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

Clinical correlates of obstructive sleep apnoea in idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

The pathogenesis of idiopathic normal pressure hydrocephalus (iNPH) remains controversial. Limited studies have indicated a high prevalence of obstructive sleep apnoea (OSA) amongst iNPH patients. The aim was to investigate the clinical correlates of OSA in iNPH patients.

METHODS

In this cross-sectional observational study, consecutive iNPH patients were prospectively enrolled. Evaluations included the iNPH Rating Scale, the Movement Disorder Society Unified Parkinson's Disease Rating Scale part III, the time and number of steps to walk 10 m, the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, a complete neuropsychological evaluation, 3-T brain MRI, full-night video-polysomnography, tap test and cerebrospinal fluid (CSF) neurodegeneration biomarkers.

RESULTS

Fifty-one patients were screened, of whom 38 met the inclusion criteria. Amongst the recruited patients, 19/38 (50%) exhibited OSA, with 12/19 (63.2%) presenting moderate to severe disorder. OSA+ iNPH patients required more time (p = 0.02) and more steps (p = 0.04) to complete the 10-m walking test, had lower scores on the gait subitem of the iNPH Rating Scale (p = 0.04) and demonstrated poorer performance on specific neuropsychological tests (Rey Auditory Verbal Learning Test immediate recall, p = 0.03, and Rey-Osterrieth Complex Figure, p = 0.01). Additionally, OSA+ iNPH patients had higher levels of total tau (p = 0.02) and phospho-tau (p = 0.03) in their CSF but no statistically significant differences in beta-amyloid (1-42) levels compared to OSA- iNPH patients.

CONCLUSION

Obstructive sleep apnoea is highly prevalent in iNPH patients, particularly at moderate to severe levels. OSA is associated with worse motor and cognitive performance in iNPH. The CSF neurodegeneration biomarker profile observed in OSA+ iNPH patients may reflect OSA-induced impairment of cerebral fluid dynamics.

A General Neurologist's Practical Diagnostic Algorithm for Atypical Parkinsonian Disorders: A Consensus Statement

Purpose of Review

The most common four neurodegenerative atypical parkinsonian disorders (APDs) are progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal syndrome (CBS), and dementia with Lewy bodies (DLB). Their formal diagnostic criteria often require subspecialty experience to implement as designed and all require excluding competing diagnoses without clearly specifying how to do that. Validated diagnostic criteria are not available at all for many of the other common APDs, including normal pressure hydrocephalus (NPH), vascular parkinsonism (VP), or drug-induced parkinsonism (DIP). APDs also include conditions of structural, genetic, vascular, toxic/metabolic, infectious, and autoimmune origin. Their differential diagnosis can be challenging early in the course, if the presentation is atypical, or if a rare or non-neurodegenerative condition is present. This review equips community general neurologists to make an early provisional diagnosis before, or in place of, referral to a tertiary center. Early diagnosis would allay diagnostic uncertainty, allow prompt symptomatic management, provide disease-specific information and support resources, avoid further pointless testing and treatments, and create the possibility of trial referral.

Recent Findings

We address 64 APDs using one over-arching flow diagram and a series of detailed tables. Most instances of APDs can be diagnosed with a careful history and neurological exam, along with a non-contrast brain MRI. Additional diagnostic tests are rarely needed but are delineated where applicable. Our diagnostic algorithm encourages referral to a tertiary center whenever the general neurologist feels it would be in the patient's best interest. Our algorithm emphasizes that the diagnosis of APDs is an iterative process, refined with the appearance of new diagnostic features, availability of new technology, and advances in scientific understanding of the disorders. Clinicians' proposals for all diagnostic tests for the APDs, including repeat visits, should be discussed with patients and their families to ensure that the potential information to be gained aligns with their larger clinical goals.

Summary

We designed this differential diagnostic algorithm for the APDs to enhance general neurologists' diagnostic skills and confidence and to help them address the less common or more ambiguous cases.

