TMS Device Explores Pneumatic Control of Nerve Impulses for Stroke Rehabilitation

Achievement date: 

Researchers at the National Science Foundation’s (NSF) Engineering Research Center (ERC) for Compact and Efficient Fluid Power (CEFP) at The University of Minnesota have prototyped a rehabilitation device that leverages pneumatic control of nerve impulses to replicate repetitive facilitation exercise (RFE) procedures. The device relies on a non-invasive form of neurostimulation called transcranial magnetic stimulation (TMS) to simulate and test weak motor command signals in the brain.


Stroke survivors commonly suffer from hemiparesis – a condition in which the limbs of one side of the body become weakened or unresponsive. By examining the neuromechanical mechanisms associated with RFE, CCEFP researchers are learning how to evolve TMS devices that can help stroke survivors recover the functional use of affected limbs. While early outcomes of the RFE treatment appear promising, CCEFP’s prototype awaits further verification with neurological data. Functional magnetic resonance imaging (fMRI) technology can be used to further clarify how RFE therapy affects the brain regions, better affirming potential success rates for the prototyped mechanism.


The RFE method, originally proposed by Dr. Kazumi Kawahira of Japan, consists of mechanical stimulation to dysfunctional muscles to promote the reorganization of neural pathways. Using a gentle tap at the affected muscle, a stretch reflex response is induced in the brain. As the exercise continues, this stretch reflex response overlaps with a voluntary motor command signal by the patient, leading to muscle response.


CCEFP’s prototype device features a pneumatically actuated medical hammer fabricated with fMRI-compatible material. Mechanical stimulation driven by the medical hammer evokes the stretch reflex response at the tendon of interest. In early testing, human subjects received mechanical stimulation and TMS with various time intervals between the two to observe the temporal dynamics of RFE. The data shows that there is a critical time window between two signals that evokes muscle response. The results indicate that the treatment contributes positively to regaining neural functionality by RFE.