Prevalence of idiopathic normal pressure hydrocephalus: A prospective, population-based study

Shunting for idiopathic normal pressure hydrocephalus

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To determine the effect of cerebrospinal fluid (CSF) shunting versus no CSF shunting in people with idiopathic normal pressure hydrocephalus (iNPH).

To determine the frequency of adverse effects of CSF shunting in iNPH

Cerebrospinal fluid biomarkers and genetic factors associated with normal pressure hydrocephalus and Alzheimer’s disease: a narrative review

Background

Normal pressure hydrocephalus is a neurologic disease leading to enlargement of ventricles which is presented with gait and balance disturbance, cognitive decline, and urinary incontinence. Diagnosis of normal pressure hydrocephalus is challenging due to the late onset of signs and symptoms. In this review, we summarize the cerebrospinal fluid, plasma, pathology, and genetic biomarkers of normal pressure hydrocephalus and related disorders.

Body

Recently, cerebrospinal fluid and serum biomarkers analysis alongside gene analysis has received a lot of attention. Interpreting a set of serum and cerebrospinal fluid biomarkers along with genetic testing for candidate genes could differentiate NPH from other neurological diseases such as Alzheimer's disease, Parkinson's disease with dementia, and other types of dementia.

Conclusion

Better understanding the pathophysiology of normal pressure hydrocephalus through genetic studies can aid in evolving preventative measures and the early treatment of normal pressure hydrocephalus patients.

Cerebrospinal fluid and venous biomarkers of shunt-responsive idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease and dementia subtype involving disturbed cerebrospinal fluid (CSF) homeostasis. Patients with iNPH may improve clinically following CSF diversion through shunt surgery, but it remains a challenge to predict which patients respond to shunting. It has been proposed that CSF and blood biomarkers may be used to predict shunt response in iNPH.

OBJECTIVE

To conduct a systematic review and meta-analysis to identify which CSF and venous biomarkers predict shunt-responsive iNPH most accurately.

METHODS

Original studies that investigate the use of CSF and venous biomarkers to predict shunt response were searched using the following databases: Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR. Included studies were assessed using the ROBINS-I tool, and eligible studies were evaluated utilising univariate meta-analyses.

RESULTS

The study included 13 studies; seven addressed lumbar CSF levels of amyloid-β 1-42, nine studies CSF levels of Total-Tau, six studies CSF levels of Phosphorylated-Tau, and seven studies miscellaneous biomarkers, proteomics, and genotyping. A meta-analysis of six eligible studies conducted for amyloid-β 1-42, Total-Tau, and Phosphorylated-Tau demonstrated significantly increased lumbar CSF Phosphorylated-Tau (- 0.55 SMD, p = 0.04) and Total-Tau (- 0.50 SMD, p = 0.02) in shunt-non-responsive iNPH, though no differences were seen between shunt responders and non-responders for amyloid-β 1-42 (- 0.26 SMD, p = 0.55) or the other included biomarkers.

CONCLUSION

This meta-analysis found that lumbar CSF levels of Phosphorylated-Tau and Total-Tau are significantly increased in shunt non-responsive iNPH compared to shunt-responsive iNPH. The other biomarkers, including amyloid-β 1-42, did not significantly differentiate shunt-responsive from shunt-non-responsive iNPH. More studies on the Tau proteins examining sensitivity and specificity at different cut-off levels are needed for a robust analysis of the diagnostic efficiency of the Tau proteins.

Waiting time for surgery influences the outcome in idiopathic normal pressure hydrocephalus - a population-based study

INTRODUCTION

Idiopathic normal pressure hydrocephalus (iNPH) is a disease that comes with a great impact on the patient's life. The only treatment for iNPH, which is a progressive disease, is shunt surgery. It is previously indicated that early intervention might be of importance for the outcome.

AIM

To investigate if a longer waiting time for surgery, negatively influences the clinical outcome.

METHODS

Eligible for this study were all iNPH patients (n = 3007) registered in the Swedish Hydrocephalus Quality Registry (SHQR) during 1^st of January 2004-12^th of June 2019. Waiting time, defined as time between the decision to accept a patient for surgery and shunt surgery, was divided into the intervals ≤ 3, 3.1-5.9 and ≥ 6 months. Clinical outcome was assessed 3 and 12 months after surgery using the modified iNPH scale, the Timed Up and Go (TUG) test and the mini mental state examination (MMSE).

RESULTS

Three months after surgery, 57% of the patients with ≤ 3 months waiting time showed an improvement in modified iNPH scale (≥ 5 points) whereas 52% and 46% of patients with 3.1-5.9 and ≥ 6 months waiting time respectively improved (p = 0.0115). At 12 months of follow-up, the corresponding numbers were 61%, 52% and 51% respectively (p = 0.0536).

CONCLUSIONS

This population-based study showed that in patients with iNPH, shunt surgery should be performed within 3 months of decision to surgery, to attain the best outcome.

Prediction of Shunt Responsiveness in Suspected Patients With Normal Pressure Hydrocephalus Using the Lumbar Infusion Test: A Machine Learning Approach

BACKGROUND

Machine learning (ML) approaches can significantly improve the classical Rout-based evaluation of the lumbar infusion test (LIT) and the clinical management of the normal pressure hydrocephalus.

OBJECTIVE

To develop a ML model that accurately identifies patients as candidates for permanent cerebral spinal fluid shunt implantation using only intracranial pressure and electrocardiogram signals recorded throughout LIT.

METHODS

This was a single-center cohort study of prospectively collected data of 96 patients who underwent LIT and 5-day external lumbar cerebral spinal fluid drainage (external lumbar drainage) as a reference diagnostic method. A set of selected 48 intracranial pressure/electrocardiogram complex signal waveform features describing nonlinear behavior, wavelet transform spectral signatures, or recurrent map patterns were calculated for each patient. After applying a leave-one-out cross-validation training-testing split of the data set, we trained and evaluated the performance of various state-of-the-art ML algorithms.

RESULTS

The highest performing ML algorithm was the eXtreme Gradient Boosting. This model showed a good calibration and discrimination on the testing data, with an area under the receiver operating characteristic curve of 0.891 (accuracy: 82.3%, sensitivity: 86.1%, and specificity: 73.9%) obtained for 8 selected features. Our ML model clearly outperforms the classical Rout-based manual classification commonly used in clinical practice with an accuracy of 62.5%.

CONCLUSION

This study successfully used the ML approach to predict the outcome of a 5-day external lumbar drainage and hence which patients are likely to benefit from permanent shunt implantation. Our automated ML model thus enhances the diagnostic utility of LIT in management.

Application of Evans Index in Normal Pressure Hydrocephalus Patients: A Mini Review

With an ever-growing aging population, the prevalence of normal pressure hydrocephalus (NPH) is increasing. Clinical symptoms of NPH include cognitive impairment, gait disturbance, and urinary incontinence. Surgery can improve symptoms, which leads to the disease's alternative name: treatable dementia. The Evans index (EI), defined as the ratio of the maximal width of the frontal horns to the maximum inner skull diameter, is the most commonly used index to indirectly assess the condition of the ventricles in NPH patients. EI measurement is simple, fast, and does not require any special software; in clinical practice, an EI >0.3 is the criterion for ventricular enlargement. However, EI's measurement methods, threshold setting, correlation with ventricle volume, and even its clinical value has been questioned. Based on the EI, the z-EI and anteroposterior diameter of the lateral ventricle index were derived and are discussed in this review.

