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Sensors on the body. Reproduced with permission from APDM Inc. (A) Location of Opal sensors. (B) Example of sensors attached to the sternum and bilateral wrists.
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Objectives: Gait and balance disturbances are common symptoms of idiopathic normal pressure hydrocephalus (iNPH). This study aimed to quantitatively evaluate gait and balance parameters after external lumbar drainage (ELD) using APDM inertial sensors.
Methods: Two-minute walkway tests were performed in 36 patients with suspected iNPH and 20 healthy...
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Citations
... Hypertension may lead to cerebrovascular damage and reduced perfusion of skeletal muscle and the brain, exacerbating frailty and mobility loss [10][11][12] . Similarly, idiopathic normal pressure hydrocephalus is characterized by gait disturbances and motor coordination deficits due to ventriculomegaly and white matter changes, making it a clinically relevant model of functional decline in older adults [13][14][15] . Local data points out these problems; for example, a 2023 survey in Deqing County indicated that 19.01% of residents were aged 60 or older, while research in Shanghai estimated that 2.59% of older adults had idiopathic normal pressure hydrocephalus 16,17 . ...
The health effects associated with particulate matter (PM) are extensively reported; nevertheless, limited research has explored the exact contributions of its chemical constituents to physical dysfunctional aging. This study assesses the relationships between prolonged exposure to significant ambient air pollutants, especially ammonium (NH4⁺), and physical dysfunction in a nationally representative cohort of older Chinese adults. We investigated data from 14,641 participants aged 45 years or older in the 2015 wave of the China Health and Retirement Longitudinal Study (CHARLS), which was integrated with high-resolution air pollution data from the ChinaHighAirPollutants (CHAP) dataset. Physical dysfunction was evaluated by self-reported challenges in executing routine activities. After controlling for a wide range of confounders, associations among eight air contaminants (averaged from 2013 to 2015) and dysfunction risk were investigated using logistic regression models. Multicollinearity among covariates in the fully adjusted models was assessed using the generalized variance inflation factor (GVIF), with a threshold value of 5 adopted as the criterion to indicate potential collinearity. Sensitivity analyses—including exclusion of high-exposure participants, standardized z-score modeling, stratified subgroup evaluations, and multipollutant adjustments—were performed to assess the robustness of associations. Dose–response relationships were modeled using both quartile-based logistic regression and restricted cubic spline (RCS) models, revealing consistent and complementary trends. To estimate independent effects and address potential collinearity, we further constructed a multipollutant model adjusting for seven co-pollutants. In all and fully adjusted models, ambient ammonium (NH4⁺) was the only air pollutant that demonstrated a significant and independent association with physical dysfunction (OR: 1.03; 95% CI: 1.01–1.05; p < 0.05); no significant associations were found for the other pollutants. This association remained robust across multiple sensitivity analyses, including exclusion of extreme exposure (OR: 1.13; 95% CI: 1.08–1.17; p < 0.001), z-score standardization (OR: 2.17; 95% CI: 1.57–2.98; p < 0.001), and 5 stratified subgroup models. A significant dose–response relationship was identified both in quartile-based trend tests (p for trend < 0.001) and restricted cubic spline analysis (p for non-linearity < 0.001). Taken together, the monotonic trend from quartile analysis and the non-linear pattern from spline modeling suggest that even moderate exposure to NH4⁺ may contribute to physical dysfunction. Furthermore, multicollinearity diagnostics based on generalized variance inflation factors (GVIFs) indicated no evidence of problematic collinearity among covariates in the fully adjusted models (all GVIF < 5). Besides, the association remained significant and became stronger in a multipollutant model, highlighting the independent effect of NH4⁺ beyond co-pollutant confounding (OR: 1.49; 95% CI: 1.26–1.76; p < 0.001). Our findings indicate that NH4⁺, a significant secondary component of PM predominantly sourced from agricultural ammonia emissions, may uniquely contribute to the deterioration of physical function. It may be important to evaluate particle chemical makeup for analyzing health concerns, as there is no association for total PM mass. Long-lasting exposure to ambient NH4⁺ has been independently associated with increased odds of physical dysfunction across older adults in China. These findings underscore the necessity for specific environmental strategies focused on ammonia reduction to alleviate age-related functional deterioration and foster healthy aging.
... In all studies, iNPH was defined by the presence of the Hakim's Triad, including gait disturbance, cognitive impairment and urinary incontinence. In most studies, clinical symptoms were associated with ventricular dilatation (n = 9) (11,(18)(19)(20)(21)(22)(23)(24)(25), and normal CSF pressure (n = 10) (17,(26)(27)(28)(29)(30)(31)(32)(33)(34). One study described that there is no obstruction to CSF flow (35), whereas three others (12,36,37) reported disturbances in CSF dynamics. ...
