A combined cognitive and gait quantification to identify normal pressure hydrocephalus from its mimics: The Geneva’s protocol

Evolution of neurodegeneration in patients with normal pressure hydrocephalus: a monocentric follow up study

BACKGROUND

The aim of this study was to examine in patients with idiopathic and neurodegenerative normal pressure hydrocephalus (NPH) if motor and cognitive performance as well as changes in biomarkers in cerebrospinal fluid (CSF) evolve differently.

METHODS

41 patients with a typical clinical and MR-/CT-morphological presentation of NPH divided into an Alzheimer-negative (AD-, n = 25) and an Alzheimer-positive (AD+, n = 16) group according to neurodegenerative biomarkers (S100 protein, neuron-specific enolase, β-amyloid 1-42, Tau protein, phospho-Tau, protein-level and CSF pressure) in CSF. Follow-up of cognitive and gait functions before and after a spinal tap of 40-50 ml CSF of up to 49 months. Clinical, motor, neuropsychological and CSF biomarkers were analyzed using a repeated multifactorial analysis of variance (ANOVA) with post-hoc testing.

RESULTS

Gait and neuropsychological performance and CSF biomarkers evolved differently between the AD- and AD+ patients. In particular, the AD+ patients benefited from the spinal tap regarding short-term memory. In contrast, gait parameters worsened over time in the AD+ patients, although they showed a relevant improvement after the first tap.

CONCLUSIONS

The results substantiate the recently reported association between a tap-responsive NPH and CSF changes of Alzheimer disease. Furthermore, they suggest that the AD changes in CSF manifest in an age-related fashion in AD- patients presenting with NPH.

Gait Apraxia and Hakim’s Disease: A Historical Review

In 1965, Prof. Salomón Hakim described, for the first time, a condition characterized by normal pressure hydrocephalus and gait alterations. During the following decades, definitions such as “Frontal Gait”, “Bruns’ Ataxia” and “Gait Apraxia” have been frequently used in pertinent literature in the attempt to best define this peculiar motor disturbance. More recently, gait analysis has further shed light on the typical spatiotemporal gait alterations that characterize this neurological condition, but a clear and shared definition of this motor condition is still lacking. In this historical review, we described the origins of the terms “Gait Apraxia”, “Frontal Gait” and “Bruns’ Ataxia”, starting with the first works of Carl Maria Finkelburg, Fritsch and Hitzig and Steinthal during the second half of the 19th century and ending with Hakim’s studies and his formal definition of idiopathic normal pressure hydrocephalus (iNPH). In the second part of the review, we analyze how and why these definitions of gait have been associated with Hakim’s disease in the literature from 1965 to the present day. The definition of “Gait and Postural Transition Apraxia” is then proposed, but fundamental questions about the nature and mechanisms underlying this condition remain unanswered.

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.

Quantification of pathological gait parameter thresholds of idiopathic normal pressure hydrocephalus patients in clinical gait analysis

The aim of the study was to distinguish the hypokinetic gait disorder in idiopathic normal pressure hydrocephalus (NPH) patients from the gait decline in the elderly population by quantifying pathological gait parameter thresholds utilizing a multiple condition gait assessment. 55 NPH patients and 55 age-matched healthy subjects underwent a standardized gait assessment with eight gait conditions. Spatiotemporal gait parameters were assessed through a pressure-sensitive carpet. Statistical analysis consisted of a binary logistic regression (BLR) model, logistic curve-fit evaluated by a Chi-square goodness-of-fit-test, receiver operating characteristic models with area under the curves (AUC), and inverse BLR. Most discriminative gait parameter thresholds were observed in pace, gait cycle, and support gait domains. The most distinct gait conditions were preferred walking speed and semantic dual task. During preferred walking speed, the most significant gait parameter thresholds were stride length ≤ 1.02 m (sensitivity 0.93/specificity 0.91/AUC 0.96), gait velocity ≤ 0.83 m/s (0.80/0.91/0.93), double support phase ≥ 27.0% (0.96/0.76/0.91), and stride length coefficient of variation ≥ 3.4% (0.93/0.72/0.90). In conclusion, the hypokinetic gait disorder in NPH can be quantitatively differentiated from gait patterns of the elderly population. In future studies, this approach may be useful to differentiate clinical entities with similar gait disorders utilizing instrumented gait analysis procedures.

Gait apraxia evaluation in normal pressure hydrocephalus using inertial sensors. Clinical correlates, ventriculoperitoneal shunt outcomes, and tap-test predictive capacity

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological condition with gait apraxia signs from its early manifestation. Ventriculoperitoneal shunt (VPS) is a surgical procedure available for treatment. The Cerebrospinal fluid Tap Test (CSF-TT) is a quick test used as selection criterion for VPS treatment. Its predictive capacity for VPS outcomes is still sub judice. This study is aimed to test the hypothesis that wearable motion sensors provide valid measures to manage iNPH patients with gait apraxia.