Deep learning assisted quantitative analysis of Aβ and microglia in patients with idiopathic normal pressure hydrocephalus in relation to cognitive outcome

Neuropathologic changes of Alzheimer disease (AD) including Aβ accumulation and neuroinflammation are frequently observed in the cerebral cortex of patients with idiopathic normal pressure hydrocephalus (iNPH). We created an automated analysis platform to quantify Aβ load and reactive microglia in the vicinity of Aβ plaques and to evaluate their association with cognitive outcome in cortical biopsies of patients with iNPH obtained at the time of shunting. Aiforia Create deep learning software was used on whole slide images of Iba1/4G8 double immunostained frontal cortical biopsies of 120 shunted iNPH patients to identify Iba1-positive microglia somas and Aβ areas, respectively. Dementia, AD clinical syndrome (ACS), and Clinical Dementia Rating Global score (CDR-GS) were evaluated retrospectively after a median follow-up of 4.4 years. Deep learning artificial intelligence yielded excellent (>95%) precision for tissue, Aβ, and microglia somas. Using an age-adjusted model, higher Aβ coverage predicted the development of dementia, the diagnosis of ACS, and more severe memory impairment by CDR-GS whereas measured microglial densities and Aβ-related microglia did not correlate with cognitive outcome in these patients. Therefore, cognitive outcome seems to be hampered by higher Aβ coverage in cortical biopsies in shunted iNPH patients but is not correlated with densities of surrounding microglia.

A bibliometric analysis and visualization of normal pressure hydrocephalus

Background

Normal pressure hydrocephalus (NPH) has drawn an increasing amount of attention over the last 20 years. At present, there is a shortage of intuitive analysis on the trends in development, key contributors, and research hotspots topics in the NPH field. This study aims to analyze the evolution of NPH research, evaluate publications both qualitatively and quantitatively, and summarize the current research hotspots.

Methods

A bibliometric analysis was conducted on data retrieved from the Web of Science Core Collection (WoSCC) database between 2003 and 2023. Quantitative assessments were conducted using bibliometric analysis tools such as VOSviewer and CiteSpace software.

Results

A total of 2,248 articles published between 2003 and 2023 were retrieved. During this period, the number of publications steadily increased. The United States was the largest contributor. The University of Gothenburg led among institutions conducting relevant research. Eide P. K. was the most prolific author. The Journal of Neurosurgery is the leading journal on NPH. According to the analysis of the co-occurrence of keywords and co-cited references, the primary research directions identified were pathophysiology, precise diagnosis, and individualized treatment. Recent research hotspots have mainly focused on epidemiology, the glymphatic system, and CSF biomarkers.

Conclusion

The comprehensive bibliometric analysis of NPH offers insights into the main research directions, highlights key countries, contributors, and journals, and identifies significant research hotspots. This information serves as a valuable reference for scholars to further study NPH.

Ventriculoperitoneal shunt patients and glaucoma: a cohort analysis of the NPH registry

BACKGROUND

Idiopathic Normal Pressure Hydrocephalus (iNPH) is a chronic condition affecting the elderly. It is characterized by a triad of symptoms and radiological findings. Glaucoma is the leading cause of irreversible blindness worldwide. Earlier studies have proposed that the rate of glaucoma is higher in iNPH patients, and of a possible link between ventriculoperitoneal shunt (VP) treatment and the development of glaucoma.

OBJECTIVES

This study aimed to determine the prevalence of glaucoma among iNPH patients and assess the impact of VPs on glaucoma prevalence.

METHODS

A cohort study was conducted at Kuopio University Hospital (KUH), including 262 patients with a ventriculoperitoneal shunt. Clinical data were obtained from the Kuopio NPH Registry and medical records. Patients were grouped by iNPH status: iNPH (+) - probable/possible iNPH (n = 192), and iNPH (-) - other causes of hydrocephalus (congenital, secondary, obstructive) (n = 70). We conducted statistical analysis using the Independent Samples T-test, Fisher's exact test, and Pearson Chi-Square. We compared demographics, glaucoma prevalence, brain biopsies positive for Amyloid-β (Aβ) and hyperphosphorylated tau (HPτ) as well as comorbidities for hypertension and diabetes medication. Age stratification assessed glaucoma prevalence in the full cohort.

RESULTS

Both iNPH (+) and iNPH (-) groups had comparable demographic and comorbidity profiles. The prevalence of glaucoma in the iNPH (+) group was 11.5% (n = 22) and 11.4% (n = 8) in the iNPH (-) group without a statistically significant difference (p = 1.000). Brain biopsies positive for Amyloid-β (Aβ) and hyperphosphorylated tau (HPτ) were similar.

CONCLUSIONS

Neither shunted iNPH patients nor those with a comorbid condition other than iNPH showed a markedly higher prevalence of glaucoma. Instead, both groups exhibited age-related increases in glaucoma prevalence, similar to the trends observed in population-based studies. Our data does not suggest a correlation between VP shunts and an elevated rate of glaucoma.

