Associations and outcomes of prenatally detected rhombencephalosynapsis

Objective: To describe the association between prenatal imaging and neurodevelopmental outcomes of fetuses with rhombencephalosynapsis (RES).

Study design: Thirty-four pregnancies complicated by RES were identified from our institutional databases based on US and/or MRI findings. Genetic testing results were gathered. In cases of termination of pregnancy, we studied the association between prenatal imaging and neuropathologic findings. For those who opted for expectant management, comprehensive developmental assessments and postnatal MRI imaging were evaluated.

Results: Over one third of fetuses in our cohort had complete RES. Common intracranial anomalies identified were mesencephalosynapsis, aqueduct stenosis and diencephalosynapsis. The degree of RES was not associated with the frequency of additional central nervous system anomalies. MRI had a good correlation with neuropathologic findings with regard to the degree of RES, aqueduct stenosis and mesencephalosynapsis. Postmortem autopsy showed that one third of our cases had VACTERL-H and almost all of those had complete RES. All liveborn neonates(n = 6) had aqueduct stenosis requiring ventriculoperitoneal shunting within days of delivery (median 5 days). While a large proportion of prenatally suspected complete RES were found to have partial RES on postnatal imaging, prenatal diagnosis of aqueduct stenosis remained unchanged. All children that were at least 2 years old (n = 3) had global developmental delay.

Conclusion: Prenatal assessment of the RES severity is challenging and may be unreliable. Nevertheless, postnatal prognosis is poor for both complete and partial RES. Associated aqueductal stenosis, can be reliably assessed prenatally and this may contribute to worse postnatal prognosis than the degree of RES.