We investigated gait performance utilizing a quantitative gait analysis for 2 groups: (1) idiopathic normal-pressure hydrocephalus (INPH) patients who had a positive response to the cerebrospinal fluid tap test (CSFTT) and (2) healthy controls. The aims of the study were (1) to analyze the characteristics of gait features, (2) to characterize changes in gait parameters before and after the CSFTT, and (3) to determine whether there was any relationship between stride time and stride length variability and Frontal Assessment Battery (FAB) scores in INPH patients. Twenty-three INPH patients and 17 healthy controls were included in this study. Compared with healthy controls, the gait of INPH patients was characterized by lower velocity, shorter stride length, and more broad-based gait. Patients with INPH had a longer stance phase with increased double-limb support. Variability in stride time and stride length was increased in INPH patients. Stride time and stride length variability were correlated with FAB score. After the CSFTT, gait velocity, stride length, and step width significantly improved. There were significant decreases in stride time and stride length variability. These results suggest that the CSFTT for INPH patients might improve the so-called balance-related gait parameter (ie, step width) as well. Stride time and stride length variability also responded to the CSFTT. Association between FAB scores and both stride time and stride length variability suggests involvement of similar circuits producing gait variability and frontal lobe functions in INPH patients.

A vision-based gait analysis method using monocular videos was proposed to estimate temporo-spatial gait parameters by leveraging deep learning algorithms. This study aimed to validate vision-based gait analysis using GAITRite as the reference system and analyze relationships between Frontal Assessment Battery (FAB) scores and gait variability measured by vision-based gait analysis in idiopathic normal pressure hydrocephalus (INPH) patients. Gait data from 46 patients were simultaneously collected from the vision-based system utilizing deep learning algorithms and the GAITRite system. There was a strong correlation in 11 gait parameters between our vision-based gait analysis method and the GAITRite gait analysis system. Our results also demonstrated excellent agreement between the two measurement systems for all parameters except stride time variability after the cerebrospinal fluid tap test. Our data showed that stride time and stride length variability measured by the vision-based gait analysis system were correlated with FAB scores. Vision-based gait analysis utilizing deep learning algorithms can provide comparable data to GAITRite when assessing gait dysfunction in INPH. Frontal lobe functions may be associated with gait variability measurements using vision-based gait analysis for INPH patients.

Objective: The aims of the study were to measure the cerebrospinal fluid (CSF) volumes in the lateral ventricle, high-convexity subarachnoid space, and Sylvian fissure region in patients with idiopathic normal-pressure hydrocephalus (INPH) and Alzheimer’s disease (AD), and to evaluate differences in these volumes between INPH and AD groups and healthy controls. Methods: Forty-nine INPH patients, 59 AD patients, and 26 healthy controls were imaged with automated three-dimensional volumetric MRI. Results: INPH patients had larger lateral ventricles and CSF spaces of the Sylvian fissure region and smaller high-convexity subarachnoid spaces than other groups, and AD patients had larger lateral ventricles and CSF spaces of the Sylvian fissure region than the control group. The INPH group showed a negative correlation between lateral ventricle and high-convexity subarachnoid space volumes, while the AD group showed a positive correlation between lateral ventricle volume and volume for CSF spaces of the Sylvian fissure region. The ratio of lateral ventricle to high-convexity subarachnoid space volumes yielded an area under the curve of 0.990, differentiating INPH from AD. Conclusions: Associations between CSF volumes suggest that there might be different mechanisms between INPH and AD to explain their respective lateral ventricular dilations. The ratio of lateral ventricle to high-convexity subarachnoid space volumes distinguishes INPH from AD with good diagnostic sensitivity and specificity. We propose to refer to this ratio as the VOSS (ventricle over subarachnoid space) index.

The aims of the study are to evaluate idiopathic normal‐pressure hydrocephalus (INPH)‐related cerebral blood flow (CBF) abnormalities and to investigate their relation to cortical thickness in INPH patients. We investigated cortical CBF utilizing surface‐based early‐phase ¹⁸F‐florbetaben (E‐FBB) PET analysis in two groups: INPH patients and healthy controls. All 39 INPH patients and 20 healthy controls were imaged with MRI, including three‐dimensional volumetric images, for automated surface‐based cortical thickness analysis across the entire brain. A subgroup with 37 participants (22 INPH patients and 15 healthy controls) that also underwent ¹⁸F‐fluorodeoxyglucose (FDG) PET imaging was further analyzed. Compared with age‐ and gender‐matched healthy controls, INPH patients showed statistically significant hyperperfusion in the high convexity of the frontal and parietal cortical regions. Importantly, within the INPH group, increased perfusion correlated with cortical thickening in these regions. Additionally, significant hypoperfusion mainly in the ventrolateral frontal cortex, supramarginal gyrus, and temporal cortical regions was observed in the INPH group relative to the control group. However, this hypoperfusion was not associated with cortical thinning. A subgroup analysis of participants that also underwent FDG PET imaging showed that increased (or decreased) cerebral perfusion was associated with increased (or decreased) glucose metabolism in INPH. A distinctive regional relationship between cerebral cortical perfusion and cortical thickness was shown in INPH patients. Our findings suggest distinct pathophysiologic mechanisms of hyperperfusion and hypoperfusion in INPH patients.

Park KH, et al. J Clin Neurol. 2021 Jul;17(3):376-384. https://doi.org/10.3988/jcn.2021.17.3.376

Objectives: In this study, we compared performance on the auditory word recognition tasks between patients with normal pressure hydrocephalus (NPH) and healthy elderly adults (HE) under different visual, auditory, and contextual conditions to determine how these variables affect auditory comprehension with cognitive decline.Methods: We conducted a standardized comprehension assessment, Paradise Korean Western Aphasia Battery Revised (PK-WAB-R) and the auditory word recognition tasks on 30 patients with NPH and 30 HE. The auditory word recognition task was divided into noisy and quiet conditions (auditory variable), blurry and clean conditions (visual variable), and low- and high-context conditions (contextual variable).Results: Patients with NPH showed relatively good comprehension on the standardized comprehension test of PK-WAB-R. For the auditory word recognition tasks, there was a significant main effect of group, a significant within-group effect of auditory and contextual conditions, and significant interaction effects between auditory condition and group, auditory condition and contextual information, and auditory condition, contextual information, and group.Conclusion: This study confirmed that patients with NPH have difficulty processing auditory comprehension at the sentence level. In addition, the auditory word recognition performance in patients with NPH was significantly lower than HE, and that their difficulties may be more pronounced under certain conditions, such as noisy conditions and low contextual information.