, pinch strength, and other motor functions of the arm. The treatment effects persisted over a three-month follow-up.

The phase II stroke recovery trial was conducted by Helekar and David Chiu, MD, Elizabeth Blanton Wareing Chair in the Eddy Scurlock Stroke Center in the Stanley H. Appel Department of Neurology.

Based on the results of the phase II trial, a pivotal multicenter clinical trial of TRPMS in chronic stroke is planned.  

As the first project to be selected for funding by the Houston Methodist Translational Research Initiative, the cap is fulfilling the fund’s mission of promoting clinical translation. The patent portfolio for the technology underlying the cap has been licensed by Seraya Medical Systems, LLC, which has supported one clinical trial in the past year and will also support the multicenter trial. Seraya plans to design a commercial version of the cap, for which it plans to apply for FDA marketing approval after the clinical trials are completed.

Previous data demonstrating the cap's ability to diminish stuttering was presented at the 2018 American Neurological Association meeting. Following a poster presentation co-authored by Rosenfield and Helekar, their research was awarded a "blitz" presentation for an audience of neurologists. Rosenfield, who is the Chair in Speech and Language in the Stanley H. Appel Department of Neurology, reported their results: When using the cap to strengthen the connection between the Broca’s and Wernicke’s speech areas in the brain, eight out of nine study participants showed improved fluency of speech.