How does a doctor treat pain for a body part that only continues to exist in a patient's mind? The answer to that is surprisingly simple: use therapy that only targets the mind, not the body by using virtual reality. Phantom limb pain (PLP) affects 60 to 80% of amputees and is not easy to treat (Jackson et al 289). PLP is something that can be excruciatingly painful and extremely uncomfortable for the people experiencing it, but due to new developments in technology virtual reality therapy could be used to relieve the PLP sufferers from their torment. Both virtual reality and phantom limbs are things that are usually not fully understood by the average layperson, and the treatment of the latter by using the former is something that is even less understood.
Phantom limbs have been documented in medical history since the 16the century, but it was not until large-scale wars such as World War II, Vietnam, and the wars in the Middle East occurred that it was acknowledged to be an important issue to be studied. Phantom limbs are a phenomenon in which the sensation of a limb or body part that has been amputated can still be felt by the amputee (Nikolaijsen and Jensen 107). Phantom limbs are usually not a major clinical problem, as it usually subsides and seems to shrink until it disappears completely. Phantom limbs become a problem when the sensation does not go away, and moves from simply existing to being painful. Phantom limb pain can be a debilitating issue that changes amputees' lives for the worse in that patients who have PLP are less likely to use their prosthetics than the people who do not have PLP. Amputees who do not use their prosthetics often have a more restricted life and may be unable to engage in everyday activities, which can lead to depression and increased dependence upon other people (Bamford et al 1465).
Currently, most modern therapies used to treat PLP are surgery, drugs, and psychotherapy such as hypnosis. One common surgical procedure used is spinal cord stimulation, in which electrodes are implanted using a special needle to both inhibit and stimulate certain nerves. The success rate of this procedure ranges from 20 to 95% in those with PLP (Graczyk et al 25). Surgery as a cure for PLP therefore has a very wide variation of success failure, and it is even less attractive as a treatment because it is very expensive, the postoperative care id difficult, and only offered in certain neurosurgery centers in Poland. Drugs are another option, but so far only one drug, Calcitonin, has been proven to be effective in treating PLP. The effects of Calcitonin are very rapid, working within several minutes to hours, and after three infusions, 75% of patients experienced lasting partial or complete relief from pain (Graczyk et al 26). The duration of the effect of Calcitonin, however, is unpredictable. Psychotherapy includes hypnosis, behavioral therapy, and relaxation, which has been able to help patients in their feelings of loss caused by a missing body part (Gracyzk et al 27).
Another treatment that is perhaps related to psychotherapeutic methods is the mirror box treatment, in which a patient looks at the reflection of their remaining limb and attempt to move their phantom limb with the image of the reflection superimposed upon it. “Its success is due to its exploitation of our natural embodied tactile-visual-kinesthetic engagement with our world” (Stuart 257). This revolutionary therapy can be successful in aiding many amputees with PLP, but it has its limitations and problems. One issue is that mirror therapy is not as helpful for those with leg amputations as it does for arm or upper body amputations (Slater et al 847). The reason for this is simple: symmetrical movements of the arms can look natural, but the symmetrical, perfectly mirrored movements of legs do not look very natural; legs do not usually move perfectly in tandem with each other. Another large drawback is in those patients who do not have an intact, functional limb. If there is no limb to make the reflection in the mirror, then the entire mirror box therapy is effectively useless and unable to be done. The solution to this dilemma is virtual reality. This relatively new idea of virtual reality therapy can relieve the pain and discomfort of amputees, increasing their quality of life and allowing them to move on from their pain.
Virtual reality is a “medium of human-computer interactions whereby a human becomes an active participant in a virtual world” (Gold et al 204). Most people in the general populace understand virtual reality technology as something that only occurs in sci-fi books and retro-futuristic movies from the '70's. However, virtual reality is something that has been worked on to be used by the general public, such as the entertainment industry's innovations of virtual reality for video games. In the course of 15 years, the use of virtual reality has been used for educational, training, and research functions. More recently, it has been adapted for use in clinical and medical settings. “Distraction from… pain has been researched and is an empirically supported form of non-pharmacological pain management” (Gold et al 204). In one preliminary virtual reality therapy session, “80% of patients showed more than a 50% reduction of pain intensity after three to eight consecutive treatment sessions” (Sato et al 626). The virtual reality therapy also helped patients that were unable to be treated by mirror therapy, which shows that virtual reality is a viable alternative to mirror therapy.
There are two ways that virtual reality is being used to treat PLP. One way is that the patient straps a glove or some other kind of device upon their remaining limb and, while watching the virtual manifestation of their limb, try to imagine their phantom limb moving in the same aspect. In control subjects, 44% found that they preferred this therapy over the mirror box (Slater et al 847). However, this has some of the same problems as the mirror therapy in that someone with both limbs missing may not be able to use it, but it does fix the problem of the unnatural movements of the reflected leg in the mirror therapy. The other way is to develop a virtual system, and then control it from the stump or part of the amputated arm or leg with a motion capture device. The patients are then asked to move their stumps while seeing a virtual limb in a pre-animated sequence. The benefits of this technique is that the system is cheap enough to mass produce, the movements are not bilateral, and the system is able to be used on patients who have had both arms amputated. The disadvantages of this are that the movements of the virtual arm are fixed and less natural.
Virtual reality has already begun to be used on patients, such as a 65-year-old woman who we shall refer to as DT. She had been a left upper-limb amputee for 1 year due to a falling accident, and she utilized a prosthetic limb. She experienced regular PLP, mostly restricted to her phantom hand, a “constant pins and needles sensation which varied in severity ”. Her phantom hand was unable to be moved, with the fingers in a clenched position. The pain was, as she described, ”… [in] the palm because I think it's like the nails of my fingers digging into my palm” (Bamford et al 1467). DT's phantom limb pain was so severe that it habitually impeded her from getting enough sleep. She went through two sessions of virtual reality therapy over a 3-week period, with a maximum of two weeks between sessions. DT reported that her PLP immediately decreased after the first trial of virtual reality use, and she also reported “vivid sensations of her phantom hand carrying out the tasks” to the point that her “left (phantom) arm ached… after the IVR sessions” (Bamford et al 1468).
There are some problems in virtual reality therapy; the technology and its significance over other proven therapies such as mirror therapy have been questioned. One such problem is that the virtual limbs do not always look natural, and they do not look as real as the mirror box reflected limbs do. However, ”… VRMVF therapy provides promising analgesic efficacy” because “it does not seem likely that analgesia provided by VRMVF therapy depends upon whether subjects recognize the virtual arm as their own” (Sato et al 627). Virtual reality has an added advantage of engaging different regions of the brain than mirror therapy while still stimulating the brain regions that mirror therapy does. Also, virtual reality, unlike surgery and drugs, is free of side effects and helps to restore neural plasticity (Sato et al 628).
Virtual reality is getting better and better every day, with new improvements and uses for everyday life as well as for medical things like phantom pain. With the technology that exists today, virtual reality therapy can be a viable alternative to more risky or expensive treatments such as surgery, drugs, or psychotherapy. Virtual reality is safe, effective, and more successful at alleviating pain for than mirror box therapy. All in all, virtual reality therapy is a novel treatment that can help the numerous sufferers of PLP find relief for their phantom pain. Virtual reality is the therapy choice for the future.
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