Abstract
Background: The subjective evaluation of pathological gait exhibits a low inter-rater reliability. Therefore, we developed a three-dimensional acceleration of the trunk during walking to assess the pathological gait quantitatively.Methods: We evaluated 97 patients who underwent the cerebrospinal tap test and were diagnosed with idiopathic normal pressure hydrocephalus (iNPH) and 68 healthy elderlies. The gait features of all patients were evaluated and classified as one of the following: freezing of gait, wide-based gait, short-stepped gait, shuffling gait, instability, gait festination, difficulty in changing direction, and balance disorder in standing up. All gait features of 68 healthy elderlies were treated as normal. Trunk acceleration was recorded automatically by a smartphone placed on the umbilicus during a 15-foot walking test. Two novel indices were created. The first index was a trunk acceleration index, which was defined as (forward acceleration fluctuation) + (vertical acceleration fluctuation) – (lateral acceleration fluctuation) based on the multivariate logistics regression model, and the second index was created by multiplying the forward acceleration with the vertical acceleration. Additionally, 95% confidence ellipsoid volume of the three-dimensional accelerations was assessed.Results: Forward and vertical acceleration fluctuations were significantly associated with the probability of an iNPH-specific pathological gait. The trunk acceleration index demonstrated the strongest association with the probability of an iNPH-specific pathological gait. The areas under the receiver-operating characteristic curves for detecting 100% probability of an iNPH-specific pathological gait were 86.9% for forward acceleration fluctuation, 88.0% for vertical acceleration fluctuation, 82.8% for lateral acceleration fluctuation, 89.0% for trunk acceleration index, 88.8% for forward × vertical acceleration fluctuation, and 87.8% for 95% confidence ellipsoid volume of the three-dimensional accelerations.Conclusions: The probability of a pathological gait specific to iNPH is high at the trunk acceleration fluctuation, reduced in the forward and vertical directions, and increased in the lateral direction.
Highlights
Gait and balance impairments are the predominant symptoms of idiopathic normal pressure hydrocephalus
From March 2017 to September 2019, 134 patients who were suspected of presenting with idiopathic normal pressure hydrocephalus (iNPH) underwent a cerebral spinal fluid (CSF) tap test, which consisted of removing ≥30 mL CSF via a lumbar tap to evaluate the response
Based on the response to the CSF tap test, 84 patients were diagnosed with possible iNPH, and 13 patients were judged as negative to the tap test
Summary
Gait and balance impairments are the predominant symptoms of idiopathic normal pressure hydrocephalus (iNPH). Measurement instruments, such as three-dimensional (3D) optical motion capture or force plates, are not been commonly used in general practice, as they are expensive and heavy, and are difficult to carry, which increases the preparation time for measurement To overcome these limitations with a device that is practical for clinical research or practice, we analyzed gait using a smartphone equipped with highprecision inertial sensors that detect changes in tilt, rotation, and acceleration in three dimensions, as well as a free application (SENIOR Quality, Digital Standard Co., Ltd.) to assess walking biomechanics (Ishikawa et al, 2019b; Yamada et al, 2019). We developed a three-dimensional acceleration of the trunk during walking to assess the pathological gait quantitatively
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