Aicardi syndrome is a very rare neurological condition due to a congenital abnormality of brain development. The characteristic features consist of under development or absence of the development (agenesis) of a brain structure known as the corpus callosum, a form of epilepsy (infantile spasms) and an abnormality to the structure and appearance of the retina of the eyes.

It is an example of one of the syndromic causes of agenesisof the corpus callosum. In Aicardi syndrome, in addition to the structural abnormality of the corpus callosum, other structures within the brain can also be abnormal. This can result in a variety of types of brain cyst and/or abnormal structure within areas of both grey or white matter of the brain.

Learning Disability is a constant feature and varies from moderate to the more commonly seen severe picture.

The associated epilepsy classically takes the form of 'infantile spasms' or is 'spasm-like.' Other types of epileptic fit may be seen. The epilepsy usually occurs by two months of age, it is often difficult and remains difficult to control. Investigating it with electroencephalogramstudies may reveal a pattern characteristic of these spasms (hypsarrhythmia). This form of epilepsy is sometimes referred to as West syndrome. As such, Aicardi syndrome can be considered to be a 'symptomatic' cause of West syndrome.

The abnormalities at the back of the eye, evident only on internal examination with an ophthalmoscope, are to the structure of the choroid and retina. They appear as distinctive multiple, round 'footprint shaped' yellow-white lesions. The level of vision depends upon the extent of these retinal lesions and the severity of any associated learning disability.

The condition is associated with a host of other variable manifestations. These can include abnormalities of the bony structure of the spine, spinal curvature (see entry, Scoliosis), cleft lip and palate.

The spectrum of disability within Aicardi syndrome is wide. Its severity is to some extent determined by the extent of theunderlying brain abnormality.

The majority of recognised cases are severely affected with persisting epilepsy. Life expectancy can be severely limited. There are some children with a milder structural brain abnormality who, although suffering visual handicap and learning difficulties, may have some understanding of language, some independent mobility and be responsive to their environment.

Aicardi syndrome is not the same as, and has no link to, a separate neurological condition referred to as Aicardi-Goutiers syndrome.

Inheritance patterns
The condition only occurs in girls. This is explained genetically by it being an X-linked dominant condition with lethality in males. Reoccurrence within a family appears to be extremely uncommon.

Prenatal diagnosis
Although structural brain abnormalities may sometimes be evident on antenatal ultrasound scan, this is not the case in the majority of cases of Aicardi syndrome. There is no prenatal diagnosis available.

Medical text written February 2000 by Dr K R E Pohl, Consultant Paediatric Neurologist, Guy's Hospital, London, UK. Last reviewed August 2005 by Dr L Rosenbloom, Consultant Paediatric Neurologist, Alder Hey Children's Hospital, Liverpool, UK.

The information below has been drawn up by Dr Orlee Udwin of the Society for the Study of Behavioural Phenotypes.

Psychological and Behavioural Characteristics

Nearly all children with Aicardi syndrome have severe learning difficulties. Most have no expressive language and remain totally dependent on adults for their self care. However, there are a few girls who have some understanding of language, can walk withsupport or independently and are fairly responsive to the environment.Self-injurious behaviours and aggression towards people and objects have been reported in some studies and may be involuntary. Disturbed sleep (possibly due to fitting) and waking in the night are also common problems.

Further Online Resources
Medical texts in The Contact a Family Directory are designed to give a short, clear description of specific conditions and rare disorders. More extensive information on this condition can be found on a range of reliable, validated web sites and links to them are included in the CD-ROM version of this Directory. Further information on these resources can be found in our Medical Information on the Internet article.

Support for Aicardi syndrome is available from CORPAL appear under the separate entry, Agenesis of the Corpus Callosum.