MYOCLONUS

Abstract

Μyoclonus is defined as a sudden, brief, lightening-like involuntary movement caused by muscular contractions (positive myoclonus) or inhibitions (negative myoclonus) ,arising abnormally from the central or peripheral nervous system. Myoclonus occurs via many different etiologies and pathophysiological mechanisms. A detailed etiological classification system yields four main categories: physiologic, essential, epileptic, symptomatic. However myoclonus can also be differentiated in terms of its anatomic origin, body distribution and relation to stimuli or movement. A practical approach to myoclonus diagnostics is based on a classification according to its anatomical origin. Thus, myoclonus is classified as cortical, subcortical, spinal (segmental, propriospinal) and peripheral. Diagnostic evaluation of a patient with myoclonus is complex and requires a thorough laboratory investigation based on the specific characteristics of each patient. Electrophysiological evaluation can determine the anatomical source of myoclonus and neuroimaging may reveal structural lesions. A significant number of metabolic, immunological, paraneoplastic and iatrogenic causes related to myoclonus should be excluded .Genetic testing can be applied to specific patients with positive family history for genetic causes of myoclonus or a similar phenotype. Treatment of myoclonus is etiological and symptomatic, with anti-epileptic drugs being the most effective. Botulinum toxin can be helpful for cases with peripheral or strictly focal localization, while DBS is promising, but it is still under investigation.