A sudden flexion, extension, or mixed extension-flexion of predominantly proximal and truncal muscles that is usually more sustained than a myoclonic movement but not as sustained as a tonic seizure. Limited forms may occur: Grimacing, head nodding, or subtle eye movements. Epileptic spasms frequently occur in clusters. Infantile spasms are the best known form, but spasms can occur at all ages. The phenotype is Human Phenotype Ontology term HP_0011097 (Epileptic spasm). Also known as: Epileptic spasms, Salaam convulsion, Salaam convulsions, Salaam seizure, Salaam seizures.