Developing a Smartphone Application, Triaxial Accelerometer-based, to Quantify Static and Dynamic Balance Deficits in Patients with Cerebellar Ataxias

Background: Cerebellar ataxia is characterized by difficulty in the planning of movement and lack of anticipatory postural adjustments, which can result in deficits of balance. Being able to have quantitative measurements in clinical practice, to detect any improvements on balance resulting from new rehabilitation treatments or experimental drugs is very important.

Aim: The purpose of this study was to develop an application (APP) able to assess static and dynamic balance in patients with cerebellar ataxias (CA). The APP that works by a wearable device (smartphone) placed at the breastbone level and immobilized by an elastic band, measures the body sway by means of a triaxial accelerometer.

Methods: We investigated 40 CA patients and 80 healthy subjects. All patients were clinically evaluated using the "Berg Balance Scale" (BBS) and the "Scale for the Assessment and Rating of Ataxia" (SARA). Balance impairment was quantitatively assessed using a validated static balance evaluating systems, i.e., Techno-body Pro-Kin footboard. All participants underwent static and dynamic balance assessments using the new APP.

Results: We observed a strong correlation between the APP measurements and the score obtained with the BBS, SARA, and Pro-Kin footboard. The intra-rater reliability and the test-retest reliability of the APP measurements, estimated by intraclass correlation coefficient, were excellent. The standard error of measurement and the minimal detectable change were small. No learning effect was observed.

Conclusions: We can state that the APP is an easy, reliable, and valid evaluating system to quantify the trunk sway in a static position and during the gait.