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.