METHODS

Forty-two participants of the Bologna PRO-Hydro observational cohort study were included in the analyses. The participants performed the Timed Up and Go (TUG) and the 18 m walking test (18mW) with inertial sensors at baseline, three days after the CSF-TT, and six months after VPS. 21 instrumental variables described gait and postural transitions from TUG and 18mW recordings. Furthermore, participants were clinically assessed with scales (clinical variables). We tested the hypothesis by analysing the concurrent validity of instrumental and clinical variables, their individual- and group-level responsiveness to VPS, and their predictive validity for VPS outcomes after CSF-TT.

RESULTS

The instrumental variables showed moderate to high correlation with the clinical variables. After VPS, most clinical and instrumental variables showed statistically significant improvements that reflect a reduction of apraxic features of gait. Most instrumental variables, but only one clinical variable (i.e., Tinetti POMA), had predictive value for VPS outcomes (significant adjusted R² in the range 0.12-0.70).

CONCLUSIONS

These results confirm that wearable inertial sensors may represent a valid tool to complement clinical evaluation for iNPH assessment and prognosis.

Dual-Task Performance in Older Adults With and Without Idiopathic Normal Pressure Hydrocephalus

Two of the main features of idiopathic normal pressure hydrocephalus (iNPH) are disturbed gait and cognition. These features are typically investigated separately, but here we combined walking with a cognitive task to investigate if older adults with iNPH were more susceptible to dual-task interference on walking than those without iNPH. In total, 95 individuals from the general population participated in our study. Of these, 20 were classified as Possible iNPH (median [interquartile range, IQR] 80 years [75–82.5]) and 75 as Unlikely iNPH (74 years [72–78]). Conversation, 10-m walking, semantic and phonemic verbal fluency were performed either combined or independently. “Stopping walking while talking” was noted. Pairwise comparisons and multiple logistic regression analyses were used. We found that the Possible iNPH group was older, stopped walking more frequently during the conversation, and had a slower single-task pace. The dual-task pace was slower for both groups. Only single-task walking pace could predict Possible iNPH when adjusted for age. We could establish a dual-task cost on gait performance in this sample of older adults from the general population, but the cost was not exclusive for individuals with Possible iNPH. To further assess the value of dual-task testing in iNPH, including observations of stopping walking while talking, a study of a clinical iNPH material with more severe symptoms would be valuable.

CSF tap test in idiopathic normal pressure hydrocephalus: still a necessary prognostic test?

Objective

To assess whether gait, neuropsychological, and multimodal MRI parameters predict short-term symptom reversal after cerebrospinal fluid (CSF) tap test in idiopathic normal pressure hydrocephalus (iNPH).

Methods

Thirty patients (79.3 ± 5.9 years, 12 women) with a diagnosis of probable iNPH and 46 healthy controls (74.7 ± 5.4 years, 35 women) underwent comprehensive neuropsychological, quantitative gait, and multimodal MRI assessments of brain morphology, periventricular white-matter microstructure, cortical and subcortical blood perfusion, default mode network function, and white-matter lesion load. Responders were defined as an improvement of at least 10% in walking speed or timed up and go test 24 h after tap test. Univariate and multivariable tap test outcome prediction models were evaluated with logistic regression and linear support vector machine classification.

Results

Sixteen patients (53%) respondedpositively to tap test. None of the gait, neuropsychological, or neuroimaging parameters considered separately predicted outcome. A multivariable classifier achieved modest out-of-sample outcome prediction accuracy of 70% (p = .028); gait parameters, white-matter lesion load and periventricular microstructure were the main contributors.

Conclusions

Our negative findings show that short-term symptom reversal after tap test cannot be predicted from single gait, neuropsychological, or MRI parameters, thus supporting the use of tap test as prognostic procedure. However, multivariable approaches integrating non-invasive multimodal data are informative of outcome and may be included in patient-screening procedures. Their value in predicting shunting outcome should be further explored, particularly in relation to gait and white-matter parameters.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11168-x.

Neuropsychological assessments and cognitive profile mostly associated with shunt surgery in idiopathic normal pressure hydrocephalus patients: diagnostic and predictive parameters and practical implications

BACKGROUND

Cognitive decline is a well-documented feature of idiopathic normal pressure hydrocephalus (iNPH) that can be reversible following cerebrospinal fluid tap tests (CSF-TT). The current gold standard for selecting iNPH patients for shunt surgery is measurable improvement in gait tests following CSF-TT. However, the diagnostic significance and predictive role of pre-surgical cognitive evaluations in probable iNPH patients is still controversial.

PURPOSE

To find the neuropsychological (NPSY) tests and cognitive aspects mostly associated with shunt surgery in iNPH.

MATERIAL AND METHODS

A retrospective comparison between probable iNPH patients who, after undergoing CSF-TT with gait and cognitive evaluations, ended up receiving a shunt (group 1) and probable iNPH patients who ended up with no shunt surgery (group 2). Differences in the diagnostic and predictive results of variety of NPSY tests at baseline, pre-CSF-TT, and post-CSF-TT were used for thorough statistical calculations.

