Acoustic schwannomas are often accompanied with disproportionately enlarged subarachnoid space hydrocephalus.

Hydrocephalus with tight high convexity and wide Sylvian fissure is called disproportionately enlarged subarachnoid space hydrocephalus (DESH). DESH on MRI is thought to be one of the characteristic features of idiopathic normal pressure hydrocephalus (iNPH) and useful to differentiate from other ventriculomegalic status. On the other hand schwannomas are often complicated by communicating hydrocephalus, among which the expansion of the Sylvian fissure is often observed. So we examined relationship between acoustic schwannoma and communicating hydrocephalus or DESH.