An overview of normal pressure hydrocephalus and its importance: how much do we really know?

Alzheimer's Disease CSF Biomarkers as Possible Indicators of Tap-Test Response in Idiopathic Normal Pressure Hydrocephalus

The aim of the present study is the evaluation of established Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers in patients with idiopathic normal-pressure hydrocephalus (iNPH), both individually and as a total profile, and the investigation of their use as potential predictors of Tap-test responsiveness. Fifty-three patients with iNPH participated in the study. Aβ42, Aβ40, total Tau and phospho-Tau proteins were measured in duplicate with double-sandwich ELISA assays. Clinical evaluation involved a 10 m timed walk test before an evacuative lumbar puncture (LP) and every 24 h for three consecutive days afterwards. Neuropsychological assessment involved a mini-mental state examination, frontal assessment battery, 5-word test and CLOX drawing test 1 and 2, which were also performed before and 48 h after LP. Response in the Tap-test was defined as a 20% improvement in gait and/or a 10% improvement in neuropsychological tests. The Aβ42/Aβ40 ratio was found to be significantly higher in Tap-test responders than non-responders. Total Tau and phospho-Tau CSF levels also differed significantly between these two groups, with Tap-test responders presenting with lower levels compared to non-responders. Regarding the AD CSF biomarker profile (decreased amyloid and increased Tau proteins levels), patients with a non-AD profile were more likely to have a positive response in the Tap-test than patients with an AD profile.

Automatic MRI volumetry in asymptomatic cases at risk for normal pressure hydrocephalus

The occurrence of significant Alzheimer's disease (AD) pathology was described in approximately 30% of normal pressure hydrocephalus (NPH) cases, leading to the distinction between neurodegenerative and idiopathic forms of this disorder. Whether or not there is a specific MRI signature of NPH remains a matter of debate. The present study focuses on asymptomatic cases at risk for NPH as defined with automatic machine learning tools and combines automatic MRI assessment of cortical and white matter volumetry, risk of AD (AD-RAI), and brain age gap estimation (BrainAge). Our hypothesis was that brain aging and AD process-independent volumetric changes occur in asymptomatic NPH-positive cases. We explored the volumetric changes in normal aging-sensitive (entorhinal cortex and parahippocampal gyrus/PHG) and AD-signature areas (hippocampus), four control cortical areas (frontal, parietal, occipital, and temporal), and cerebral and cerebellar white matter in 30 asymptomatic cases at risk for NPH (NPH probability >30) compared to 30 NPH-negative cases (NPH probability <5) with preserved cognition. In univariate regression models, NPH positivity was associated with decreased volumes in the hippocampus, parahippocampal gyrus (PHG), and entorhinal cortex bilaterally. The strongest negative association was found in the left hippocampus that persisted when adjusting for AD-RAI and Brain Age values. A combined model including the three parameters explained 36.5% of the variance, left hippocampal volumes, and BrainAge values, which remained independent predictors of the NPH status. Bilateral PHG and entorhinal cortex volumes were negatively associated with NPH-positive status in univariate models but this relationship did not persist when adjusting for BrainAge, the latter remaining the only predictor of the NPH status. We also found a negative association between bilateral cerebral and cerebellar white matter volumes and NPH status that persisted after controlling for AD-RAI or Brain Age values, explaining between 50 and 65% of its variance. These observations support the idea that in cases at risk for NPH, as defined by support vector machine assessment of NPH-related MRI markers, brain aging-related and brain aging and AD-independent volumetric changes coexist. The latter concerns volume loss in restricted hippocampal and white matter areas that could be considered as the MRI signature of idiopathic forms of NPH.

Cerebrospinal fluid transcripts may predict shunt surgery responses in normal pressure hydrocephalus

Molecular biomarkers for neurodegenerative diseases are critical for advancing diagnosis and therapy. Normal pressure hydrocephalus (NPH) is a neurological disorder characterized by progressive neurodegeneration, gait impairment, urinary incontinence and cognitive decline. In contrast to most other neurodegenerative disorders, NPH symptoms can be improved by the placement of a ventricular shunt that drains excess CSF. A major challenge in NPH management is the identification of patients who benefit from shunt surgery. Here, we perform genome-wide RNA sequencing of extracellular vesicles in CSF of 42 NPH patients, and we identify genes and pathways whose expression levels correlate with gait, urinary or cognitive symptom improvement after shunt surgery. We describe a machine learning algorithm trained on these gene expression profiles to predict shunt surgery response with high accuracy. The transcriptomic signatures we identified may have important implications for improving NPH diagnosis and treatment and for understanding disease aetiology.