RESULTS

A total of 147 patients with probable iNPH were included. Of those, 58 (39.45%, group 1) patients underwent shunt surgery, while 89 (60.55%, group 2) did not. For the vast majority of the cognitive tests used, no statistically significant differences were found between the groups at baseline (pre-CSF-TT). Following CSF-TT, the "naming" component of the Cognistat test was the only single test to show statically significant difference in improvement between the two groups. Combining at least two tests led to increased levels of accuracy and specificity; however, the sensitivity remained < 50. The only two combinations that were associated with sensitivity ≥ 70 were either any improvement in the Cognistat test (p = 0.627) or any improvement in either its naming, memory, or judgment components (p = 0.015).

CONCLUSION

Cognitive tests, even when combined to cover several cognitive aspects, are not sensitive enough to act as an independent reliable diagnostic and predictive tool, especially when relying on their scores as baseline. In order to avoid cumbersome and unnecessary tests to our patients and to reduce the number of patients who are denied proper treatment due to misdiagnosis, we recommend to use NPSY tests that examine the cognitive aspects of naming and memory, in addition to 2-3 tests for executive functions.

Alzheimer's Disease Biomarkers in Idiopathic Normal Pressure Hydrocephalus: Linking Functional Connectivity and Clinical Outcome

BACKGROUND

Alzheimer's disease (AD) pathology impacts the response to treatment in patients with idiopathic normal pressure hydrocephalus (iNPH), possibly through changes in resting-state functional connectivity (rs-FC).

OBJECTIVE

To explore the relationship between cerebrospinal fluid biomarkers of AD and the default mode network (DMN)/hippocampal rs-FC in iNPH patients, based on their outcome after cerebrospinal fluid tap test (CSFTT), and in patients with AD.

METHODS

Twenty-six iNPH patients (mean age: 79.9±5.9 years; 12 females) underwent MRI and clinical assessment before and after CSFTT and were classified as responders (Resp) or not (NResp), based on the improvement at the timed up and go test and walking speed. Eleven AD patients (mean age: 70.91±5.2 years; 5 females), matched to iNPH for cognitive status, were also included. DMN and hippocampal rs-FC was related to amyloid-β42 and phosphorylated tau (pTau) levels.

RESULTS

Lower amyloid-β42 levels were associated with reduced inter- and intra-network rs-FC in NResp, and the interaction between amyloid-β42 and rs-FC was a predictor of outcome after CSFTT. The rs-FC between DMN and salience networks positively correlated to amyloid-β42 levels in both NResp and AD patients. The increase in the inter-network rs-FC after CSFTT was associated with higher pTau and lower amyloid-β42 levels in NResp, and to lower pTau levels in Resp.

CONCLUSION

Amyloid-β42 and pTau impact on rs-FC and its changes after CSFTT in iNPH patients. The interaction between AD biomarkers and rs-FC might explain the responder status in iNPH.

Integrated care pathways in neurosurgery: A systematic review

Introduction

Integrated care pathways (ICPs) are a pre-defined framework of evidence based, multidisciplinary practice for specific patients. They have the potential to enhance continuity of care, patient safety, patient satisfaction, efficiency gains, teamwork and staff education. In order to inform the development of neurosurgical ICPs in the future, we performed a systematic review to aggregate examples of neurosurgical ICP, to consider their impact and design features that may be associated with their success.

Methods

Electronic databases MEDLINE, EMBASE, and CENTRAL were searched for relevant literature published from date of inception to July 2020. Primary studies reporting details of neurosurgical ICPs, across all pathologies and age groups were eligible for inclusion. Patient outcomes in each case were also recorded.

Results

Twenty-four studies were included in our final dataset, from the United States, United Kingdom, Italy, China, Korea, France, Netherlands and Switzerland, and a number of sub-specialties. 3 for cerebrospinal fluid diversion, 1 functional, 2 neurovascular, 1 neuro-oncology, 2 paediatric, 2 skull base, 10 spine, 1 for trauma, 2 miscellaneous (other craniotomies). All were single centre studies with no regional or national examples. Thirteen were cohort studies while 11 were case series which lacked a control group. Effectiveness was typically evaluated using hospital or professional performance metrics, such as length of stay (n = 11, 45.8%) or adverse events (n = 17, 70.8%) including readmission, surgical complications and mortality. Patient reported outcomes, including satisfaction, were evaluated infrequently (n = 3, 12.5%). All studies reported a positive impact. No study reported how the design of the ICP was informed by published literature or other methods

Conclusions

ICPs have been successfully developed across numerous neurosurgical sub-specialities. However, there is often a lack of clarity over their design and weaknesses in their evaluation, including an underrepresentation of the patient’s perspective.

Evaluation of the effect comorbid Parkinson syndrome on normal pressure hydrocephalus assessment

OBJECTIVE

The primary aim of the study was to assess the effect comorbid Parkinson syndromes have on results of CSF tap test (TT) and shunt outcomes for patients presenting with Normal Pressure Hydrocephalus (NPH). We hypothesized that patients with possible NPH and comorbid Parkinson syndromes with Positive DaT scans will not respond to CSF TT at the same rate as patients without comorbid Parkinson syndromes. Additionally, we followed a small number of patients with positive DaT scans who were shunted to assess long term outcome of comorbid Parkinson syndromes.

