Four decades of normal pressure hydrocephalus: are we doing better?
© The Author(s) 2004
Published: 23 December 2004
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.
First paper to mention about clinical symptoms and signs of NPH
Adams et al.
Simple Constant-infusion manometric test for measurement of CSF absorption
Katzman and Hassey
Characters of dementia
Albert et al.
CT scan and ICP monitoring in hydrocephalus with dementia
Crocard et al.
CSF fluid tap test
Wikkelso et al.
Conductance to outflow of CSF in normal pressure hydrocephalus
Borgesen et al.
CSF drainage test (120–500 ml for 5 days)
Improvement in neuropsychological tests was observed in patients with a Cout of <0.051
Thomsen et al.
Cerebral blood flow in NPH
Mamo et al.
Phosphorus MR spectra in NPH – reversible periventricular acidosis
Arnold et al.
External ventricular drain of 300 ml CSF for 5 days
Haan et al.
Third ventriculostomy in the treatment of NPH (microsurgical)
Magnaes et al.
Resistance to CSF outflow in prediction of outcome after shunting
Delwel et al.
High resolution SPECT in NPH before and after shunting
Waldemar et al.
MR CSF flow studies in NPH
Bradley et al.
CANTAB – Neuropsychological application in NPH
Iddon et al.
Enlarged ventricles; periventricular hypodensities; flattened cortical sulci; small or absent perihippocampal fissure
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 in the ventricles remains static > 72 hours
with no distribution over the convexities
Removal of CSF
External lumbar drain, lumbar puncture, external ventricular drain
Increase in number, peak and pulse pressure beta waves
Sr Alpha-1 antichymotripsin, Tau proteins, Sulfatides, neurofilament protein & GFAP, Myelin based protein, TNF-alpha, Lipocalin-type PG-D synthase, galanin
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.
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