Epileptic spasms true West syndrome UMLS:C1527366 human_phenotype A sudden flexion, extension or mixed extension-flexion of predominantly proximal and truncal muscles which is usually more sustained than a myoclonic movement but not as sustained as a tonic seizure. An epileptic spasm is a sudden flexion, extension or mixed flexion-extension of proximal and truncal muscles, lasting 1-2 seconds i.e. longer than a myoclonic jerk (which lasts milliseconds) but not as long as a tonic seizure (which lasts > 2 seconds). Spasms typically occur in a series, usually on wakening. Subtle forms may occur with only chin movement, grimacing, or head nodding. 2011-05-04T01:56:31Z UMLS:C0037769 The maximum age of onset is between 3 and 12 months, the peak being at 6 months. However, spasms may start from birth, or appear long after the age of 12 months, including into adulthood. Infantile spasms represent a specific type of seizure seen in an epilepsy syndrome of infancy and childhood known as West Syndrome. West Syndrome is characterized by infantile spasms, developmental regression, and hypsarrhythmia (as demonstrated by electroencephalography). MSH:D013036 SNOMEDCT_US:28055006 peter Salaam seizures https://www.epilepsydiagnosis.org/seizure/motor-overview.html HP:0011097 Salaam convulsions Focal motor seizure generalized motor onset seizure