A Rare Presentation of Functional Movement Disorder Mimicking Normal Pressure Hydrocephalus

Herein, we describe a 55-year-old female patient with a functional movement disorder (FMD) who presented with normal pressure hydrocephalus (NPH)-like clinic. The neuroimaging data and positive response to the tap test initially suggested NPH. However, a detailed investigation of the clinic features yielded a final diagnosis of FMD. Via the presentation of this patient, we expand the phenomenology of FMD. To our knowledge, this is the first presentation of a patient with FMD mimicking NPH. Therefore, we think this rare illustration is interesting and may provide valuable perspectives for clinical practice.

Structural neuroimaging markers of normal pressure hydrocephalus versus Alzheimer's dementia and Parkinson's disease, and hydrocephalus versus atrophy in chronic TBI-a narrative review

Introduction

Normal Pressure Hydrocephalus (NPH) is a prominent type of reversible dementia that may be treated with shunt surgery, and it is crucial to differentiate it from irreversible degeneration caused by its symptomatic mimics like Alzheimer's Dementia (AD) and Parkinson's Disease (PD). Similarly, it is important to distinguish between (normal pressure) hydrocephalus and irreversible atrophy/degeneration which are among the chronic effects of Traumatic Brain Injury (cTBI), as the former may be reversed through shunt placement. The purpose of this review is to elucidate the structural imaging markers which may be foundational to the development of accurate, noninvasive, and accessible solutions to this problem.

Methods

By searching the PubMed database for keywords related to NPH, AD, PD, and cTBI, we reviewed studies that examined the (1) distinct neuroanatomical markers of degeneration in NPH versus AD and PD, and atrophy versus hydrocephalus in cTBI and (2) computational methods for their (semi-) automatic assessment on Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) scans.

Results

Structural markers of NPH and those that can distinguish it from AD have been well studied, but only a few studies have explored its structural distinction between PD. The structural implications of cTBI over time have been studied. But neuroanatomical markers that can predict shunt response in patients with either symptomatic idiopathic NPH or post-traumatic hydrocephalus have not been reliably established. MRI-based markers dominate this field of investigation as compared to CT, which is also reflected in the disproportionate number of MRI-based computational methods for their automatic assessment.

Conclusion

Along with an up-to-date literature review on the structural neurodegeneration due to NPH versus AD/PD, and hydrocephalus versus atrophy in cTBI, this article sheds light on the potential of structural imaging markers as (differential) diagnostic aids for the timely recognition of patients with reversible (normal pressure) hydrocephalus, and opportunities to develop computational tools for their objective assessment.

Forget About Memory: Disentangling the Amnestic Syndrome in Idiopathic Normal Pressure Hydrocephalus

Background

Idiopathic normal pressure hydrocephalus (iNPH) can present with both episodic amnestic syndrome and biomarkers of Alzheimer's disease (AD) pathology.

Objective

To examine the associations between amnestic syndrome and cerebrospinal fluid (CSF) AD biomarkers in iNPH and the CSF tap test response in iNPH patients with amnestic syndrome.

Methods

We used the Free and Cued Selective Reminding Test to divide iNPH into amnestic and non-amnestic patients. We compared their clinical, biological, and radiological characteristics and examined the reversibility of gait spatiotemporal parameters and neuropsychological performances after a CSF tap test. Univariate and multiple linear regression models examined the association between memory performance and clinical-biological characteristics.

Results

Sixty-two non-amnestic patients (mean age 77.0±7.0 years, 38.7% female) and thirty-eight amnestic patients (mean age 77.0±5.9 years, 36.8% female) presented similar levels of AD biomarkers and clinical-radiological profiles. Global cognition and education levels were lower in the amnestic iNPH group. We found no association between AD biomarkers and memory performances (total tau: β= -4.50; 95% CI [-11.96;2.96]; p = 0.236; amyloid-β (1-42): β= 8.60, 95% CI [-6.30;23.50]; p = 0.240). At baseline, amnestic iNPH patients performed worse on executive functions, attention, and gait speed but improved similarly to the non-amnestic iNPH patients after the tap test.

Conclusions

In our clinical sample of iNPH patients, we confirm the lack of specificity of the amnestic profile for predicting AD pathology. Clinicians should not preclude amnestic iNPH patients from undergoing an invasive procedure of CSF derivation.