METHODS

Medical records and neurological exams of 251 patients were reviewed. In our analysis 101 patients with no parkinsonian symptoms and no DaT scans were included as a control group, there were 52 patients with DaT scans, 31 patients were positive (DaT-P). Gait measures were assessed before and after CSF TT using the Wilcoxon matched-pairs signed-rank test or paired t-tests were used. To compare the effect of DaT-P and Control, we used an ANCOVA controlling for age, sex, assistive device used, and past medical history effecting gait.

RESULTS

There was not a significant difference in response between Control and DaT-P group. The Control group improved on timed up and go (TUG) by 14.82%, DualTUG 16.35%, 10-meter Walk Test (10MWT) 18.13%, MiniBEST 15.91%, and 6-minute Walk Test (6MWT) 13.96%, while the DaT-P group improved on TUG by 14.93%, DualTUG 17.24%, 10MWT 22.68%, MiniBEST 18.07%, and 6MWT 16.06%.

CONCLUSION

Our findings suggest that patients with possible NPH and suspected comorbid movement disorder, showed similar improvement after diagnostic CSF TT compared to participants with no parkinsonian symptoms present on exam.

DATA AVAILABILITY STATEMENT

Data relevant to the study will be made available from the corresponding author upon a reasonable request.

Communicating chronic hydrocephalus: A review

Formerly called normal pressure hydrocephalus, communicating chronic hydrocephalus (CCH) is a condition affecting 0.1 to 0.5% of patients over 60years of age. The pathophysiology of this disease is poorly understood, but a defect in cerebrospinal fluid (CSF) resorption appears to be commonly defined as the cause of the neurological disorders. The last important discovery is the description of the glymphatic system and its implication in CCH and CSF resorption. Comorbidities (Alzheimer's disease, microangiopathy, parkinsonism) are very frequent, and involve a diagnostic challenge. The clinical presentation is based on the Hakim and Adams triad, comprising gait disorders, mainly impairing walking, cognitive disorders, affecting executive functions, episodic memory, visuospatial cognition, and sphincter disorders as urinary incontinence (detrusor hyperactivity). The diagnosis is suspected through a set of arguments, combining the clinical presentation, the radiological data of the magnetic resonance imaging (MRI) showing a ventriculomegaly associated with signs of transependymomous resorption of the CSF and disappearance of the cortical sulci, and the clinical response to the depletion of CSF. In the presence of all these elements, or a strong clinical suspicion, the standard treatment will be of a permanent CSF shunt, using a ventriculoatrial or ventriculoperitoneal shunt. The effectiveness of this treatment defines the diagnosis. The clinical improvement is better when treatment occurs early after the onset of the disorders, reaching 75 to 90% of motor improvement.

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.

Dynamic functional networks in idiopathic normal pressure hydrocephalus: Alterations and reversibility by CSF tap test

Idiopathic Normal Pressure Hydrocephalus (iNPH)—the leading cause of reversible dementia in aging—is characterized by ventriculomegaly and gait, cognitive and urinary impairments. Despite its high prevalence estimated at 6% among the elderlies, iNPH remains underdiagnosed and undertreated due to the lack of iNPH‐specific diagnostic markers and limited understanding of pathophysiological mechanisms. INPH diagnosis is also complicated by the frequent occurrence of comorbidities, the most common one being Alzheimer's disease (AD). Here we investigate the resting‐state functional magnetic resonance imaging dynamics of 26 iNPH patients before and after a CSF tap test, and of 48 normal older adults. Alzheimer's pathology was evaluated by CSF biomarkers. We show that the interactions between the default mode, and the executive‐control, salience and attention networks are impaired in iNPH, explain gait and executive disturbances in patients, and are not driven by AD‐pathology. In particular, AD molecular biomarkers are associated with functional changes distinct from iNPH functional alterations. Finally, we demonstrate a partial normalization of brain dynamics 24 hr after a CSF tap test, indicating functional plasticity mechanisms. We conclude that functional changes involving the default mode cross‐network interactions reflect iNPH pathophysiological mechanisms and track treatment response, possibly contributing to iNPH differential diagnosis and better clinical management.

Can the radiological scale "iNPH Radscale" predict tap test response in idiopathic normal pressure hydrocephalus?

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) presents typical radiological signs that have been summarised in a semi-quantitative scale named the iNPH Radscale. However, the iNPH Radscale's predictive value for response to cerebrospinal fluid (CSF) tap test has never been studied. This study aims to investigate if the iNPH Radscale can predict locomotion improvement after CSF tap test.

METHODS

A total of 100 patients with iNPH (age: 76.3 ± 7.9, gender: 36% female) were included in this retrospective study. Two raters, blinded to the response of the CSF tap test, evaluated the iNPH Radscale and its seven subitems (Evan's index, callosal angle, size of temporal horns, narrow high-convexity sulci, dilated Sylvian fissures, focally dilated sulci, and periventricular hypodensities). Locomotion improvement was assessed by the Timed Up and Go (TUG) performed before, and 24 h after, the CSF tap test.

