Background: Parkinson�s disease (PD) is a neurodegenerative disorder resulting in\r\nmotor disturbances that can impact normal gait. Although PD initially responds well\r\nto pharmacological treatment, as the disease progresses efficacy often fluctuates over\r\nthe course of the day, and clinical management would benefit from long-term\r\nobjective measures of gait. We have previously described a small device worn on the\r\nshank that uses acceleration and angular velocity sensors to calculate stride length\r\nand identify freezing of gait in PD patients. In this study we extend validation of the\r\ngait monitor to 24-h using simultaneous video observation of PD patients.\r\nMethods: A sleep laboratory was adapted to perform 24-hr video monitoring of\r\npatients while wearing the device. Continuous video monitoring of a sleep lab,\r\nhallway, kitchen and conference room was performed using a 4-camera security\r\nsystem and recorded to hard disk. Subjects (3) wore the gait monitor on the left\r\nshank (just above the ankle) for a 24-h period beginning around 5 pm in the\r\nevening. Accuracy of stride length measures were assessed at the beginning and\r\nend of the 24-h epoch. Two independent observers rated the video logs to identify\r\nwhen subjects were walking or lying down.\r\nResults: The mean error in stride length at the start of recording was 0.05 m (SD 0)\r\nand at the conclusion of the 24 h epoch was 0.06 m (SD 0.026). There was full\r\nagreement between observer coding of the video logs and the output from the gait\r\nmonitor software; that is, for every video observation of the subject walking there\r\nwas a corresponding pulse in the monitor data that indicated gait.\r\nConclusions: The accuracy of ambulatory stride length measurement was\r\nmaintained over the 24-h period, and there was 100% agreement between the\r\nautonomous detection of locomotion by the gait monitor and video observation.
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