Exploring the Association Between Visual Field Testing and CERAD Neuropsychological Battery in Idiopathic Normal Pressure Hydrocephalus Patients

Background

Association between visual field test indices and The Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Battery (CERAD-NB) is unknown. Idiopathic normal pressure hydrocephalus (iNPH) patients provide a unique set of patient data for analysis.

Objective

To assess the reliability of visual field testing using the CERAD-NB in patients with iNPH and to investigate the association between visual field test results and cognitive function.

Methods

62 probable iNPH patients were subjected to comprehensive ophthalmological examination, ophthalmological optical coherence tomography imaging studies, visual field testing, and CERAD-NB. Based on visual field indices, the patients were divided into two groups: unreliable (n = 19) and reliable (n = 43). Independent T-test analysis was performed to examine the relationship between visual field test results and cognitive function. Pearson Chi-square test was used for non-continuous variables.

Results

The unreliable group performed worse in CERAD-NB subtests compared to the reliable group. Statistically significant differences were observed in nine out of ten subtests, with only Clock Drawing showing no statistical significance. Pairwise comparison of the groups showed no statistical significance between amyloid-β (Aβ) biopsy, hyperphosphorylated tau biopsy, apolipoprotein E allele or the ophthalmological status of the patient. But there was a statistically significant difference in cerebrospinal fluid Aβ42 and age between the groups.

Conclusions

Patients with unreliable visual field tests performed worse on CERAD-NB subtests. CERAD-NB subtests do not provide a specific cut-off value to refrain patients from visual field testing. Should patients with unreliable visual field tests be screened for cognitive impairment?

Gait Analysis in Idiopathic Normal Pressure Hydrocephalus: A Meta-Analysis

Background

Gait analysis objectively quantifies gait impairment in idiopathic normal pressure hydrocephalus (iNPH), may improve diagnosis and evaluation for surgical candidacy.

Objectives

This meta-analysis aims to understand which objective gait parameters improve after tap-test (TT) and CSF shunt surgery (CSS), also comparing responders (R) with non-responders (NR) and to assess if gait restores within the range of healthy controls after procedures.

Methods

Studies enrolling iNPH with at least one instrumented gait measure were selected. Three time points of gait assessment were defined: PRE, POST-TT, and POST-CSS. Gait velocity, cadence, step length, stride length, and double limb support time were evaluated. Patients were categorized based on responsiveness to CSF diversion procedures.

Results

Seventeen studies including 527 patients were selected. iNPH improved significantly in almost all gait parameters POST-TT, and to a greater extent POST-CSS. Gait parameters consistently discriminated iNPH from healthy controls. Despite the aforementioned improvements, iNPH's gait did not completely normalize after CSF diversion procedures. Meta-regression analysis also revealed that TT's effect on gait velocity plateaus after 24-48 hr and returns to baseline in 90-100 hr.

Conclusions

Gait analysis is a reliable quantitative instrument to assess gait impairment in iNPH, demarking a net differentiation from healthy controls, according to the notion that the iNPH CSF dynamic alteration also leads to an irreversible damage. Specific gait parameters improve among TT-R, providing an opportunity to select patients that will respond to CSS. Future studies validating a standardized reporting method including criteria of responsiveness, specific gait parameters, and timeframe of assessment are needed.

MDS-UDPRS-III in the diagnosis of idiopathic Normal Pressure Hydrocephalus and identification of candidates for Ventriculo-Peritoneal Shunting surgery. Results from a retrospective large cohort of patients

OBJECTIVES

To evaluate the entity of extrapyramidal signs, characterize them and evaluate the dynamics of change by the mean of MDS-UPDRS-III in iNPH patients after the TT to determine if this tool may help the diagnosis of iNPH and the identification of candidates for Ventriculo-Peritoneal Shunting.

MATERIALS AND METHODS

We retrospectively collected data from 120 patients with the initial diagnosis of possible iNPH; they underwent neurological examination by the means of MDS-UPDRS-III and other scales before and after Tap Test (TT). They were then classified as defined iNPH (57), probable iNPH (35), and NOT-iNPH (28) based on the clinical response after the Tap Test and VPS.

RESULTS

After the Tap Test, defined and probable iNPH groups improved by 3.35 (2.57-4.12, p < 0.001) and 3.43 (2.43-4.4, p < 0.001) points on MDS-UPDRS-III respectively; NOT-iNPH did not improve significantly on MDS-UPDRS-III and on any other variable studies. Defined iNPH also shifted significantly from asymmetric prevalence of symptoms to a more symmetric form (from 70% before to 57% after).

