Familial aggregation of idiopathic normal pressure hydrocephalus: novel familial case and a family study of the NPH triad in an iNPH patient cohort

Genetic Risk Factors in Normal Pressure Hydrocephalus: What We Know and What Is Next

Knowledge of the genetic factors in normal pressure hydrocephalus (NPH) is rapidly evolving, with significant advances in recent years. We conducted a systematic review examining genetic contributions to NPH risk. Ovid Embase, Ovid Medline, Web of Science, and Cochrane Central were searched from inception through October 14, 2024, for human studies in English reporting familial NPH cases, genetic variants associated with NPH, and associations with other neurogenetic disorders and exploring transcriptomics. Studies on secondary, obstructive, and congenital hydrocephalus were excluded, and findings were reported narratively. Of 2562 titles and abstracts screened, 56 met inclusion criteria, predominantly involving European populations. More than 30 familial cases were identified, and two cohorts found that 10%-16% of patients with NPH had relatives with NPH symptoms. Whole-genome/exome sequencing, copy-number variant analyses, and genome-wide association studies showed risk variants enriched in NPH cohorts in or near CFAP43, SFMBT1, CWH43, AK9, RXFP2, PRKD1, HAVCR1, OTOG, MYO7A, NOTCH1, SPG11, MYH13, FOXJ1, AMZ1/GNA12, and C16orf95, alongside protective variants near SLCO1A2 and MLLT10. These genes are associated with blood-brain and blood-cerebrospinal fluid barriers, cilia, and ependymal function. In addition, higher rates of pathological C9orf72 repeat expansions were observed in an NPH cohort compared with controls. NPH was also more prevalent in frontotemporal dementia cohorts without this expansion and co-occurred with myotonic dystrophy type 1 in several cases. Despite heterogeneity in outcome measures, this review highlights the genetic contribution to NPH risk. Future research should encourage collaborations for big data generation, identify genetic variants addressing diversity, and integrate clinical, environmental, and shunt-response data. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Familial vs sporadic normal pressure hydrocephalus: a comparative study

INTRODUCTION

Normal pressure hydrocephalus (NPH) is a syndrome characterized by the buildup of cerebrospinal fluid that results in the clinic triad of gait impairment, urinary incontinence, and cognitive impairment. NPH can be categorized as secondary, idiopathic, or familial. Here, we report a comparison of sporadic to familial types from clinical, radiological, and surgery response aspects as well as a novel gene mutation as a cause of familial NPH.

METHOD

We analyzed 139 patients evaluated for NPH at our center from 2010 to 2022. Ninety-five patients diagnosed with probable (n = 26) or definite (n = 69) iNPH were included. Clinical, radiological, and gait data were retrospectively collected. In patients with a positive familial history of NPH, we defined the inheritance pattern when possible. The results of performed genetic tests were reported.

RESULT

Nine patients (9.5%) had a familial history of NPH. Familial and sporadic groups were largely comparable in age, sex, and disease duration. However, familial cases had better cognitive scores (p = 0.022) and a higher prevalence of upper-limb action tremor (56% vs. 14%; p = 0.008). No significant differences were noted in radiological markers, and both groups showed a positive response to ventriculoperitoneal shunting (VPS). Whole exome sequencing identified a novel pathogenic NEIL1 variant in twin patients with familial NPH.

CONCLUSIONS

Familial NPH occurred in roughly 1 in 10 reviewed iNPH cases and demonstrates better cognition and increased tremor incidence compared to sporadic cases but otherwise similar characteristics. The genetic underpinning of these cases is heterogeneous and NEIL1 might represent another associated gene.

What is idiopathic in normal pressure hydrocephalus?

INTRODUCTION

Normal pressure hydrocephalus (NPH) can be caused by acquired events - e.g. subarachnoid hemorrhage, meningitis, or trauma - or can be "idiopathic" (iNPH) when no clear cause is identifiable. The entity and nosology of iNPH has received renewed attention and has recently gone through scrutiny and academic debate.

