This patient presented with multiple CNS anomalies, causing severe psychomotor and mental retardation and intractable seizures as well as major ophthalmological malformations and ENT anomalies. The triad of infantile spasms, callosal agenesis and chorioretinal lacunae (Fig. 6) was described first by Aicardi in 1969 [1]. Associated conditions include Arnold-Chiari malformation, septo-optic dysplasia, ventriculomegaly, gyral anomalies with schizencephaly and grey matter heterotopia as well as delayed and asymmetric myelination. Choroid plexus cysts and papillomata, porencephaly, interhemispheric cysts, midline lipoma, aqueduct stenosis, absent pineal gland, craniosynostosis, scalp lipomas, microphthalmia, optic disc coloboma, retrobulbar encephalocele as well as vertebral and rib anomalies are also described [1]. Around 200 cases of Aicardi syndrome in children have been reported to date. A broad spectrum of manifestations has been described ranging from relatively indolent cases to very severe presentations [2]. This patient is at the more severe end of this spectrum in view of the extensive nervous system and ophthalmological anomalies.
Aicardi syndrome is a congenital X-linked dominant disorder with heterozygous male lethality, thus it affects girls only [1]. The only male presentation occurred in a boy with an XXY chromosomal karyotype [3]. The chromosomal anomaly is situated on chromosome Xp22 with a breaking point between p22.2 and p22.3. The occurrence is due to a new spontaneous mutation without genetic transmission [4]. No specific test, antenatal or postnatal, exists to date for Aicardi syndrome.
Age of onset is in the first few months of life, usually from 3 to 5 months [1]. A more indolent form of this syndrome has been described in a 49-year-old woman with well-controlled epilepsy and mild mental disablement only [2]. The insult occurs between the 12th and 17th week of gestation due to an injury to the commissural plate. Most of the described malformations in Aicardi syndrome originate from this early embryonic period, such as agenesis of the corpus callosum, which is complete in 72% and partial in 28% of patients [4].
The patient in this case was diagnosed with Aicardi syndrome at the age of 6.5 months. This was based mainly on the MRI findings and to a lesser extent on retrospective review of the neonatal CT. The simultaneous presence of major CNS and ophthalmological anomalies led to the correct radiological diagnosis. She also had a cleft soft palate and a laryngeal type 1 cleft.
Interhemispheric cysts have been previously described in Aicardi syndrome [1]. Barkovich et al. established a classification of interhemispheric cysts [5]. They distinguish cysts extending from the ventricular system (type 1) from separately loculated cysts (type 2). Whereas type 2a cysts are not associated with any malformations other than callosal agenesis/hypogenesis, type 2b cysts are associated with deficiencies of the falx cerebrum, grey matter heterotopia and polymicrogyria. These type 2b cysts are specifically identified with Aicardi syndrome [5].
Plagiocephaly was present in this patient but without evidence of craniosynostosis. Vertebral and rib anomalies have been reported in 39% of Aicardi syndrome patients [4], but neither was present in this patient.
In summary, the diagnosis of Aicardi syndrome, even though rare, is important for genetic counselling. The diagnosis is made clinically and based on the presence of seizures (usually infantile spasms), severe mental retardation, callosal agenesis and chorioretinal lacunar defects.
