Relieving phantom pain with virtual reality

Virtual reality has made strides and is now leading to real physical reactions. Virtual sensory impressions perceived by the brain are so real that arachnophobes perspire and suffer palpitations just by touching a creepy-crawly in a VR environment. The "Prosthetics and Orthotics for Mobile and Specific Phantom and Deafferentation Pain Therapy" (PROMPT) now aims to take advantage of that effect.

Many amputees use prostheses controlled by electrical muscle activity based on their remaining nerves. Built-in microvibrators or somatosensory feedback on personal body perception will be provided as part of PROMPT. Various VR games and experiences are used to train the sufferer's sensory perception.

Amputees without an arm and who suffer from phantom pain or people whose arm is paralysed e.g., because the arm's  nerves were severed after a motorbike accident are at centre of PROMPT. An interruption of the nerves results in deafferentation, which is combated with VR. The arm becomes healthy and supple and patients are given various tasks. "They reach into water and set it in motion, stack dice or throw and catch balls and always with both hands," Wilke explained. The VR approach is thus a continuation of mirror therapy. A mirror is placed in front of the patient so that movements of the healthy arm are mirrored and perceived as movements of the affected arm.

Both therapy approaches try to trick the brain. Wilke remarked: "Research on phantom and deafferentation pain assumes that the cause could lie in a sensorimotor incongruence." The brain sends the command "move the arm", which is impossible because of the missing limb and there is no visual and sensory feedback. That results in an error message, so to speak. Enter VR: The virtual experience gives the brain the expected feedback and the number of error messages decrease and so does the pain. "That's the theory. However, the effect has not yet been proven. This is still a feasibility study." To come up with more long-term results and to verify their theory, researchers are now keen on finding test persons to take part in studies all over Germany. Wilke stressed: "People suffering pain after lower or upper arm amputations or arm paralysis are welcome to contact us on promptstudie@gmail.com."

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