Depending on their etiology, infantile spasms are usually classified as
symptomatic, cryptogenic, or idiopathic. Symptomatic infantile spams are present if a
factor responsible for the syndrome can be identified. Theoretically, any
form of brain injury (congenital or acquired) can be associated with
infantile spasms. Infantile spasms are termed cryptogenic, if no cause could be
identified, although the seizures are considered to be symptomatic in
origin. If psychomotor development was normal prior to the onset of the
spasms, but no abnormalities can be found to explain the findings, the term
idiopathic infantile spasms has been used, although for some neurologist the two terms
“cryptogenic” and “idiopathic” are interchangeable. The proportions of
cryptogenic and idiopathic infantile spasms therefore varies widely and with
diagnostic tools becoming more and more sophisticated, their overall
frequency is declining.