Increasing amount of research in recent years has added to developing knowledge of phantom limb pain (PLP). In this research proposal I aim to test the mirror therapy as an effective treatment in PLP. Phantom limb pain occurs in at least 90% of limb amputees. PLP may be stimulated by disconnection between visual feedback and proprioceptive representations of the amputated limb. Therefore, I will research both the neurobiology behind this phenomenon and whether illusions and/or imagery of movement of the amputated limb (mirror therapy) is effective in alleviating PLP of lower limbs. Mirror therapy has been used with noted success in patients who have had upper body amputation, but has not been determined in lower limb amputations. I would like to identify if form of treatment is equally effective in lower limb amputations. Yet, to consider mirror therapy as an effective means of treatment, one must understand PLP in its entirety. The main concern being if a limb is no longer attached to the body, how can neurons in the limb transport signals to the nervous system in order for the body to detect sensations? The biological significance of this project is to determine what occurs on the sensory level to cause PLP. Once that is discovered we can address whether or not mirror therapy is a plausible form of treatment.
Sensation, as we know it, is thought to be a result of direct contact between the body and an internal or external stimulus. However, in the case of phantom limb phenomenon, sensation is explained rather differently. The phantom limb phenomenon, in short, occurs when a person with a missing limb still has sensations of limb being there; it is having the perception of missing limbs and feeling sensations from it following amputation, paralysis, or destruction of the sensory roots (Melzack 1990). About 90 percent of people with phantom limb, feel excruciating pain generated from the missing limb, describing it as burning, aching, or 'as if a missing hand is being crushed in a vice’ (Jackson 1889, Katz and Melzack 1990). The occurrence of phantom limb pain (PLP) in amputee-patients ranges between 90-98 %. As these numbers vary between studies, it can be noted that 70 % of patients experience this pain within the first days or quickly after the anaesthetic wears off. Other patients claim to experience this pain with a few week of amputation (Hirstein and Ramachandran 1998). The duration of phantom limb pain can also last anywhere from a couple of hours to over the course of many years. Ramachandran suggests that in amputee patients, the brain receives signals from the missing limb, which can cause the patient to feel sensations as if the limb were present (1996). This phenomenon can be explained, as the phantom sensation is a result of cross activation between different brain regions. That is, PLP in amputees is associated with reorganizational changes in the somatosensory system (Karl et al. 2001).
The neurobiology behind...