Using a Brief Body Sway Assessment Device to Track Balance Differences across the Huntington's Disease Integrated Staging System Spectrum.

Background: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the huntingtin gene on chromosome 4, leading to progressive cognitive decline, motor impairment, and functional disability. Although balance impairment is recognized in HD, its onset and evolution with disease stage remain poorly understood.

Objective: The aim was to track the onset and evolution of balance impairment in HD with progression of disease stage using the BTrackS Balance Plate.

Methods: Total body sway (TBS) was assessed in 123 gene-positive participants and 33 healthy controls (HC) using the BTrackS Balance Plate and laptop software. The prognostic index-derived Huntington's Disease Integrated Staging System (HD-ISS) was used to stratify these subjects into stage 0/1 (n = 51), stage 2 (n = 38), and Stage 3 (n = 34). Nonparametric receiver operating characteristic curve analysis was used to compute optimal cutoff values for TBS.

Results: Balance assessment revealed significant differences in TBS between HCs and gene-positive participants (P < 0.001). TBS varied significantly across disease stages (P < 0.001), with mean values of 9.56 cm (stage 0/1), 14.46 cm (stage 2), and 28.26 cm (Stage 3). The comparison between HCs and stage 0/1 individuals revealed strong discrimination (area under the curve [AUC] = 0.709), with a threshold of 7.72 cm achieving 74.5% sensitivity. The most robust discrimination emerged between stage 2 and Stage 3 participants (AUC = 0.71), with a threshold of 11.85 cm at 82.4% sensitivity.

Conclusions: In conclusion, this cross-sectional study demonstrates that balance impairment is an early and progressive feature of HD, detectable even before the onset of overt motor symptoms.