New method developed to treat phantom limb pain

Researchers at the Chalmers University of Technology developed a new method, based on a combination of several technologies, for the treatment of phantom limb pain after amputation.

Initially tested on a patient who had severe phantom limb pain for 48 years, the new method uses muscle signals from the patient’s arm stump to drive a system known as augmented reality. According to a press release, electrical signals in the muscles are sensed by electrodes on the skin and translated into arm movements by complex algorithms. Patients can see themselves on a screen with a superimposed virtual arm, which is controlled using their own neural command in real time.

“There are several features of this system which combined might be the cause of pain relief,” Max Ortiz Catalan, a researcher at Chalmers University of Technology, stated in the release. “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 into believing there is an arm executing such motor commands. He experiences himself as a whole, with the amputated arm back in place.”

In addition to pain relief, the treatment also resulted in the patient experiencing a position of rest in his phantom hand in its normal state. The patient also learned to control the movements of his phantom hand, even when he is not connected to the treatment system, and now experiences the phantom hand as being at the anatomically correct location.

The researchers report several advantages to their new method. The treatment noninvasive, it can be used when both arms and legs have been amputated, it enables most of the movements that the biological arm can execute and generate motivation with computer games and can exact measurements of the patient’s progress.

“Our method differs from previous treatment because the control signals are retrieved from the arm stump, and thus the affected arm is in charge,” Catalan stated in the release. “The promotion of motor executive and the vivid sensation of completion provided by augmented reality may be the reason for the patient improvement, while mirror therapy and medicaments did not help previously.”

In collaboration with Sahlgrenska University Hospital, the University of Gothenburg and Integrum, researchers at Chalmers University of Technology are conducting a clinical study involving three Swedish hospitals and other European clinics that will target patients with phantom pain who have not responded to other available treatments.

Disclosure: The research is funded by Jimmy Dahlstens Fond, Conacyt, Vinnova, Picosolve, IKV and Integrum.

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