RESULTS

The iNPH Radscale (total score) was similar between the CSF tap test responders and non-responders (responders: 8.31 ± 1.96, non-responders: 9.18 ± 2.51, p = 0.128). However, the temporal horns score was smaller in the responders group (1.66 ± 0.57 versus 1.94 ± 0.24, p = 0.045), even after adjusting for age, gender, education level, white matter changes, and global cognition (β: -0.250, C.I. 95%: [-3.185; -0.161], p = 0.031).

CONCLUSION

The iNPH Radscale (total score) does not predict locomotion improvement after CSF tap test, while a smaller temporal horns score at baseline is associated with a positive tap test responder status.

Normal pressure hydrocephalus and CSF tap test response: the gait phenotype matters

This study compared gait speed changes after CSF tap test in patients with idiopathic normal pressure hydrocephalus presenting with various gait phenotypes (frontal, parkinsonian, normal, or other). All patients improved, except those with parkinsonian gait.

Treatment for secondary deterioration in idiopathic normal pressure hydrocephalus in the later course of the disease: a retrospective analysis

BACKGROUND

Cerebrospinal fluid (CSF) shunting is a highly effective treatment for idiopathic normal pressure hydrocephalus (iNPH). However, secondary deterioration can occur at a later time. Thus, the current study aimed to evaluate the incidence rate and causes of secondary deterioration.

METHODS

A retrospective analysis was conducted on all patients with iNPH who were treated with implantation of a CSF shunt since 1993. A meticulous shunt workup was recommended to all patients who presented to our department with secondary deterioration during their follow-up visits. Data about the proportion of patients with such deterioration and its causes, subsequent treatment, and clinical outcome were obtained.

RESULTS

A total of 169 patients were included, and the mean follow-up time was 69.2 months. In total, 119 (70.4%) patients presented with a total of 153 secondary deteriorations. In 9 cases (5.9%), the deterioration was caused by delayed subdural hematoma and in 27 (22.1%) cases, by shunt dysfunction. Invasive shunt testing was commonly required to validate shunt failure. Moreover, 19 of 27 patients experienced a satisfactory improvement after revision surgery. In total, 86 deteriorations were attributed to nonsurgical causes, and the valve pressure was decreased in 79 patients, with only 16.5% presenting with a satisfactory improvement after lowering of valve pressure.

CONCLUSIONS

Most patients with shunted iNPH presented with deterioration in the later course of the disease. Shunt dysfunction was considered a cause of secondary deterioration. Moreover, shunt revision surgery was a highly effective treatment, and patients with deterioration should undergo screening procedures for shunt dysfunction, including invasive shunt testing.

Prevalence of Alternative Diagnoses and Implications for Management in Idiopathic Normal Pressure Hydrocephalus Patients

BACKGROUND

Following Bayes theorem, ventriculomegaly and ataxia confer only a 30% chance of idiopathic Normal Pressure Hydrocephalus (NPH). When coupled with positive responses to best diagnostic testing (extended lumbar drainage), 70% of patients recommended for shunting will not actually have NPH. This is inadequate clinical care.

OBJECTIVE

To determine the proportion of alternative and treatable diagnoses in patients referred to a multidisciplinary NPH clinic.

METHODS

Patients without previously diagnosed NPH were queried from prospectively collected data. At least 1 neurosurgeon, cognitive neurologist, and neuropsychologist jointly formulated best treatment plans.

RESULTS

Of 328 total patients, 45% had an alternative diagnosis; 11% of all patients improved with treatment of an alternative diagnosis. Of 87 patients with treatable conditions, the highest frequency of pathologies included sleep disorders, and cervical stenosis, followed by Parkinson disease. Anti-cholinergic burden was a contributor for multiple patients. Of 142 patients undergoing lumbar puncture, 71% had positive responses and referred to surgery. Compared to NPH patients, mimickers were statistically significantly older with lower Montreal Cognitive Assessment (MoCA) score and worse gait parameters. Overall, 26% of the original patients underwent shunting. Pre-post testing revealed a statistically significant improved MoCA score and gait parameters in those patients who underwent surgery with follow-up.

CONCLUSION

Because the Multidisciplinary NPH Clinic selected only 26% for surgery (corroborating 30% in Bayes theorem), an overwhelming majority of patients with suspected NPH will harbor alternative diagnoses. Identification of contributing/confounding conditions will support the meticulous work-up necessary to appropriately manage patients without NPH while optimizing clinical responses to shunting in correctly diagnosed patients.

Standardized regression-based clinical change score cutoffs for normal pressure hydrocephalus

Background

Presently, for patients presenting with suspected Normal Pressure Hydrocephalus (NPH) who undergo temporary drainage of cerebrospinal fluid (CSF) there is no defined model to differentiate chance improvement form clinical significance change at the individual patient level. To address this lack of information we computed standard regression based clinical change models for the 10 Meter Walk Test, Timed Up & Go, Dual Timed Up & Go, 6-Minute Walk Test, Mini-Balance Evaluation Systems Test, Montreal Cognitive Assessment, and Symbol Digit Modalities using data from patients with suspected NPH that underwent temporary drainage of CSF. These clinically significant change modes can classify clinically significant improvement following temporary drainage of CSF at the individual patient level. This allows for physicians to differentiate a clinically significant improvement in symptoms from chance improvement.

