(Verbatim from application) The goal of this research is to develop a reversible method for chronically blocking the conduction of action potentials in human peripheral nerves. Unwanted or uncoordinated generation of nerve impulses is a major factor in many disabling conditions, such as peripheral pain, spinal cord injury, stroke, cerebral palsy and multiple sclerosis. For example, unregulated nerve impulses produce spasticity in stroke, cause spasms in spinal cord injury, and generate neuroma pain in amputation. If these impulses can be intercepted along the peripheral nerves over which they travel, then the disabling condition can be reduced or eliminated. Although there are a few existing methods for surgically or pharmacologically blocking nerve impulses, none of these methods are broadly applicable or successful, are non-specific with sometimes serious side-effects, and, in many cases, are destructive to the nerve. Therefore, there is a widespread clinical need for a safe, reliable and reversible nerve block. The use of electrical stimulation, delivered through electrodes surrounding the nerve, has previously been shown to block nerve impulses in a reversible and predictable manner in acute situations. However, the present methods of electrical nerve block are likely to be damaging to the nerve during chronic usage. A novel stimulus waveform has now been developed that is likely to be safe for chronic human applications, while still producing an effective and reversible nerve conduction block. In this project, the effectiveness of this waveform to block action potential propagation in whole nerves in acute in-vivo experiments will be measured. Specifically, it will be demonstrated that this new waveform is capable of a complete block of both motor and sensory activity, including A-delta and C-fiber activity, and that this new waveform can also be used to selectively block activity in large diameter axons. The effect of nerve diameter and nerve fiber size on block effectiveness will also be evaluated. At the completion of this project, it will have demonstrated that an electrical nerve block can be achieved, and that it is effective in blocking conduction in both motor and sensory nerve fibers. In the future, chronic in vivo studies will be performed to test the long-term safety of this technique prior to human use. The initial intended human application will be to alleviate pain in individuals with neuromas secondary to limb amputation.