The timed up and go test in idiopathic normal pressure hydrocephalus: a Nationwide Study of 1300 patients

BACKGROUND

The aim of this study was to describe the outcome measure timed up and go (TUG) in a large, nationwide cohort of patients with idiopathic normal pressure hydrocephalus (iNPH) pre- and post-operatively. Furthermore, to compare the TUG test to the 10-m walk test (10MWT), the iNPH scale, the modified Rankin scale (mRS) and the Mini Mental State Examination (MMSE), which are commonly applied in clinical assessment of iNPH.

METHODS

Patients with iNPH (n = 1300), registered in the Swedish Hydrocephalus Quality Registry (SHQR), were included. All data were retrieved from the SHQR except the 10MWT, which was collected from patient medical records. Clinical scales were examined pre- and 3 months post-operatively. Data were dichotomised by sex, age, and preoperative TUG time.

RESULTS

Preoperative TUG values were 19.0 [14.0-26.0] s (median [IQR]) and 23 [18-30] steps. Post-operatively, significant improvements to 14.0 [11.0-20.0] s and 19 [15-25] steps were seen. TUG time and steps were higher in women compared to men (p < 0.001) but there was no sex difference in improvement rate. Worse preoperative TUG and younger age favoured improvement. TUG was highly correlated to the 10MWT, but correlations of post-operative changes were only low to moderate between all scales (r = 0.22-0.61).

CONCLUSIONS

This study establishes the distribution of TUG in iNPH patients and shows that the test captures important clinical features that improve after surgery independent of sex and in all age groups, confirming the clinical value of the TUG test. TUG performance is associated with performance on the 10MWT pre- and post-operatively. However, the weak correlations in post-operative change to the 10MWT and other established outcome measures indicate an additional value of TUG when assessing the effects of shunt surgery.

Idiopathic normal pressure hydrocephalus; treatment and outcome in the Region of Southern Denmark

OBJECTIVE

Idiopathic normal pressure hydrocephalus (iNPH) is a prevalent and cost-effective disease to treat. However, no gold standard exists to confidently select patients for shunt surgery. The aim of this study was to investigate how patients with suspected iNPH at our center responded to shunt surgery and to compare pre-surgical variables between shunt responders and non-responders.

METHODS

Preoperative baseline characteristics, MRI and/or CT scans were retrospectively obtained in 55 shunt-operated iNPH patients. Evan's index, third ventricle diameter, dilation of Sylvian fissures, tight high convexity, focal sulci, callosal angle, Rout value, MMSE score, CSF phosphorylated tau, CSF tau, and a combination of radiologic findings (DESH score) were compared according to whether or not patients expressed satisfactory response to shunt treatment at 1-month follow-up.

RESULTS

Multiple logistic regression controlling for age and gender (α = 0.05) showed that tight high convexity, dilated Sylvian fissures, focal sulci, CSF tau, CSF phosphorylated tau, and DESH score correlated significantly with subjective shunt response at 1-month follow-up.

CONCLUSION

In line with current literature, Shunt responders had lower levels of CSF tau and CSF phosphorylated tau compared to non-responders. While commonly used radiologic markers are of value, they can be aggregated into a score for better selection of shunt candidates.

A clinical primer for the glymphatic system

The complex and dynamic system of fluid flow through the perivascular and interstitial spaces of the central nervous system has new-found implications for neurological diseases. Cerebrospinal fluid movement throughout the CNS parenchyma is more dynamic than could be explained via passive diffusion mechanisms alone. Indeed, a semi-structured glial-lymphatic (glymphatic) system of astrocyte-supported extracellular perivascular channels serves to directionally channel extracellular fluid, clearing metabolites and peptides to optimize neurologic function. Clinical studies of the glymphatic network has to date proven challenging, with most data gleaned from rodent models and post-mortem investigations. However, increasing evidence suggests that disordered glymphatic function contributes to the pathophysiology of CNS aging, neurodegenerative disease, and CNS injuries, as well as normal pressure hydrocephalus. Unlocking such pathophysiology could provide important avenues toward novel therapeutics. We here provide a multidisciplinary overview of glymphatics and critically review accumulating evidence regarding its structure, function, and hypothesized relevance to neurological disease. We highlight emerging technologies of relevance to the longitudinal evaluation of glymphatic function in health and disease. Finally, we discuss the translational opportunities and challenges of studying glymphatic science.

Comparison of comfortable and maximum walking speed in the 10-meter walk test during the cerebrospinal fluid tap test in iNPH patients: A retrospective study

BACKGROUND

The 10-meter walking test (10 MWT) is widely used during a cerebrospinal fluid tap test (CSFTT) for idiopathic normal-pressure hydrocephalus (iNPH). However, various previous studies and guidelines do not specify whether to adopt a comfortable walking speed or maximum walking speed when implementing the 10 MWT. In this study, we analyzed the values of comfortable and maximum walking speeds during the CSFTT in patients who underwent shunt surgery to determine which walking form is desirable for evaluation.

METHODS

The patients were 29 consecutive cases in which a CSFTT was performed, followed by shunting, between October 2012 and April 2019. Data on the 10 MWT comfortable walking speed and maximum walking speed were collected, as were data on the timed up and go (TUG) test and Mini-Mental State Examination (MMSE). We analyzed the rate of change in comfortable walking speed and maximum walking speed before CSFTT and on the first day after CSFTT, and the amount of improvement compared to baseline ability. In addition, diagnostic performance was compared using a receiver operating characteristic (ROC) analysis.

RESULTS

Twenty-eight patients who underwent shunt surgery improved their symptoms and were designated as shunt responders. The remaining patient who underwent surgery was considered a non-responder with no improvement in symptoms. The parameters of the shunt responders that changed were muscle strength, the 10 MWT, and the TUG test, and there was no significant change in cognitive function. The rate of change, amount of change, and sensitivity were large at a comfortable walking speed, but ROC analysis showed that the maximum walking speed had a large area under the curve and excellent specificity. The higher the preoperative gait function, the lower the improvement rate of gait function.

DISCUSSION

The comfortable walking speed is easy to measure, but its specificity is inferior to the maximum walking speed. However, the maximum walking speed may be affected by the ceiling effect and measurement errors. Despite this, we concluded that the maximum walking speed had a better diagnostic performance. Because the causes of gait disturbance in iNPH include decreased muscle output, postural instability, and gait rhythm disorder, and maximum walking speed is strongly related to each of these factors, this accounts for the changes in maximum walking speed.

CONCLUSION

In conclusion, although comfortable walking speed was easy to measure in terms of changes and had high sensitivity, the maximum walking speed had the highest specificity and comprehensive diagnostic performance. It is recommended that maximum walking speed be evaluated when making a definitive diagnosis of iNPH.

