myoclonus
Pronunciation: MY-oh-kloh-nus
Sudden, brief, involuntary muscle jerks or contractions that can be focal or generalized, arising from various levels of the nervous system.
Full Definition
Myoclonus refers to sudden, shock-like, involuntary movements caused by brief muscle contractions (positive myoclonus) or sudden cessation of muscle activity (negative myoclonus or asterixis). The movements can be focal, affecting single muscles, or generalized, involving multiple muscle groups simultaneously. Myoclonus can originate from cortical, subcortical, brainstem, or spinal sources, with different etiologies including metabolic disorders, infections, neurodegenerative diseases, and drug toxicity. Classification includes physiologic myoclonus (normal hiccups, sleep starts), essential myoclonus, and symptomatic myoclonus secondary to underlying pathology. Accurate description of timing, distribution, and triggers is essential for clinical documentation.
Usage
Usage note: Singular form is 'myoclonus', plural can be 'myoclonus' or 'myocloni'. Not hyphenated.
In Context
- "The patient experienced cortical myoclonus following the anoxic brain injury, with stimulus-sensitive jerks in both arms." — Movement disorder evaluation
- "Nocturnal myoclonus disrupted the patient's sleep pattern and required medication adjustment." — Neurology follow-up