Resiniferatoxin for the Management of Refractory Morton s Neuroma Pain

Morton s neuroma is an irritation of the nerves that affect the feet. People with this condition may have burning or shooting pain in the balls of their feet. They may also have numbness in adjacent areas. These symptoms may become more frequent and severe over time. The pain may become permanent. Current treatments tend to be short-lived, and they do not work in all people. Better treatments are needed. Objective: To test a study drug, resiniferatoxin (RTX), in people with Morton s neuroma. Eligibility: Healthy people aged 18 and older who have Morton s neuroma and have tried other standard treatments that did not ease their pain. Design: Participants will be involved in the study up to 4 months. They will be screened. They will have a physical exam with blood tests. They will have a test of their heart function. They will have X-rays of their affected feet. They will have tests to assess their pain and how their feet react to touch and changes in temperature. They will complete questionnaires about their pain. RTX is injected into the foot at the site of the nerve pain. Participants will receive a shot to numb the area before the RTX is administered. They will be monitored in the clinic for 4 hours after they receive the RTX. Participants will receive up to 5 follow-up phone calls per week. Each call will take 5 to 10 minutes. They will be asked about their foot pain and whether they have had any side effects from the RTX. Participants will return to the clinic 4 weeks after the treatment. Previous tests will be repeated.