Approach to managing myoclonus in palliative care
Myoclonus is a rapid, brief, irregular, usually multifocal contraction (jerking) of part or all of a muscle. Presentations can range from occasional twitching to frequent, severe jerks or spasms. Myoclonus can be physiological, occurring during sleep transitions. Pathological causes of myoclonus include:
- drug toxicity—particularly opioids and their metabolites—see Opioid-induced myoclonus in palliative care
- drug withdrawal (eg benzodiazepines)
- organ failure—particularly kidney and liver failure
- metabolic abnormalities (eg hyponatraemia, hypoxia, hypercapnia, hypoglycaemia)
- neurodegenerative diseases (eg Creutzfeldt-Jakob disease, Alzheimer disease)
- epilepsy.
Management of myoclonus in palliative care depends on the cause(s), severity, potential benefits and burdens of investigations and treatment, and the patient’s prognosis, preferences and goals of care—see Principles of symptom management in palliative care.
As appropriate, address reversible causes. Ongoing myoclonus may benefit from drug therapy if symptoms cause distress.
For symptomatic management of myoclonus in patients with palliative care needs who are neither bed-bound nor in the last weeks of life, treatment options include an antiepileptic (eg levetiracetam, sodium valproate) or clonazepam—see the Neurology guidelines for further adviceLevy, 2016.
For symptomatic management of myoclonus in patients with palliative care needs who are bed-bound or in the last weeks of life, consider clonazepam (oral or subcutaneous) or a midazolam subcutaneous infusion.
If clonazepam is considered appropriate, use:
1clonazepam 0.5 mg orally or sublingually, once or twice daily1. Monitor response and adjust dosage as needed, up to 2 mg 3 times daily. Seek specialist advice if symptom management is inadequate clonazepam
OR
1clonazepam 0.5 mg subcutaneously, once or twice daily. Monitor response and adjust dosage as needed, up to 2 mg 3 times daily. Seek specialist advice if symptom management is inadequate. clonazepam
If midazolam continuous subcutaneous infusion (CSCI) is considered appropriate, give a single dose of subcutaneous midazolam when starting the midazolam infusion. UseZaporowska-Stachowiak, 2019:
midazolam 5 mg subcutaneously, as a single dose, followed by 10 mg/24 hours by continuous subcutaneous infusion. Monitor response and adjust dose as needed, up to 60 mg/24 hours. Seek specialist advice if symptom management is inadequate. midazolam
If response to benzodiazepine therapy is inadequate, seek specialist advice—an antiepileptic drug may be appropriate.