New evidence for gait abnormalities among Parkinson's disease patients who suffer from freezing of gait: insights using a body-fixed sensor worn for 3 days

Previous studies conducted in laboratory settings suggest that the gait pattern in between freezing of gait (FOG) episodes is abnormal among patients with Parkinson's disease (PD) who suffer from FOG (i.e., "freezers''), compared to those who do not (i.e., "nonfreezers''). We evaluated whether long-term recordings also reveal gait alterations in freezers and if these features were related to freezing severity and its impact on daily function. 72 patients with PD wore a 3-D accelerometer for 3 days. Acceleration-derived gait features included quantity (e.g., the amount of walking) and quality measures (e.g., gait variability). The New FOG-Questionnaire evaluated the subject's perceptions of FOG severity and its impact. Age, gender, and disease duration were similar (p > 0.19) in the 28 freezers and 44 non-freezers. Walking quantity was similar in the two groups, while freezers walked with higher gait variability (i.e., larger anterior-posterior power spectral density width; p = 0.003) and lower gait consistency (i.e., lower vertical stride regularity; p = 0.007). Group differences were observed when comparing the typical (i.e., median), best, and worst performance among the multiple walking bouts measured. Vertical and medio-lateral gait consistency were associated with the impact of FOG on daily living (r < -0.39, p < 0.044). The present findings demonstrate that freezers have altered gait variability and consistency during spontaneous community ambulation, even during optimal performance, and that these measures are associated with the impact of FOG on daily function. Long-term recordings may provide new insights into PD and augment the monitoring of FOG and its response to therapy.