What imaging finding is typical of normal pressure hydrocephalus when examining the ventricles relative to the sulci?

What imaging finding is typical of normal pressure hydrocephalus when examining the ventricles relative to the sulci?

• A. Ventricles are enlarged with ventriculomegaly out of proportion to the sulci
• B. Sulci are markedly enlarged with normal ventricles
• C. Only the frontal horns enlarge
• D. Ventricles are small and sulci are atrophied

Answer: (A)

The key idea is that normal pressure hydrocephalus shows ventriculomegaly that is out of proportion to the amount of sulcal (cortical) atrophy. In NPH, the ventricles enlarge due to CSF accumulation, but the overlying brain tissue isn’t as severely atrophied as expected for that level of ventricle size, so the ventricles look disproportionately large compared with the sulci. This contrasts with brain atrophy (hydrocephalus ex vacuo), where sulci widen in tandem with or more than the ventricles, making the pattern less about CSF accumulation than about cortical loss. Therefore, the imaging hallmark you’d pick is enlarged ventricles with relatively preserved or less-widened sulci—ventriculomegaly out of proportion to sulcal widening.

The key idea is that normal pressure hydrocephalus shows ventriculomegaly that is out of proportion to the amount of sulcal (cortical) atrophy. In NPH, the ventricles enlarge due to CSF accumulation, but the overlying brain tissue isn’t as severely atrophied as expected for that level of ventricle size, so the ventricles look disproportionately large compared with the sulci. This contrasts with brain atrophy (hydrocephalus ex vacuo), where sulci widen in tandem with or more than the ventricles, making the pattern less about CSF accumulation than about cortical loss. Therefore, the imaging hallmark you’d pick is enlarged ventricles with relatively preserved or less-widened sulci—ventriculomegaly out of proportion to sulcal widening.