Histological findings after long-term infusion of intrathecal ketamine for chronic pain: A case report

(K)etamine, a selective, noncompetitive N-methyl-D-aspartate (NMDA)-receptor antagonist, is able to alter-pain perception at the spinal level. Lit tie clinical data exist on the intracthecal and epidural use of ketamine in chronic pain. Histopathologic findings after intrathecal injection of ketamine with and without preservatives are rarely reported. This outcome was evaluated in a 72-year-old woman with adominal pain due to cancer. who was treated with the intrathecal application of bupivacaine, clonidine, and morphine. We reached satisfactory pain relief with the addition of ketamine to the mixture for 7 days. On postmortem, focal lymphocytic vasculitis close to the catheter injection site was found. This finding has not been described previously after long-term application of ketamine intrathecally. The intrathecal infusion of ketamine with preservative, or the mixture of ketamine, clonidine, morphine, and bupivacaine resulted in isolated lymphocytic vasculitis of the spinal cord and leptomeninges without any clinical signs of neurological deficit. (C) U.S. Cancer Pain Relief Committee, 1999.