Imaging Markers for Normal Pressure Hydrocephalus: An Overview

Idiopathic bormal pressure hydrocephalus (iNPH) is a neurological syndrome that clinically presents with Hakim's triad, namely cognitive impairment, gait disturbances, and urinary incontinence. The fact that iNPH is potentially reversible makes its accurate and early diagnosis of paramount importance. Its main imaging characteristic is the dilation of the brain's ventricular system and the imaging parameters are also included in its diagnostic criteria along with clinical data. There is a variety of different modalities used and a great number of imaging markers that have been described while assessing iNPH patients. The present literature review attempts to describe the most important of these imaging markers and to shed some light on their role in diagnosis, differential diagnosis, and possibly prognosis of this potentially reversible neurological syndrome.

Cerebrospinal Fluid Biomarkers in iNPH: A Narrative Review

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological syndrome characterized by the clinical triad of gait disorder, cognitive impairment and urinary incontinence. It has attracted interest because of the possible reversibility of symptoms, especially with timely treatment. The main pathophysiological theory is based on a vicious circle of disruption in circulation of cerebrospinal fluid (CSF) that leads to the deceleration of its absorption. Data regarding CSF biomarkers in iNPH are contradictory and no definite CSF biomarker profile has been recognized as in Alzheimer's disease (AD), which often co-exists with iNPH. In this narrative review, we investigated the literature regarding CSF biomarkers in iNPH, both the established biomarkers total tau protein (t-tau), phosphorylated tau protein (p-tau) and amyloid peptide with 42 amino acids (Aβ42), and other molecules, which are being investigated as emerging biomarkers. The majority of studies demonstrate differences in CSF concentrations of Aβ42 and tau-proteins (t-tau and p-tau) among iNPH patients, healthy individuals and patients with AD and vascular dementia. iNPH patients present with lower CSF Aβ42 and p-tau concentrations than healthy individuals and lower t-tau and p-tau concentrations than AD patients. This could prove helpful for improving diagnosis, differential diagnosis and possibly prognosis of iNPH patients.

Comparison of ventriculoperitoneal shunt to lumboperitoneal shunt in the treatment of idiopathic: A monocentric, assessor-blinded, randomized controlled trial

BACKGROUND

Ventriculoperitoneal shunt (VPS) and lumboperitoneal shunt (LPS) remain the mainstay of idiopathic normal pressure hydrocephalus (INPH). There are no randomized controlled trials completed to compare the efficacy of these 2 shunt techniques.

METHODS/DESIGN

We will conduct a monocentric, assessor-blinded, and randomized controlled trial titled "Comparison of Ventriculoperitoneal Shunt to Lumboperitoneal Shunt for the treatment of Idiopathic Normal Pressure Hydrocephalus: Phase I (COVLINPH-1)" trial and recruit patients at West China Hospital of Sichuan University since June 2021. And this trial is expected to end in December 2030. Eligible participants will be randomly assigned into LPS group and VPS group at ratio of 1:1 followed by evaluation before surgery, 1 month, 12 months, and 5 years after surgery. The primary outcome is the rate of shunt failure within 5 years. The secondary outcomes include modified Rankin Scale (mRS), INPH grading scale (INPHGS), mini-mental state examination (MMSE), and Evans index. We will calculate the rate of favorable outcome, which is defined as shunt success and an improvement of more than 1 point in the mRS at evaluation point. We will also analyze the complications throughout the study within 5 years after shunt insertion.

DISCUSSION

The results of this trial will provide state-of-the-art evidence on the treatment option for patients with INPH, and will also generate the discussion regarding this subject.

TRIAL REGISTRATION NUMBER

ChiCTR2000031555; Pre-results.

SVM-Based Normal Pressure Hydrocephalus Detection

Background and Purpose

As magnetic resonance imaging (MRI) signs of normal pressure hydrocephalus (NPH) may precede clinical symptoms we sought to evaluate an algorithm that automatically detects this pattern.

Methods

A support vector machine (SVM) was trained in 30 NPH patients treated with ventriculoperitoneal shunts and 30 healthy controls. For comparison, four neuroradiologists visually assessed sagittal MPRAGE images and graded them as no NPH pattern, possible NPH pattern, or definite NPH pattern.