EVIDENCE ACQUISITION

Authors searched PubMed using the following keywords: "adult hydrocephalus," "alfa synuclein," "Alzheimer's disease," "beta-amyloid," "cerebrospinal fluid," "cilia," "CSF," "genes," "hydrocephalus," "idiopathic," "Lewy Body Dementia," "phosphorylated tau," "shunt responsiveness".

EVIDENCE SYNTHESIS

During the past decades several studies have reshaped our view of iNPH, examples are the identification of monogenic forms of iNPH caused by genes involved in the structure and function of cilia or the discovery of the glymphatic system. This review will discuss the causes of iNPH and particularly the relationship with neurodegeneration in terms of: 1) coincidental association; 2) iNPH predisposing to neurodegeneration, 3. neurodegeneration predisposing to iNPH, and 4. independent processes (genetic and environmental) predisposing to both. Based on the gathered evidence, a unified model is then presented, characterized by three sequential events: impairment of CSF dynamic, occurrence of reversible signs, occurrence of irreversible signs.

CONCLUSIONS

Almost 70 years after its description, a growing literature on its basic mechanisms is clarifying that iNPH is a syndrome with pathogenetic mechanisms arising from different causes. The paradigm shift has been recognizing that iNPH is not just a CSF disorder but rather a brain disorder expressing with ventriculomegaly. Finally, the better understanding of what causes iNPH support the proposal of changing its name into "Hakim's disease."

Classification of Chronic Hydrocephalus in Adults: A Systematic Review and Analysis

BACKGROUND

Chronic hydrocephalus in adults (CHiA) includes all nonacute forms of hydrocephalus occurring in adulthood. It covers a spectrum of disorders. Some of these have relatively agreed on definitions, while others are less well characterized. The existing medical classification systems lack adequate structure and are neither clinically oriented nor easy to use, which severely hampers research and clinical care efforts.

METHODS

A systematic literature review and data analysis were performed, focusing on the terms "adult hydrocephalus" and "classification," using the PubMed, Scopus, and Cochrane Library databases. Data on terminology, definitions, patient demographics, symptom duration, and clinical presentations were extracted, analyzed, and compiled. A Delphi process was followed to define CHiA disorders.

RESULTS

A total of 33 studies collectively used 48 terms to define various CHiA disorders. Different terms were used to describe similar conditions. CHiA disorders were found to be clustered into 7 distinctive clinical entities based on the clinical characteristics.

CONCLUSIONS

An evidence-based new clinical classification for CHiA is suggested. Our review identified gaps in knowledge and areas for further research.

A role for mutations in AK9 and other genes affecting ependymal cells in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is an enigmatic neurological disorder that develops after age 60 and is characterized by gait difficulty, dementia, and incontinence. Recently, we reported that heterozygous CWH43 deletions may cause iNPH. Here, we identify mutations affecting nine additional genes (AK9, RXFP2, PRKD1, HAVCR1, OTOG, MYO7A, NOTCH1, SPG11, and MYH13) that are statistically enriched among iNPH patients. The encoded proteins are all highly expressed in choroid plexus and ependymal cells, and most have been associated with cilia. Damaging mutations in AK9, which encodes an adenylate kinase, were detected in 9.6% of iNPH patients. Mice homozygous for an iNPH-associated AK9 mutation displayed normal cilia structure and number, but decreased cilia motility and beat frequency, communicating hydrocephalus, and balance impairment. AK9+/- mice displayed normal brain development and behavior until early adulthood, but subsequently developed communicating hydrocephalus. Together, our findings suggest that heterozygous mutations that impair ventricular epithelial function may contribute to iNPH.