Methods

Data was collected from 323 patients, over the age of 60, with suspected NPH that underwent temporary drainage of CSF with corresponding gait and cognitive testing. McSweeney Standardized Regression Based Clinical Change Models were computed for standard gait and cognitive measures: Timed Up & Go, Dual Timed Up & Go, 10 Meter Walk Test, MiniBESTest, 6-Minute Walk Test, Montreal Cognitive Assessment, and Symbol Digit Modalities Test. To assess the discriminate validity of the measures we used correlations, Chi², and regression analyses.

Results

The clinical change models explained 69–91.8% of the variability in post-drain performance (p <  0.001). As patient scores became more impaired, the percent change required for improvement to be clinically significant increased for all measures. We found that the measures were not discriminate, the Timed Up & Go was highly related to the 10 Meter Walk Test (r = 0.85, R² = 0.769–0.738, p <  0.001), MiniBESTest (r = − 0.67, R² = 0.589–0.734, p <  0.001), and 6 Minute Walk Test (r = − 0.77, R² = 0.71–0.734, p <  0.001).

Conclusion

Standardized Regression Based Clinically Significant Change Models allow for physicians to use an evidence-based approach to differentiate clinically significant change from chance improvement at the individual patient level. The Timed Up & Go was shown to be predictive of detailed measures of gait velocity, balance, and endurance.

Parkinsonian gait in aging: A feature of Alzheimer's pathology?

INTRODUCTION

Central neurological gait abnormalities (CNGA; i.e. frontal or parkinsonian) are frequently associated with neurodegenerative conditions in older adults, but their pathophysiological substrates remain poorly described. This cross-sectional study aims to assess the association between cerebrospinal fluid (CSF) Alzheimer's biomarkers and CNGA.

METHODS

CSF biomarkers (phosphor-tau, total tau and Aβ1-42) were measured in 52 patients with CNGA (77.33 ± 6.09 years; 28.8% female). Gait phenotypes were evaluated by two diagnosis-blinded assessors and classified as frontal gait, parkinsonian gait or other gait abnormalities.

RESULTS

Parkinsonian gait was significantly associated with a decreased CSF Aβ42 even after adjusting on age, gender, comorbidities and white matter changes (β: -0.32; 95% CI: [-340.6; -22.9]; p value: 0.026). Phosphor-tau and total tau were not associated with any other CNGA (i.e. frontal gait and other gait abnormalities).

DISCUSSION

Parkinsonian gait represents a gait phenotype of Alzheimer's pathology in patients with CNGA.

The effects of cerebrospinal fluid tap-test on idiopathic normal pressure hydrocephalus: an inertial sensors based assessment

Background

Gait disturbances are typical of persons with idiopathic normal pressure hydrocephalus (iNPH) without signs distinctive from other neurodegenerative and vascular conditions. Cerebrospinal fluid tap-test (CSF-TT) is expected to improve the motor performance of iNPH patients and is a prognostic indicator in their surgical management. This observational prospective study aims to determine which spatio-temporal gait parameter(s), measured during instrumented motor tests, and clinical scale(s) may provide a relevant contribution in the evaluation of motor performance pre vs. post CSF-TT on iNPH patients with and without important vascular encephalopathy.

Methods

Seventy-six patients (20 with an associated vascular encephalopathy) were assessed before, and 24 and 72 h after the CSF-TT by a timed up and go test (TUG) and an 18 m walking test (18 mW) instrumented using inertial sensors. Tinetti Gait, Tinetti Balance, Gait Status Scale, and Grading Scale were fulfilled before and 72 h after the CSF-TT. Stride length, cadence and total time were selected as the outcome measures. Statistical models with mixed effects were implemented to determine the relevant contribution to response variables of each quantitative gait parameter and clinical scales.

Results and conclusion

From baseline to 72 h post CSF-TT patients improved significantly by increasing cadence in 18 mW and TUG (on average of 1.7 and 2.4 strides/min respectively) and stride length in 18 mW (on average of 3.1 cm). A significant reduction of gait apraxia was reflected by modifications in double support duration and in coordination index.

Tinetti Gait, Tinetti Balance and Gait Status Scale were able to explain part of the variability of response variables not covered by instrumental data, especially in TUG. Grading Scale revealed the highest affinity with TUG total time and cadence when considering clinical scales alone.

Patients with iNPH and an associated vascular encephalopathy showed worst performances compared to pure iNPH but without statistical significance. Gait improvement following CSF-TT was comparable in the two groups. Overall these results suggest that, in order to augment CSF-TT accuracy, is key to assess the gait pattern by analyzing the main spatio-temporal parameters and set post evaluation at 72 h.