Results

Human accuracy to visually detect a NPH was between 0.85 and 0.97. Interobserver agreement was substantial (κ = 0.656). Accuracy of the SVM algorithm was 0.93 and AUROC 0.99. Among 272 prespecified regions, gray matter and CSF volumes of both caudate, the right parietal operculum, the left basal forebrain, and the 4th ventricle showed the highest discriminative power to separate a NPH and a no NPH pattern.

Conclusion

A NPH pattern can be reliably detected using a support vector machine (SVM). Its role in the work-up of asymptomatic patients or neurodegenerative disease has to be evaluated.

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.

Repeated Cerebrospinal Fluid Removal Procedure in Older Patients With Idiopathic Normal Pressure Hydrocephalus Ineligible for Surgical Treatment

OBJECTIVES

To evaluate the effects of repeated cerebrospinal fluid (CSF) tap procedures in idiopathic normal pressure hydrocephalus (iNPH) patients ineligible for surgical treatment.

DESIGN

Prospective, monocentric, pilot study.

SETTING

University hospital.

PARTICIPANTS

Thirty-nine patients aged 75 years and older, ineligible for shunting surgical intervention.

INTERVENTION

Repeated CSF taps.

MEASUREMENTS

All patients underwent a comprehensive geriatric assessment before and after each CSF tap. Adverse events were recorded.

RESULTS

No major side effect was reported. Eleven patients showed no response to the first CSF tap test and were excluded. In the remaining 28 patients, all physical and cognitive functions improved after the drainage procedures, except for continence (which seemed poorly influenced). According to clinical judgment, the mean time frame of benefit between CSF taps was 7 months. Patients withdrawing from the protocol during the clinical follow-up showed a worsening of functional and cognitive performances after the interruption.

CONCLUSIONS/IMPLICATIONS

Periodic CSF therapeutic taps are safe, allow a better control of iNPH symptoms, and prevent functional decline in geriatric patients.

Sex Differences in Cardiovascular Risk Factors for Dementia

Dementia, characterized by a progressive cognitive decline and a cumulative inability to behave independently, is highly associated with other diseases. Various cardiovascular disorders, such as coronary artery disease and atrial fibrillation, are well-known risk factors for dementia. Currently, increasing evidence suggests that sex factors may play an important role in the pathogenesis of diseases, including cardiovascular disease and dementia. Recent studies show that nearly two-thirds of patients diagnosed with Alzheimer’s disease are women; however, the incidence difference between men and women remains vague. Therefore, studies are needed to investigate sex-specific differences, which can help understand the pathophysiology of dementia and identify potential therapeutic targets for both sexes. In the present review, we summarize sex differences in the prevalence and incidence of dementia by subtypes. This review also describes sex differences in the risk factors of dementia and examines the impact of risk factors on the incidence of dementia in both sexes.

Considering sex and gender in Alzheimer disease and other dementias

Suffering related to dementia is multifaceted because cognitive and physical functioning slowly deteriorates. Advanced age and sex, two of the most prominent risk factors for dementia, are not modifiable. Lifestyle factors such as smoking, excessive alcohol use, and poor diet modulate susceptibility to dementia in both males and females. The degree to which the resulting health conditions (eg, obesity, type 2 diabetes, and cardiovascular disease) impact dementia risk varies by sex. Depending on the subtype of dementia, the ratio of male to female prevalence differs. For example, females are at greater risk of developing Alzheimer disease dementia, whereas males are at greater risk of developing vascular dementia. This review examines sex and gender differences in the development of dementia with the goal of highlighting factors that require further investigation. Considering sex as a biological variable in dementia research promises to advance our understanding of the pathophysiology and treatment of these conditions.

A Curious Distal Tibiofibular Neuropathic Fracture: A Case Report

Hindfoot and distal leg neuropathic fracture collapse secondary to normal pressure hydrocephalus is a very rare clinical pathology. The authors present a case of a 69-year-old woman who sustained a distal tibiofibular fracture that resulted in a recurvatum deformity with idiopathic neuropathy and gait instability on initial presentation. A subtalar and ankle joint arthrodesis was performed achieving rectus alignment of the lower extremity with no postoperative complications. Her neuropathic etiology was negative for common causative factors, including diabetes, infection, nutritional deficiencies, congenital neuropathy, and trauma. Approximately 6 months postoperatively, the patient had persistent bilateral lower extremity weakness with the sensation of her "feet sticking to the floor" on ambulation. A referral to neurology revealed a normal pressure hydrocephalus as a possible etiology for her gait abnormalities and neuropathy. She required a ventriculoperitoneal shunt, with resolved gait disturbance and associated weakness approximately 1.5 years postoperatively.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Case report.

