Injury to peripheral nerves associated with trauma, amputation, or surgery may lead to the formation of neuromas that can produce severe pain refractory to pharmacotherapy. Ectopic impulse activity arising in blindly ending axons within the neuroma, which contain abnormal accumulations of sodium channels, is thought to be a major contributor to this pain. The effect of surgical excision has remained controversial. Here we report a prospective study on the effect of neuroma removal on pain.
A series of 6 patients with chronic neuropathic pain owing to neuromas after nerve injury were studied before and 3 months after neuroma excision. Quantitative sensory testing included measurement of areas of brush-evoked allodynia, pinprick hyperalgesia, and mechanical and thermal thresholds. The hypothesis that the analgesic response to a preoperative, intravenous infusion of the sodium channel blocker lidocaine can predict outcome of surgery was also tested.
Surgery only relieved spontaneous pain in 2 out of the 6 patients. One of those patients had a prior poor response to neuroma removal. In one patient the pain worsened. Response to surgical removal of neuromas was not predicted by the response to preoperative infusion of intravenous lidocaine.
Our findings suggest that, as a therapeutic maneuver, surgical excision of neuromas should be reserved for only those patients with intractable pain, who have failed to respond to other therapies. However, prior poor response to neuroma removal does not preclude relief of pain after a new excision.