WT, Arnold SE, Frosch MP, Duy PQ, Kahle KT. Cases of familial idiopathic normal pressure hydrocephalus implicate genetic factors in disease pathogenesis

Idiopathic normal pressure hydrocephalus is a disorder of unknown pathophysiology whose diagnosis is paradoxically made by a positive response to its proposed treatment with cerebrospinal fluid diversion. There are currently no idiopathic normal pressure hydrocephalus disease genes or biomarkers. A systematic analysis of familial idiopathic normal pressure hydrocephalus could aid in clinical diagnosis, prognosis, and treatment stratification, and elucidate disease patho-etiology. In this 2-part analysis, we review literature-based evidence for inheritance of idiopathic normal pressure hydrocephalus in 22 pedigrees, and then present a novel case series of 8 familial idiopathic normal pressure hydrocephalus patients. For the case series, demographics, familial history, pre- and post-operative symptoms, and cortical pathology were collected. All novel familial idiopathic normal pressure hydrocephalus patients exhibited improvement following shunt treatment and absence of neurodegenerative cortical pathology (amyloid-beta and hyperphosphorylated tau), in contrast to many sporadic cases of idiopathic normal pressure hydrocephalus with variable clinical responses. Analysis of the 30 total familial idiopathic normal pressure hydrocephalus cases reported herein is highly suggestive of an autosomal dominant mechanism of inheritance. This largest-ever presentation of multiply affected idiopathic normal pressure hydrocephalus pedigrees provides strong evidence for Mendelian inheritance and autosomal dominant transmission of an idiopathic normal pressure hydrocephalus trait in a subset of patients that positively respond to shunting and lack neurodegenerative pathology. Genomic investigation of these families may identify the first bona fide idiopathic normal pressure hydrocephalus disease gene.

Current research of idiopathic normal pressure hydrocephalus: Pathogenesis, diagnosis and treatment

Idiopathic normal pressure hydrocephalus (iNPH) is caused by impaired cerebrospinal fluid absorption in the elderly; it is a surgically treatable form of dementia. Gait disturbance, dementia, and urinary incontinence are the triad of signs for iNPH. In addition to these clinical findings, imaging studies show characteristic ventricular enlargement. High Evans Index and 'disproportionately enlarged subarachnoid hydrocephalus' are other well-known imaging findings of iNPH. If the tap test shows improved symptoms, shunt surgery is performed. The disease was first described by Hakim and Adams in 1965, followed by the publication of the first, second, and third editions of the guidelines in 2004, 2012, and 2020, respectively. Recent studies signal the glymphatic system and classical cerebrospinal fluid (CSF) absorption from the dural lymphatics as aetiological mechanisms of CSF retention. Research is also underway on imaging test and biomarker developments for more precise diagnosis, shunting technique options with fewer sequelae and complications, and the influence of genetics. Particularly, the newly introduced 'suspected iNPH' in the third edition of the guidelines may be useful for earlier diagnosis. However, less well-studied areas remain, such as pharmacotherapy in non-operative indications and neurological findings other than the triadic signs. This review briefly presents previous research on these and future issues.

Idiopathic normal pressure hydrocephalus: historical context and a contemporary guide

Idiopathic normal pressure hydrocephalus (NPH) was described in 1965 as a syndrome in which hydrocephalus develops but with a normal cerebrospinal fluid (CSF) pressure, causing shunt-responsive gait apraxia, cognitive impairment and urinary incontinence. Not all patients respond to shunting despite having the clinical syndrome with appropriate radiological features. This has led to considerable debate over subsequent decades regarding idiopathic NPH. It is now understood that asymptomatic communicating hydrocephalus can develop in many healthy older people, and that over time this can develop into a symptomatic state that sometimes responds to CSF shunting, but to a variable extent. This review looks at the historical background of NPH, the use of predictive tests, the current state of clinical evidence for the diagnosis and treatment of idiopathic NPH and the possible underlying causes, to provide a contemporary practical guide for assessing patients with the radiological features of idiopathic NPH.

Incidental findings of typical iNPH imaging signs in asymptomatic subjects with subclinical cognitive decline

Background

The etiology of idiopathic normal pressure hydrocephalus (iNPH) remains unclear. Little is known about the pre-symptomatic stage. This study aimed to investigate the association of neuropsychological data with iNPH-characteristic imaging changes compared to normal imaging and unspecific atrophy in a healthy population.

