Rhombencephalosynapsis
- Rhombencephalosynapsis is a rare congenital malformation characterized by hypogenesis or agenesis of the vermis, fusion of cerebellar hemispheres, dentate nuclei, and superior cerebellar peduncles.
- MRI findings include: fused cerebellar hemispheres and dentate nuclei, absent or severely hypoplastic vermis (axial and coronal images), lack of visualization of primary vermian fissure, and lack of a normal fastigial point of the fourth ventricle on sagittal images.
- Associated malformations: midline anomalies (aqueductal stenosis, absent septum pellucidum, holoprosencephaly, callosal dysgenesis or agenesis), heterotopias, encephaloceles, clefts, and facial anomalies.
- Prenatal identification of rhombencephalosynapsis is useful for counseling since prognosis is poor. Ataxia, involuntary head movements, developmental delay, self injurious behavior, and early death are postnatal presentations.
Suggested Reading
McAuliffe F, Chitayat D, Halliday W, et al. Rhombencephalosynapsis: prenatal imaging and autopsy findings. Ultrasound Obstet Gynecol 2008;31:542-48. SUBSCRIPTION REQUIRED (ABSTRACT ONLY)
Utsunomiya H, Takano K, Ogasawara T, et al. Rhombencephalosynapsis: cerebellar embryogenesis. AJNR Am J Neuroradiol 1998;19:547-49.