INFANTILE EPILEPTIC SPASMS SYNDROME (IESS)

Overview

Infantile epileptic spasms syndrome is characterized by the onset of epileptic spasms in the infant (age 1-24 months). This syndrome includes West syndrome, where patients have a triad of epileptic spasms, hypsarrhythmia on EEG and developmental plateauing or regression.

NOTE Infantile epileptic spasms syndrome is a syndrome with developmental and epileptic encephalopathy.

Clinical context

This syndrome is characterized by onset of epileptic spasms between 1-24 months of age (peak 3-12 months). Infants may have no antecedent history and normal head size and neurological examination, or their history and examination may reflect the underlying cause (e.g. previous acquired structural brain abnormality). Infants may have had no prior epilepsy, or may have had a prior epilepsy or syndrome (e.g. early-infantile developmental and epileptic encephalopathy syndrome). Both sexes are affected, with a male predominance. Developmental slowing or regression may be seen at onset of epileptic spasms. Occasionally development may be normal and developmental trajectory continues as expected.

Causes:

• Structural brain abnormalities, both developmental and acquired (e.g. tuberous sclerosis or hypoxic-ischemic encephalopathy)
• Chromosomal disorders e.g. Down syndrome or Miller-Dieker syndrome
• Gene abnormalities e.g. ARX, CDKL5, SPTAN1, STXBP1
• Metabolic etiologies