Infantile Spasms

An epileptic spasm is a specific type of seizure seen in an epilepsy syndrome of infancy and childhood often called West Syndrome.  These are more commonly called infantile spasms (IS) since they are seen most often in the first year of life.  West Syndrome/IS is characterized by epileptic spasms, developmental problems, and a specific brain wave pattern on electroencephalography (EEG) testing called hypsarrhythmia.  The onset is usually in the first year of life, typically between 4-8 months.  The seizures often look like a sudden bending forward of the body with stiffening of the arms and legs lasting for 1-2 seconds; some children arch their backs as they extend their arms and legs.

Spasms tend to occur upon awakening and often occur in multiple clusters and hundreds of seizures per day.  Most children, but not all, will have EEG readings of hypsarrhythmia.  Infantile spasms usually stop by age five, but may be replaced by other seizure types. Many underlying disorders, such as birth injury, metabolic disorders, and genetic disorders can give rise to IS, making it important to identify the underlying cause.  In some children, no cause can be found.


The prognosis for children with IS is largely dependent on the underlying cause. The intellectual prognosis for children with IS is generally poor because many babies with IS have neurological impairment prior to the onset of spasms.   Children who have rapid initiation of treatment, normal development prior to infantile spasms, and no identifiable cause may do well.  IS usually resolves by mid-childhood, but more than half of the children with IS will develop other types of seizures such as Lennox-Gastaut syndrome, an epileptic disorder of later childhood.

In addition, children with IS are at a higher risk for autism.  Shorter duration between the onset of IS and initiation of standard treatment appears to lead to an improved outcome; therefore early recognition of the seizures and early treatment are essential.


Standard first-line therapies for IS include several forms of hormonal therapy (including adrenocorticotrophic hormone [ACTH] or prednisolone) or the anti-seizure medication vigabatrin.  These treatments are high effective but have serious side effects and sholud be administered in consultation with a pediatric neurologist.   The goal of treatment for infantile spasms is for the seizures to stop and the EEG to improve (hypsarrhythmia should resolve).

Some children have spasms as the result of brain lesions and surgical removal of these lesions may result in improvement.  When standard treatments do not lead to improvement, other options such as the ketogenic diet and anti-seizure medications are considered.  Regardless of the specific treatment chosen, it is critical to begin therapy as soon as possible.  Ongoing IS (and hypsarrhythmia) have the potential to adversely impact all aspects of brain development.


March 31, 2019
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