Methods

We extracted data from the community-dwelling Austrian Stroke Prevention Family Study (ASPS-Fam) database (2006–2010). All subjects underwent a baseline and identical follow-up examination after 3–5 years with MR imaging and an extensive neuropsychological test battery (Trail Making Test B, short physical performance balance, walking speed, memory, visuo-practical skills, composite scores of executive function and g-factor). We categorized the subjects into “iNPH”-associated, non-specific “atrophy,” and “normal” based on the rating of different radiological cerebrospinal fluid (CSF) space parameters. We noted how the categories developed over time. We assessed the association of the image categories with the neuropsychological data, different demographic, and lifestyle parameters (age, sex, education, alcohol intake, arterial hypertension, hypercholesterolemia), and the extent of white matter hyperintensities. We investigated whether neuropsychological data associated with the image categories were independent from other parameters as confounders.

Results

One hundred and thirteen subjects, aged 50–70 years, were examined. The imaging category “iNPH” was only present at follow-up. A third of subjects with “atrophy” at baseline changed to the category “iNPH” at follow-up. More white matter hyperintensities (WMH) were present in later “iNPH” subjects. Subjects with “iNPH” performed worse than “normal” subjects on executive function (p = 0.0118), memory (p = 0.0109), and Trail Making Test B (TMT-B. p < 0.0001). Education, alcohol intake, diabetes, arterial hypertension, and hypercholesterolemia had no effect. Age, number of females, and the extent of white matter hyperintensities were higher in “iNPH” than in “normal” subjects but did not significantly confound the neuropsychological results.

Conclusions

Apparent asymptomatic subjects with “iNPH” imaging characteristics presented with subclinical cognitive decline and showed worse executive function, memory, and TMT-B results than “normal” subjects. WMH seem to play a role in the etiology before ventriculomegaly. Clinical screening of individuals with incidental iNPH-characteristic imaging and conspicuous results sof these neurocognitive tests needs further validation.

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.

Deletions in CWH43 cause idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder that occurs in about 1% of individuals over age 60 and is characterized by enlarged cerebral ventricles, gait difficulty, incontinence, and cognitive decline. The cause and pathophysiology of iNPH are largely unknown. We performed whole exome sequencing of DNA obtained from 53 unrelated iNPH patients. Two recurrent heterozygous loss of function deletions in CWH43 were observed in 15% of iNPH patients and were significantly enriched 6.6‐fold and 2.7‐fold, respectively, when compared to the general population. Cwh43 modifies the lipid anchor of glycosylphosphatidylinositol‐anchored proteins. Mice heterozygous for CWH43 deletion appeared grossly normal but displayed hydrocephalus, gait and balance abnormalities, decreased numbers of ependymal cilia, and decreased localization of glycosylphosphatidylinositol‐anchored proteins to the apical surfaces of choroid plexus and ependymal cells. Our findings provide novel mechanistic insights into the origins of iNPH and demonstrate that it represents a distinct disease entity.

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.

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.

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.

Management of idiopathic normal pressure hydrocephalus (iNPH) - a retrospective study

Background: Normal pressure hydrocephalus (NPH) is communicating hydrocephalus characterised by normal intraventricular pressures. It presents with the triad of gait impairment, cognitive decline, and urinary incontinence. The term idiopathic normal pressure hydrocephalus (iNPH) is used in cases where the etiology is unknown. The aim of this study was to assess the prevalence and management of iNPH in our institution.Method: This was a retrospective study carried out at a tertiary health care center. Retrospective case series analysis was conducted using the existing electronic medical record data (2009-2017) on patients with hydrocephalus.Results: Forty-two (6.7%) patients with iNPH were identified, mean age 71.5 ± 8.8 years, 21 male (mean age 71.5 ± 9.3 years) and 21 female (mean age 71.5 ± 8.5 years). Ataxia was recorded in 39, symptoms of dementia in 31, and urinary incontinence in 29 patients. Forty patients were treated surgically by placing a ventriculoperitoneal (VP) shunt. One of the two patients treated by endoscopic third ventriculostomy (ETV) was subsequently treated by placing a VP shunt due to clinical deterioration. Significant improvements were noticed in cognitive and urinary symptoms, in the triad symptom sum score on the Japanese NPH scale, as well as in Evans' index and callosal angle (CA) on brain MRI (p < 0.05). Significant positive correlation was found between age and gait disturbance (Spearman's rho = 49.86% p = 0.0017), age and incontinence (Spearman's rho = 35.22%, p = 0.0351), age and triad symptom sum score (Spearman's rho = 44.67%, p = 0.0056), female gender and dementia (Spearman's rho = 34.94%, p = 0.0367), and among all three variables on the Japanese NPH scale (p < 0.0001).Conclusions: Treatment of iNPH with VP shunt showed significant improvement. A properly designed study is required to address the efficacy of ETV in the treatment of iNPH.

