- A condition of abnormal contraction of muscles or portions of muscles.
* * *One or a series of shock-like contractions of a group of muscles, of variable regularity, synchrony, and symmetry, generally due to a central nervous system lesion. [myo- + G. klonos, tumult]- benign infantile m. a seizure disorder of infancy in which myoclonic movements occur in the neck, trunk, and extremities; the EEG is normal, and seizures do not persist beyond 2 years of age. SYN: benign m. of infancy.- m. multiplex an ill-defined disorder marked by rapid and widespread muscle contractions. SYN: paramyoclonus multiplex, polyclonia, polymyoclonus.- palatal m. rhythmic contractions of the soft palate, the facial muscles, and the diaphragm, related to lesions of the olivocerebellar pathways. SEE ALSO: palatal nystagmus.- stimulus sensitive m. m. induced by a variety of stimuli, e.g., talking, calculation, loud noises, tapping, etc.
* * *my·oc·lo·nus .mī-'äk-lə-nəs n irregular involuntary contraction of a muscle usu. resulting from functional disorder of controlling motor neurons also a condition characterized by myoclonus
* * *n.a sudden spasm of the muscles. Occasional myoclonic jerks occur between seizures in patients with idiopathic epilepsy, and myoclonus is a major feature of some progressive neurological illnesses with extensive degeneration of the brain cells (including the spongiform encephalopathy). Myoclonic jerks on falling asleep (nocturnal myoclonus) occur in normal individuals.• myoclonic adj.
* * *my·oc·lo·nus (mi-okґlo-nəs) [myo- + clonus] shocklike contractions of a portion of a muscle, an entire muscle, or a group of muscles, restricted to one area of the body or appearing synchronously or asynchronously in several areas. It may be part of a disease process (e.g., epileptic or post-anoxic myoclonus) or be a normal physiological response (e.g., nocturnal myoclonus). myoclonic adj
Medical dictionary. 2011.