Easing phantom pain with augmented reality

New study finds amputees are able to reduce the amount of pain they feel from their missing limb using AR.

2nd December 2016
Easing phantom pain with augmented reality © Ortiz-Catalan et al., The Lancet, 2016.

In the augmented reality environment, the patients can see themselves on a screen with a superimposed virtual arm, which is controlled by muscle signals from their arm stump © Ortiz-Catalan et al., The Lancet, 2016.

One thing has hit the headlines in a big way this year is virtual reality. We can’t seem to fall over for a new VR headset being released (or maybe it’s because we’re wearing one) and before long we could be seeing them in any self-respecting gamer’s home. But it’s not just for immersive gaming that VR has its uses, it is also providing new ways to treat psychological conditions such as PTSD or vertigo. Now, a new study suggests that phantom limb pain can be eased using augmented reality.

A phantom limb is the perception of a limb that is no longer there, such as an arm that has been amputated. Changes in the wiring of the brain after loss of a limb mean it is tricked into thinking the limb is still there, which is understandably very irritating, and in some cases painful.

Up to 90 per cent of amputees experience this phenomenon straight after the loss of a limb, however the sensation usually dissipates after a few days. But for an unlucky handful of people a phantom limb can stick around for years – and current treatments are limited, involving a combination of drugs, acupuncture and mirror therapy, none of which may be successful.

A team of Swedish researchers have published the results of a clinical trial in The Lancet, in which a new treatment, termed ‘phantom motor execution’, is used to alleviate phantom limb pain. The therapy uses augmented reality to visualise the phantom limb, in a similar way to mirror therapy. Sensors are placed on the limb to sense muscle activity, which is then fed into a computer that creates a virtual arm on screen, which can then be moved by the user.

The clinical trial involved 14 amputees experiencing phantom limb pain, for whom other treatment didn’t work. After 12 sessions of augmented reality treatment, patients reported a 50 per cent reduction in pain, and at a six-month follow-up, the majority of patients reported sustained pain reduction.

The success of the small clinical trial would need to be confirmed by a larger study, with a control group, but the researchers are hopeful. "The results from our study suggest that it may be useful to 'exercise' the phantom limb,” says assistant Professor Max Ortiz Catalan. “Our treatment offers an engaging way to do this while also providing a non-invasive and non-pharmacological treatment which was found to reduce chronic pain with no observed side effects.”

 


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