Elevated CSF inflammatory markers in patients with idiopathic normal pressure hydrocephalus do not promote NKCC1 hyperactivity in rat choroid plexus

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a potentially reversible neurological condition of unresolved etiology characterized by a clinical triad of symptoms; gait disturbances, urinary incontinence, and cognitive deterioration. In the present study, we aimed to elucidate the molecular coupling between inflammatory markers and development of iNPH and determine whether inflammation-induced hyperactivity of the choroidal Na⁺/K⁺/2Cl^- cotransporter (NKCC1) that is involved in cerebrospinal fluid (CSF) secretion could contribute to the iNPH pathogenesis.

METHODS

Lumbar CSF samples from 20 iNPH patients (10 with clinical improvement upon CSF shunting, 10 without clinical improvement) and 20 elderly control subjects were analyzed with the novel proximity extension assay technique for presence of 92 different inflammatory markers. RNA-sequencing was employed to delineate choroidal abundance of the receptors for the inflammatory markers found elevated in the CSF from iNPH patients. The ability of the elevated inflammatory markers to modulate choroidal NKCC1 activity was determined by addition of combinations of rat version of these in ex vivo experiments on rat choroid plexus.

RESULTS

11 inflammatory markers were significantly elevated in the CSF from iNPH patients compared to elderly control subjects: CCL28, CCL23, CCL3, OPG, CXCL1, IL-18, IL-8, OSM, 4E-BP1, CXCL6, and Flt3L. One inflammatory marker, CDCP1, was significantly decreased in iNPH patients compared to control subjects. None of the inflammatory markers differed significantly when comparing iNPH patients with and without clinical improvement upon CSF shunting. All receptors for the elevated inflammatory markers were expressed in the rat and human choroid plexus, except CCR4 and CXCR1, which were absent from the rat choroid plexus. None of the elevated inflammatory markers found in the CSF from iNPH patients modulated the choroidal NKCC1 activity in ex vivo experiments on rat choroid plexus.

CONCLUSION

The CSF from iNPH patients contains elevated levels of a subset of inflammatory markers. Although the corresponding inflammatory receptors are, in general, expressed in the choroid plexus of rats and humans, their activation did not modulate the NKCC1-mediated fraction of choroidal CSF secretion ex vivo. The molecular mechanisms underlying ventriculomegaly in iNPH, and the possible connection to inflammation, therefore remains to be elucidated.

Changes in Ventricular and Cortical Volumes following Shunt Placement in Patients with Idiopathic Normal Pressure Hydrocephalus

BACKGROUND AND PURPOSE

While changes in ventricular and extraventricular CSF spaces have been studied following shunt placement in patients with idiopathic normal pressure hydrocephalus, regional changes in cortical volumes have not. These changes are important to better inform disease pathophysiology and evaluation for copathology. The purpose of this work is to investigate changes in ventricular and cortical volumes in patients with idiopathic normal pressure hydrocephalus following ventriculoperitoneal shunt placement.

MATERIALS AND METHODS

This is a retrospective cohort study of patients with idiopathic normal pressure hydrocephalus who underwent 3D T1-weighted MR imaging before and after ventriculoperitoneal shunt placement. Images were analyzed using tensor-based morphometry with symmetric normalization to determine the percentage change in ventricular and regional cortical volumes. Ventricular volume changes were assessed using the Wilcoxon signed rank test, and cortical volume changes, using a linear mixed-effects model (P < .05).

RESULTS

The study included 22 patients (5 women/17 men; mean age, 73 [SD, 6] years). Ventricular volume decreased after shunt placement with a mean change of -15.4% (P < .001). Measured cortical volume across all participants and cortical ROIs showed a mean percentage increase of 1.4% (P < .001). ROIs near the vertex showed the greatest percentage increase in volume after shunt placement, with smaller decreases in volume in the medial temporal lobes.

CONCLUSIONS

Overall, cortical volumes mildly increased after shunt placement in patients with idiopathic normal pressure hydrocephalus with the greatest increases in regions near the vertex, indicating postshunt decompression of the cortex and sulci. Ventricular volumes showed an expected decrease after shunt placement.

The First Examination of Diagnostic Performance of Automated Measurement of the Callosal Angle in 1856 Elderly Patients and Volunteers Indicates That 12.4% of Exams Met the Criteria for Possible Normal Pressure Hydrocephalus

BACKGROUND AND PURPOSE

Many patients with dementia may have comorbid or misdiagnosed normal pressure hydrocephalus, a treatable neurologic disorder. The callosal angle is a validated biomarker for normal pressure hydrocephalus with 93% diagnostic accuracy. Our purpose was to develop and evaluate an algorithm for automatically computing callosal angles from MR images of the brain.

MATERIALS AND METHODS

This article reports the results of analyzing callosal angles from 1856 subjects with 5264 MR images from the Open Access Series of Imaging Studies and the Alzheimer's Disease Neuroimaging Initiative databases. Measurement variability was examined between 2 neuroradiologists (n = 50) and between manual and automatic measurements (n = 281); from differences in simulated head orientation; and from real-world changes in patients with multiple examinations (n = 906). We evaluated the effectiveness of the automatic callosal angle to differentiate normal pressure hydrocephalus from Alzheimer disease in a simulated cohort.

RESULTS

The algorithm identified that 12.4% of subjects from these carefully screened cohorts had callosal angles of <90°, a published threshold for possible normal pressure hydrocephalus. The intraclass correlation coefficient was 0.97 for agreement between neuroradiologists and 0.90 for agreement between manual and automatic measurement. The method was robust to different head orientations. The median coefficient of variation for repeat examinations was 4.2% (Q1 = 3.1%, Q3 = 5.8%). The simulated classification of normal pressure hydrocephalus versus Alzheimer using the automatic callosal angle had an accuracy, sensitivity, and specificity of 0.87 each.

CONCLUSIONS

In even the most pristine research databases, analyses of the callosal angle indicate that some patients may have normal pressure hydrocephalus. The automatic callosal angle measurement can rapidly and objectively screen for normal pressure hydrocephalus in patients who would otherwise be misdiagnosed.

Evaluation of aquaporins in the cerebrospinal fluid in patients with idiopathic normal pressure hydrocephalus

Brain aquaporin 1 (AQP1) and AQP4 are involved in cerebrospinal fluid (CSF) homeostasis and might participate in the origin of hydrocephalus. Studies have shown alterations of perivascular AQP4 expression in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD). Due to the overlapping of clinical signs between iNPH and certain neurological conditions, mainly AD, specific biomarkers might improve the diagnostic accuracy for iNPH. The goal of the present study was to analyze and quantify the presence of AQP1 and AQP4 in the CSF of patients with iNPH and AD to determine whether these proteins can be used as biomarkers of iNPH. We examined AQP1 and AQP4 protein levels in the CSF of 179 participants (88 women) classified into 5 groups: possible iNPH (81 participants), hydrocephalus associated with other neurological disorders (13 participants), AD (41 participants), non-AD dementia (32 participants) and healthy controls (12 participants). We recorded each participant's demographic and clinical variables and indicated, when available in the clinical history, the record of cardiovascular and respiratory complications. An ELISA showed virtually no AQP content in the CSF. Information on the vascular risk factors (available for 61 patients) confirmed some type of vascular risk factor in 86% of the patients with possible iNPH and 58% of the patients with AD. In conclusion, the ELISA analysis showed insufficient sensitivity to detect the presence of AQP1 and AQP4 in CSF, ruling out the possible use of these proteins as biomarkers for diagnosing iNPH.

