Phantom limb pain occurs in a majority of people with amputated limbs, including over half of people with upper extremity, e.g., arm or hand, amputations. This pain results from the loss of understandable input from the missing limb, which presumably causes changes along the neural pathway. Currently, individuals experiencing this pain use pharmacological (drug) treatments with varying success and sometimes significant negative side effects. There are no treatment options clinically available that attempt to directly address the neural changes in an attempt to treat the painful sensations. This study will evaluate non-invasive electrical stimulation of a tapping sensation as a method to reduce phantom limb pain. In addition, the patterns of electrical activity in the brain will be analyzed to assess changes to the neural pathway. Given the current opioid crisis, the development of treatment options that do not require drugs would be a momentous advance for people suffering from phantom limb pain and potentially others with neurological disorders in the future. This project will also contribute to the training of a diverse group of undergraduate students who will obtain valuable research experiences and to the development of outreach activities that will engage and excite pre-college students about biomedical engineering.
The long-term goal of this research is to develop electrical stimulation as a method to promote neuroplasticity for recovery after neurological injury or illness. The objective of this project is to analyze cortical activity during non-invasive surface electrical stimulation of the peripheral nerve in order to assess whether cortical plasticity can be induced. The initial target population will be people with an amputated limb for whom inducing neuroplasticity may alleviate phantom limb pain. The central hypothesis of this approach is that neuroplasticity in the somatosensory cortex can be facilitated using targeted, non-invasive activation of sensation logically paired with visual input and that this neuroplasticity will reduce or eliminate phantom limb pain. The rationale for performing this work is based on the expectation that knowledge of how the central nervous system responds to electrical stimulation will help develop customized therapies for phantom limb pain and other neurological disorders. A non-invasive stimulation method to evoke sensation in the phantom limb of people with amputations has already been developed by the project team. In the next phase of work conducted during this project, the cortical activity in response to physical and electrically induced somatosensation will be characterized. It is expected that peripheral nerve activation of sensation will evoke cortical activation similar to physical touch. Building on an initial exploratory trial in able-bodied subjects, subjects with amputations will be given a therapy consisting of simultaneous electrical activation of a tapping sensation and visual feedback of that tapping on their prostheses. The therapy will occur multiple times per week over twelve weeks and the effects of this long-term activation on cortical activity and severity of phantom limb pain will be evaluated. In addition, a multichannel stimulation system that can be easily calibrated to generate realistic sensation across all individuals will be developed to reduce the barriers to a home-based therapy.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
