Infantile spasms are a specific type of seizure associated with the epilepsy syndrome called West Syndrome, according to the National Institute of Neurological Disorders and Stroke. The seizures are characterized by a sudden bending of the body in a forward position with knees pulled to the chest and arms stiffened.
Infantile spasms also consist of the child's body or head arching back as his arms and legs stiffen outward, says the Epilepsy Foundation. Infantile spasms tend to occur when the child wakes from sleep and usually last a couple of seconds. Infantile spasms typically begin in the first year of a child's life and subside by 2 to 4 years of age.
Infantile spasms are often the result of an underlying disorder such as infection, injury during birth, brain development abnormalities, neurocutaneous syndromes, or genetic and chromosomal abnormalities, reports the National Center for Biotechnology Information. Infantile spasms are diagnosed using electroencephalography, or EEG, testing. Babies experiencing infantile spasms demonstrate an EEG pattern called hypsarrhythmia when seizures are not occurring. A hypsarrhythmia pattern is chaotic and high-voltage.
Prognosis for infantile spasms is highly dependent on the underlying cause of the seizures, states NINDS. Most children who develop infantile spasms experience developmental delays ranging from mild to severe. Children who had normal development before the onset of seizures have a better prognosis. More than half of children with infantile spasms go on to develop other types of seizures.