Morphologic Features and Flow Void Phenomenon in Normal Pressure Hydrocephalus and Other Dementias

ABSTRACT Normal pressure hydrocephalus (NPH) is a syndrome characterized by the triad of gait disturbance, mental deterioration and urinary incontinence, associated with ventriculomegaly and normal cerebrospinal fluid (CSF) pressure. The clinical presentation (triad) may be atypical or incomplete, or mimicked by other diseases, hence the need for supplementary tests, particularly to predict postsurgical outcome, such as CSF tap-tests and computed tomography (CT) or magnetic resonance imaging (MRI). The CSF tap-test, especially the 3 to 5 days continuous external lumbar drainage of at least 150 ml/day, is the only procedure that simulates the effect of definitive shunt surgery, with high sensitivity (50-100%) and high positive predictive value (80-100%). According to international guidelines, the following are CT or MRI signs decisive for NPH diagnosis and selection of shunt-responsive patients: ventricular enlargement disproportionate to cerebral atrophy (Evans index >0.3), and associated ballooning of frontal horns; periventricular hyperintensities; corpus callosum thinning and elevation, with callosal angle between 40º and 90º; widening of temporal horns not fully explained by hippocampal atrophy; and aqueductal or fourth ventricular flow void; enlarged Sylvian fissures and basal cistern, and narrowing of sulci and subarachnoid spaces over the high convexity and midline surface of the brain. On the other hand, other imaging methods such as radionuclide cisternography, SPECT, PET, and also DTI or resting-state functional MRI, although suitable for NPH diagnosis, do not yet provide improved accuracy for identifying shunt-responsive cases.

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

European Psychiatry ◽

10.1016/j.eurpsy.2017.01.1024 ◽

2017 ◽

Vol 41 (S1) ◽

pp. S629-S630 ◽

Cited By ~ 1

Author(s):

A. Zacharzewska-Gondek ◽

T. Gondek ◽

M. Sąsiadek ◽

J. Bladowska

Keyword(s):

Normal Pressure Hydrocephalus ◽

Brain Atrophy ◽

Correct Diagnosis ◽

Normal Pressure ◽

Third Ventriculostomy ◽

Imaging Features ◽

Central Brain ◽

Flow Void ◽

Competing Interest ◽

Magnetic Resonance Imaging Mri

IntroductionNormal 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.ResultsThe 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.ConclusionsCorrect 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 interestThe authors have not supplied their declaration of competing interest.

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Flow Void of Cerebrospinal Fluid in Idiopathic Normal Pressure Hydrocephalus of the Elderly: Can It Predict Outcome after Shunting?

Neurosurgery ◽

10.1097/00006123-199701000-00015 ◽

1997 ◽

Vol 40 (1) ◽

pp. 67-74 ◽

Cited By ~ 10

Author(s):

Joachim K. Krauss ◽

Jens P. Regel ◽

Werner Vach ◽

Freimut D. J??ngling ◽

Dirk W. Droste ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Normal Pressure Hydrocephalus ◽

Normal Pressure ◽

The Elderly ◽

Idiopathic Normal Pressure Hydrocephalus ◽

Flow Void

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Cine-MR Imaging of Aqueductal CSF Flow in Normal Pressure Hydrocephalus Syndrome before and after CSF Shunt

Acta Radiologica ◽

10.1177/028418519303400612 ◽

1993 ◽

Vol 34 (6) ◽

pp. 586-592 ◽

Cited By ~ 18

Author(s):

M. Mascalchi ◽

G. Arnetoli ◽

D. Inzitari ◽

G. Dal Pozzo ◽

F. Lolli ◽

...

Keyword(s):

Normal Pressure Hydrocephalus ◽

Normal Pressure ◽

Csf Shunt ◽

Communicating Hydrocephalus ◽

Csf Flow ◽

Cine Mr ◽

Csf Shunting ◽

Before And After ◽

Flow Void ◽

Central Flow

Reproducibility of the aqueductal CSF signal intensity on a gradient echo cine-MR sequence exploiting through plane inflow enhancement was tested in 11 patients with normal or dilated ventricles. Seven patients with normal pressure hydrocephalus (NPH) syndrome were investigated with the sequence before and after CSF shunting. Two patients exhibiting central flow void within a hyperintense aqueductal CSF improved after surgery and the flow void disappeared after shunting. One patient with increased maximum and minimum aqueductal CSF signal as compared to 18 healthy controls also improved and the aqueductal CSF signal was considerably decreased after shunting. Three patients with aqueductal CSF values similar to those in the controls did not improve, notwithstanding their maximum aqueductal CSF signals decreasing slightly after shunting. No appreciable aqueductal CSF flow related enhancement consistent with non-communicating hydrocephalus was found in the last NPH patient who improved after surgery. Cine-MR with inflow technique yields a reproducible evaluation of flow-related aqueductal CSF signal changes which might help in identifying shunt responsive NPH patients. These are likely to be those with hyperdynamic aqueductal CSF or aqueductal obstruction.

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