Virtual Reality Tricked Stroke Victims Into Using Their Weak Limbs

In virtual reality, an arm impaired by a stroke can seem strong again. And, according to new research, that illusion could be the key to give patients the confidence they need to practice using their weakened limbs in real life.

After a stroke, patients may compensate for losing the muscle strength in one limb by using the working limb more frequently. Eventually, a behavioural pattern of non-use can form, where the weak limb is totally ignored. This is called "learned non-use." While it may initially result in making life a little easier, if a stroke patient doesn't learns to properly use the arm with reduced strength, they may never get to.

Traditional therapy for this condition involved constraining the working limb and forcing the patient to use their impaired limb to complete tasks. But, according to researchers from the Laboratory of Synthetic, Perceptive, Emotive and Cognitive Systems at the Universitat Pompeu Fabra in Spain, the real key to getting people to use their affected limbs could be giving them a boost of confidence in VR.

In a pilot study involving 20 patients, the researchers got patients to reach for a target in a virtual world using their strong and weak arms; their movements were captured and digitized by an Xbox Kinect. The performance values for their "bad" arms—which controlled how fast and accurate they appeared in virtual reality—were then manipulated and enhanced. In subsequent tests, where their strength was unmodified, the patient's' actual performance and the likelihood of using their bum limb was calculated.

"After enhancement of movement, patients started using their paretic limb more frequently," Belén Rubio Ballester, the study's lead author, said in a statement. "This suggests that changing patients' beliefs on their capabilities significantly improves the use of their paretic limb. Surprisingly, only ten minutes of enhancement was enough to induce significant changes in the amount of spontaneous use of the affected limb."

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The results of the study were published today in the Journal of NeuroEngineering and Rehabilitation.

Curiously, not one of the patients reported noticing the VR enhancements to their impaired limbs. However, "one of the patients commented that both virtual limbs moved faster during session 2, where only the paretic hand moved faster," the researchers write. Apparently, the illusion was both subtle and convincing.

Virtual reality is finding more and more uses in therapy, precisely because you can test the impossible in the digital realm. For example, researchers can simulate triggering situations in order to treat PTSD in military veterans. When it comes to medical therapy, the principle is pretty much the same: if you you can simulate the right conditions, maybe you can improve patient responses.

Of course, this is just one study, and a small one at that. The results will need to be tested and retested on larger groups of patients to ensure replicability. But the results are nonetheless promising, and may indicate yet another use for virtual worlds in improving how we navigate the physical.