Infantile Spasms

West syndrome and infantile spasms are two conditions which occur together so frequently that the two terms are used interchangeably. West syndrome involves developmental arrest and possible loss of developmental milestones and has a distinctive EEG pattern called hypsarrhythmia.

Infantile spasms are clusters of brief seizures involving various combinations of flexion and extension of the trunk and limbs, most common in the early morning or upon wakening from naps. In the most common form, the body bends as the outstretched arms jerk forward -- so called "salaam seizures. The condition is often mistaken for colic, at least initially, because the babies double up during the spasm and cry afterwards.

Eighty-five percent of children who develop infantile spasms do so before the age of 12 months; most stop having spasms by age 5. During this period, 40 percent will have other types of seizures.

The most common causes are tuberous sclerosis and perinatal asphyxia (lack of oxygen). In 40 percent of cases, there is no known cause and these children have the best prognosis; causes that are symptomatic have the worst. As many as 20 percent die before age 5; 75 percent are mentally retarded; and more than 50 percent have persistent epilepsy, half of whom develop Lennox-Gastaut syndrome.