[Agenesis of the corpus callosum: etiological and clinical aspects, diagnostic methods and prognosis]

[Early onset schizophrenia and partial agenesis of corpus callosum]

We report a case of schizophrenia with partial agenesis of the corpus callosum in a 14-year-old girl. Diagnosis of schizophrenia was confirmed in the longitudinal follow-up and partial agenesis of the corpus callosum was found on brain MRI at the prodromal stage of disease. The prodromal symptom was progressive deterioration of social and academic adjustment in a context of non-specified psychotic disorder in the father. We found no abnormality in the development but a history of seizures that did not require specific treatment. Follow-up at 8 months showed an increase in negative symptoms and the onset of delusional symptoms and disorganization leading to the prescription of antipsychotic treatment. A review of the literature shows that agenesis of corpus callosum is the most reliable brain morphology abnormality in schizophrenia and is related to the neurodevelopmental and abnormal brain connectivity hypothesis in schizophrenia. Although this abnormality may be a marker of disease severity, our case report highlights the lack of longitudinal follow-up to allow the characterization of a specific outcome pattern of schizophrenic adolescents with partial agenesis of the corpus callosum.

Prenatal diagnosis of agenesis of corpus callosum: what is the neurodevelopmental outcome?

BACKGROUND

Corpus callosum is the largest cerebral commissure that connects neocortical areas. Agenesis of corpus callosum (ACC) can be partial or complete, isolated or associated with other malformations. Its prenatal diagnosis creates problems within parental counselling due to its uncertain prognosis. The aim of this study was to correlate the neurodevelopmental outcome with both the clinical picture and the neuroradiological features, in order to improve prenatal parental counselling in a group of nine children with ACC, prenatally diagnosed by ultrasound and then confirmed by postnatal magnetic resonance imaging (MRI).

METHODS

In all patients, cerebral ultrasound scans, electroencephalogram (EEG) examinations, cerebral MRI, cytogenetic analysis, general physical evaluation, neurological examination and neuropsychological assessment (Griffiths Scale, Wechsler Primary and Preschool Scale of Intelligence, Wechsler Intelligence Scale for Children) were carried out.

RESULTS

In six patients the callosal agenesis was isolated, while in 3/9 it was associated with other cerebral malformations. Children with isolated callosal agenesis were asymptomatic or presented a mild hypotonia and the EEG was normal in five of them. All children with other associated brain malformations presented epilepsy, poor psychomotor development and cerebral palsy.

CONCLUSION

The prenatal suspicion of ACC needs an accurate diagnostic approach, in order to well determine its isolated or associated nature, linked to different neurodevelopmental outcome.

Trends in elective terminations of pregnancy between 1989 and 2000 in a French county (the Isère)

OBJECTIVES

This study was performed in order to provide a description of indications for induced elective terminations of pregnancy (ETOP), their characteristics (e.g. gestational age), and their evolution over time.

DESIGN OF THE STUDY

This is an epidemiological study. The geographic area covered is the French county of 'Isère', which represents a mean of 14 000 births per year over the study period.

MATERIALS AND METHODS

Data on ETOPs were collected actively from medical records by a register of childhood deficiencies and adverse perinatal events in this county. Between 1989 and 2000, 996 ETOPs were notified.

RESULTS

Four main grounds for ETOPs were identified: (1) morphological anomalies with normal karyotype (39%), (2) chromosomal anomalies (35%), (3) other fetal grounds (16%), and (4) maternal indications (10%). Prevalence rates for the first two grounds increased significantly over the study period respectively from 2.0 to 2.9 and from 1.4 to 2.7 per 1000. Among the ETOPs carried out because of fetal indications, the percentage of late ETOPs (from 24 weeks of gestation) was 34.6%, and remained stable over the studied period. In some cases, a medical consensus was not reached with respect to indications for termination (sex chromosome anomalies, limb defects). We estimated the percentage of these cases as being 2.7% of the figure for fetal indications, without any variation in prevalence over the whole period (p = 0.59). The increasing number of ETOPs that occurred in the chromosomal aberrations group during the study period is thought to be due to an increase in diagnostic sensitivity. The increase that occurred in the morphological anomalies group is thought to be due both to an increase in sensitivity and to a widening of the field with respect to indications, some of which have an uncertain prognosis (e.g. agenesis of the corpus callosum).

CONCLUSION

This study provides useful data for monitoring medical practice consistency within the field of prenatal diagnosis, and for the drive to keep medical practice within ethically acceptable limits.

Ivemark syndrome with agenesis of the corpus callosum: a case report with a review of the literature

Asplenia associated with situs ambiguus, symmetric liver, bilateral trilobulated lungs, and a complex heart defect was diagnosed on autopsy in a 14-day-old infant. Furthermore, examination of the brain displayed agenesis of the corpus callosum (ACC) with pachygyria and hydrocephalus. The characteristic association of asplenia with visceroatrial heterotaxia is traditionally named after the Swedish pediatrician, Ivemark. Although exceptional, association of Ivemark syndrome with callosal agenesis has been reported recently. The concept of 'developmental fields' describes morphogenetically reactive units of the embryo determining and controlling the development of complex structures in a hierarchical manner. Lateralization defects such as situs inversus, asplenia or polysplenia due to defective left-right axis development, as well as decussation defects such as ACC, are considered as defects of the primary developmental field. Therefore, additional callosal agenesis in Ivemark syndrome may be a coherent and synchronic defect in the primary developmental field rather than a causally independent malformation.