Imaging features associated with idiopathic normal pressure hydrocephalus have high specificity even when comparing with vascular dementia and atypical parkinsonism

Background

Vascular dementia (VaD) and atypical parkinsonism often present with symptoms that can resemble idiopathic normal pressure hydrocephalus (iNPH) and enlarged cerebral ventricles, and can be challenging differential diagnoses. The aim was to investigate frequencies of imaging features usually associated with iNPH and their radiological diagnostic accuracy in a sample containing the relevant differential diagnoses VaD, progressive supranuclear palsy (PSP), multiple system atrophy parkinsonian type (MSA-P), and healthy controls.

Methods

Nine morphological imaging features usually associated with iNPH were retrospectively investigated in MR images of 55 patients with shunt-responsive iNPH, 32 patients with VaD, 30 patients with PSP, 27 patients with MSA-P, and 39 age-matched healthy controls. Logistic regression and receiver operating characteristic curves were used to assess diagnostic accuracy, sensitivity, and specificity for each imaging finding.

Results

In a logistic regression model using iNPH diagnosis as a dependent variable, the following imaging features contributed significantly to the model: callosal angle (OR = 0.95 (0.92–0.99), p = 0.012), Evans’ index * 100 (OR = 1.51 (1.23–1.86), p < 0.001), enlarged Sylvian fissures (OR = 6.01 (1.42–25.40), p = 0.015), and focally enlarged sulci (OR = 10.18 (1.89–55.02), p = 0.007). Imaging features with 95% specificity for iNPH were: callosal angle ≤ 71°, temporal horns ≥ 7 mm, Evans’ index ≥ 0.37, iNPH Radscale ≥ 9, and presence of DESH, bilateral ventricular roof bulgings or focally enlarged sulci. A simplified version of the iNPH Radscale with only four features resulted in equally high diagnostic accuracy as the original iNPH Radscale.

Conclusions

There is a notable overlap between some of the commonly used imaging markers regarding iNPH, VaD and atypical parkinsonism, such as PSP. However, this study shows that the specificity of imaging markers usually associated with iNPH was high even when comparing with these challenging differential diagnoses. The callosal angle was the single imaging feature with highest diagnostic accuracy to discriminate iNPH from its mimics. A simplified rating scale using only a few selected features could be used with retained specificity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00270-3.

When to Assess: Cognitive Impact of Ventriculoperitoneal Shunt Operation in Elderly Adults with Normal Pressure Hydrocephalus

OBJECTIVE

Normal pressure hydrocephalus (NPH) has clinical manifestations with different cognitive difficulties. Despite the intense interest, the change in cognitive functions after ventriculoperitoneal shunt (VPS) treatment varies widely. The aims of this study were to monitor the effect of NPH on cognition in elderly and the progress of cognitive abilities after VPS surgery.

METHODS

Patients diagnosed with idiopathic NPH (iNPH) who had ventriculomegaly with narrow callosal angle and/or periventricular signal changes not attributable to ischemic changes were included in study. All patients (n = 30) underwent comprehensive neuropsychological assessment and received programmable VPS. After VPS placement, 2 consecutive examinations were performed at approximately 6-month intervals.

RESULTS

At the baseline evaluation, patients with iNPH displayed poorer performance in executive functions (EFs) compared with the matched control group (n = 30). Among those patients, significant improvement was observed in semantic fluency (M = 13.94; standard deviation, 4.95) and clock drawing (M = 3.67; standard deviation, 1.57) at the second follow-up evaluation (P = 0.015 and P = 0.024, respectively). The other prominent finding was in memory process: patients with iNPH showed improvement in delayed recall (P = 0.011), recognition (P = 0.033), and learning scores (P = 0.041) at the second follow-up compared with evaluation before VPS placement.

CONCLUSIONS

iNPH seems to have a detrimental effect predominantly on EFs. As EFs become corrupted, decline occurs in learning and recall processes of memory. VPS provides an improvement of cognitive deterioration; however, efficacy of this treatment on cognitive abilities is shows in a longer period compared with other iNPH symptoms.

Screening for idiopathic normal pressure hydrocephalus in the elderly after falls

OBJECTIVE

Many patients with idiopathic normal pressure hydrocephalus (iNPH) have reportedly fallen prior to diagnosis. However, there are no previous reports on the iNPH prevalence among the elderly with history of falls. This study investigated the effectiveness of screening for iNPH in elderly patients presenting after a fall.

METHODS

We retrospectively assessed the Evans' index (EI) of 235 consecutive patients aged 60-89 who presented after falls between May and October 2020. We also assessed the presence of the iNPH triad (gait disturbance, cognitive impairment, and urinary incontinence). Patients with EI > 0.3 and with all 3 triad were defined as having possible iNPH; those with clinical improvement after a cerebrospinal fluid (CSF) tap test as having probable iNPH; and those with clinical improvement after a shunt surgery as having definite iNPH. We also examined the 235 patients' EI, and performed a case-control study of EI using sex- and age-matched control patients.

RESULTS

Among the included 235 cases presenting after falls, 44 (18.7%) were diagnosed with possible iNPH, 29 (12.3%) with probable iNPH, and 25 (10.6%) with definite iNPH. The mean EI of these 235 patients was significantly larger than that of controls (0.30 ± 0.04 vs 0.26 ± 0.02, p < 0.0001). The proportion of possible iNPH in the cases was 44 out of 235 (18.7%), significantly higher than that of the controls (0%, p < 0.0001).

CONCLUSION

Screening for iNPH in the elderly presenting after falls can possibly identify iNPH patients in the earlier stage who may benefit more from surgical treatments.

The role of diffusion tensor imaging in idiopathic normal pressure hydrocephalus: A literature review

Idiopathic normal pressure hydrocephalus (iNPH) is a syndrome that comprises a triad of gait disturbance, dementia and urinary incontinence, associated with ventriculomegaly in the absence of elevated intraventricular cerebrospinal fluid (CSF) pressure. It is important to identify patients with iNPH because some of its clinical features may be reversed by the insertion of a CSF shunt. The diagnosis is based on clinical history, physical examination and brain imaging, especially magnetic resonance imaging (MRI). Recently, some papers have investigated the role of diffusion tensor imaging (DTI) in evaluating white matter alterations in patients with iNPH. DTI analysis in specific anatomical regions seems to be a promising MR biomarker of iNPH and could also be used in the differential diagnosis from other dementias. However, there is a substantial lack of structured reviews on this topic. Thus, we performed a literature search and analyzed the most recent and pivotal articles that investigated the role of DTI in iNPH in order to provide an up-to-date overview of the application of DTI in this setting. We reviewed studies published between January 2000 and June 2020. Thirty-eight studies and four reviews were included. Despite heterogeneity in analysis approaches, the majority of studies reported significant correlations between DTI and clinical symptoms in iNPH patients, as well as different DTI patterns in patients with iNPH compared to those with Alzheimer or Parkinson diseases. It remains to be determined whether DTI could predict the success after CSF shunting.

