Opioid-induced myoclonus in palliative care

In patients with palliative care needs, opioids and their metabolites can accumulate, causing myoclonus. This opioid-induced neurotoxicity appears to be dose dependent, but the dose at which it occurs varies. It is frequently associated with impaired kidney function but can also occur when kidney function is normal. There are case reports of myoclonus caused by all opioids, but it is more common with morphine and is thought to be caused by the metabolite morphine-3-glucuronide.

Treat opioid-induced myoclonus by reducing the opioid dose or switching opioids. Consider rehydration if dehydration and kidney impairment are potential contributors. If symptoms persist despite changes to opioid therapy, consider low-dose benzodiazepine therapy—see regimens in Approach to managing myoclonus in palliative care.