(47) Peripheral Nerve Stimulation as a Treatment for Phantom Limb Pain

Introduction: Phantom limb pain is characterized by pain and discomfort in a missing extremity after amputation. It is hypothesized that phantom limb pain may be reduced by restoring sensation coming from the amputated limb through electrical stimulation. The overall goal of this research is to develop a non-invasive, at-home, therapy that consists of electrically evoking somatosensation in the amputated extremity to decrease phantom limb pain and promote neuroplasticity within the brain.

Methods: A participant with a trans-tibial lower limb amputation, caused by vascular disease stemming from Cryoglobulinemia, was recruited for the study. The proposed therapy was implemented once a week for six weeks. The therapy consisted of surface electrical stimulation of the common peroneal nerve in the popliteal fossa to evoke a tapping sensation in the missing limb. This evoked sensation was paired with simultaneous tapping on the reported sensation location.

Before starting the therapy and just prior to the final session, the participant's cortical activity was recorded using EEG. Data on pain levels were collected weekly using the pain portion of the Trinity Amputation and Prosthesis Experience Scales (TAPES-part 2) and the visual analog scale. These same surveys were collected for the 6 weeks following completion of the therapy.

Results: Initial nerve stimulation elicited referred sensations in the residual limb only. With extended stimulation, the participant reported sensations along the lateral shank, experienced in both the residual and phantom limb. During simultaneous tapping and nerve activation, the area of reported sensation shifted to match the size and location of the physical tapping. The participant described the experience as “a trip” and remarked that his “brain is befuddled,” later adding that the “location is very appropriate” and “that feels natural.”

Over the course of the therapy, the participant did not experience his typical 24-36 hour bouts of phantom limb pain. Prior to starting stimulation, this participant reported 24+ hour long bouts of phantom limb pain about once a month. Over the 73 days between starting the therapy and stopping data collection, the participant did not have an extended bout of phantom limb pain.

Conclusion: The case study suggests that non-invasive, occasional, peripheral nerve stimulation paired with appropriate visual information can provide relief from phantom limb pain.