MRI
The lateral and third ventricles are markedly enlarged with evidence of transependymal oedema and effacement of the cortical sulci. The aqueduct is stenosed in its middle third and no flow through it is evident on CSF flow studies. The tectal plate appears normal.
Flow does appear to extend through the third ventricular floor, although this could represent pulsation on the inferiorly displaced floor by the adjacent basilar artery.