Trial registration

Approved by ethics committee: CE 14131 23/02/2015.

Is frontal gait a myth in normal pressure hydrocephalus?

BACKGROUND

Patients with idiopathic normal pressure hydrocephalus (iNPH) are considered to present a magnetic, slow, wide-based gait, also called frontal gait. However, this gait profile is not specific for iNPH and encountered in patients with other neurological conditions mimicking iNPH (i.e. iNPH mimics), such as vascular dementia. We aimed to characterize the gait profiles in iNPH and their mimics and to compare the prevalence of clinical gait abnormalities between both groups.

METHODS

This retrospective study included 140 patients suspected of iNPH (76.3 ± 6.8 yo; 30.7% female). Eighty patients (57.1%) were diagnosed with iNPH according to the NPH consensus guidelines criteria; the remaining sixty patients were classified as mimics (23 neurodegenerative conditions, 12 multifactorial conditions, 9 vascular dementia, 7 mixed dementias, 6 toxic conditions, 2 psychiatric conditions, and 1 stroke). Two independent diagnosis-blinded clinicians (kappa, 0.73) evaluated gait according to four categories: frontal gait, parkinsonian gait, other clinical gait abnormalities, and normal gait.

RESULTS

iNPH patients and mimics shared similar clinical characteristics. Frontal gait occurred in only 26% of patients (with a similar prevalence for the mimics). Parkinsonian gait was significantly more prevalent among the mimics (32% versus 15%; p-value: 0.032). This association between parkinsonian gait and mimics remained significant after adjusting for age, gender, comorbidities and white matter changes (OR: 2.404; 95% CI: [1.03-5.64]; p value: 0.044).

CONCLUSION

Frontal gait is not the most prevalent gait abnormality in iNPH and does not discriminate iNPH from its mimics. Parkinsonian gait is more prevalent among the mimics.

Quantitative Evaluation of Gait Disturbance on an Instrumented Timed Up-and-go Test

Although the 3-m timed up-and-go test (TUG) is reliable for evaluating mobility, TUG time is insufficient to evaluate mild gait disturbance; we, therefore aimed to investigate other measurements with instrumented TUG (iTUG) using a free smartphone application. Our inclusion criterion in this study is only that participants can walk without any assistance. This study included three heterogeneous groups; patients who underwent a tap test or shunt surgery, 29 inpatients hospitalized for other reasons, and 87 day-care users. After the tap test, 28 were diagnosed with tap-positive idiopathic normal-pressure hydrocephalus (iNPH) and 8 were diagnosed with tap-negative. Additionally, 18 patients were assessed iTUG before and after shunt surgery. During iTUG, time and 3-dimensional (3D) acceleration were automatically recorded every 0.01 s. A volume of the 95% confidence ellipsoid (95%CE) of all plots for 3D acceleration was calculated. Additionally, an iTUG score was defined as (95%CE volume) ^0.8 / 1.9 - 1.9 × (time) + 60. The measurement reliability was evaluated using intraclass correlations and Bland-Altman plots. The participants with mild gait disturbance who accomplished within 13.5 s on the iTUG time had the 95%CE volumes for 3D acceleration of ≥70 m³/s⁶ and iTUG scores of ≥50. The mean iTUG time was shortened and the mean 95%CE volumes and iTUG scores were increased after the tap test among 28 patients with tap-positive iNPH and after shunt surgery among 18 patients with definite iNPH. Conversely, the mean iTUG score among 8 patients with tap-negative was decreased after the tap test. The intraclass correlations for the time, 95%CE volume and iTUG score were 0.97, 0.80 and 0.90, respectively. Not only the iTUG time but also the 95%CE volume was important for evaluating mobility. Therefore, the novel iTUG score consisting both is useful for the quantitative assessment of mobility.

Current Updates on Idiopathic Normal Pressure Hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is one of the neurodegenerative diseases which can be treated surgically with favorable outcome. The gait disturbance, cognitive, and urinary symptoms are known as the clinical triad of iNPH. In this review, we have addressed the comorbidities, differential diagnoses, clinical presentations, and pathology of iNPH. We have also summarized the imaging studies and clinical procedures used for the diagnosis of iNPH. The treatment modality, outcomes, and prognosis were also discussed.

Computerized gait analysis with inertial sensor in the management of idiopathic normal pressure hydrocephalus

BACKGROUND

Gait disturbance (GD) is usually the first and most prominent symptom observed in idiopathic normal pressure hydrocephalus (iNPH). The reversibility of symptoms is related to early diagnosis and treatment. Nowadays early recognition of patients is challenging because GD in the elderly is frequently neglected, leading to late diagnosis and increased disability. In addition, GD is generally assessed by clinical evaluation since computerized gait analysis methods are rarely available. In the present study, we demonstrate the clinical application of an inertial sensor system for gait analysis in iNPH.

AIM

The primary aim was to test the sensor performance in quantifying impairment in gait parameters in iNPH. The secondary aim was to detect a range of improvement after CSF subtraction test, which could be considered as predictive of favorable shunt response.

DESIGN

We performed a case-control prospective study from March 2012 to May 2014.

