Effective treatment of severe cancer pain of the head using low-dose ketamine in an opioid-tolerant patient.

We report the case of a 39-year-old man with severe pain due to unresectable squamous-cell carcinoma of the maxillary sinus that had invaded cranial bone and had metastasized to the cervical spine. Tolerance to opioids had developed, and high doses of transdermal, continuous intravenous, and epidural opioids did not control his pain. An acute episode of extremely severe head pain was immediately controlled with a subanesthetic dose of ketamine after failure of a stress dose of corticosteroid and intravenous lidocaine. Because the patient was terminally ill and invasive procedures were not options, we controlled his pain using a low-dose ketamine infusion until his death 13 days later. Ketamine may be a good co-analgesic for breakthrough pain and for severe pain caused by terminal cancer when invasive techniques are inappropriate. Its mechanism of action may include reversal of opioid tolerance in addition to an inherent analgesic effect.