West Syndrome/IS is characterized by epileptic spasms, developmental problems, and a specific brain wave pattern on electroencephalography (EEG) testing called hypsarrhythmia
[childneurologyfoundation.org]
Results: All six affected boys had myoclonic seizures and TCS; two had infantile spasms, but only one had hypsarrhythmia.
[neurology.org]
syndrome Synonyms: Infantile spasm, IS, X-linked infantile spasm syndrome, X-linked infantile spasms, West's syndrome, Tonic spasms with clustering, arrest of psychomotor
[rarediseases.info.nih.gov]