Successful Reversal of Hyperalgesia/Myoclonus Complex with Low‐Dose Ketamine Infusion

Abstract

We report the successful use of low-dose ketamine infusion for treating a severe episode of painful myoclonus in the lower extremities, associated with opioid-induced hyperalgesia (OIH), in a patient who was receiving long-term, high dose intrathecal hydromorphone therapy. A low-dose ketamine infusion immediately relieved the painful myoclonus. It also enabled a reduction in the intrathecal opioid dosage leading to a resolution of the acute symptoms attributed to OIH.

Myoclonus and hyperalgesia following intended epidural morphine administration in a dog

“…When used in a case of intrathecal morphine overdose in a dog (Da Cuhna and others 2007), effects quickly diminished with repeated doses until no effect was seen. Ketamine, an NMDA receptor antagonist, has also been reported to resolve hyperalgesia and myoclonus following chronic intrathecal opioid administration in a person when given as a low dose infusion (Forero and others 2011). Experimentally, a systemic bolus of ketamine resolved morphine induced hindlimb myoclonus in mice (Kolesnikov and others 1997).…”

Opioid-Induced Hyperalgesia

“…6,11 OIH may be accompanied by generalized neuroexcitation, such as agitation, multifocal myoclonus, seizures, and even delirium. 8,9 Before a diagnosis of OIH is assigned, a differential diagnosis that involves ruling out other possible explanations for failure of the opioid to relieve pain must be conducted. 1,2 These include worsening pain pathology, opioid tolerance, opioid withdrawal, and pseudoaddiction.…”

“…[3][4][5] Although most case reports of OIH concern systemic or intrathecal administration of morphine, raising the possibility that morphine metabolites may be involved, 5 hyperalgesia has also been seen in patients with opioid addiction receiving methadone maintenance therapy, 5 and it has been observed anecdotally during treatment with other drugs. [3][4][5]9 High intraoperative doses of fast-acting opioids, such as fentanyl and remifentanil, have been implicated, 3,5 and methods to optimally control the dose of these drugs have been shown to reduce postoperative hyperalgesia. 10 Development of OIH may vary between different opioid medications, but which opioids are most likely to contribute to OIH is as yet unknown.…”

Morphine and Hydromorphone-Induced Hyperalgesia in a Hospice Patient

“…Forero et al note a case of OIH and opioid neurotoxicity in a 52-year-old male with chronic low back pain from disk herniation. 16 Over the course of 17 years, the patient received numerous interventions for his poorly controlled pain including a L5-S1 laminectomy, nonsteroidal anti-inflammatory drugs, acetaminophen, oral opioids, nerve blocks, medial branch ablations, physiotherapy, intrathecal morphine, and a spinal cord stimulator. An intrathecal hydromorphone pump was placed at year 11 and the dose was titrated to 12 mg/day over the next 6 years.…”