CONCLUSION

extrapyramidal signs improved significantly after the Tap Test in definite and probable iNPH patients. MDS-UPDRS-III may be a useful complementary tool in the diagnosis of iNPH and identification of candidates for Ventriculo-Peritoneal Shunting.

Clinical Features of Idiopathic Normal Pressure Hydrocephalus: Critical Review of Objective Findings

Background

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by the classic clinical triad of gait, cognitive, and urinary dysfunction, albeit incomplete in a relevant proportion of patients. The clinical findings and evolution of these symptoms have been variably defined in the literature.

Objectives

To evaluate how the phenomenology has been defined, assessed, and reported, we performed a critical review of the existing literature discussing the phenomenology of iNPH. The review also identified the instrumental tests most frequently used and the evolution of clinical and radiologic findings.

Methods

The review was divided into 3 sections based on gait, cognitive, and urinary dysfunction. Each section performed a literature search using the terms "idiopathic normal pressure hydrocephalus" (iNPH), with additional search terms used by each section separately. The number of articles screened, duplicates, those meeting the inclusion criteria, and the number of articles excluded were recorded. Findings were subsequently tallied and analyzed.

Results

A total of 1716 articles with the aforementioned search criteria were identified by the 3 groups. A total of 81 full-text articles were reviewed after the elimination of duplicates, articles that did not discuss phenomenological findings or instrumental testing of participants with iNPH prior to surgery, and articles with fewer than 10 participants.

Conclusions

"Wide-based gait" was the most common gait dysfunction identified. Cognitive testing varied significantly across articles, and ultimately a specific cognitive profile was not identified. Urodynamic testing found detrusor overactivity and "overactive bladder" as the most common symptom of urinary dysfunction.

Alpha-Synuclein RT-QuIC in Idiopathic Normal Pressure Hydrocephalus

This study quantified the occurrence of an underlying synucleinopathy in 50 patients with idiopathic normal pressure hydrocephalus by means of real-time quaking-induced conversion, a highly sensitive and specific technique capable of detecting and amplifying misfolded aggregated forms of α-synuclein in the cerebrospinal fluid. Seven patients were positive and they did not differ from negative cases, except for a more frequent L-dopa responsiveness and gait characterized by a wider base. The two groups did not differ in terms of response rate to tap test or shunt surgery, although step length and gait velocity improved by a lesser extent in positive cases. This article is protected by copyright. All rights reserved.

Addressing the Devil Within: Normal Pressure Hydrocephalus—A Narrative Review

Normal pressure hydrocephalus (NPH) is the most frequently occurring form of hydrocephalus among adults. It is characterized clinically by the classical triad, called Hakim's triad, comprising gait issues, cognitive impairment, and urinary problems. NPH may be primary or idiopathic (iNPH) or secondary. Characteristic neuroimaging features occur, which are vital to diagnosis. Diagnostic criteria in the form of Japanese guideline and Congress of Neurological Surgeons 2005 guidelines have been devised, and broadly, are based on a constellation of clinical and neuroimaging features, in association with cerebrospinal fluid (CSF) testing. CSF tap test, extended lumbar drainage, and CSF infusion tests are invasive diagnostic tests. CSF tap test and extended lumbar drainage are used to demonstrate clinical reversibility with CSF drainage, and patients who demonstrate this are candidates for CSF shunting. However, due to the low negative predictive value of these tests, potential response to shunting cannot be negated among patients who do not respond to CSF drainage. Various shunting procedures are used for treatment, including ventriculoperitoneal, lumboperitoneal, and ventriculoatrial shunts. Endoscopic third ventriculostomy has also been attempted with limited success. Among the clinical features, gait abnormalities are most responsive to shunting. Persistent long-term response to shunting has been reported. Patients need to be meticulously followed up after the shunting procedure, to assess clinical and neuroimaging response, and detect possible shunt-related complications, especially CSF over-drainage. Early treatment is associated with better prognosis, and it is crucial to recognize and treat this condition before the development of severe symptoms.