Feasibility of action observation effect on gait and mobility in idiopathic normal pressure hydrocephalus patients

Action observation (AO) has been proved to be of benefit in several neurological conditions, but no study has previously been conducted in idiopathic normal pressure hydrocephalus (iNPH).

Deficient visuomotor hand coordination in normal pressure hydrocephalus

Objective

To investigate if visuomotor coordination of hand movements is impaired in patients with normal pressure hydrocephalus (NPH) identified by dedicated testing procedures.

Methods

Forty-seven patients admitted for diagnostic workup for suspected NPH were studied prospectively with MRI, testing of cognitive and motor functions, lumbar puncture, and visuomotor coordination of hand movements using the PABLO^R-device before and after a spinal tap of 40–50 ml CSF. Statistical analyses were carried out with repeated measures ANOVA and non-parametric correlation analyses.

Results

Fourteen patients were found to suffer from ideopathic NPH. They were severely impaired in visuomotor control of intermittent arm movements in comparison to patients who were found not to be affected by NPH (n = 18). In the patients with NPH the deficient arm control was improved after the spinal tap in proportion to the improvement of gait. There was no improvement of cognitive and motor functions in the patients not affected by NPH, while the patients with possible NPH (n = 15) showed intermediate deficit and improvement patterns.

Interpretation: Our data underline the importance of a multiparametric assessment of NPH and provide evidence for a motor control deficit in idiopathic NPH involving leg and arm movements. It is suggested that this motor control deficit resulted from an affection of the output tracts from the supplementary motor area in the periventricular vicinity.

Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus (Third Edition): Endorsed by the Japanese Society of Normal Pressure Hydrocephalus

Among the various disorders that manifest with gait disturbance, cognitive impairment, and urinary incontinence in the elderly population, idiopathic normal pressure hydrocephalus (iNPH) is becoming of great importance. The first edition of these guidelines for management of iNPH was published in 2004, and the second edition in 2012, to provide a series of timely, evidence-based recommendations related to iNPH. Since the last edition, clinical awareness of iNPH has risen dramatically, and clinical and basic research efforts on iNPH have increased significantly. This third edition of the guidelines was made to share these ideas with the international community and to promote international research on iNPH. The revision of the guidelines was undertaken by a multidisciplinary expert working group of the Japanese Society of Normal Pressure Hydrocephalus in conjunction with the Japanese Ministry of Health, Labour and Welfare research project. This revision proposes a new classification for NPH. The category of iNPH is clearly distinguished from NPH with congenital/developmental and acquired etiologies. Additionally, the essential role of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) in the imaging diagnosis and decision for further management of iNPH is discussed in this edition. We created an algorithm for diagnosis and decision for shunt management. Diagnosis by biomarkers that distinguish prognosis has been also initiated. Therefore, diagnosis and treatment of iNPH have entered a new phase. We hope that this third edition of the guidelines will help patients, their families, and healthcare professionals involved in treating iNPH.

Long-Term Prognosis of Cognitive Function in Patients With Idiopathic Normal Pressure Hydrocephalus After Shunt Surgery

The long-term prognosis of cognitive function in patients with idiopathic normal pressure hydrocephalus (iNPH) remains unclear. This study aimed to determine the long-term prognosis of cognitive function in patients with iNPH, as well as the factors related to it. It included 48 patients with iNPH who were treated with cerebrospinal fluid shunting between January 2015 and December 2017 at Osaka Medical College Hospital, with follow-up evaluation of their cognitive function for >2 years. Cognitive function was measured using the Mini-Mental State Examination (MMSE) preoperatively and at 3 months, 1 and 2 years post-operatively. The mean MMSE score (22.4 ± 5.4 preoperatively) improved at 3 months [23.8 ± 5.0 (p = 0.0002)] and 1 year [23.7 ± 4.8 (p = 0.004)] post-operatively. At 2 years post-operatively, they were able to maintain their preoperative level (22.6 ± 5.3). The patients were classified in to the cognitive decline group [11 (23%) patients; a decrease in the MMSE score by ≥ 2 points 2 years after surgery] and the maintenance/improvement group [37 (77%) patients]. Univariate and receiver operating characteristic analyses were performed for the two groups to identify factors associated with cognitive prognosis. In both groups, the patients who were younger (p = 0.009) or had milder symptoms (p = 0.035) had a better long-term prognosis of cognitive function. The cutoffs for age and disease severity (idiopathic normal-pressure hydrocephalus grading scale; INPHGS) were 78 years (area under the curve = 0.77) and 5 points (area under the curve = 0.71), respectively. In conclusion, most patients (77%) were able to improve and maintain cognitive function for at least 2 years after surgery. The fact that disease severity and age are associated with cognitive prognosis suggests that early iNPH intervention is desirable to improve cognitive prognosis.

The Pathogenesis Based on the Glymphatic System, Diagnosis, and Treatment of Idiopathic Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a rare neurological disorder with no clear prevalence factors and is a significant danger to the elderly. The intracranial glymphatic system is the internal environment that maintains brain survival and metabolism, and thus fluid exchange changes in the glymphatic system under various pathological conditions can provide important insights into the pathogenesis and differential diagnosis of many neurodegenerative diseases such as iNPH. iNPH can be diagnosed using a combination of clinical symptoms, imaging findings and history, and cerebrospinal fluid biomarkers due to the glymphatic system disorder. However, only few researchers have linked the two. Shunt surgery can improve the glymphatic system disorders in iNPH patients, and the surgical approach is determined using a combination of clinical diagnosis and trials. Therefore, we have composed this review to provide a future opportunity for elucidating the pathogenesis of iNPH based on the glymphatic system, and link the glymphatic system to the diagnosis and treatment of iNPH. The review will provide new insights into the medical research of iNPH.

Pathogenesis and pathophysiology of idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH), the most common type of adult-onset hydrocephalus, is a potentially reversible neuropsychiatric entity characterized by dilated ventricles, cognitive deficit, gait apraxia, and urinary incontinence. Despite its relatively typical imaging features and clinical symptoms, the pathogenesis and pathophysiology of iNPH remain unclear. In this review, we summarize current pathogenetic conceptions of iNPH and its pathophysiological features that lead to neurological deficits. The common consensus is that ventriculomegaly resulting from cerebrospinal fluid (CSF) dynamics could initiate a vicious cycle of neurological damages in iNPH. Pathophysiological factors including hypoperfusion, glymphatic impairment, disturbance of metabolism, astrogliosis, neuroinflammation, and blood-brain barrier disruption jointly cause white matter and gray matter lesions, and eventually lead to various iNPH symptoms. Also, we review the current treatment options and discuss the prospective treatment strategies for iNPH. CSF diversion with ventriculoperitoneal or lumboperitonealshunts remains as the standard therapy, while its complications prompt attempts to refine shunt insertion and develop new therapeutic procedures. Recent progress on advanced biomaterials and improved understanding of pathogenesis offers new avenues to treat iNPH.