Performance of the fixed pressure valve with antisiphon device SPHERA® in the treatment of normal pressure hydrocephalus and prevention of overdrainage

Normal pressure hydrocephalus (NPH) is characterized by the triad of gait apraxia, dementia and urinary incontinence associated with ventriculomegaly and normal pressure of cerebrospinal fluid. Treatment is accomplished through the implantation of a ventricular shunt (VPS), however some complications are still frequent, like overdrainage due to siphon effect. This study analyses the performance of a valve with anti-siphon device (SPHERA®) in the treatment of patients with NPH and compares it with another group of patients with NPH who underwent the same procedure without anti-siphon mechanism (PS Medical® valve). 30 patients were consecutively enrolled in two groups with 15 patients each and followed clinically and radiologically for 1 year. Patients submitted to VPS with SPHERA® valve had the same clinical improvement as patients submitted to VPS with PS Medical®. However, complications and symptomatology due to overdrainage were significantly lower in SPHERA® group, suggesting it as a safe tool to treat NPH.

Optimized surgical treatment for normal pressure hydrocephalus: comparison between gravitational and differential pressure valves

OBJECTIVES

In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005.

METHODS

The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups.

RESULTS

Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group).

CONCLUSIONS

Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment and urinary incontinency without the risk of overdrainage complications requiring surgical intervention when compared with patients who received differential pressure valves in previous years.

Endoscopic third ventriculostomy in the management of hydrocephalus: Outcome analysis of 168 consecutive procedures

BACKGROUND

Endoscopic third ventriculostomy (ETV) is the treatment of choice for obstructive hydrocephalus, but the outcome is still controversial in terms of age and aetiology.

METHODS

Between 1998 and 2011, 168 consecutive procedures were performed in 164 patients, primarily children (56%<18 years of age and 35%<2 years of age). The causes of obstructive hydrocephalus included tumoural pathology, Chiari malformation, congenital obstruction of the aqueduct, post-infectious and post-haemorrhagic membranes, and ventriculo-peritoneal shunt (VPS) malfunctions. Successful ETV was defined by the resolution of symptoms and the avoidance of a shunt.

RESULTS

ETV was successful in 75.6% of patients, but 19% of the patients required VPS in the first month after ETV, and 5.4% required a VPS more than one month after ETV. Four patients were ultimately submitted for second ETVs. In this series, no major permanent morbidity or mortality was observed.

CONCLUSIONS

ETV is a safe procedure and an effective treatment for obstructive hydrocephalus even following the dysfunction of previous VPSs and in children younger than two years.

The differential diagnosis and treatment of normal-pressure hydrocephalus

BACKGROUND

Normal-pressure hydrocephalus (NPH) arises in adulthood and is characterized by a typical combination of clinical and radiological findings. The mean basal intracranial pressure is normal or mildly elevated. The typical signs of the disease are gait impairment, urinary incontinence, and dementia. The difficulty of distinguishing NPH from other neurodegenerative disorders is the likely reason why some 80% of cases remain unrecognized and untreated. According to current evidence, the spontaneous course of NPH ends, for the vast majority of patients, in dependence on nursing care.

METHODS

This review article is based on relevant publications retrieved by a selective search in Medline and on national and international guidelines for the management of NPH.

RESULTS

Studies with a high evidence level are lacking; thus, the current state of knowledge about NPH is derived from studies of low or intermediate evidence levels, e.g., observational studies. Modern forms of treatment lead to clinical improvement in 70% to 90% of treated patients. The treatment of choice is the implantation of a ventriculoperitoneal shunt. The differential diagnosis is complicated by the fact that three-quarters of patients with NPH severe enough to require treatment also suffer from another neurodegenerative disorder. Therefore, the clinical findings and imaging studies often do not suffice to establish the indication for surgery. To do this, a further, semi-invasive diagnostic procedure is recommended. Current risk/benefit analyses indicate that shunt operations improve outcome compared to the spontaneous course of the disease.

CONCLUSION

Normal pressure hydrocephalus should always enter into the differential diagnosis of patients who present with its characteristic manifestations. If the diagnosis of NPH is confirmed, it should be treated at an early stage.