History: 2-year-old boy with developmental delay, nystagmus, and blindness
Findings: Dysplasia of the vermis and slight enlargement of the fourth ventricle are demonstrated on the midline sagittal T1-weighted image (not shown). The roof of the fourth ventricle is convex superiorly. An axial T1-weighted MR image at the level of the pons shoes an unusual ‘batwing’ configuration of the fourth ventricle, which is convex anteriorly. Thnning of the superior cerebellar peduncles was also present.
Dx: Joubert syndrome