Outcome of Fetuses with Supratentorial Extra-Axial Intracranial Cysts: A Systematic Review.

Objective: To investigate the incidence of associated anomalies, aneuploidy, cyst progression, need for surgery and neurodevelopmental outcome in fetuses with extra-axial supratentorial intracranial cysts.

Data Sources: Medline, Embase and CINAHL databases were searched and the following outcomes analyzed: associated central nervous system (CNS) and extra-CNS anomalies detected at the scan, chromosomal anomalies, additional CNS anomalies detected only at prenatal MRI, additional CNS anomalies detected only after birth, cyst progression in utero, neurological outcome and need for surgery. Two authors reviewed all abstracts independently. Results were reported as proportions, and between-study heterogeneity was explored using the I² statistic; fixed or random effect models were used accordingly.

Results: Ten studies involving 47 fetuses were included in the meta-analysis. Arachnoid cysts (n = 24) had associated CNS anomalies and extra-CNS in 73% (95% CI 56-88) and 14% (95% CI 4-29), respectively. The most common associated anomalies were ventriculomegaly and callosal abnormalities. Chromosomal abnormalities were present in 6% (95% CI 0-30), but fetuses with isolated cysts were always euploid (0/7; 95% CI 0-29). Fetal MRI and postnatal examination identified 5 additional cases (21%, 95% CI 1-57). Cavum veli interpositi (CVI) cysts had associated CNS and extra-CNS anomalies in 31% (95% CI 13-52) and 6% (95% CI 0-29), respectively. No chromosomal or callosal anomalies were found in these cases. In isolated CVI cysts, no cases of associated anomalies were detected postnatally. Intrauterine regression occurred in 23% of CVI cysts and in none of the arachnoid cysts. In children with arachnoid cyst, the occurrence of hydrocephaly and mass effect on the adjacent structures were observed in 23.9% (95% CI 8.3-4.4) and 26.8% (95% CI 4.0-60.1), respectively. None of the cases included had abnormal motor outcome or intelligence. The rate of surgery was 34.7% (95% CI 16.0-56.4). None of the children with a prenatal diagnosis of isolated CVI cyst experienced any of the adverse outcomes explored in this review.

Conclusions: Extra-axial supratentorial cysts diagnosed in utero are frequently associated with other neural and extra-neural anomalies. However, this may represent the consequence of a selection bias. Interhemispheric arachnoid cysts were typically associated with callosal anomalies. Abnormal karyotypes were seen only in fetuses with multiple anomalies. Arachnoid, but not CVI, cysts frequently increased in size throughout gestation.