... The studies either involved shunt surgery (n = 13), TT in addition to shunt surgery (n = 6), TT alone (n = 11), lumbar CSF drainage (n = 1) or lumbar CSF drainage plus shunt surgery (n = 1). Follow-up periods differed considerably across studies, and most studies (n = 14) did not have a long-term follow-up after the intervention, i.e., 1 hour to 1 week after the intervention (21,24,29,32,33,35) or did not provide follow-up information (1,25,34,(38)(39)(40)(41)(42). Five studies had a 6 month follow-up period (12,18,28,36,43) and another six studies had a follow-up of three months (11,22,31,37,44) or 12 weeks (19) after shunt surgery, and a one-month follow-up was reported by two studies (20,26). ...
... Many iNPH patients suffer from a shuffling gait, which is often described as magnetic (18,41,43). In addition, significantly increased variance in stride length (20,24,38), as well as reduced cadence (24,29) and gait speed (24,27,29,31,45) have been reported in iNPH patients. Freezing of gait may also occur during walking (24,34,43). ...
Background
Idiopathic normal pressure hydrocephalus (iNPH) is characterized by impaired gait and cognition, and urinary incontinence. Even though iNPH still lacks standardized diagnostic criteria, many patients may potentially benefit from treatment which are often invasive procedures.
Objectives
To provide an overview of the current state of research on physical activity behavior and gait in patients with iNPH, and examine potential changes after treatment (i.e., shunt surgery, spinal tap test or lumbar drainage).
Methods
This literature review was carried out based on the PRISMA statement and we searched PubMed, Web of Science and Scopus databases in April 2023.
Results
In total, 32 studies were included: 29 focusing on gait, 2 focusing on gait and physical activity, and 1 focusing on physical activity. All studies reported improvements in gait, such as reduced gait ataxia or shuffling gait and greater variability of gait cycle length, after an intervention or treatment. Improvements may depend on patients’ age, symptom duration, and treatment method, among others.
Conclusion
Improvements in gait after iNPH treatment (e.g., shunt surgery) are well documented, whereas results on physical activity behavior in iNPH patients are inconsistent. More research on physical activity and gait outcomes before and after treatment is needed, also with regard to treatment success.
... A frequently used system is a pressure-sensitive carpet that analyzes spatial and temporal gait parameters for a short distance [11][12][13][14]. Inertial sensor systems with sensors attached to the patient's body to quantify gait variables have been used in a few studies [15][16][17]. The advantage of body-worn sensors is that they allow the patient to walk freely across the environment for a longer distance. ...
... The basal gait parameters are more commonly described in previous research. This study confirms previous results emphasizing that patients with iNPH exhibit slower walking speed, shorter strides [11][12][13][14]16,17,26], decreased cadence [11,12,16,17,26] and increased stride variability [11][12][13][14] , compared to the 20-meter walk performed in our study, could account for these differences. The actual walked distance may have an impact on gait speed in short-distance walking tests [27]. ...
... The basal gait parameters are more commonly described in previous research. This study confirms previous results emphasizing that patients with iNPH exhibit slower walking speed, shorter strides [11][12][13][14]16,17,26], decreased cadence [11,12,16,17,26] and increased stride variability [11][12][13][14] , compared to the 20-meter walk performed in our study, could account for these differences. The actual walked distance may have an impact on gait speed in short-distance walking tests [27]. ...
Background
Gait disturbance is the most pronounced symptom in idiopathic normal pressure hydrocephalus (iNPH). Some gait parameters have been previously described, but an in-depth description of the gait pattern is lacking. The aim was to quantitatively evaluate gait in iNPH patients before and after shunt surgery and compare it to healthy individuals (HI), and correlate it with functional tests preoperatively.
Methods
In total, 47 patients and 42 HI were included. The patients were assessed with the iNPH scale (total, gait and balance domain scores were analyzed), the timed up and go test (TUG) and an inertial sensor gait analysis system, RehaGait®, pre- and postoperatively. The HI were assessed with TUG and RehaGait®. Gait variables were: stride length, stride duration, velocity, cadence, variability, stance, swing, single support, double support, step height, hip, knee and ankle joint angles.
Results
Compared to HI, the main differences in the gait variables were: decreased stride length (p < 0.01), velocity (p < 0.01), swing time (p < 0.01), single support (p < 0.01), hip flexion (p < 0.01), heel strike angle (p < 0.01) and toe-off angle (p < 0.01). Step height was normalized postoperatively; all other variables remained significantly worse than the HI. There were strong correlations between stride length, velocity, heel strike angle, and toe-off angle and the functional gait tests, but no correlations for any variable and the balance domain score.
