Targeted Reinnervation for Neuromas as a Means to Improve Prosthesis Control in Major Limb Amputation

Overview

Subjects are being asked to participate in this study because they have an arm or leg amputation and have developed pain related to a neuroma (an ongoing localized pain related to a cut nerve ending). The investigators are studying how targeted reinnervation (TR) helps to both treat neuroma pain and to have increased prosthetic control. This surgery connects these cut nerve endings to nerves going into nearby nonfunctional muscles. This surgery was developed to allow amputees to have better prosthesis control. By chance, neuroma pain improved significantly with TR. The investigators, therefore, are conducting this clinical trial. The investigators will ask all participants to fill out a questionnaire both before and after surgery. This will help us understand how a neuroma affects the quality of life of amputee will allow us to understand how to best improve neuroma pain and prosthesis control. In order to confirm the presence and location of the neuroma before surgery, a magnetic resonance image (MRI) will be performed. Taking these pictures requires subjects to lie still for a short period of time but does not involve any invasive procedures.

Loss of an arm or leg is a significant injury that affects a person's job prospects, personal relationships, and overall quality of life. Approximately 25% of all amputees will develop chronic local pain in the remaining part of their amputated limb. This pain is caused by neuromas- disorganized nerve endings and scar tissue that form when an injured nerve tries to heal. Every cut nerve will develop a neuroma unless the two ends of the nerve can be rejoined. With limb amputation, the nerves are cut and one end is lost with the limb, preventing the nerve from repairing itself. Instead, the cut nerve ending forms a painful neuroma. Chronic pain from neuromas is a major reason that amputees cannot wear or use their prostheses comfortably and increases their disability. Even when a limb is amputated, the nerves that used to control that limb still carry messages from the brain. Those messages are intended to tell the muscles how or when to move the missing limb, but after amputation, these limb-control nerves are no longer connected to muscles. In 2002, researchers at Northwestern Memorial Hospital in conjunction with the Rehabilitation Institute of Chicago developed a new type of surgery called targeted muscle reinnervation (TMR). In TMR, limb-control nerves are transferred so that they can control new target muscles. The neuromas from the limb-control nerves are removed, then the small nerve that controls the target muscle is cut. The two nerves are joined together so that the limb-control nerve can then grow into, or reinnervate the target muscle. After TMR, when the person tries to move the missing limb, the target muscle contracts instead and these signals can be detected and used to control a prosthesis. TMR has now been done successfully almost 100 times worldwide. Interestingly, almost all of the patients who had painful neuromas before TMR had no neuroma pain after surgery. This result was investigated in laboratory studies - both rat and rabbit amputee neuromas were "cured" with TMR. We think that giving the cut nerve endings somewhere to go and something to do prevents a neuroma from forming. We will measure the effectiveness of both surgeries using an internet-based amputee pain questionnaire. We expect that TMR will be more effective for neuroma pain and prosthesis control than the standard treatment. This will change how patients with neuroma pain are treated and help thousands of patients with amputations.