Infantile spasms (IS) are a unique and severe form of
epilepsy associated with poor neurologic and developmental outcomes. The refractory
spasms and abnormal electroencephalogram (EEG) patterns associated with the condition are believed to have a progressively detrimental impact. Therefore, rapid and complete control of
spasms is the primary goal of treatment. Well-controlled clinical trials in Europe, Canada, and the United States have demonstrated that
vigabatrin is efficacious and generally well-tolerated as monotherapy for IS. Several key studies, including pivotal trials that led to United States approval of
vigabatrin in 2009, as well as comparative trials of
vigabatrin and hormonal treatment, are the focus of this review. All studies assessed
spasm cessation - usually as the primary endpoint - and adverse events.
Vigabatrin dosages generally ranging from 100 to 150 mg/kg/day demonstrated efficacy to decrease or eradicate
spasms and eliminate hypsarrhythmic EEG in patients with newly diagnosed IS. Several studies demonstrated long-term sustainability of
spasm freedom with no negative impact on developmental outcomes.
Vigabatrin was generally well-tolerated with few severe adverse events. Visual field defects cannot be adequately assessed in infants and young children, so this potential adverse effect was not evaluated in children with
spasms. Notably, the time to response with
vigabatrin was very rapid, generally occurring within 2 weeks of initial treatment. This allows for early treatment modification as needed. For infants who respond well to
vigabatrin,
treatment duration up to 6 months appears to be appropriate for realizing
spasm freedom while limiting potential risks of adverse events and recurrences.