Quantification of Trunk Postural Stability Using Convex Polyhedron of the Time-Series Accelerometer Data

Abstract

Techniques to quantify postural stability usually rely on the evaluation of only two variables, that is, two coordinates of COP. However, by using three variables, that is, three components of acceleration vector, it is possible to describe human movement more precisely. For this purpose, a single three-axis accelerometer was used, making it possible to evaluate 3D movement by use of a novel method, convex polyhedron (CP), together with a traditional method, based on area of the confidence ellipse (ACE). Ten patients (Pts) with cerebellar ataxia and eleven healthy individuals of control group (CG) participated in the study. The results show a significant increase of volume of the CP (CPV) in Pts or CG standing on foam surface with eyes open (EO) and eyes closed (EC) after the EC phase. Significant difference between Pts and CG was found in all cases as well. Correlation coefficient indicates strong correlation between the CPV and ACE in most cases of patient examinations, thus confirming the possibility of quantification of postural instability by the introduced method of CPV.

Postural Instability Induced by Visual Motion Stimuli in Patients With Vestibular Migraine

“…Given that cervical proprioception is one of the important intra-conflictive sensory components causing motion sickness, postural instability that precedes motion sickness may not only be confined to the body center, but the other segments such as the head and neck may show rather more movements for maintaining a stance in patients with VM. However, the traditional posturography allows for measuring the 2D movements in transversal plane and produces parameters associated with the center of pressure movements of the whole body ( 29 ). Instead of the conventional platforms, assessment of body movements by the triaxial sensor system can yield high-accuracy measurement of the 3D motions of the multiple body segments ( 29 ).…”

“…However, the traditional posturography allows for measuring the 2D movements in transversal plane and produces parameters associated with the center of pressure movements of the whole body ( 29 ). Instead of the conventional platforms, assessment of body movements by the triaxial sensor system can yield high-accuracy measurement of the 3D motions of the multiple body segments ( 29 ). Analyses of the sway area in our study indeed revealed that patients with VM showed larger motions of the head and neck, which are more distant from the center of body pressure than the lumbar region.…”

The application of accelerometers to measure movements of upper limbs: Pilot study

“…The second rotation matrix R AG is obtained during the calibration process of the MTx unit. The calibration method and the application of the rotation matrix are described in detail in Melecky et al (2016). The calculated acceleration vector a Ai = (a APi a MLi a SIi ) T of the instantaneous accelerations represents the superior-inferior (SI) acceleration (a SIi ), medio-lateral (ML) acceleration (a MLi ) and anterior-posterior (AP) acceleration (a APi ).…”

Fifteen Years of Wireless Sensors for Balance Assessment in Neurological Disorders

“…Previous studies using wearable sensors have investigated balance impairment in Parkinson's disease [114,122,124,125,[156][157][158][159][160][161][162][163][164][165][166][167][168], multiple sclerosis [118,146,[169][170][171][172][173][174][175][176][177], stroke [52,[178][179][180][181][182][183][184], traumatic brain injuries [123,126,[185][186][187][188][189], cerebellar ataxia [130,[190][191][192][193][194]…”