From the Guidelines

Myoclonus is typically triggered by various factors, including hypocalcemia, hypomagnesemia, fever, medications, and cerebral dysfunction.

Hypocalcemia: a common trigger for myoclonus, especially in patients with 22q11.2 deletion syndrome 1
Hypomagnesemia: can also trigger myoclonus, particularly in patients with underlying cerebral dysfunction 1
Fever: a potential trigger for myoclonus, especially in patients with a history of seizures or epilepsy 1
Medications: certain medications, such as antipsychotics, can trigger myoclonus in susceptible individuals 1
Cerebral dysfunction: primary or secondary cerebral dysfunction can increase the risk of myoclonus, particularly in patients with 22q11.2 deletion syndrome 1

Cardiac arrest: myoclonus can occur after cardiac arrest, particularly in patients with post-anoxic encephalopathy 1
Electrolyte imbalances: other electrolyte imbalances, such as hyponatremia or hypernatremia, can also trigger myoclonus 1
Neurodegenerative disorders: certain neurodegenerative disorders, such as Parkinson's disease, can increase the risk of myoclonus 1 It is essential to note that the triggers of myoclonus can vary depending on the underlying condition and individual patient factors. A comprehensive evaluation and diagnosis are necessary to determine the underlying cause of myoclonus and develop an effective treatment plan.

From the Research

Myoclonus can be triggered by a variety of factors, including:

Neurological disorders such as dementia, Creutzfeldt-Jakob disease, Alzheimer's disease, and Lewy body dementia 2
Progressive ataxia, which can suggest a clinical form of the Ramsay-Hunt syndrome or other conditions such as coeliac disease, mitochondriopathies, or spino-cerebellar degenerations 2
Encephalopathy, which can be caused by metabolic or hydro-electrolytic disorders, brain anoxia, or other factors 2
Toxic or drug exposures, which can induce myoclonus as an adverse effect 3
Infections, such as encephalic and/or spinal infectious disorders 2
Focal neurological signs, which can be associated with thalamic lesions or other conditions 2
Segmental spinal myoclonus or propriospinal myoclonus, which can be associated with spinal-cord disorders 2

The physiological mechanisms underlying myoclonus can be classified into different categories, including:

Cortical myoclonus, which can be associated with neurodegenerative syndromes such as multiple system atrophy, corticobasal degeneration, and progressive supranuclear palsy 4
Subcortical myoclonus, which can be associated with conditions such as Huntington's disease and dentato-rubro-pallido-luysian atrophy 4
Segmental myoclonus, which can be associated with spinal-cord disorders 2
Negative myoclonus, which can be characterized by a sudden, brief interruption of muscle activity, and can be associated with epileptic disorders or other conditions 5

The clinical features of myoclonus can vary depending on the underlying cause, but may include:

Sudden, brief, involuntary muscle jerks or contractions 6
Negative myoclonus, which can appear as a shock-like involuntary jerky movement caused by a sudden, brief interruption of muscle activity 5
Asterixis, which is a type of negative myoclonus that occurs typically in toxic-metabolic encephalopathies 5
Stimulus sensitivity, which can be a feature of some forms of myoclonus 6