Infantile spasms.

Abstract

Infantile spasms is a catastrophic form of epilepsy found only in infants and young toddlers, with the peak incidence between 4 - 7 months of age. Estimated prevalence is 1 in 2000 - 6000 live births. There are many causes of infantile spasms, including tuberous sclerosis, hypoxic-ischaemic injury, congenital infectious diseases, inborn errors of metabolism, malformations of cortical development, genetic syndromes such as Aicardi's syndrome and chromosomal abnormalities. A small percentage of patients have idiopathic infantile spasms, with normal growth and development prior to the onset of infantile spasms and no known aetiology. Because of the poor prognosis of infantile spasms, treatment is usually aggressive and immediate, with the hopes of altering the natural history of the disease. The majority of patients with infantile spasms have a poor prognosis with intractable epilepsy, severe developmental delays and/or significant cognitive impairments. Of all patients with infantile spasms, 70 - 90% have mental retardation. Furthermore, 20 - 50% of patients with infantile spasms develop Lennox-Gastaut syndrome with multiple seizure types, cognitive impairments and a markedly abnormal electroencephalogram, arguably one of the most difficult epilepsy syndromes to treat. Infantile spasms are resistant to most of the standard antiepileptic drugs. Adrenocorticotropin hormone (ACTH) or oral steroids result in a significant reduction of seizures, as well as an improvement in the electroencephalogram. Some studies have indicated that infants treated with ACTH within the first month of onset have a more favourable prognosis. Vigabatrin has also been shown to be effective in the treatment, although it is not yet FDA-approved in the US. Valproate has also been used in the treatment of infantile spasms, with an efficacy of approximately 25 - 40%. However, in the very young infant, it does carry a high risk of fatal hepatotoxicity. Surgical resection may be the treatment of choice for those infants with focal cortical dysplasia and intractable infantile spasms. Emerging therapeutic possibilities include topiramate, felbamate, lamotrigine, zonisamide and perhaps levetiracetam. With the advancements in molecular biology, genetics and neuroimaging, there is the hope of novel therapies in the future.