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Dr. George Mochizuki

Understanding the brain-muscle link

Stroke doesn’t only damage the brain. It attacks the muscles.

As many as 40 per cent of people who have a stroke experience a condition called spasticity – tightness or stiffness in an arm, shoulder, hand or leg – within the first year.

The result? A hand so tightly curled it can’t open a door, pick up a coffee cup or hold a brush. Fingernails that cut into a palm. A rigid leg that feels stuck to the floor. Problems walking, standing, maintaining balance.

CPSR-Investigator Dr. George Mochizuki, who did graduate work in Exercise Science and a PhD in Neuroscience, is studying the brain-muscle connection to understand changes in the brain that contribute to this tightness or rigidity.

“We want to know what’s happening at the muscle and brain level with people who have spasticity,” he says. “We want to develop more quantitative ways to measure tightness. And we want to develop ways of measuring the impact of spasticity on performing the activities of daily living.” In a major study, Dr. Mochizuki is using the drug BOTOX™ to relax muscles in stroke patients with spasticity while he tests combinations of different therapies to find what’s most effective and what results in the most improved outcomes.

Changes in the muscle and brain are being measured with electromyography (EMG) to record the firing patterns of different muscles and electroencephalography (EEG) to record electrical activity in the brain.

Dr. Mochizuki’s research also involves the use of a robot to move tightened arms at different speeds and in different directions to measure when muscle resistance kicks in.

“Until now, measuring resistance in the affected arm has been very subjective,” Dr. Mochizuki says. “Now we can characterize the catch (when resistance is first felt) and release in muscles.” The information allows researchers to better design and implement individualized treatments for spasticity.

“If we can be more quantitative in how we measure the effects of spasticity, we can better design and implement spasticity-management interventions and focus therapy to address specific issues,” Dr. Mochizuki says.