Objective
To systematically review published data on the neurodevelopment of children that were diagnosed prenatally with isolated agenesis of the corpus callosum.
Study Design
Medline and Scopus searches (1960-July 2011); cross-referencing of retrieved articles.
Results
Sixteen reports (132 cases of apparently isolated agenesis of the corpus callosum) were included in the analysis. The rates of normal outcome, borderline or moderate disability and severe disability were 94/132 (71.2%; 95% confidence interval [CI], 63.0–78.3), 18/132 (13.6%; 95% CI, 8.8–20.5), and 22/132 (15.2%; 95% CI, 10.0–22.2), respectively. Magnetic resonance imaging detected additional cerebral abnormalities in 22.5% (95% CI, 12.3–37.5) of apparently isolated agenesis of the corpus callosum cases. In truly isolated agenesis of the corpus callosum (confirmed by magnetic resonance imaging), the rates of normal neurodevelopment and severe disability were 52/69 (75.4%; 95% CI, 64.0–84.0) and 8/69 (11.6%; 95% CI, 6.0–21.2), respectively.
Conclusion
Prenatally diagnosed, isolated agenesis of the corpus callosum is usually associated with a favorable outcome. Larger, prospective series are required, as current data are limited, inconsistent, and prevent subgroup analyses (eg, complete vs partial agenesis of the corpus callosum).
The corpus callosum is the main cerebral commisure, comprising of approximately 190 million axons that connect the 2 hemispheres.
Agenesis of the corpus callosum (ACC) can result from genetic, infectious, vascular, or toxic causes, and it can be either complete (CACC) or partial (PACC). Its reported prevalence is approximately 1:4000-1:5000 in live births, but much higher rates (2-3%) have been reported among patients assessed for neurodevelopmental disorders.
Prenatal diagnosis of ACC has been reported since the late 1980s, and typical sonographic signs have been described, either direct (complete or partial absence of the corpus callosum in the midsagittal plane) or indirect (obliteration of the cavum septum pellucidum, colpocephaly, elevation and dilatation of the third ventricle, abnormal course of the pericallosal artery). The indirect signs may be subtle, or even absent, in PACC, and mild colpocephaly may be the only finding in these cases. Recently, 3-dimensional sonography is being successfully used for the reconstruction of callosal anatomy, both in normal and abnormal cases.
ACC is commonly associated with other cerebral and/or extracerebral anomalies, and it is a feature in more than 200 syndromes ( http://omim.org ). Before the era of prenatal diagnosis, ACC was usually detected during the diagnostic workup of patients with developmental delay or neurologic symptoms (eg, infantile spasms), and, as a result, the early literature focused heavily on the association of ACC with other defects, syndromes, and morbidity in general. The progress in obstetric ultrasound led to the recognition of an increasing number of apparently isolated cases of ACC, which appeared to carry an excellent prognosis, with an 85% chance of a normal developmental outcome. As a result, the counseling for isolated cases changed, and many parents started to opt not to terminate when isolated ACC was diagnosed in their fetus. However, the degree of uncertainty, and therefore the rates of termination are still high, and ACC was reported as the most common reason for central nervous system (CNS) related termination after 24 weeks in a French study.
Objective
The aim of this study was to systematically review published evidence about the prognosis of prenatally diagnosed, apparently isolated ACC, pool the evidence, and explore for potential favorable or adverse prognostic factors.
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