Quantification of postural stability in minimally disabled multiple sclerosis patients by means of dynamic posturography: an observational study

Abstract

BackgroundMultiple Sclerosis (MS) is a widespread progressive neurologic disease with consequent impairments in daily activities. Disorders of balance are frequent and equilibrium tests are potentially useful to quantify disability and to verify treatment effectiveness. The fair sensitivity of the widely used not-perturbed tests to detect balance disturbances in MS patients have prompted the development of mechatronic systems capable to impose known equilibrium perturbations, in order to challenge the balance control and, consequently, to better assess the level of impairment. We sought to clarify whether the proposed perturbed-test is capable to discriminate healthy subjects from patients with MS, even in mild or in the absence of clinically evident balance disturbances.MethodsWe assessed balance performances of 17 adults with MS and 13 age-matched healthy controls (HC) using both perturbed (PT) and not-perturbed (NPT) postural tests by means of a 3 Degree Of Freedom (DOF) rotational mechatronic platform. Participants stood barefoot on the platform in standing position and their center of pressure (CoP) was gathered by using a pressure matrix. Each trial lasted 30 s and was carried out with and without visual stimuli. Several postural indices were computed for each trial. Correlations between postural indices and clinical scales were analyzed.ResultsNo significant differences were found between groups for all indices when subjects performed NPTs. Conversely, significant differences in postural indices between MS and HC emerged during PTs. Additionally, PTs revealed significant differences between patients without any cerebellar impairment (cerebellar EDSS subscore equal to 0) and HC. The discrimination capability of PTs was confirmed by the ROC analysis. No significant change of the selected metrics occurred in HC when NPTs were performed with eyes closed, while indices presented a significant worsening in MS subjects.ConclusionsNot-perturbed tests showed lower sensitivity than perturbed ones in the identification of equilibrium impairments in minimally disabled MS patients. However, not-perturbed tests allow to better evaluate the influence of visual flow disturbances on balance control in MS. In conclusion, our findings proved that the use of the novel tests based on a 3DOF mechatronic device represents an effective tool to investigate early balance disturbances in MS.

Postural control quantification in minimally and moderately impaired persons with multiple sclerosis: The reliability of a posturographic test and its relationships with functional ability

“… 8 , 9 , 11 , 14 , 15 Some reliability studies have shown that posturographic protocols have good relative consistency (intraclass correlation coefficient (ICC): 0.62–0.93), allowing a proper classification of pwMS according to their postural control level. 7 , 16 , 17 However, the samples of pwMS in these studies were very heterogeneous (as participants showed a broad range of Expanded Disability Status Scale (EDSS) scores) that, owing to ICC sensitivity to sample heterogeneity, 18 could have artificially increased the relative reliability of these protocols and thus facilitated the classification of the patients. Moreover, to the authors’ best knowledge, there are no studies that have assessed the absolute reliability of the posturographic protocols (i.e., trial-to-trial variation); therefore, their ability to discriminate between clinically relevant changes in postural control (caused by the disease progression) and normal day-to-day variability remains unknown.…”

Assessing the Effects of Kata and Kumite Techniques on Physical Performance in Elite Karatekas

“…The evaluated point can be assumed as the center of pressure (COP); then, the antero-posterior (AP) and the medio-lateral components (ML) of the COP were computed. Finally, as stability indices we computed parameters that are typical considered in posturographic analysis [40][41][42]. Specifically, the path length (PL), the ellipse area (EA) and the mean frequency (FREQ) were evaluated by following the equations reported in Reference [41].…”

“…For all the above-mentioned parameters, the Romberg Index (RI) was also computed as the ratio between the stability parameters obtained during the EC and EO conditions [40]. Values of RI close to 1 indicate a better adaptation to the closed eyes condition.…”

An observational study of balance and proprioception function in patients with spinocerebellar ataxias type 3

“…Each trial lasted 30 seconds. Five key parameters are measured [30] : 1 [31] . COP is the point of application of forces exchanged between feet and ground.…”