Idiopathic normal-pressure hydrocephalus: the cost-effectiveness of delivering timely and adequate treatment in Germany

BACKGROUND AND PURPOSE

Idiopathic normal-pressure hydrocephalus (iNPH) is a progressive, severe brain disorder, which mainly affects people above the age of 65 years. iNPH is characterized by the accumulation of excess cerebrospinal fluid in the brain's ventricles. In most cases, iNPH patients can be effectively treated with shunt surgery, which involves placing a tube into the brain to drain the excess fluid. As part of the European Brain Council-led Value of Treatment project, this study aimed to investigate the cost-effectiveness of delivering timely and adequate iNPH treatment in Germany.

METHODS

The study identified treatment gaps that prevent iNPH patients from receiving adequate and timely treatment. The cost-effectiveness of delivering shunt surgery to iNPH-prevalent patients aged ≥65 years in Germany was calculated using decision-analytical modelling. The model compared two alternatives, current care (shunt surgery in 25% of iNPH cases) and target care (shunt surgery in 90% of iNPH cases), and looked at healthcare costs (diagnosis, shunt intervention and follow-up care) from the public health insurance perspective, as well as effectiveness outcomes in terms of lives saved and quality-adjusted life-years (QALYs) gained.

RESULTS

Delivering timely and adequate iNPH treatment proved to be cost-effective. Cost per life saved varied between €27 921 at 5 years and €246 726 at 15 years. Cost-per-QALY estimates varied between €10 202 at 5 years and €35 128 at 15 years.

CONCLUSIONS

Idiopathic normal-pressure hydrocephalus is a treatable but often not-treated disease, resulting in unnecessary and avoidable disease burden for the healthcare system. Actions required to close this treatment gap are straightforward and their implementation has been modelled with successful outcomes.

Inpatient diagnoses of idiopathic normal pressure hydrocephalus in the United States: Demographic and socioeconomic disparities

INTRODUCTION

Epidemiology provides an avenue for identifying disease pathogenesis, hence determining national incidence, along with socioeconomic and demographic variables involved in iNPH, can provide direction in elucidating the etiology and addressing healthcare inequalities.

METHODS

To investigate incidence (per 100,000) of iNPH diagnoses applied to the inpatient population, with respect to sex, age, income, residence, and race/ethnicity, we queried the largest American administrative dataset (2008-2016), the National (Nationwide) Inpatient Sample (NIS), which surveys 20% of United States (US) discharges.

RESULTS

Annual national inpatient incidence (with 25th and 75th quartiles) for iNPH diagnoses was 2.86 (2.72, 2.93). Males had an inpatient incidence of 3.27 (3.11, 3.39), higher (p = 0.008) than female at 2.45 (2.41, 2.47). Amongst age groups inpatient incidence varied (p = 0.000004) and was largest amongst the 85+ group at 18.81 (16.40, 19.95). Individuals with middle/high income had an inpatient incidence of 2.96 (2.77, 3.06), higher (p = 0.008) than the 2.37 (2.24, 2.53) of low-income patients. Depending on whether patients lived in urban, suburban, or rural communities, inpatient incidence diverged (p = 0.01) as follows, respectively: 2.65; 2.66; 3.036. Amongst race/ethnicity (p = 0.000003), inpatient incidence for Whites, Blacks, Hispanics, Asian/Pacific Islanders, and Native Americans were as follows, respectively: 3.88 (3.69, 3.93), 1.065 (1.015, 1.14); 0.82 (0.76, 0.85); 0.43 (0.33, 0.52); 0.027 (0.026, 0.12).

CONCLUSION

In the US, inpatient incidence for iNPH diagnoses exhibited disparities between socioeconomic and demographic strata, emphasizing a healthcare inequality. Disproportionately, diagnoses were applied most to patients who were White, male, 65 and older, middle/high income, and living in rural communities.

In Vivo Evidence for Impaired Glymphatic Function in the Visual Pathway of Patients With Normal Pressure Hydrocephalus

Purpose

Impaired ability to remove toxic metabolites from central nervous system may be an important link between cerebral and ophthalmic degenerative diseases. The aim of the present study was to compare the glymphatic function in the visual pathway in patients with idiopathic normal pressure hydrocephalus (iNPH), a neurodegenerative dementia subtype, with a reference group.

Methods

We compared 31 subjects with Definite iNPH (i.e., shunt-responsive) with 13 references in a prospective and observational study. After intrathecal injection of the magnetic contrast agent gadobutrol (Gadovist, 0.5 mL, 1.0 mmol/mL, Bayer Pharma AG), serving as a tracer, consecutive magnetic resonance imaging (MRI) scans were obtained (next 24-48 hours). The normalized MRI T1 signal recorded in the cerebrospinal fluid (CSF) and along the visual pathway served as a semi-quantitative measure of tracer enrichment. Gadobutrol does not penetrate the blood-brain barrier and is thus confined to the extravascular space. Overnight measurements of pulsatile intracranial pressure were used as a surrogate marker for the intracranial compliance.

Results

The tracer enriched the prechiasmatic cistern similarly in both groups, but clearance was delayed in the iNPH group. Moreover, both delayed enrichment and clearance of the tracer were observed in the visual pathway in the iNPH subjects. The enrichment in the visual pathway and the CSF correlated. Individuals with elevated pulsatile intracranial pressure showed reduced enrichment within the visual pathway.

Conclusions

There was delayed enrichment and clearance of a tracer in the visual pathway of iNPH patients, which suggests impaired glymphatic function in the visual pathway in this disease.

Wide temporal horns are associated with cognitive dysfunction, as well as impaired gait and incontinence

The association between morphology of the brain and symptoms of suspected idiopathic normal pressure hydrocephalus (iNPH) is largely unknown. We investigated how ventricular expansion (width of the temporal horns [TH], callosal angle [CA], and Evans' index [EI]) related to symptom severity in suspected iNPH. Participants (n = 168; 74.9 years ± SD 6.7; 55% females) from the general population underwent neurological examination, computed tomography, and neuropsychological testing. Multiple linear regression analysis revealed that wide TH was independently associated with all examined iNPH symptoms (p < 0.01) except for fine-motor performance, whereas a narrow CA only was associated to specific motor and cognitive functions (p < 0.05). TH and EI correlated significantly with incontinence (r_s 0.17 and r_s 0.16; p < 0.05). In conclusion, wide TH was significantly associated with most iNPH-symptoms. This finding potentially reflects the complex nature of the hippocampus, however further studies are needed to demonstrate functional connectivity.

Gaps, Controversies, and Proposed Roadmap for Research in Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus is considered common but remains underinvestigated. There are no uniformly accepted diagnostic criteria and therapeutic guidelines. We summarize the accumulated evidence regarding the definition, pathophysiology, diagnosis, and treatment of idiopathic normal pressure hydrocephalus, highlighting the many gaps and controversies, including diagnostic challenges, the frequent association with neurodegeneration and vascular disease, and the many unknowns regarding patient selection and outcome predictors. A roadmap to fill these gaps and solve the controversies around this condition is also proposed. More evidence is required with respect to diagnostic criteria, the value of ancillary testing, prospective population-based studies and novel trial designs. Furthermore, a need exists to develop new advanced options in shunt technology. © 2020 International Parkinson and Movement Disorder Society.

