West syndrome is a severe epilepsy syndrome composed of the triad of infantile spasms, an interictal electroencephalogram (EEG) pattern termed hypsarrhythmia, and mental retardation. The International League Against Epilepsy’s (ILAE) revised classification and terminology of seizures and epilepsies, published in 2010, designates West syndrome as an electroclinical syndrome with onset in infancy, and epileptic spasms as a type of seizure.
(See Presentation and Workup.)
West syndrome is an age-dependent expression of a damaged brain, and most patients with infantile spasms have some degree of developmental delay. The term infantile spasm has been used to describe the seizure type, the epilepsy syndrome, or both. In this article, the term infantile spasm is synonymous with West syndrome. (See Prognosis and Presentation.)
The syndrome’s namesake, Dr W J West, gave the first detailed description of infantile spasms, which occurred in his own child.
In a letter to the editor of The Lancet in 1841, West described the events as “bobbings” that “cause a complete heaving of the head forward towards his knees, and then immediately relaxing into the upright position … [T]hese bowings and relaxings would be repeated alternately at intervals of a few seconds, and repeated from 10 to 20 or more times at each attack, which would not continue more than 2 or 3 minutes; he sometimes has 2, 3 or more attacks in the day.”
This detailed clinical description was followed approximately 100 years later by the report of the typical interictal EEG pattern termed hypsarrhythmia. (See Workup.)
The eponym West syndrome was created in the early 1960s by Drs. Gastaut, Poirier, and Pampiglione.
Conditions to consider in the differential diagnosis of West syndrome include the following:
Epilepsy in children with mental retardation
Epileptic and epileptiform encephalopathies
Benign myoclonus of early infancy