OBJECTIVE: To evaluate the feasibility and utility of a shoe-worn inertial sensor to measure gait abnormalities in Huntington disease (HD) in the home setting.

BACKGROUND: Clinical rating scales provide only point assessments of disease-related impairments in HD, lack sensitivity, and require that a clinician experienced in the scale’s use evaluate the patient. A tool that would allow longitudinal, objective, quantitative measurement of impairments may offer advantages over standard clinical rating scales.

DESIGN/METHODS: This was a pilot, single-blind, controlled observational study. Five ambulatory HD subjects and 5 age/gender-matched healthy controls wore inertial sensors manufactured by APDM, Inc. attached to each shoe during waking hours for 7 days. Gait parameters calculated from the sensors included stride length([percnt]height); stride velocity([percnt]height/sec); step duration(sec); double support time([percnt]); pitch at toe off (degrees) and heel strike (degrees); cadence(steps/min); and variability in each of these measures. Following blinded descriptive data analysis by APDM, independent samples t-tests were used to compare means for selected gait metrics between HD and control subjects, and Pearson correlation coefficients were used to interrogate the relationships between gait metrics, chorea score, and Total Functional Capacity (TFC, a measure of disease severity).

RESULTS: Subjects were able to successfully apply, wear and charge the sensors. Blinded gait analysis correctly identified the HD and control subjects for 4/5 pairs. Significant differences were found between HD/control groups in mean(SD) stride length [53.96(9.25), 67.68(7.25), p=0.03]; mean(SD) variability per week (as measured by coefficient of variation) in stride length [28.57(5.54), 20.27(3.78), p=0.02] and pitch at toe off [25.57(4.00), 17.56(4.07), p=0.01]. Lower TFC scores correlated with greater variability in stride length[R=-0.82]; pitch at toe off[R=-0.80]; and increased double support time[R=-0.75]. Higher chorea scores correlated with shorter stride length[R=-0.76]. CONCLUSIONS: Inertial sensors may offer a feasible mechanism to objectively measure clinically-relevant gait abnormalities in HD.