Imagine waking up one day, unable to move half your body. This is the stark reality for stroke survivors like Don Lewis, who, at 55, experienced a stroke that left him paralyzed on his left side. But here's where it gets even more challenging: many stroke survivors face a hidden battle with proprioception—the body's ability to sense movement and position—a crucial yet often overlooked aspect of recovery.
Don’s story began when his neighbor noticed his truck hadn’t moved for two days, prompting a welfare check. Paramedics found him paralyzed on one side, the result of an aneurysm-induced stroke. After two months in the hospital and extensive physical therapy, Don regained use of his left leg, but his left arm remains paralyzed. He describes a haunting disconnect: ‘I feel pain if I hit it, but I can’t control the movement.’ Since then, Don, a cancer survivor, has endured two more strokes, making his journey even more complex.
Now, Don is collaborating with researchers at the University of Delaware to shed light on proprioception deficits—a critical yet underrecognized challenge in stroke recovery. ‘Close your eyes and touch your nose,’ explains Jennifer Semrau, associate professor of kinesiology and applied physiology. ‘If you can’t do that, it’s a sign of impaired proprioception.’ This simple test underscores the complexity of the issue, but it’s just the tip of the iceberg.
In a groundbreaking study published in Neurorehabilitation and Neural Repair, Semrau and doctoral candidate Joanna Hoh introduced a novel robotic testing method. This approach can identify hidden sensory losses after a stroke without requiring patients to move their affected limb—a game-changer for clinical assessments. Using a KINARM robotic exoskeleton, researchers track upper limb movement to better understand the neural and behavioral mechanisms behind sensory and motor recovery.
One innovative test involves moving the patient’s stroke-affected arm robotically while they respond with their non-affected arm if they can feel the movement. ‘We’re pinpointing the smallest movement someone can detect,’ Semrau explains. For context, the average person can sense movement as small as half a centimeter, but for stroke survivors, this threshold varies dramatically. ‘Some can’t detect movement even when their arm is shifted 10 centimeters—a difference that could mean accidentally touching a hot stove or a knife,’ she adds. And this is the part most people miss: proprioception deficits aren’t just about movement; they’re about safety and independence.
But here’s where it gets controversial: while proprioception deficits are critical, they’re often overshadowed by motor deficits in clinical settings. The brain’s communication with muscle receptors is disrupted after a stroke, impairing movement coordination. Yet, someone with proprioceptive deficits might still feel pain or retain touch sensitivity, as these functions rely on different neural pathways. ‘Every stroke survivor’s impairments are as unique as a fingerprint,’ Semrau notes, emphasizing the need for individualized treatment.
The challenge? Untangling sensory deficits from motor deficits is like solving a puzzle with missing pieces. ‘Is the issue feeling the arm or moving it?’ Semrau asks. Her lab’s research aims to answer this question, bridging the gap between clinic and classroom. Hoh, an occupational therapist turned researcher, was inspired by her work with stroke patients. ‘We focus so much on motor function that we often overlook the sensory system,’ she admits. Her dissertation now explores how sensory issues post-stroke impact daily activity levels.
Semrau and Hoh hope their research will spark a paradigm shift, encouraging clinicians to integrate precision testing for proprioception. ‘Only 1% of clinicians assess proprioception in stroke patients,’ Semrau reveals. ‘Without sensory recovery, full functional recovery is unlikely.’ This raises a thought-provoking question: Are we doing enough to address the hidden challenges stroke survivors face?
As they push for a personalized medicine approach, both researchers stress the need for a deeper understanding of post-stroke impairments. ‘Just because someone has motor deficits doesn’t mean their sensory abilities are unaffected,’ Hoh points out. Semrau adds, ‘Understanding the motor-sensory connection is key to tailoring therapies for individual recovery.’
So, what do you think? Is proprioception getting the attention it deserves in stroke rehabilitation, or are we missing a critical piece of the puzzle? Share your thoughts in the comments—let’s spark a conversation that could change the way we approach stroke recovery.
