Myoclonus

BACKGROUND- Myoclonus is a sudden, brief, shock-like, involuntary movement caused by muscular contractions (positive myoclonus) or inhibition (negative myoclonus). Myoclonus is not a diagnosis but rather a descriptive term for the clinical event. However, it is a useful sign of clinical significance that may lead to a syndromic diagnosis. Myoclonic jerks may be subtle or may interfere severely with the execution of even the simplest motor task. REVIEW SUMMARY- In this review, we describe the classification of myoclonus and the many possible variant and pathophysiological features. Myoclonus may arise from various sites in the neuraxis, including the cortex, subcortex, spinal cord, and peripheral nervous system. Electrodiagnostic testing may be useful for clinical diagnosis and may impact therapeutic options. Myoclonus may be difficult to differentiate from other hyperkinetic movement disorders with similar presentations. Therapy is limited and usually symptomatic. CONCLUSIONS- Careful attention should be given to the fundamental clinical and electrophysiological characteristics of the hyperkinetic movement phenomenology and the clinical circumstances in which myoclonus appears. This approach may provide clues to the underlying neurologic disorder and may also suggest appropriate treatment options.