The Enigma of Low-Dose Ketamine for Treatment of Opioid-lnduced Hyperalgesia in the Setting of Psychosocial Suffering and Cancer-Associated Pain

摘要

Opioid-induced hyperalgesia is a paradoxical adverse effect of opioid therapy with unclear strategies for its treatment and management. We report the successful use of low-dose ketamine infusion for the treatment of opioid-induced hyperalgesia in a 38-year-old woman presenting with psychosocial suffering and high opioid requirement secondary to pain from a poorly differentiated neuroendocrine tumor. Over the course of a month, her opioid requirement escalated to the gram level of oral morphine equivalents, upon which she was hospitalized at University of California San Diego Health for an acute on chronic pain crisis. Despite use of patient-controlled analgesia, her pain level remained unchanged for nearly 2 days after initiation of a low-dose ketamine infusion. The infusion ultimately allowed reduction of her opioid use to a third of her original daily requirement and improved her function and ability to interact for several days. Although her pain profile became increasingly complicated by psychosocial suffering and disease progression, she did not experience the same pain event for the remainder of her hospital course. Findings from this case report demonstrate the utility of low-dose ketamine infusion in opioid-induced hyperalgesia.