Partial rhombencephalosynapsis

Abstract

We describe an infant in whom partial rhombencephalosynapsis was diagnosed by using MR imaging. The anterior vermis and nodulus were normally developed, but part of the posterior vermis was deficient. There was partial fusion of the hemispheres in the inferior part of the cerebellum. Partial rhombencephalosynapsis is described for the first time, and our findings support the recent embryologic observations.

Fig 1.

Axial T2-weighted double-echo short tau inversion recovery image (A), axial 3D T1-weighted gradient-echo images with a 1-mm thickness (B, C), and sagittal T1-weighted spin-echo image (D). A, An axial section at the level of the pontomedullary junction shows the vermis separate from the hemispheres at the level of the anterior vermis. B and C, The rotation of the cerebellum in the transverse axis can be observed. C and D, The prepyramidal and secondary fissure in the partially fused inferior cerebellum can be recognized (arrows). D, The sagittal image demonstrates the normal appearance of the anterior vermis and the thinning of the corpus callosum.