Volume 1 Supplement 1

48th Annual Meeting of the Society for Research into Hydrocephalus and Spina Bifida

Open Access

Four decades of normal pressure hydrocephalus: are we doing better?

Cerebrospinal Fluid Research20041(Suppl 1):S61

DOI: 10.1186/1743-8454-1-S1-S61

Published: 23 December 2004

Background

In the UK it is estimated that about 5% patients with dementia above the age of 60 suffer from Normal pressure hydrocephalus (NPH). This 5% could represent up to 24,000 people who may be suitable for assessment for treatment. Awareness of this condition is constantly rising both among doctors and patients. A recognised difficulty is the confirmation of the diagnosis and selection of those patients who will benefit from treatment. Despite emerging knowledge of over 40 years, the results of patient selection and shunt insertion have not improved significantly.

Since the historic paper by Hakim and Adams in 1965, a great deal of further research has accumulated. Patients are currently classified into those whose NPH has a known cause and an idiopathic group (INPH). Table 1 highlights the key research findings so far.

Table 1:

1965

First paper to mention about clinical symptoms and signs of NPH

Adams et al.

1960's

Isotope Scintigraphy

-

1970

Simple Constant-infusion manometric test for measurement of CSF absorption

Katzman and Hassey

1974

Characters of dementia

Albert et al.

1977

CT scan and ICP monitoring in hydrocephalus with dementia

Crocard et al.

1982

CSF fluid tap test

Wikkelso et al.

1982

Conductance to outflow of CSF in normal pressure hydrocephalus

Borgesen et al.

1986

CSF drainage test (120–500 ml for 5 days)

Dilauro

1986

Improvement in neuropsychological tests was observed in patients with a Cout of <0.051

Thomsen et al.

1987

Cerebral blood flow in NPH

Mamo et al.

1988

Phosphorus MR spectra in NPH – reversible periventricular acidosis

Arnold et al.

1988

External ventricular drain of 300 ml CSF for 5 days

Haan et al.

1989

Third ventriculostomy in the treatment of NPH (microsurgical)

Magnaes et al.

1993

Resistance to CSF outflow in prediction of outcome after shunting

Delwel et al.

1993

High resolution SPECT in NPH before and after shunting

Waldemar et al.

1996

MR CSF flow studies in NPH

Bradley et al.

1999

CANTAB – Neuropsychological application in NPH

Iddon et al.

Patient Selection

No single test is predictive to determine the shunt responders. Over the years several combinations of tests have been used to predict those who will respond to a shunt operation. Surgery is believed to benefit 50–70% of patients where there is a known cause, and 30–50% where the cause is idiopathic if identified correctly. It is equally important to identify patients unlikely to benefit. Shunting, particularly in elderly patients, is associated with a significant incidence of both acute and cumulative longer-term complication. Only a few papers report the extended follow-up of patients and the value of the predicting factors in the long term. A guide to some of the tests and predictive feature identified in the literature is summarised in Table 2.

Table 2:

CT

Enlarged ventricles; periventricular hypodensities; flattened cortical sulci; small or absent perihippocampal fissure

MRI

All of the above; especially small or absent perihippocampal fissure

Cerebral blood flow

Reduction in frontal lobe BF, global reduction in cerebral metabolism, perventricular decreased BF, basal ganglia and thalamus reduced BF (Transcranial Doppler, SPECT)

Isotope

Isotope in the ventricles remains static > 72 hours

Cisternography/ MRI

with no distribution over the convexities

Removal of CSF

External lumbar drain, lumbar puncture, external ventricular drain

ICP monitoring

Increase in number, peak and pulse pressure beta waves

CSF markers

Sr Alpha-1 antichymotripsin, Tau proteins, Sulfatides, neurofilament protein & GFAP, Myelin based protein, TNF-alpha, Lipocalin-type PG-D synthase, galanin

Conclusion

Few studies have examined the long-term prognosis for those with treated and untreated NPH. Indeed, the recent Cochrane review (2002) indicated that shunt insertion was ineffective in treating NPH but this may be due to inappropriate comparison groups and lack of class 1 evidence. Tests revolving around CSF lumbar puncture, lumbar tap and drainage have been the main stay of assessing likelihood to respond to treatment. But, how reliable is this in predicting outcome? Since the disease is complex and there may not be a gold standard test to predict shunt response, future efforts should be directed towards better identification of the pathogenesis of idiopathic NPH.

Many CSF factors have been identify that can diagnose the disease and predict outcome. MR CSF flow studies can predict shunt responders and PET scans have been used to detect peri-ventricular blood flow improvement post shunt. Non-invasive methods of investigation and prediction of outcome is being increasingly recognised. Treatment has been challenged with ventriculostomy. Thus, it is clear that further work needs to be conducted to ascertain the best way of diagnosing patients likely to benefit from surgery.

Authors’ Affiliations

(1)
Royal Preston Hospital and University of Central Lancashire

Copyright

© The Author(s) 2004

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Advertisement