Cryoneurolysis for Spasticity Treatment: Long-term Clinical Outcomes and Mechanisms in the Central Nervous System

Spasticity can make regular daily activities difficult or impossible. Cryoneurolysis is a new technique to treat spasticity that is currently being tested. For this technique, a needle is inserted alongside a nerve implicated in spasticity. The needle then freezes and causes the nerve to break down. The nerve breaking down seems to provide relief for spasticity. The investigators are interested in testing the long-term effects of cryoneurolysis on the function of the brain over six months after treatment. The investigators are testing the brain's function using transcranial magnetic stimulation (TMS) which involves a magnet activating specific parts of the brain that cause muscles to fire; magnetic resonance imaging (MRI) which uses to examine brain structure; functional near-infrared spectroscopy (fNIRS) to examine brain function. The investigators believe that there will be a change in these measures that are related to the long-lasting effects of cryoneurolysis. Cryoneurolysis is not a part of standard care after stroke but is approved in Canada for patients. It has been used extensively in the past for treating pain. TMS is a way of studying how the brain sends signals to muscles to make movement. During these sessions, a researcher will use a magnet to turn on specific neurons in the brain that will cause muscles to contract. The investigators can study the way eyes and muscles respond to better understand how the brain is sending information about moving the body to the muscles. FNIRS is a new way of studying how the brain works. During these sessions, a researcher will fit the participant with a cap that has several lights on it. The light travels through hair, scalp, and skull where it interacts with blood in the brain. By studying the changes in the colour of the blood in the brain, researchers can understand which parts of the brain are active during specific tasks. Magnetic Resonance Imaging (MRI) involves a powerful magnet that takes very detailed pictures of the brain. These images help the investigators to understand how a stroke is related to spasticity. Also, these images are helpful to make the stimulation with TMS more accurate. Study participation will require five visits to the Parkwood Institute Main Building and one visit to St. Joseph's Hospital. The entire study will take place over roughly six months. The investigators are recruiting 25 people with stroke who are eligible for cryoneurolysis to participate in the study.