Nonsense mutation in CFAP43 causes normal-pressure hydrocephalus with ciliary abnormalities

Objective

To identify genes related to normal-pressure hydrocephalus (NPH) in one Japanese family with several members with NPH.

Methods

We performed whole-exome sequencing (WES) on a Japanese family with multiple individuals with NPH and identified a candidate gene. Then we generated knockout mouse using CRISPR/Cas9 to confirm the effect of the candidate gene on the pathogenesis of hydrocephalus.

Results

In WES, we identified a loss-of-function variant in CFAP43 that segregated with the disease. CFAP43 encoding cilia- and flagella-associated protein is preferentially expressed in the testis. Recent studies have revealed that mutations in this gene cause male infertility owing to morphologic abnormalities of sperm flagella. We knocked out mouse ortholog Cfap43 using CRISPR/Cas9 technology, resulting in Cfap43-deficient mice that exhibited a hydrocephalus phenotype with morphologic abnormality of motile cilia.

Conclusion

Our results strongly suggest that CFAP43 is responsible for morphologic or movement abnormalities of cilia in the brain that result in NPH.

Copy number loss in SFMBT1 is common among Finnish and Norwegian patients with iNPH

Objective

To evaluate the role of the copy number loss in SFMBT1 in a Caucasian population.

Methods

Five hundred sixty-seven Finnish and 377 Norwegian patients with idiopathic normal pressure hydrocephalus (iNPH) were genotyped and compared with 508 Finnish elderly, neurologically healthy controls. The copy number loss in intron 2 of SFMBT1 was determined using quantitative PCR.

Results

The copy number loss in intron 2 of SFMBT1 was detected in 10% of Finnish (odds ratio [OR] = 1.9, p = 0.0078) and in 21% of Norwegian (OR = 4.7, p < 0.0001) patients with iNPH compared with 5.4% in Finnish controls. No copy number gains in SFMBT1 were detected in patients with iNPH or healthy controls. The carrier status did not provide any prognostic value for the effect of shunt surgery in either population. Moreover, no difference was detected in the prevalence of hypertension or T2DM between SFMBT1 copy number loss carriers and noncarriers.

Conclusions

This is the largest and the first multinational study reporting the increased prevalence of the copy number loss in intron 2 of SFMBT1 among patients with iNPH, providing further evidence of its role in iNPH. The pathogenic role still remains unclear, requiring further study.

Alzheimer's Disease-Related Polymorphisms in Shunt-Responsive Idiopathic Normal Pressure Hydrocephalus

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a late onset, surgically treated progressive brain disease caused by impaired cerebrospinal fluid dynamics and subsequent ventriculomegaly. Comorbid Alzheimer's disease (AD) seems to be frequent in iNPH.

OBJECTIVE

We aim to evaluate the role of AD-related polymorphisms in iNPH.

METHODS

Overall 188 shunt-operated iNPH patients and 688 controls without diagnosed neurodegenerative disease were included into analysis. Twenty-three single-nucleotide polymorphisms (SNPs FRMD4A [rs7081208_A, rs2446581_A, rs17314229_T], CR1, BIN, CD2AP, CLU, MS4A6A, MS4A4E, PICALM, ABCA7, CD33, INPP5D, HLA_DRB5, EPHA1, PTK2B, CELF1, SORL1, FERMT2, SLC24A, DSG2, CASS4, and NME8) adjusted to APOE were analyzed between groups by using binary logistic regression analysis. Neuroradiological characteristics and AD-related changes in the right frontal cortical brain biopsies were available for further analysis.

