Stroke patients make great strides in a different reality

From: New Scientist vol 177 issue 2378 - January 18, 2003, page 14
By: Ian Sample

People who have suffered a stroke are learning to walk again thanks to a close relation of virtual reality technology.

Unlike virtual reality, "augmented reality" does not completely immerse the user in a wrap-around artificial world of 3D computer graphics. Instead, it superimposes computer-generated objects onto their view of the real world.

David Jaffe, a biomedical engineer at the US Department of Veterans Affairs rehabilitation research centre in Palo Alto, California, has been using an augmented reality system to improve rehabilitation therapy for stroke patients. The brain damage a stroke causes can leave people unable to fully coordinate their movements. "They may not bend enough at the knee or hip during walking," says Jaffe. They may also be too weak on one side to move the affected leg properly.

Jaffe recruited a group of stroke patients to test the system. Wearing a harness for safety, the subjects walked on a treadmill while wearing a virtual reality headset that showed video pictures of their legs and feet viewed side-on. The system also displayed computer-generated blocks that they had to step over.

Using a camera to monitor reflective tape on the subjects' shoes, the system monitored how high they lifted their feet. Any collision with the virtual obstacle set off an audible alarm and activated vibrators attached to the shoes encouraging the patient to try harder. As the patients got better at negotiating the obstacles, the system gave them bigger fake objects to step over.

The virtual training regime significantly improved the volunteers' ability to walk. After just six 1-hour sessions over two weeks, they walked on average 32 per cent faster with a 19 per cent longer stride. The improvement persisted two weeks after treatment. A control group who were given therapy that involved stepping over real foam blocks showed less of an improvement: gaining 26 per cent and 11 per cent improvements respectively.

The augmented reality system might be more effective because it helps people focus their attention on how they walk, Jaffe suggests. "It's weird to see yourself walking from the side, but because the rest of the environment is shut out, the training becomes very focused and perhaps that contributes to their progress," he says. Jaffe will present his work at the Medicine Meets Virtual Reality Conference in California, next week.

Jaffe's next step is to treat patients for four weeks to see if that encourages further speed and stride improvement.