A powerful new robotic testing method has shed light on a hidden challenge faced by stroke survivors: proprioception deficits. This often-overlooked aspect of stroke recovery can significantly impact a person’s ability to move and sense their body’s position.
Don Lewis, a stroke survivor and cancer survivor, has been helping researchers at the University of Delaware uncover this crucial issue. At 55, Don suffered a stroke that left him paralyzed on his left side. Despite regaining use of his left leg, his left arm remains paralyzed, causing him pain and a lack of control over its movement.
But here’s where it gets controversial… While pain and touch impairments are often associated with stroke, Don’s case highlights a different aspect. Jennifer Semrau, an associate professor of kinesiology and applied physiology, explains that proprioception, the body’s ability to sense movement and position, is a critical yet overlooked factor in stroke recovery.
Semrau and her team, including doctoral candidate Joanna Hoh, have published findings in Neurorehabilitation and Neural Repair, suggesting a way to identify these hidden sensory losses without requiring patients to move their affected arm. This breakthrough could make assessments more accessible and improve clinical care.
The Lab’s Approach
Inside the lab, Don is fitted with a KINARM robotic exoskeleton that tracks upper limb movement. This allows Semrau to study the neural and behavioral mechanisms contributing to sensory and motor function recovery. Using various tests, including the innovative single-arm measurement, they gauge perception-based movement. Don responds with his non-affected arm to indicate if he can feel the movement of his stroke-affected arm.
Uncovering Sensory Deficits
The average person can detect movement as little as half a centimeter. However, for stroke survivors, this sensitivity varies. Some may not realize their arm has moved 10 centimeters, which could have serious implications in daily life, such as touching a hot stove or a knife.
The Brain-Muscle Connection
A stroke disrupts communication between the brain and muscle receptors responsible for detecting movement. When we move, these receptors lengthen or shorten, but without proper brain-to-receptor communication, movement coordination is impaired. Interestingly, this doesn’t always affect pain or touch sensitivity, as these are relayed through different nerve pathways.
The Challenge for Clinicians
Semrau emphasizes the difficulty in distinguishing sensory deficits from motor deficits, as they are deeply intertwined. This makes it hard to determine whether the issue lies with feeling the arm or moving it. The tasks developed in their lab aim to get to the heart of this matter.
Raising Awareness
Hoh, an occupational therapist, became interested in upper-limb stroke research after working with patients in rehabilitation. She realized the sensory system’s importance in stroke recovery, an area often overlooked by clinicians.
Semrau hopes their research will encourage more clinicians to integrate this precise testing. Their studies have found that only 1% of clinicians assess proprioception in stroke patients, highlighting the need for awareness and action.
Personalized Medicine Approach
Both Semrau and Hoh stress the importance of understanding post-stroke impairments to develop personalized treatment approaches. Just because someone has motor impairments doesn’t mean they won’t also have sensory impairments, and vice versa. Understanding the connection between these impairments is key to tailoring recovery plans.
And this is the part most people miss… Proprioception deficits after stroke are a critical yet often overlooked aspect of recovery. By raising awareness and implementing precise testing, clinicians can better target therapies and improve outcomes for stroke survivors.