The posterior cranial fossa is abnormal. The inferior cerebellar vermis is hypoplastic and there is continuity between the cisterna magna and dilated fourth ventricle. The tentorium cerebelli is high. The vermis is present, but small. Scalloping of the posterior cranial fossa inner table (remodelling).
Conclusions:
Findings are in keeping with a Dandy-Walker spectrum abnormality with cerebellar hemispheric and vermian hypoplasia.