SETTING

Inpatients at the Division of Neurology, Department of Clinical and Experimental Sciences, Brescia.

POPULATION

We enrolled 79 patients with clinical and radiological findings of iNPH and 300 healthy adults over 70 years old without GD as a control group.

METHODS

We performed gait analysis, CSF Tap Test (TT), and shunt surgery in all patients with a diagnosis of iNPH according to the International Guidelines. According to clinical outcomes, we divided patients in responsive (group A) and non-responsive (group B). We then compared pre-operative gait analysis of group A with the control group, and calculated the percentage of improvement after TT between group A and group B.

RESULTS

Shunt surgery was performed in 52 patients. After 3 months, 35 patients (group A: 67.3%) showed a positive response to shunt. We quantified the impaired gait parameters in iNPH and assessed the differences with controls. Improvement of speed, stride length and double support time after TT was predictive of positive shunt response.

CONCLUSIONS

The proposed inertial sensor system is a reliable and easy-to-use system for early detection of iNPH and may be used in any clinical setting.

CLINICAL REHABILITATION IMPACT

Identification of a GD pattern for iNPH, especially in rehabilitation, may be useful for recognizing patients who are candidates for surgery, thus avoiding permanent disability.

Apathy in idiopathic normal pressure hydrocephalus: A marker of reversible gait disorders

OBJECTIVE

Apathy-the most common behavioral disturbance in idiopathic normal pressure hydrocephalus (iNPH)-is associated with poor gait, but the role of apathy on gait improvement after cerebrospinal fluid (CSF) tapping has not been studied yet. This study aims to compare gait improvement after CSF tapping in iNPH patients with and without apathy.

METHODS

Stride time variability (STV), a marker of higher level of gait control, was measured in 33 iNPH patients (78.4 ± 5.7 years; 36.4% women) with an optoelectronic system during usual walking (single task) and during walking while dual tasking of counting and verbal fluency before and 24 hours after CSF tapping. Apathy was defined by a score ≥14 on the Starkstein apathy scale.

RESULTS

Apathy was present in 60.6% of patients. Cerebrospinal fluid tapping led to greater improvement of STV (ie, decrease) during dual-task walking (and more specifically categorical verbal fluency) in apathetic compared to nonapathetic patients (-44.7 ± 58.1% versus +4.24 ± 67.6%, respectively; P = .040), even after adjusting for age and depressive symptoms. More severe apathy was correlated with better STV improvement while dual tasking (categorical verbal fluency) after CSF tapping (r = -0.412; P-value = 0.021), while it was not correlated with improvement on executive tests.

CONCLUSIONS

Our findings suggest that the presence of apathy is a predictor of better outcomes of gait disorders after CSF tapping in patients with iNPH.

Brain comorbidities in normal pressure hydrocephalus

BACKGROUND AND PURPOSE

This cross-sectional study aims to compare gait changes after the cerebrospinal fluid (CSF) tap test between normal pressure hydrocephalus patients with and without brain comorbidities (NPH+ and NPH- respectively) and then to identify significant contributors to a poor CSF tap test amongst individuals with NPH+.

METHODS

Gait changes (during the single task and the dual task of backward counting) were quantified before and 24 h after the CSF tap test with an optoelectronic system in 52 NPH patients (77.4 ± 6.0 years; 34.6% women). Changes after the CSF tap test in stride time variability (STV, %) were our main outcome. CSF Alzheimer's disease biomarkers, cerebrovascular white matter changes assessed with brain imaging and neurodegenerative diseases with parkinsonian syndrome represented the three individual brain comorbidities.

RESULTS

Brain comorbidities were frequently identified, NPH+ patients representing 40 patients of our sample (76.9%). NPH- patients improved their STV better in the single task (delta of STV = -58.6% ± 54.3% vs. -14.1% ± 62.0%; P = 0.031) and in the dual task (delta of STV =-32.2% ± 33.7% vs. 6.3% ± 58.4%; P = 0.028) after the CSF tap test than NPH+ patients. Amongst NPH+ individuals, only comorbid Alzheimer's disease was associated with STV increase (i.e. deterioration of gait) in the dual task [β 38.4; 95% confidence interval (5.64; 71.24); P = 0.023] after the CSF tap test, whilst it was borderline in the single task [β 35.0; 95% confidence interval (-1.97; 71.90); P = 0.063].

CONCLUSIONS

Brain comorbidities affect gait improvement after the CSF tap test in NPH patients; this influence is driven by Alzheimer's disease-related pathology.

CSF tapping also improves mental imagery of gait in normal pressure hydrocephalus

This study aims to compare the changes of Timed Up and Go (TUG) and its imagined version (iTUG) after CSF tapping between patients with idiopathic normal pressure hydrocephalus (iNPH) and its mimics. TUG and iTUG were performed before and 24 h after CSF tapping in 117 patients (75.8 ± 6.9 years; 35% female) with suspicion of iNPH (68 iNPH and 49 mimics). Mental imagery of locomotion was modified after CSF tapping in iNPH patients, but not in the mimics.