How much do you know about evaluating patients with myoclonus?

Guidelines for Evaluating Patients with Myoclonus

• Myoclonus can be classified as physiological, essential, epileptic, or secondary myoclonus based on clinical features.
• The initial steps in evaluating a patient with myoclonus are history and examination.
• The examination should identify the distribution, temporal profile, and activation characteristics of the myoclonic movement.
• Myoclonus can be confused with other involuntary movements such as chorea, dystonia, tremor, and tics.
• Clinical neurophysiology studies can help differentiate myoclonus from other involuntary movements.
• Myoclonus induced by drugs or toxins is potentially treatable and can resolve upon withdrawal of the offending agent(s).
• Ancillary testing should be performed if the myoclonus etiology is unclear from history and examination findings.
• Suggested ancillary tests include electrolytes, glucose, renal and liver function tests, thyroid function tests, and vitamin E level.
• Brain imaging and spine imaging may reveal lesions or atrophy supporting a specific myoclonus etiology.
• EEG can identify both ictal and interictal patterns in the epileptic myoclonus category.
• Infection workup may be necessary if there are localizing signs of fever, leukocytosis, or encephalopathy.
• Cerebrospinal fluid analysis is useful to differentiate an infectious/inflammatory etiology from a toxic, drug-induced, or metabolic etiology.