Normal Pressure Hydrocephalus as a Possible Reversible Cause of Dementia, Neuroimaging Findings

Abstract

Introduction

Normal pressure hydrocephalus (NPH) occurs in 0.5% of persons over 65 years old. The etiology of NPH is still unknown. Clinically NPH is characterised by cognitive deterioration, gait impairment and urinary incontinence. NPH is a possible reversible cause of dementia. Neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) allow to assess typical brain changes in this disorder.

The objectives are to present the typical findings of NPH on CT and MRI and to demonstrate differences between NPH and central brain atrophy in neuroimaging.

Results

The imaging features of NPH include: supratentorial ventriculomegaly with callosal angle less than 90o, tight sulci at the vertex and considerable out of proportion enlargement of Sylvian fissures. In case of central brain atrophy there may be a predominance of ventriculomegaly and/or widened sulci without crowding of the gyri at the vertex and callosal angle greater than 90o. In both entities, the decrease of density in periventricular region may be seen: in NPH could be a sign of transependymal oedema or in brain atrophy as an accompanying leukoaraiosis. Additionally, it is possible to assess changes in flow of cerebrospinal fluid (CSF) on MRI: in NPH an increased pulsatile CSF circulation in aqueduct as flow void sign may be observed.

Conclusions

Correct diagnosis of NPH on CT or MRI in relation to clinical data is very important. Treatment with ventriculoperitoneal shunt or third ventriculostomy may partially improve the quality of life in some patients with cognitive impairment due to NPH.

Disclosure of interest

The authors have not supplied their declaration of competing interest.