People who lose an arm or a leg often experience phantom sensations, as if the missing limb were still there. Seventy per cent of amputees experience pain in the amputated limb despite that it no longer exists.
Phantom limb pain can be a serious chronic and deteriorating condition that reduces the quality of the persons life considerably. The exact cause of phantom limb pain and other phantom sensations is yet unknown.
Different treatment methods
Phantom limb pain is currently treated with several different methods. Examples include mirror therapy, different types of medication, acupuncture and hypnosis. In many cases, however, nothing helps.
This was the case for the patient that Chalmers researcher Max Ortiz Catalan selected for a case study of the new treatment method he has envisaged as a potential solution.
The patient lost his arm 48 years ago, and had since that time suffered from phantom pain varying from moderate to unbearable. He was never entirely free of pain.
Drastically reduced pain
The patients pain was drastically reduced after a period of treatment with the new method. He now has periods where he is entirely free of pain, and he is no longer awakened by intense periods of pain at night like he was previously.
The new method uses muscle signals from the patients arm stump to drive a system known as augmented reality. The electrical signals in the muscles are sensed by electrodes on the skin. The signals are then translated into arm movements by complex algorithms. The patient can see himself on a screen with a superimposed virtual arm, which is controlled using his own neural command in real time.
"There are several features of this system which combined might be the cause of pain relief" says Max Ortiz Catalan. "The motor areas in the brain needed for movement of the amputated arm are reactivated, and the patient obtains visual feedback that tricks the brain in
|Contact: Krister Svahn|
University of Gothenburg