Conclusions
The patients walked with reduced hip flexion, heel strike angle and toe-off angle, and had shorter strides, decreased velocity, and increased time for swing and single support, compared to HI. Step height was the only gait variable normalized after shunt surgery. Ankle joint kinematics correlated strongly with the results in functional gait tests. More research is warranted about how gait speed affects other gait variables in iNPH.
Trial registration
ClinicalTrials.gov NCT04795089
... A few studies have analysed the gait pattern in controlled studies compared to healthy individuals (HI) [40][41][42][43][44][45][46][47][48][49] . Studies of joint kinematics are limited 40,45 . ...
... A few studies have analysed the gait pattern in controlled studies compared to healthy individuals (HI) [40][41][42][43][44][45][46][47][48][49] . Studies of joint kinematics are limited 40,45 . Most frequently basal gait cycle parameters are reported e.g. ...
... Most frequently basal gait cycle parameters are reported e.g. decreased speed [40][41][42][43][44][45][46][47][48][49] , decreased cadence [40][41][42][43]45,47 , decreased stride length [40][41][42][43][44][45][46][47][48][49] , increased variability 40,41,43,44,46 and increased step width 40,41,43,44,[47][48][49] . Additionally increased time for double support [40][41][42][44][45][46] , increased stance duration 40,42,44 and decreased swing duration 42,44,46 are reported. ...
... Compared to healthy controls, individuals with iNPH have been shown to exhibit a slower speed, shorter stride length, broad base of support, increased percentage of stance phase and double limb support, increased step number, step time, and decreased cadence 13,22,23 . They also had a greater variability of step time and stride length 22,23 . ...
... Until present, the positive and negative responsiveness criteria to the CSF tap test are varied among studies 3,13,22,[25][26][27] . The proposed criteria include; observation of clinical symptoms 13,25 , self-report from the patients or caregivers 13,26 , or an improvement in the iNPH grading scale of 1 score or an improvement of more than 5-10% of change in the Timed Up and Go or gait speed using the 10-m walk test 3,22,27 . ...
... In contrast, the tap test non-responders showed no significant improvements in all tested variables. This is consistent with previous studies which reported increases in stride length 13,19,51 , cadence 13 , and gait speed 13,19,54 in the tap test responders. However, previous studies found an increase in double limb support 13,19 , which was not seen in this current study. ...
Idiopathic Normal Pressure Hydrocephalus (iNPH) is a neurological condition that often presents gait disturbance in the early stages of the disease and affects other motor activities. This study investigated changes in temporospatial gait variables after cerebrospinal fluid (CSF) removal using a spinal tap test in individuals with idiopathic normal pressure hydrocephalus (iNPH), and explored if the tap test responders and non-responders could be clinically identified from temporospatial gait variables. Sixty-two individuals with iNPH were recruited from an outpatient clinic, eleven were excluded, leaving a total of 51 who were included in the analysis. Temporospatial gait variables at self-selected speed were recorded at pre- and 24-h post-tap tests which were compared using Paired t-tests, Cohen’s d effect size, and percentage change. A previously defined minimal clinical important change (MCIC) for gait speed was used to determine the changes and to classify tap test responders and non-responders. A mixed model ANOVA was used to determine the within-group, between-group, and interaction effects. Comparisons of the data between pre- and post-tap tests showed significant improvements with small to medium effect sizes for left step length, right step time, stride length and time, cadence, and gait speed. Gait speed showed the largest percentage change among temporospatial gait variables. Within-group and interaction effects were found in some variables but no between-group effect was found. Tap test responders showed significant improvements in right step length and time, stride length and time, cadence, and gait speed while non-responders did not. Some individuals with iNPH showed clinically important improvements in temporospatial gait variables after the tap test, particularly in step/stride length and time, cadence, who could be classified by gait speed. However, gait-related balance variables did not change. Therefore, additional treatments should focus on improving such variables.
... Improvement of gait velocity after the CSF removal test was determined by Stolze et al. (14), and the authors connected increased gait velocity with increased stride length rather than the cadence. However, He et al. (15) showed that stride length and cadence were increased after the external lumbar drainage. Similar to He et al. (15), our data confirmed a marked improvement in cadence. ...
... However, He et al. (15) showed that stride length and cadence were increased after the external lumbar drainage. Similar to He et al. (15), our data confirmed a marked improvement in cadence. Further studies are required for verification. ...
Introduction:Gait impairment is the earliest symptom of idiopathic normal pressure hydrocephalus (iNPH). This study objectively investigates gait changes using Ambulatory Parkinson’s Disease Monitoring inertial sensors after cerebrospinal fluid withdrawal in patients with iNPH.Methods:Two-minute walkway tests were performed in eleven patients with iNPH before and after the spinal tap test (TT) or ventriculoperitoneal shunt surgery. Gait parameters were analyzed and compared for each patient individually before and after the intervention.Results:Eleven patients with iNPH (six female, five male) with a median age of 76 (68-76) were included in the study. After the spinal TT or ventriculoperitoneal shunt surgery, patients exhibited increased cadence (steps per minute) and decreased step and stride time (p=0.008, for all).Conclusion:APDM inertial sensors may provide a quantitative gait assessment in patients with iNPH.
