Causes

Myoclonus may be caused by a variety of underlying problems. Doctors often separate the types of myoclonus based on their causes, which helps determine treatment. Types of myoclonus include the following categories.

Physiological myoclonus

This type of myoclonus occurs in normal, healthy people and rarely needs treatment. Examples include:

• Hiccups
• Sleep starts
• Shakes or spasms due to anxiety or exercise
• Infant muscle twitching during sleep or after a feeding

Essential myoclonus

Essential myoclonus occurs on its own, usually without other symptoms and without being related to any underlying illness. The cause of essential myoclonus is often unexplained (idiopathic) or, in some cases, hereditary.

Epileptic myoclonus

This type of myoclonus occurs as part of an epileptic disorder.

Symptomatic (secondary) myoclonus

Symptomatic myoclonus occurs as a result of an underlying medical condition. Examples include:

• Head or spinal cord injury
• Infection
• Kidney or liver failure
• Lipid storage disease
• Chemical or drug poisoning
• Prolonged oxygen deprivation
• Medication reaction
• Autoimmune inflammatory conditions
• Metabolic disorders
• Coronavirus disease 2019 (COVID-19)

Nervous system conditions that result in secondary myoclonus include:

• Stroke
• Brain tumor
• Huntington's disease
• Creutzfeldt-Jakob disease
• Alzheimer's disease
• Parkinson's disease and Lewy body dementia
• Corticobasal degeneration
• Frontotemporal dementia
• Multiple system atrophy