Myoclonies

Myoclonus is defined as a sudden, brief, jerky, shock-like, involuntary movement, which can be caused by a muscular contraction (positive myoclonus), or by an interruption of muscular activity (negative myoclonus). It may be physiological or caused by a very wide variety of hereditary and acquired conditions. Myoclonus can be studied by electromyography; this technique shows the co-contraction of agonists and antagonists muscles, in positive myoclonus, or silent period in the negative type. The contribution of electrophysiology can be useful for comprehension of the origin of myoclonus. Myoclonus may be cortical, thalamocortical, midbrain, or spinal. The condition of occurrence and the rhythm of the event may provide clinical clues relevant to the diagnosis. Myoclonus associated with dystonia as in inherited myoclonus-dystonia, associated with parkinsonian syndromes where myoclonus is not rare, particularly in multiple system atrophy and corticobasal degeneration. Myoclonus with epilepsy may occur in symptomatic or idiopathic epilepsy with special reference for the new concept of cortical tremor. Myoclonus may also occur in association with dementia, particularly in Lewy's body dementia and Alzheimer's disease. Piracetam, Valproate and Clonazepam are main drugs used in myoclonus.