Agenesis of the Corpus Callosum and Aicardi Syndrome: A Neuroimaging and Clinical Comparison

Aicardi syndrome in a Nigerian female child: A case report and literature review of a rare neuro-developmental disorder from North-Western Nigeria

Aicardi syndrome is a very rare neurodevelopmental disorder, inherited as an X-linked dominant condition with a triad of infantile spasm, partial or complete agenesis of the corpus callosum, and chorio-retinal "lacunae." We report a case of a female infant with the classical triad of Aicardi syndrome. A female infant presented to the Paediatric Neurology Clinic of the Federal Medical Centre Birnin-Kebbi, North-western Nigeria, at the age of two months with complaints of recurrent afebrile convulsions typical for infantile spasms. The patient was delivered at term with normal Apgar scores and anthropometry. Examination revealed an infant with no dysmorphic features and normal systemic examination. Magnetic Resonance Imaging (MRI) of the brain however, showed complete agenesis of the corpus callosum and dilatation of the posterior horn of the lateral and third ventricles. Fundoscopy showed multiple yellowish spots along the vascular arcades in the right eye. The left eye had a one-disc diameter lacuna in the superior nasal quadrant adjacent to the optic disc with multiple yellowish spots. A diagnosis of Aicardi syndrome was made. The child was placed on oral phenobarbital and followed up. At the age of 18 months, the child can only sit without support, hold an object in each hand, smile socially, and babble. The frequency of the seizures had also reduced from >100 episodes per day to 2-3 episodes per day, but the child had developed right-sided spastic hemiparesis. The patient was commenced on physiotherapy and the anti-epileptic drugs were maintained. We recommend clinicians consider Aicardi syndrome in the differential diagnosis of any child presenting with infantile spasms.

Imaging Similarities Between Oral-Facial-Digital Syndrome Type 1 and Aicardi Syndrome: Prenatal and Postnatal Magnetic Resonance Imaging (MRI) Findings in 4 Patients

Prenatal identification by magnetic resonance imaging (MRI) of callosal anomalies, particularly with accompanying intracranial abnormalities, poses a challenge for accurate prognostication and fetal counseling as outcome can vary widely depending on underlying etiology. In female patients, Aicardi syndrome is an important consideration, and prompt postnatal ophthalmologic assessment to identify ocular stigmata of Aicardi syndrome can aid with anticipatory guidance and greater vigilance for seizures. We present a case of a female with fetal and postnatal MRI findings of agenesis of corpus callosum and type 2b interhemispheric cysts, characteristically found in Aicardi syndrome, but was found to have oral-facial-digital syndrome type 1 (OFD1). We also present 3 other companion cases with pre- and postnatal imaging of patients with Aicardi syndrome. These cases highlight the importance of widening the differential diagnosis to also include OFD1 for female patients with callosal anomalies.

Dissecting the neurological phenotype in children with callosal agenesis, interhemispheric cysts and malformations of cortical development

OBJECTIVES

To describe the neurological phenotype of children with prenatal diagnosis of agenesis of corpus callosum (ACC) and interhemispheric cysts associated with malformations of cortical development (MCD).

METHODS

We reviewed the neuroimaging, neurologic, EEG, and genetic data of 36 patients (21 males, mean age 7 years) with ACC and interhemispheric cysts. Associations were tested with Chi-squared and Fisher exact tests.

RESULTS

According to the 2001 Barkovich classification, we found 4 type 1c (11.1%), 6 type 2a (16.6%), 18 type 2b (50%, 6/18 girls with Aicardi syndrome), and 9 type 2c cysts (22.2%). EEG showed specific epileptic activity in 27/36 patients (75%). Epilepsy was diagnosed in 16 subjects (16/36, 44.4%), including all Aicardi patients, and was associated with cognitive impairment (p = 0.032). Severe intellectual disability and epilepsy were associated with type 2b cysts, always due to Aicardi patients (p < 0.05). After excluding Aicardi patients, all subjects with type 2b cysts had mild neurological phenotype. Patients with 2a and 2c cysts more frequently had normal cognition (83.3% and 62.5% of cases, respectively). Patients with type 1c cyst mostly had mild/moderate cognitive impairment. Severe neurologic deficits were associated with 1c cysts and 2b cysts with Aicardi syndrome (p < 0.05). Multilobar and/or bilateral MCD were associated with severe neurological and epileptic phenotypes (p < 0.05).

CONCLUSION

Once excluded Aicardi syndrome, most patients with ACC and interhemispheric cysts have a mild clinical phenotype characterized by borderline/normal cognition and minor neurological signs. Despite the high prevalence of EEG epileptic abnormalities, epilepsy in these cases is infrequent and usually responsive to antiepileptic drugs.

Aicardi syndrome, an unsolved mystery: Review of diagnostic features, previous attempts, and future opportunities for genetic examination

Aicardi syndrome is a rare, severe neurodevelopmental disorder classically characterized by the triad of infantile spasms, central chorioretinal lacunae, and agenesis of the corpus callosum. Aicardi syndrome only affects females, with the exception of a few males with a 47, XXY chromosome constitution. All cases are de novo and the only cases of definitive recurrence in families are in identical twins. It is now recognized that individuals with Aicardi syndrome commonly exhibit a variety of other neuronal migration defects, eye anomalies, and other somatic features, including skin, skeletal, and craniofacial systems. The etiology of Aicardi syndrome remains unknown despite an international effort exploring different genetic mechanisms. Although various technologies examining candidate genes, copy number variation, skewing of X-chromosome inactivation, and whole-exome sequences have been explored, no strong genetic candidates have been identified to date. New technologies that can detect low-level mosaicism and balanced rearrangements, as well as platforms examining changes at the DNA and chromatin level affecting regulatory regions are all potential avenues for future studies that may one day solve the mystery of the etiology of Aicardi syndrome.