Response of central pain syndromes to intravenous lidocaine.

In this study, 8 patients with central pain syndromes, 6 with hemispheric lesions, and 2 with spinal cord lesions were treated with a 1 mg/kg dose of intravenous lidocaine. Patients first received the same volume of normal saline, in single-blind fashion, to monitor placebo effects. Of the 8 patients, 7 responded to lidocaine, and only 1 responded to normal saline. Responses ranged from partial to complete. All components of central pain, including constant pain, paroxysms ofpain, and evoked pain, responded to lidocaine. In addition, 3 patients had pain relief that lasted for 8-20 wk. These findings, which are in agreement with two previous open-label studies, suggest that a single dose of a local anesthetic, lidocaine, can provide lasting pain relief for patients with central pain syndromes. This analgesic action may be central, and possibly supraspinal, at least in patients with hemispheric lesions.