Idiopathic normal pressure hydrocephalus-like MRI features in patients with progressive supranuclear palsy: a comparative case-control study

BACKGROUND

The occurrence of neurodegenerative disease in patients with normal pressure hydrocephalus (NPH) is emphasized in recent reports. Based on this common co-occurrence, some of the hydrocephalic disorders appearing in late adulthood have been hypothesized to result from initially unapparent parenchymal abnormalities of neurodegenerative origin. Among these diseases, progressive supranuclear palsy (PSP) has been specifically remarked on. We aimed to comparatively investigate the neuroimaging clues of iNPH in our PSP subjects.

METHODS

Eighteen patients with a clinical diagnosis of PSP, 44 with Parkinson's disease (PD), and 44 healthy control (HC) individuals were enrolled. The disproportionately enlarged subarachnoid space hydrocephalus (DESH) score, the Evans' index (EI), and the callosal angle (CA) were measured on the conventional magnetic resonance imaging (MRI). The comparative analyses were performed using IBM SPSS Statistics 26.

RESULTS

We found that dilated Sylvian fissures score (p = 0.016) and focal sulcal dilatation score (p = 0.037) were higher in the PSP group in comparison to HC whereas the CA score was higher in PSP subjects in comparison to both PD patients and HC (p = 0.000). Remarkably, the DESH score was also found to be higher in the PSP group in comparison to the age-matched HC group (p = 0.024).

CONCLUSIONS

We found that the NPH-like MRI features were more common in PSP subjects in comparison to PD subjects and age-matched HC. These results may provide critical contributions to the literature regarding the overlap between PSP and NPH.

Can Shunt Response in Patients with Idiopathic Normal Pressure Hydrocephalus Be Predicted from Preoperative Brain Imaging? A Retrospective Study of the Diagnostic Use of the Normal Pressure Hydrocephalus Radscale in 119 Patients

BACKGROUND AND PURPOSE

The Normal Pressure Hydrocephalus Radscale is a combined scoring of 7 different structural imaging markers on preoperative brain CT or MR imaging in patients with idiopathic normal pressure hydrocephalus: callosal angle, Evans Index, Sylvian fissure dilation, apical sulcal narrowing, mean temporal horn diameter, periventricular WM lesions, and focal sulcal dilation. The purpose of this retrospective study was to assess the performance of the Normal Pressure Hydrocephalus Radscale in distinguishing idiopathic normal pressure hydrocephalus shunt responders from nonresponders.

MATERIALS AND METHODS

The preoperative MR imaging and CT scans of 119 patients with idiopathic normal pressure hydrocephalus were scored using the Normal Pressure Hydrocephalus Radscale. A summary shunt-response score assessed within 6 months from ventriculoperitoneal shunt surgery, combining the effect on cognition, gait, and urinary incontinence, was used as a reference. The difference between the mean Normal Pressure Hydrocephalus Radscale for responders and nonresponders was tested using the Student t test. The area under the curve was calculated for the Normal Pressure Hydrocephalus Radscale to assess shunt response. To ascertain reproducibility, we assessed the interobserver agreement between the 2 independent observers as intraclass correlation coefficients for the Normal Pressure Hydrocephalus Radscale for 74 MR imaging scans and 19 CT scans.

RESULTS

Ninety-four (79%) of 119 patients were shunt responders. The mean Normal Pressure Hydrocephalus Radscale score for shunt responders was 8.35 (SD, 1.53), and for nonresponders, 7.48 (SD, 1.53) (P = .02). The area under the curve for the Normal Pressure Hydrocephalus Radscale was 0.66 (range, 0.54-0.78). The intraclass correlation coefficient for the Normal Pressure Hydrocephalus Radscale was 0.86 for MR imaging and 0.82 for CT.

CONCLUSIONS

The Normal Pressure Hydrocephalus Radscale showed moderate discrimination for shunt response but cannot, on its own, be used for selecting patients with idiopathic normal pressure hydrocephalus for shunt surgery.

Progression in Neuroimaging of Normal Pressure Hydrocephalus

Normal-pressure hydrocephalus is a clinical syndrome that mainly targets the elderly population. It features dementia, impaired walking, and the malfunction of sphincters. The rapid identification and large-scale screening of patients with normal-pressure hydrocephalus (NPH) are of great significance as surgical interventions can greatly improve or even reverse the symptoms. This review aims to summarize the traditional parameters used to diagnose NPH and the emerging progression in neuroimaging of the disease, hoping to provide an up-to-date overall perspective and summarize the possible direction of its future development.