... The most common form of hydrocephalus in 'adults' is iNPH (Williams and Malm, 2016), which is often confused with AD due to similarities in symptoms (Graff-Radford, 2014;Yamada et al., 2016). Although the cognitive impairment can be confused between the NPH and AD, gait dysfunction is a primary differentiating feature, which is present in NPH but not in AD (He D. et al., 2021;He M. et al., 2021;Chunyan et al., 2021;Davis et al., 2021;Hnin et al., 2021;Jeong et al., 2021;Kuruvithadam et al., 2021;Morel et al., 2021;Nikaido et al., 2021;Yamada et al., 2021;Maier et al., 2022;Nikaido et al., 2022;Sun et al., 2022;Suzuki et al., 2022). ...
Symptoms of normal pressure hydrocephalus (NPH) and Alzheimer’s disease (AD) are somewhat similar, and it is common to misdiagnose these two conditions. Although there are fluid markers detectable in humans with NPH and AD, determining which biomarker is optimal in representing genetic characteristics consistent throughout species is poorly understood. Here, we hypothesize that NPH can be differentiated from AD with mRNA biomarkers of unvaried proximity to telomeres. We examined human caudate nucleus tissue samples for the expression of transient receptor potential cation channel subfamily V member 4 (TRPV4) and amyloid precursor protein (APP). Using the genome data viewer, we analyzed the mutability of TRPV4 and other genes in mice, rats, and humans through matching nucleotides of six genes of interest and one house keeping gene with two factors associated with high mutation rate: 1) proximity to telomeres or 2) high adenine and thymine (A + T) content. We found that TRPV4 and microtubule associated protein tau (MAPT) mRNA were elevated in NPH. In AD, mRNA expression of TRPV4 was unaltered unlike APP and other genes. In mice, rats, and humans, the nucleotide size of TRPV4 did not vary, while in other genes, the sizes were inconsistent. Proximity to telomeres in TRPV4 was <50 Mb across species. Our analyses reveal that TRPV4 gene size and mutability are conserved across three species, suggesting that TRPV4 can be a potential link in the pathophysiology of chronic hydrocephalus in aged humans (>65 years) and laboratory rodents at comparable ages.
... The inertial measurement units (IMUs) are increasingly employed as motion sensors in instrumenting motor tests in the clinical routine [19]. Nowadays, IMUs are wireless, lightweight, costeffective, and operate on commercially available mobile devices, thus allowing the plug-and-play execution of gait analysis tests without the need for specialized personnel or dedicated laboratories [20,21]. ...
... Only a few studies employed an instrumented gait analysis for studying iNPH gait apraxia and its improvement after CSF-TT [17,[21][22][23][24][25][26][27]. Stolze et al. reported gait speed and stride length as the most responsive parameters in a pre vs. 24 h post-CSF-TT comparison [22]. ...
... On iNPH patients instrumented with inertial sensors, He et al. found a decreased cadence, reduced gait speed, a higher duration of double support, decreased elevation at mid-swing, reduced foot strike angle, shorter stride length, difficulty in turning, and impaired balance functions [21]. They also showed that most previously listed gait manifestations were significantly improved after external lumbar drainage in responders to external lumbar drainage. ...
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.
Normal pressure hydrocephalus (NPH) is a recognized cause of reversible cognitive and motor decline, with gait and balance impairments often emerging early. Technologies providing gait and balance measures can aid in early detection, diagnosis, and prognosis of the disease. This systematic review comprehensively discusses previous studies on the instrumental assessment of gait and balance in NPH. A PubMed search following PRISMA guidelines identified studies published between 2000 and 2024 that used laboratory instruments to assess gait and balance in NPH. Studies underwent quality assessment for internal, statistical, and external validity. Methodological details such as motor tasks, instruments, analytical approaches, and main findings were summarized. Overall, this review includes 41 studies on gait and 17 on balance, most of which used observational, cross-sectional designs. These studies employed various tools, such as pressure-sensitive platforms, optoelectronic motion-capture systems, and wearable inertial sensors. Significant differences in kinematic measures of gait and balance have been found in NPH patients compared to healthy controls and individuals with other neurological conditions. Finally, this review explores potential pathophysiological mechanisms underlying the kinematic changes in gait and balance in NPH and emphasizes the absence of longitudinal data, which hinders drawing definitive conclusions for prognostic purposes.
