West Syndrome, developmental delay is the defining feature. So so the negation is important

West_Syndrome

ILAE 1989 West Syndrome Usually, West syndrome consists of a characteristic triad: infantile spasms, arrest of psychomotor development, and hypsarrhythmia, although one element may be missing. Spasms may be flexor, extensor, lightning, or nods, but most commonly they are mixed. Onset peaks between the ages of 4 and 7 months and always occurs before the age of 1 year. Boys are more commonly affected. The prognosis is generally poor. West syndrome may be separated into two groups. The symptomatic group is characterized by previous existence of brain damage signs (psychomotor retardation, neurologic signs, radiologic signs, or other types of seizures) or by a known etiology. The smaller, cryptogenic group is characterized by a lack of previous signs of brain damage and of known etiology. The prognosis appears to be partly based on early therapy with adrenocorticotropic hormone (ACTH) or oral steroids. Engel 2001 West Syndrome ILAE 2010 West Syndrome