Figure 1.

Shown are three axial slices of a cerebral MRI from a single non-shunted idiopathic normal pressure hydrocephalus patient with ventriculomegaly. The Evans index (EI) is calculated by dividing the maximal diameter of the frontal horns of the lateral ventricles [(A), I] by the maximal diameter of the skull [(A), II], values above 0.3 are considered hydrocephalic (20). Disproportionately enlarged subarachnoid space hydrocephalus features additionally consist of a focal enlargement of the cerebral sulci [(B), arrow] and tight high-convexity (C).