Definitions and Diagnostic Criteria for Infantile Spasms and West Syndrome - Historical Perspectives and Practical Considerations.

The term infantile spasms has been used inconsistently within the medical literature for decades. We are also without formal consensus on the diagnostic criteria for West syndrome. Author-specific definitions for these terms will determine the populations studied within research studies and thus impact the relevance of the data acquired. In addition, how one defines these terms may have serious consequences for children presenting with infantile spasms such as the inappropriate withholding of standard therapy in those who fail to meet criteria for West syndrome. The overreliance on the term hypsarhythmia is particularly problematic given that many children presenting with infantile spasms will not have this classic pattern and because the determination of hypsarhythmia has poor inter-rater reliability. Herein I review historical perspectives, relying heavily on published monographs and consensus statements, and promote practical definitions and diagnostic criteria for infantile spasms and West syndrome. In an effort to encourage best clinical practice and research methodology, I include guidance for the diagnosis of infantile spasms (a seizure type) and West syndrome (an epilepsy syndrome).