What is a common symptom of myoclonus?

Myoclonus is characterized by sudden, brief involuntary jerking of the muscles. This can occur as a single muscle twitch or in sequences involving multiple muscle groups. The critical aspect of myoclonus is the abruptness and rapidity of these muscle jerks, which can happen in various situations, including during sleep or wakefulness.

The nature of these muscle contractions makes it a distinct feature of myoclonus, differentiating it from other muscular disturbances or involuntary movements. Understanding this symptom is essential for identifying the underlying causes of myoclonus, which can range from neurological disorders to metabolic conditions.

Other symptoms included in the choices, such as emotional outbursts or uncontrolled facial movements, do not align with the specific definition or presentation of myoclonus. Long-term muscle spasms, while they may involve muscle contractions, are more associated with other conditions such as dystonia or spasticity rather than the transient jerking characteristic of myoclonus.