Stinging, tingling, twitching. After an amputation, it is not uncommon for pain to occur in the missing body part. The phenomenon of phantom limb pain still poses unanswered questions for medicine and science. In many cases, the drugs used are not very effective. We think it is time to explore new treatment methods.

It is estimated that 50-80% of all amputees experience phantom limb pain during their lifetime. The direct cause remains unknown. However, recent studies using functional magnetic resonance imaging (fMRI) suggest that phantom limb pain after amputation may be caused by poor reorganization of pain pathways in the brain. It is thought that therapies aimed at restructuring the pain pathways may provide pain relief.¹

One example of such a therapy is the use of virtual reality (VR).  This is a computer-generated reality that is transmitted three-dimensionally in designated rooms or via special VR goggles. In the case of an amputee patient, virtual reality can be used to simulate movements of the missing limb. To do this, an image of the missing limb is projected into the VR environment. The patient must now solve various tasks with his virtual hand. Muscle contractions in the residual limb, which are detected by a sensor wristband, can be used to control the movement of the virtual hand.

Acting in a virtual reality causes the patient to increasingly identify with the fictitious world or to immerse himself in an illusory world in which he has two healthy hands.

In our daily lives, we rely on the use of our hands. Cars, smartphones, electrical appliances: everything works by finger touch or hand grip. Therefore, even a partial loss of hand or arm function can lead to impairments in social and professional life, phantom limb pain or depression.

After an amputation, virtual reality (VR) can provide useful services in the context of rehabilitation: for people with upper limb limitations, entering a virtual environment is a promising technology that can even alleviate phantom limb pain. The central starting point of VR therapy is to engage users in a virtual world through games and activities (immersion), where they can experience their missing or impaired limbs fully functioning again.

To detect what actions the amputee user wants to perform in the virtual environment, he wears a sensor bracelet on his residual limb. Inside, an adaptive system converts muscle signals into control commands for a virtual replica of the corresponding limb. Both the user and the therapist can teach the system new patterns at any time, correcting unstable signals or making adjustments to new actions.