Diabetes is associated with familial idiopathic normal pressure hydrocephalus: a case-control comparison with family members

BACKGROUND

The pathophysiological basis of idiopathic normal pressure hydrocephalus (iNPH) is still unclear. Previous studies have shown a familial aggregation and a potential heritability when it comes to iNPH. Our aim was to conduct a novel case-controlled comparison between familial iNPH (fNPH) patients and their elderly relatives, involving multiple different families.

METHODS

Questionnaires and phone interviews were used for collecting the data and categorising the iNPH patients into the familial (fNPH) and the sporadic groups. Identical questionnaires were sent to the relatives of the potential fNPH patients. Venous blood samples were collected for genetic studies. The disease histories of the probable fNPH patients (n = 60) were compared with their ≥ 60-year-old relatives with no iNPH (n = 49). A modified Charlson Comorbidity Index (CCI) was used to measure the overall disease burden. Fisher's exact test (two-tailed), the Mann-Whitney U test (two-tailed) and a multivariate binary logistic regression analysis were used to perform the statistical analyses.

RESULTS

Diabetes (32% vs. 14%, p = 0.043), arterial hypertension (65.0% vs. 43%, p = 0.033), cardiac insufficiency (16% vs. 2%, p = 0.020) and depressive symptoms (32% vs. 8%, p = 0.004) were overrepresented among the probable fNPH patients compared to their non-iNPH relatives. In the age-adjusted multivariate logistic regression analysis, diabetes remained independently associated with fNPH (OR = 3.8, 95% CI 1.1-12.9, p = 0.030).

CONCLUSIONS

Diabetes is associated with fNPH and a possible risk factor for fNPH. Diabetes could contribute to the pathogenesis of iNPH/fNPH, which motivates to further prospective and gene-environmental studies to decipher the disease modelling of iNPH/fNPH.

Prevalence and Trends in Management of Idiopathic Normal Pressure Hydrocephalus in the United States: Insights from the National Inpatient Sample

BACKGROUND

Over the past 2 decades, management of idiopathic normal pressure hydrocephalus (iNPH) has evolved significantly. In the current study, we sought to evaluate the national prevalence and management trends of iNPH in the United States using a national database.

METHODS

The National Inpatient Sample was queried for patients with an International Classification of Diseases diagnosis code for iNPH from 2007 to 2017. Trends in prevalence and procedure type were evaluated per 100,000 discharges and as a percentage of discharges, using weighted discharges. Utilization of procedure type across U.S. regions and hospital types was also compared.

RESULTS

From 2007 to 2017, 302,460 weighted discharges with any diagnosis code for iNPH, aged ≥60 years, were identified. Prevalence ranged from 0.04% to 0.20% (41/100,000 to 202/100,000) among admitted patients ≥60 years old, giving an average prevalence during the study duration of 0.18% (179/100,000). Of 66,759 weighted discharges with a primary diagnosis code of iNPH undergoing surgical management, ventriculoperitoneal shunt (72.0% of discharges, n = 48,977) was most commonly used; of these, 9.3% (n = 4567) were performed laparoscopically. This result was followed by lumbar peritoneal shunt (15.1% of discharges, n = 10,441). Up to 15.1% (n = 9990) of discharges reported only a lumbar puncture, assumed to be only diagnostic, for screening, or part of serial cerebrospinal fluid removal procedures. Significant discrepancies in procedure utilization were also identified among hospitals in the Western, Southern, Northeast and Midwest regions, as well as between urban and rural hospitals (P < 0.05).

CONCLUSIONS

We have summarized the national prevalence of iNPH, trends in its management over the previous decade and trends by region and hospital type.

Normal Pressure Hydrocephalus Associated with Alzheimer's Disease

OBJECTIVE

The aim was to investigate whether neurodegenerative biomarkers in cerebrospinal fluid (CSF) differentiate patients with suspected normal pressure hydrocephalus (NPH) who respond to CSF drainage from patients who do not respond.

METHODS

Data from 62 consecutive patients who presented with magnetic resonance imaging changes indicative of NPH were studied with regard to cognitive and gait functions before and after drainage of 40-50ml of CSF. Additionally, S100 protein, neuron-specific enolase, β-amyloid protein, tau protein and phospho-tau were determined in CSF. Statistical analyses were carried out with ANOVA and multiple linear regression.

RESULTS

Patients with CSF constellations typical for Alzheimer's disease (n = 28) improved significantly in cognitive and gait-related functions after CSF drainage. In contrast, those patients without a CSF constellation typical for Alzheimer's disease (n = 34) did not improve in cognitive and gait-related functions after CSF drainage. In addition, positive CSF biomarkers for Alzheimer's disease predicted these improvements.

INTERPRETATION

Our data suggest an association between Alzheimer's disease and NPH changes, supporting the recently suggested dichotomy of a neurodegenerative NPH and a true idiopathic NPH, with the latter appearing to be rare. ANN NEUROL 2020;88:703-711.

High prevalence of cervical myelopathy in patients with idiopathic normal pressure hydrocephalus

BACKGROUND

Both idiopathic normal pressure hydrocephalus (iNPH) and cervical myelopathy may result in progressive gait impairment. Some patients who do not respond to shunting despite a positive tap test may have gait dysfunction from cervical myelopathy. The objective of this study was to determine the prevalence of cervical myelopathy in patients with iNPH.

METHODS

A consecutive series of patients undergoing shunt placement for iNPH were screened for cervical stenosis. Clinical manifestations of iNPH and cervical myelopathy, grade of cervical stenosis, cervical spine surgical intervention, timing of intervention, and outcomes were recorded.

RESULTS

Fifty-two patients shunted for treatment of iNPH were included for analysis. 58 % were male with a mean age of 75.2 years (SD 7.3 years). All patients presented with gait disturbances. 39/52 (75 %) had cervical stenosis, and 9/52 (17.3 %) had significant (grade 2-3) cervical stenosis with myelopathy and were subsequently treated with surgical decompression. There was an association between increasing grade of stenosis and disproportionately enlarged subarachnoid space hydrocephalus (DESH). All patients with grade 2-3 cervical stenosis and symptoms of cervical myelopathy in addition to iNPH underwent cervical decompression surgery.

CONCLUSIONS

Clinically significant cervical myelopathy was prevalent in patients with iNPH and was associated with increased rate of DESH, a finding that requires validation in a larger cohort. Based on these results, cervical imaging could be considered preoperatively in patients with iNPH, particularly when upper motor neuron findings are identified. Additionally, concomitant cervical stenosis should be ruled out in patients whose gait does not improve after shunt placement.