RESULTS

Logistic regression analysis adjusted to age, gender, and other SNPs indicated allelic variation of NME8 between iNPH patients and non-demented controls (p = 0.014). The allelic variation of NME8 was not related to the neuropathological changes in the brain biopsies of iNPH patients. However, periventricular white matter changes (p = 0.017) were more frequent in the iNPH patients with the AA-genotype, an identified risk factor of AD.

CONCLUSIONS

Our findings increase the evidence that iNPH is characterized by genetic and pathophysiological mechanisms independent from AD. Considering that NME8 plays a role in the ciliary function and displays SNP-related diversity in white matter changes, the mechanisms of NME8 in iNPH and other neurodegenerative processes are worth further study.

A Segmental Copy Number Loss of the SFMBT1 Gene Is a Genetic Risk for Shunt-Responsive, Idiopathic Normal Pressure Hydrocephalus (iNPH): A Case-Control Study

Little is known about genetic risk factors for idiopathic normal pressure hydrocephalus (iNPH). We examined whether a copy number loss in intron 2 of the SFMBT1 gene could be a genetic risk for shunt-responsive, definite iNPH. Quantitative and digital PCR analyses revealed that 26.0% of shunt-responsive definite iNPH patients (n = 50) had such a genetic change, as compared with 4.2% of the healthy elderly (n = 191) (OR = 7.94, 95%CI: 2.82–23.79, p = 1.8 x 10⁻⁵) and 6.3% of patients with Parkinson’s disease (n = 32) (OR = 5.18, 95%CI: 1.1–50.8, p = 0.038). The present study demonstrates that a copy number loss within intron 2 of the SFMBT1 gene may be a genetic risk factor for shunt-responsive definite iNPH.

CSF tap test - Obsolete or appropriate test for predicting shunt responsiveness? A systemic review

OBJECTIVES

There is no accurate test for diagnosing normal pressure hydrocephalus or for screening for patients who will benefit from shunt surgery. Additional tests, such as cerebrospinal fluid tap test (CSF-TT), are often used in practice to provide further predictive value in detecting suitable patients for shunting. We performed a systematic review of the literature to evaluate the CSF-TT's effect on the outcome of main symptoms and on validity parameters in screening patients suitable for shunting.

METHODS

In February 2015 we searched electronic databases from their inception to the current date, using the following key words: normal pressure hydrocephalus, idiopathic normotensive hydrocephalus, shunt operation, CSF tap test, predictive value, validity. The search retrieved 8 articles explicitly addressing the topic.

RESULTS

There was a very high positive predictive value of CSF-TT: 92% (range from 73% to 100%) but a low negative predictive value: 37% (18%-50%). Also, the CSF-TT has high specificity: 75% (33%-100%) but average sensitivity: 58% (26%-87%). The overall accuracy of the test was 62% (45%-83%).

CONCLUSIONS

This systematic review did not provide unambiguous validity of the CSF-TT in the screening of patients for shunting. The validity of the CSF-TT is good for patient inclusion for shunting due to the fact that the positive response to the test is very reliable. Unfortunately, the negative response to the test does not reliably make these patients ineligible for shunting. Further studies are needed to improve and standardize the methodology in order to optimize the detection power of the test.

