Objective: To evaluate whether movement parameters derived from wearable inertial sensors differentiate individuals with SCA3 from healthy controls and whether these parameters correlate with clinical severity measured by the Scale for the Assessment and Rating of Ataxia (SARA).

Background: Spinocerebellar Ataxia Type 3 (SCA3), also known as Machado-Joseph disease, is characterized by progressive coordination impairment and gait instability. Quantifying these changes using clinical scales alone can be challenging. Wearable inertial sensors may provide objective measures of motor performance and support the development of digital biomarkers for disease monitoring.

Method: Ten patients with genetically confirmed SCA3 (mean age 48.5 ± 7.5 years; mean SARA score 8.6 ± 4.2) and nine healthy controls (mean age 48.8 ± 10.4 years) were included. Kinematic data were collected using six wearable inertial sensors placed bilaterally on the feet, on the lower back, on the sternum, and on both wrists. Participants performed a 2-minute walk test on a continuous 10-meter course at a comfortable speed. Parameters related to gait, turning, and anticipatory postural adjustments (APA) were extracted. Group comparisons were performed using the Mann–Whitney U test. Associations with SARA scores were assessed using Spearman correlation. Diagnostic performance of significant variables was evaluated using receiver operating characteristic (ROC) analysis.

Results: Several sensor-derived parameters correlated with SARA scores. Step cadence (rs = −1.000; p < 0.001) and gait cycle duration (rs = 1.000; p < 0.001) were strongly associated with disease severity. Trunk transverse rotation increased with higher SARA scores (rs = 0.929; p = 0.003), whereas mean turn angle decreased (rs = −0.881; p = 0.004). Temporal parameters related to turning and postural transitions showed the strongest ability to distinguish groups. APA duration demonstrated high classification accuracy (AUC = 0.986; p < 0.001), while turn duration (AUC = 0.889) and mean turn angle (AUC = 0.861) also differentiated patients from controls.

Conclusion: Wearable sensor metrics, particularly parameters related to anticipatory postural adjustments and turning, capture motor alterations associated with SCA3 and correlate with clinical severity, supporting their potential use as digital biomarkers.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/digital-biomarkers-of-spinocerebellar-ataxia-type-3-wearable-sensor-metrics-during-turning-and-postural-adjustments/