Single sensor measurement of heel-height during the push-off phase of gait

Objective. In healthy gait a forceful push-off is needed to get an efficient leg swing and propulsion, and a high heel lift makes a forceful push-off possible. The power of the push-off is decreased with increased age and in persons with impaired balance and gait. The aim of this study was to evaluate whether a wearable equipment (Striton) and algorithms to estimate vertical heel-height during gait from a single optical distance sensor is reliable and feasible for clinical applications.Approach. To assess heel-height with the Striton system an optical distance sensor was used to measure the distance to the floor along the shank. An algorithm was created to transform this measure to a vertical distance. The heel-height was validated in an experimental setup, against a 3D motion capture system (MCS), and test-retest and day-to-day tests were performed on 10 elderly persons. As a reference material 83 elderly persons were included, and heel-height was measured before and after surgery in four patients with the neurological disorder idiopathic normal pressure hydrocephalus (iNPH).Main results. In the experimental setup the accuracy was high with a maximum error of 2% at all distances, target colours and inclination angles, and the correlation to the MCS wasR= 0.94. Test-retest and day-to-day tests were equal within ±1.2 cm. Mean heel-height of the elderly persons was 16.5 ± 0.6 cm and in the patients with iNPH heel-height was increased from 11.2 cm at baseline to 15.3 cm after surgery.Significance. Striton can reliably measure heel-height during gait, with low test-retest and day-to-day variability. The system was easy to attach, and simple to use, which makes it suitable for clinical applications.

Ventriculoatrial Shunting: An Escape Option in Patients with Idiopathic Normal Pressure Hydrocephalus Failing Ventriculoperitoneal Drainage

BACKGROUND

Ventriculoperitoneal (VP) shunting is widely accepted as the gold-standard treatment for idiopathic normal pressure hydrocephalus (iNPH). However, a restricted group of patients experience only minimal or no improvement after the operation. In such cases, the question whether the diagnosis was incorrect or the shunt is malfunctioning remains unanswered.

METHODS

We retrospectively collected data on a 10-year series of VP-shunted patients with iNPH showing transient or minimal improvement of symptoms within 3 weeks from surgery. A full workup (including noninvasive diagnostic, cognitive, and invasive tests) was performed. After ruling out mechanical malfunction, we performed a tap test followed by a Katzman test 2 weeks later. The confirmed persistence of disturbance of cerebrospinal fluid dynamics was treated by shunt revision and, if found working, by its replacement into the atrial cavity.

RESULTS

Twenty patients were diagnosed with shunt insufficiency. At surgery, the distal end of the shunt was easily extruded and found working in all cases. It was then repositioned into the right atrium (the first 8 patients of the series also underwent failed contralateral abdominal replacement). Early postoperative clinical improvement was always confirmed. In 1 case, shunt overdrainage was corrected by valve upregulation.

CONCLUSIONS

According to our experience, inadequate distal end placement of a shunt might be one of the reasons needing investigation in patients with iNPH failing improvement after surgery. In such situations, the conversion to a ventriculoatrial shunt proved to be a low-cost and successful treatment option.

Parkinsonism and cerebrospinal fluid disorders

BACKGROUND

Although various motor manifestations can be seen in patients with cerebrospinal fluid (CSF) disorders, such as hydrocephalus or intracranial hypotension, the clinical presentation with parkinsonism is not clearly elucidated.

METHODS

We searched the literature for studies describing the occurrence of parkinsonism in subjects with normal pressure hydrocephalus (NPH), obstructive hydrocephalus, and intracranial hypotension. We analyzed the clinical presentation (particularly with respect to bradykinesia, rigidity, rest tremor, and gait disturbance/postural instability) as well as the response to treatment.

RESULTS

Parkinsonism was most commonly reported in NPH patients. Although gait disturbance/postural instability is a well-known motor symptom of NPH, other cardinal signs include upper limb involvement or asymmetric presentation. As for obstructive hydrocephalus, parkinsonism was mainly observed in subjects with aqueductal stenosis and more often after shunt surgery. Patients with NPH or obstructive hydrocephalus rarely improved with levodopa therapy, while most subjects only improved with shunt surgery. Although the mechanism is still controversial, a functional involvement of nigrostriatal pathway has been hypothesized based on imaging studies and case reports. Brain imaging is also helpful for atypical cases of intracranial hypotension presenting with parkinsonism. Parkinsonism improved after treatment in such cases as well.