Role of psychiatric, cardiovascular, socioeconomic, and demographic risk factors on idiopathic normal pressure hydrocephalus: A retrospective case-control study

OBJECTIVES

Currently, predicting and preventing idiopathic normal pressure hydrocephalus (iNPH) remains challenging, especially for patients without a history of cerebrovascular disease. By exploring the role of cardiovascular and psychiatric history, demographics, and socioeconomic status in iNPH, will provide better direction for elucidating the etiology or addressing healthcare inequalities.

PATIENTS AND METHODS

To investigate iNPH with respect to the selected risk factors, we conducted a retrospective case-control study from a neuroscience institute in Hawaii with a patient pool of 25,843. After excluding patients with a history of cerebrovascular disease, we identified 29 cases which meet the American-European guidelines for iNPH diagnosis. Meanwhile, 116 controls matched to age, sex, and race were also randomly selected.

RESULTS

Median age at diagnosis was 83 (IQR: 74-88), with cases estimated 22 years older than controls (95 % CI: 14.00-29.00; p = 0.0000001). Patients with iNPH were more likely to be White (OR 4.01, 95 % CI: 1.59-10.11; p = 0.0042) and less likely Native Hawaiian and other Pacific Islander (OR 0.010, 95 % CI: 0.00-0.78; p = 0.014). Median household income was $2874 (95 % CI: 0.000089-6905; p = 0.088) greater amongst iNPH cases. Effect size amongst cardiovascular risk factors was not found statistically significant (i.e., body mass index, hyperlipidemia, type 2 diabetes mellitus, hypertension, coronary artery disease or prior myocardial infarction history, peripheral vascular disease, smoking status, congestive heart failure, atrial fibrillation/flutter, and history of prosthetic valve replacement). However, iNPH patients were more likely to have a history of alcohol use disorder (OR 8.29, 95 % CI: 0.99-453.87; p = 0.050) and history of a psychiatric disorder (OR 2.48; 95 % CI: 1.08-5.68; p = 0.029). Odds ratio for autoimmune disorder, thyroid disorder, glaucoma, and seizures did not reach statistical significance.

CONCLUSION

Patient race (i.e., White; Native Hawaiian or other Pacific Islander) was found associated with iNPH development. Meanwhile, after excluding those with cerebrovascular disease, cardiovascular risk factors were not found associated with iNPH. Lastly, iNPH cases were more inclined to have a history of alcohol use disorder and prior psychiatric disorder. Overall, this data reveals that a racial disparity exists amongst iNPH, as well as highlights the role of various cardiovascular and psychiatric risk factors, which can potentially provide direction in etiology elucidation.

Diagnostic accuracy of the iNPH Radscale in idiopathic normal pressure hydrocephalus

Background and purpose

The idiopathic normal pressure hydrocephalus (iNPH) Radscale was developed to standardize the evaluation of radiological signs in iNPH. The purpose of this study was to estimate the diagnostic accuracy of the iNPH Radscale in a sample of “true positive” and “true negative” cases.

Methods

Seventy-five patients with definite iNPH, i.e. who had improved at clinical follow-up one year after ventriculoperitoneal shunt surgery, were compared with 55 asymptomatic individuals from the general population. A radiologist assessed the seven radiological features of the iNPH Radscale in computed tomography of the brain in the patients (preoperatively) and controls.

Results

The iNPH Radscale score was significantly higher in the iNPH group (Median = 10, interquartile range 9–11) than in the control group (Median = 1, interquartile range 1–2) (p <0.001). Receiver operated characteristics analysis yielded an area under the curve of 99.7%, and an iNPH Radscale score ≤ 4 identified those without iNPH, with a sensitivity of 100%, specificity of 96% and overall accuracy of 98.5%.

Conclusions

In this study, iNPH Radscale could accurately discriminate between patients with definite iNPH and asymptomatic individuals over 65 years old. According to the results, a diagnosis of iNPH is very likely in patients with an iNPH Radscale score above 8 and corresponding clinical symptoms. On the other hand, the diagnosis should be questioned when the iNPH Radscale score is below the cut-off level of 4. We conclude that the iNPH Radscale could work as a diagnostic screening tool to detect iNPH. Whether the scale also can be used to predict shunt outcome needs further studies.

A systematic review on the epidemiology of normal pressure hydrocephalus

BACKGROUND

The aim of this systematic review is to gather all available studies reporting prevalence and incidence rates of iNPH and to assess their methodological quality and consistency.

METHODS

All available studies published up to June 2019 were retrieved searching the databases PubMed, ISI Web of Science, and the Cochrane Database of Systematic Reviews. All included studies were qualitatively assessed by two independent reviewers using the MORE Checklist for Observational Studies of Incidence and Prevalence.

KEY RESULTS

Bibliographic searches and other sources yielded 659 records. A total of 28 studies were selected and applied the predefined inclusion and exclusion criteria. Fourteen studies were further excluded, and 14 studies (10 on prevalence and 6 on incidence) were included in the qualitative analysis. Results from the prevalence studies reported crude overall rates ranging from 10/100 000 to 22/100 000 for probable iNPH and 29/100 000 for possible iNPH, and age-specific rates ranging from 3.3/100 000 in people aged 50-59 to 5.9% in people aged ≥ 80 years. Results from incidence studies reported overall crude rates ranging from 1.8/100 000 to 7.3/100 000 per year, and age-specific rates ranging from 0.07/100 000/year in people aged < 60 years to 1.2/1000/year in people aged ≥ 70 years.

CONCLUSIONS & INFERENCES

The high methodological and clinical heterogeneity of included studies does not allow drawing adequate conclusions on the epidemiology of iNPH. Further, high-quality, population-based studies should be carried out to allow for a better understanding of the epidemiology of this condition. Moreover, the implementation in current clinical practice of guidelines on the diagnosis and management of iNPH should also be endorsed.

Survival in treated idiopathic normal pressure hydrocephalus

OBJECTIVE

To describe survival and causes of death in 979 treated iNPH patients from the Swedish Hydrocephalus Quality Registry (SHQR), and to examine the influence of comorbidities, symptom severity and postoperative outcome.

METHODS

All 979 patients operated for iNPH 2004-2011 and registered in the SHQR were included. A matched control group of 4890 persons from the general population was selected by Statistics Sweden. Data from the Swedish Cause of Death Registry was obtained for patients and controls.

RESULTS

At a median 5.9 (IQR 4.2-8.1) year follow-up, 37% of the iNPH patients and 23% of the controls had died. Mortality was increased in iNPH patients by a hazard ratio of 1.81, 95% CI 1.61-2.04, p < 0.001. More pronounced symptoms in the preoperative ordinal gait scale and the Mini-mental State Examination were the most important independent predictors of mortality along with the prevalence of heart disease. Patients who improved in both the gait scale and in the modified Rankin Scale postoperatively (n = 144) had a similar survival as the general population (p = 0.391). Deaths due to cerebrovascular disease or dementia were more common in iNPH patients, while more controls died because of neoplasms or disorders of the circulatory system.

CONCLUSIONS

Mortality in operated iNPH patients is 1.8 times increased compared to the general population, a lower figure than previously reported. The survival of iNPH patients who improve in gait and functional independence is similar to that of the general population, indicating that shunt surgery for iNPH, besides improving symptoms and signs, can normalize survival.