Instrumented version of the modified dynamic gait index in subjects with neurological disorders.

Background: Gait instability is common in adults with neurologic disorders and the modified Dynamic Gait Index (mDGI) was recently introduced to assess dynamic balance. However, instrumental assessment is needed to provide quantitative measures. Objective: To develop and validate an instrumented version of the mDGI. Design: Cross-sectional study. Setting: Clinical setting. Participants: Thirty adults with neurologic disorders (10 with multiple sclerosis, 10 with Parkinson disease, and 10 with stroke) and 20 healthy volunteers. Methods: Participants were assessed with the Timed Up and Go test (TUG) and with the mDGI. During the assessment of mDGI, data were collected by a single Inertial Measurement Unit (IMU) positioned on the sternum. Principal component analysis (PCA) was performed on the instrumented data extracting eight PC scores (ImPC) describing dynamic balance. The instrumented overall score (ImDGI) was then calculated as the sum of the mPCs. PCA revealed two components associated with stride features and regularity (ImDGI_Gait_Pattern) and trunk movements (ImDGI_Trunk_Sway). Spearman coefficients were calculated between mDGI and ImDGI, whereas Mann-Whitney (U) and Kruskal-Wallis (H) tests assessed differences between groups and neurologic conditions. Main Outcome Measurements: ImDGI. Results: ImDGI did not show ceiling effects, and good correlations were found between ImDGI and mDGI (r = .84), and TUG (r = .84) for people with neurologic disorders (P < .001). Significant differences among pathologies (H test((2)) = 12.5, P = .002) and between healthy participants and adults with neurologic disorders (U test = 47.0, P = .001) were found. ImDGI_Trunk_Sway discriminated between people using or not using walking aids and among the three pathologies (H-(2) = 10.0, P = .007). Conclusions: The ImDGI test seems to provide valid measures to objectively assess dynamic balance in neurologic conditions and possibly quantify balance deficits also in adults with neurologic disorders.