An infantile spasm (IS) is a specific type of seizure seen in an epilepsy syndrome of infancy and childhood known as West Syndrome.
West Syndrome is characterized by:
- Infantile spasms
- Developmental regression
- A specific pattern on electroencephalography (EEG) testing called hypsarrhythmia (chaotic brain waves)
Prevalence of West Syndrome is around 1 out of 3,500 live births. Boys are more likely to be affected than girls. The onset of infantile spasms is usually in the first year of life, typically between 4-8 months.
Many underlying disorders, such as birth injury, metabolic disorders, and genetic disorders can give rise to spasms, making it important to identify the underlying cause. In some children, no cause can be found.
The seizures primarily consist of a sudden bending forward of the body with stiffening of the arms and legs; some children arch their backs as they extend their arms and legs. Spasms tend to occur upon awakening or after feeding, and often occur in clusters of up to 100 spasms at a time. Infants may have dozens of clusters and several hundred spasms per day. Infantile spasms usually stop by age five, but may be replaced by other seizure types.
The prognosis for children with IS is dependent on the underlying causes of the seizures. The intellectual prognosis for children with IS is generally poor because many babies with IS have neurological impairment prior to the onset of spasms. Spasms usually resolve by mid-childhood, but more than half of the children with IS will develop other types of seizures. There appears to be a close relationship between IS and Lennox-Gastaut Syndrome, an epileptic disorder of later childhood.
Treatment with corticosteroids such as prednisone is standard, although serious side effects can occur. Several newer antiepileptic medications, such as topiramate may ease some symptoms. Some children have spasms as the result of brain lesions, and surgical removal of these lesions may result in improvement.