Background Patients with Huntington's disease (HD) develop a progressive impairment of stability of stance and walking (Rumpf et al. 2007), frequently resulting in falls and injuries. Objective assessment of postural control in HD may be helpful to assess the risk of injury and may serve as a surrogate marker for motor phenotype dysfunction.

Objective To investigate whether HD patients exhibit impairments in balance control that can be assessed by the BBS and whether the BBS correlates to the severity of disease as assessed by the UHDRS-TMS and quantitative measures of balance recorded by a force plate (posturography).

Methods HD patients (n=48: 11 premanifest, 37 symptomatic HD) and age-and-sex-matched controls (n=20) were assessed by the Berg Balance Scale (BBS), the UHDRS-TMS and a force plate (standing still with eyes open and closed for 25 s). Stability of center of mass (COM) location was assessed by the variables SURFACE, VELOCITY and DISTANCE. Non-parametric statistics were performed to compare patients and controls (Mann-Whitney-Test) and to assess dependent variables (Wilcoxon-Test) using SAS 9.2. Correlation analysis was performed using non-parametric Spearman correlations.

Results The BBS correlated in all HD gene-carriers to the UHDRS-TMS with r=−0.786 in symptomatic patients the correlation was r=−0.826. In symptomatic patients BBS correlated with force plate measures SURFACE (r≥−0.665), VELOCITY (r≥−0.453) and DISTANCE (r≥−0.465). However, BBS was insensitive to impairments of balance in patients with UHDRS-TMS ≤20. Force plate measures were significantly increased in HD compared to controls (p<0.001). All variables correlated to the severity of the disease as assessed in the UHDRS-TMS (r≥0.705).

Conclusions Assessment of balance with the BBS is limited to patients with UHDRS-TMS scores ≥20. In contrast, objective and quantitative force plate measures are more sensitive covering a wider range of disease.