CONCLUSIONS

Studies exploring the relationship between CSF disorders and parkinsonism are mainly descriptive and their quality is generally poor. However, considering that these disorders can be treated, clinicians' awareness of the differential diagnosis is important and future studies better exploring the underlying pathophysiological mechanisms are warranted. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

The etiopathogenetic and pathophysiological spectrum of parkinsonism

Parkinsonism is a syndrome characterized by bradykinesia, rigidity, and tremor. Parkinsonism is a common manifestation of Parkinson's disease and other neurodegenerative diseases referred to as atypical parkinsonism. However, a growing body of clinical and scientific evidence indicates that parkinsonism may be part of the phenomenological spectrum of various neurological conditions to a greater degree than expected by chance. These include neurodegenerative conditions not traditionally classified as movement disorders, e.g., dementia and motor neuron diseases. In addition, parkinsonism may characterize a wide range of central nervous system diseases, e.g., autoimmune diseases, infectious diseases, cerebrospinal fluid disorders (e.g., normal pressure hydrocephalus), cerebrovascular diseases, and other conditions. Several pathophysiological mechanisms have been identified in Parkinson's disease and atypical parkinsonism. Conversely, it is not entirely clear to what extent the same mechanisms and key brain areas are also involved in parkinsonism due to a broader etiopathogenetic spectrum. We aimed to provide a comprehensive and up-to-date overview of the various etiopathogenetic and pathophysiological mechanisms of parkinsonism in a wide spectrum of neurological conditions, with a particular focus on the role of the basal ganglia involvement. The paper also highlights potential implications in the diagnostic approach and therapeutic management of patients. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Comorbid alpha synucleinopathies in idiopathic normal pressure hydrocephalus

OBJECTIVE

This study aimed to determine the prevalence and clinical features of Parkinson's disease (PD)/PD dementia (PD/PDD) or dementia with Lewy bodies (DLB) in idiopathic normal pressure hydrocephalus (iNPH).

METHODS

Patients with iNPH who were admitted to the Department of Neurology, Juntendo University School of Medicine over the past 10 years have been retrospectively analyzed. The diagnosis of iNPH and concomitant PD/PDD or DLB was established using diagnostic criteria. Motor symptoms were assessed by the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III. ¹²³I-ioflupane single-photon emission computed tomography (DaT-SPECT) and cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC)-based assay were performed for alpha synuclein aggregation.

RESULTS

Overall, 79 patients met the criteria for iNPH, of which 34 developed iNPH without accompanying disorders (iNPHa; 43%), 23 developed iNPH with comorbid PD/PDD (iNPHc + PD/PDD; 29.1%), and 8 developed iNPH with comorbid DLB (iNPHc + DLB; 10.1%). Significant differences in facial expansion and upper-limb parkinsonism were observed with a comorbidity of either PD/PDD or DLB. The specific binding ratio (SBR) of DaTscan was reduced in iNPHa (p = 0.02), but it reduced further with comorbid PD/PDD (p < 0.01) or DLB (p < 0.01). RT-QuIC was positive for all 13 comorbid PD/PDD and negative for all 19 iNPHa.

CONCLUSION

These results highlight that synucleinopathies coexist with iNPH. These can be differentiated by performing DaTscan and RT-QuIC, which can affect its clinical features.

Reappraisal of Pediatric Normal-Pressure Hydrocephalus

While normal-pressure hydrocephalus (NPH) is most commonly diagnosed in older adulthood, a significant body of literature has accumulated over half a century documenting the clinical phenomenon of an NPH-like syndrome in pediatric patients. As in adult NPH, it is likely that pediatric NPH occurs due to a heterogeneous array of developmental, structural, and neurodegenerative pathologies, ultimately resulting in aberrant cerebrospinal fluid (CSF) flow and distribution within and around the brain. In this review, we aimed to systematically survey the existing clinical evidence supporting the existence of a pediatric form of NPH, dating back to the original recognition of NPH as a clinically significant subtype of communicating hydrocephalus. Leveraging emergent trends from the old and more recent published literature, we then present a modern characterization of pediatric NPH as a disorder firmly within the same disease spectrum as adult NPH, likely with overlapping etiology and pathophysiological mechanisms. Exemplary cases consistent with the diagnosis of pediatric NPH selected from the senior author’s neurosurgical practice are then presented alongside the systematic review to aid in discussion of the typical clinical and radiographic manifestations of pediatric NPH. Common co-morbidities and modern surgical treatment options are also described.