Aicardi syndrome is rare and appears to affect all ethnicities equally. Based on only the accepted clinical phenotype, there are currently about 1,000 cases in the United States and at least 4,000 cases worldwide. However, many cases may go undiagnosed because of access to good medical care, atypical presentation, or early death. The incidence of Aicardi syndrome is estimated about 1 in every 100,000 live births. Survival is highly variable and likely depends on the severity of seizures and other organ system involvement, particularly conditions that affect the respiratory system. Median survival from birth is more than 30 years, and as children age, their chance of survival increases. For example, the probability of surviving another 5 years is over 85% for an affected person that is 25 years old. The ages of highest mortality risk are in the first few years of life and in adolescence. Common causes of death include respiratory failure, systemic infections with difficult to treat pathogens, and SUDEP.

Development and Long Term Outcomes

Most affected individuals have moderate to severe developmental and intellectual disability, although some children with Aicardi syndrome have a more mild form of disability. The severity of Aicardi syndrome can vary greatly. Affected children should enter the early intervention system as soon as possible although it is not clear how much of the disabilities can be attenuated through therapies or are pre-determined. Many children with Aicardi will learn to sit independently and feed themselves and many are able to walk. Some children can speak in short sentences but complex oral language is the exception. The majority of children with Aicardi syndrome communicate with gestures, sounds and other nonverbal means and receptive communication is more advanced than expressive. Chronic developmental regressions have been documented, mostly due to a change or increase in seizures.