Infantile Spasms



Infantile spasms (IS) are an epileptic disorder of infancy and young childhood. Over 90 percent of cases present before 1 year of age and the average age of onset is between 3 and 7 months. The incidence of IS is approximately 1.6-4.5 cases per 10,000 live births. Both males and females are affected equally and there is no difference in incidence among ethnic groups.


While the majority of cases are sporadic, current research suggests there may be a multifactorial genetic susceptibility.



  • “Symptomatic” IS: Cases with a known etiology, such as brain malformations, neurocutaneous disorders, and known perinatal and postnatal insults. These account for 60 to 70 percent of IS cases.
  • “Cryptogenic” IS: Cases without known causes and with normal development at the onset of IS.
  • West Syndrome: The triad of spasms, hypsarrhythmia (a pattern of waves and spikes seen on EEG) and arrest of psychomotor development.


The dominant theory is that the spasms develop due to an insult to the brain, either prenatal or postnatal. However, the pathogenesis is unknown.

Clinical features:

The disease occurs in three stages:

  • Stage 1: Spasms occur infrequently, are isolated and relatively mild. Patients with previously normal development may develop abrupt regression.
  • Stage 2 (most severe): The spasms increase in frequency and appear in clusters or series. During this stage, developmental regression is most pronounced.
  • Stage 3: Progressive and sustained decrease in frequency and severity of spasms. This stage may be followed by the development of other types of seizures.

The spasms usually involve the muscles of the neck, trunk and extremities, but may also involve the abdominal muscles. There are typically two phases to the spasm, with sudden, brief contractions of one or more muscle groups followed by a longer tonic period. Eye deviation or rhythmic nystagmoid eye movements are found in over half of cases.


The diagnosis is made based off clinical findings, a hypsarrthmic pattern on EEG and neuroimaging (MRI).


  • First line: ACTH
  • Shown to control spasms in 60 to 70 percent of cases
  • Common side effects: Hypertension, electrolyte imbalances, suppressed growth, immunosuppresion, cerebral atrophy (reversible), and irritability.
  • Second line: Vigabatrin
  • Shown to be particularly effective in patients with tuberous sclerosis
  • Major side effect: Permanent retinal toxicity
  • Other agents that may be tried in children refractive to ACTH (note, currently there is insufficient evidence to support many of the following treatments):
  • Anti-seizure medications
  • Ketogenic diet
  • Pyridoxine
  • IVIG
  • Liposteroid
  • TRH
  • Surgery
  • If an infant relapses after therapy is stopped, the infant should be restarted on a second course of the agent that originally obtained control.


  • The majority of patients with infantile spasms have a poor prognosis with chronic epilepsy and global developmental delay.
  • Children with normal MRI findings have been shown to have better outcomes.
  • In one study of children with untreated IS, the majority of patients had resolution of spasms by age 3 to 4 years. However, other seizure types were found to develop and persist.
  • Mortality of IS patients ranges from 3 to 30 percent.


  1. Wolf S.M. and Ballaban-Gil K. Infantile Spasms Current Therapy and Progress. Peds in Review 1996
  2. Wong M. and Trevathan E. Infantile Spasms. Pediatric Neurology 2001 
  3. Saltik S. Kocer N. Dervent A. Informative value of magnetic resonance imaging and EEG in the prognosis of infantile spasms. Epilepsia 2002
  4. Mackay M.T. Weiss S.K. Adams-Webber T. et al. Practice parameter: medical treatment of infantile spasms: report of the American Academy of Neurology and the Child Neurology Society. Neurology 2004
  5. Pellock J.M. Hrachovy R. Shinnar S. et al. Infantile spasms: a U.S. consensus report. Epilepsia 2010