Rhombencephalosynapsis is an abnormalty of the cerebellar midline including a missing vermis and fusion of the cerebellar hemispheres with or without other brain abnormalities. Ishak et al. (Brain 2012, Advance access March 26, 2012) offers a nice description of associated genetic syndromes and clinical features associated with this malformation. Interestingly, this brain abnormality can be seen with VACTERL features. This implies that careful consideration should be given to MRI imaging of the hindbrain in individuals with VACTERL.
-Hilary Vernon MD PhD