Radiology, Vol 147, 109-114, Copyright © 1983 by Radiological Society of North America
Dandy-Walker syndrome studied by computed tomography and pneumoencephalography
JC Masdeu, GD Dobben and B Azar-Kia
Based on air studies, some authors have disputed the ability of computed
tomography (CT) to diagnose posterior fossa cysts. The authors correlated
the pneumoencephalographic, CT, and pathological findings in 4 patients
with classic Dandy-Walker syndrome. Three cases had been misdiagnosed as
retrocerebellar arachnoid cysts because the fourth ventricle was
incorrectly considered normal on brow-up or erect air studies, reflecting
the inability of such studies to evaluate an agenetic vermis and deficient
posterior medullary velum which are characteristic of Dandy-Walker
malformation. Careful correlation with autopsy findings showed that even
with complete agenesis of the inferior vermis, if the slit between the
cerebellar hemispheres is narrow, the fourth ventricle could be
misinterpreted as normal on pneumoencephalography and sagittal CT.
Radionuclide studies, a small amount of air, or metrizamide may be needed
to determine whether the cyst communicates with the subarachnoid space.