Panventriculomegaly with a wide foramen of Magendie and large cisterna magna

OBJECT The authors' goal in this paper is to provide the first clinical, radiological, and genetic studies of panventriculomegaly (PaVM) defined by a wide foramen of Magendie and large cisterna magna. METHODS Clinical and brain imaging data from 28 PaVM patients (including 10 patients from 5 families) were retrospectively studied. Five children were included. In adult patients, the age at onset was 56.0 ± 16.7 years. Tetraventricular dilation, aqueductal opening with flow void on T2-weighted images, and a wide foramen of Magendie and large cisterna magna (wide cerebrospinal fluid space at the fourth ventricle outlet) were essential MRI findings for PaVM diagnosis. 3D fast asymmetrical spin echo sequences were used for visualization of cistern membranes. Time-spatial labeling inversion pulse examination was performed to analyze cerebrospinal fluid movement. Copy number variations were determined using high-resolution microarray and were validated by quantitative polymerase chain reaction with breakpoint sequencing. RESULTS Adult patients showed gait disturbance, urinary dysfunction, and cognitive dysfunction. Five infant patients exhibited macrocranium. Patients were divided into 2 subcategories, those with or without downward bulging third ventricular floors and membranous structures in the prepontine cistern. Patients with bulging floors were successfully treated with endoscopic third ventriculostomy. Genetic analysis revealed a deletion in DNAH14 that encodes a dynein heavy chain protein associated with motile cilia function, and which co-segregated with patients in a family without a downward bulging third ventricular floor. CONCLUSIONS Panventriculomegaly with a wide foramen of Magendie and a large cisterna magna may belong to a subtype of congenital hydrocephalus with familial accumulation, younger age at onset, and symptoms of normal pressure hydrocephalus. In addition, a family with PaVM has a gene mutation associated with dysfunction of motile cilia.

[Hakim-Adams syndrome]

Hakim-Adams syndrome is little known, although quite common disease. The etiology is not fully clear. Pathogenetic mechanisms included the blockage of cerebrospinal fluid outflow along the upper lateral surface of the brain, development of hydrocephalus with the expansion of the brain ventricles while maintaining normotensive cerebrospinal fluid (CSF). Main manifestations are ataxia, apraxia, symptoms of dementia and urinary disturbances, up to incontinence. Diagnosis is based on clinical symptoms, exploratory lumbar and neuroimaging. Main treatment is ventriculoperitoneal (stomach) shunt placement for fluid drainage. Timely surgical intervention gives good results and improves quality of life of patients.

Cerebrospinal fluid biomarker and brain biopsy findings in idiopathic normal pressure hydrocephalus

Background

The significance of amyloid precursor protein (APP) and neuroinflammation in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) is unknown.

Objective

To investigate the role of soluble APP (sAPP) and amyloid beta (Aβ) isoforms, proinflammatory cytokines, and biomarkers of neuronal damage in the cerebrospinal fluid (CSF) in relation to brain biopsy Aβ and hyperphosphorylated tau (HPτ) findings.

Methods

The study population comprised 102 patients with possible NPH with cortical brain biopsies, ventricular and lumbar CSF samples, and DNA available. The final clinical diagnoses were: 53 iNPH (91% shunt-responders), 26 AD (10 mixed iNPH+AD), and 23 others. Biopsy samples were immunostained against Aβ and HPτ. CSF levels of AD-related biomarkers (Aβ42, p-tau, total tau), non-AD-related Aβ isoforms (Aβ38, Aβ40), sAPP isoforms (sAPPα, sAPPβ), proinflammatory cytokines (several interleukins (IL), interferon-gamma, monocyte chemoattractant protein-1, tumor necrosis factor-alpha) and biomarkers of neuronal damage (neurofilament light and myelin basic protein) were measured. All patients were genotyped for APOE.

Results

Lumbar CSF levels of sAPPα were lower (p<0.05) in patients with shunt-responsive iNPH compared to non-iNPH patients. sAPPβ showed a similar trend (p = 0.06). CSF sAPP isoform levels showed no association to Aβ or HPτ in the brain biopsy. Quantified Aβ load in the brain biopsy showed a negative correlation with CSF levels of Aβ42 in ventricular (r = −0.295, p = 0.003) and lumbar (r = −0.356, p = 0.01) samples, while the levels of Aβ38 and Aβ40 showed no correlation. CSF levels of proinflammatory cytokines and biomarkers of neuronal damage did not associate to the brain biopsy findings, diagnosis, or shunt response. Higher lumbar/ventricular CSF IL-8 ratios (p<0.001) were seen in lumbar samples collected after ventriculostomy compared to the samples collected before the procedure.

Conclusions

The role of sAPP isoforms in iNPH seems to be independent from the amyloid cascade. No neuroinflammatory background was observed in iNPH or AD.