Long-term Ambulatory Gait Monitor for Parkinson's Disease

Moore, Steven

Abstract

One of the primary and disabling clinical manifestations of Parkinson's disease (PD) is locomotor dysfunction, such as small, variable stride length and freezing of gait. Treatment of PD to a large extent focuses on replacing depleted dopamine at the striatum to maintain mobility for as long as possible. Clinical assessment relies on brief observation and frequently unreliable clinical histories, and to date no objective method exists for long-term monitoring of Parkinsonian gait, assessment of locomotor complications of dopamine replacement therapy, or detection of freezing of gait. We have developed and validated a novel technique for monitoring of pathological gait in PD patients. The laboratory prototype is too cumbersome for commercial use, and in this project we will use the technological expertise of IM Systems to produce a fully ambulatory, self-contained commercial version suitable for clinical implementation. The stride and gait evaluation monitor (SAGE-M) is a small device (the size of a pager) mounted on the shank just above the ankle, and consists of a combined accelerometer/gyroscope sensor array with onboard storage of data over a 24-h epoch. Linear acceleration and angular velocity of the measured leg are processed by SAGE software (SAGE-S) to provide an accurate measure of every stride taken by the subject, and the frequency characteristics of shank vertical acceleration are used to detect freezing. Data on consecutive strides characterize Parkinsonian gait and provide a dynamic assessment of the patient's locomotor response to therapy, allowing an objective evaluation of pharmacological, surgical, and rehabilitation interventions that could be used to adjust ongoing treatments and improve clinical trials. In this Phase I study we aim to manufacture and conduct preliminary validation tests on 8 prototype SAGE-Ms, utilizing 24-h assessment of gait in PD patients during in-house objective video monitoring (utilizing IM Systems' sleep lab facility), and in the community. In addition, subject comfort and compliance will be evaluated. Successful completion of Phase I will allow us to propose (in Phase II) refinement of the monitor measurements using (i) larger clinical tests of PD patients and normative populations assessing abnormal gait features, including detection of freezing (at three sites: Mount Sinai School of Medicine, New York; Baylor College of Medicine, Houston; and Royal Prince Alfred Hospital, Sydney, Australia), (ii) refinement of design for commercial production, (iii) addition of clinically friendly computer interfaces, and (iv) development of a patient version suitable for personal use. The SAGE system provides, for the first-time, long- term ambulatory monitoring of pathological gait specifically designed to evaluate PD patients. It is expected that most neurologists and virtually all clinical programs treating PD patients will purchase this device to improve treatment evaluation. This transfer of laboratory technology to a viable commercial clinical device will significantly enhance PD patient care. A major goal in the treatment of the common brain disorder Parkinson's disease is to minimize the profound disturbance on walking ability that so severely affects quality of life. The disturbance of a patient's ability to walk varies considerably over the course of a day, and current evaluations, typically based on brief observation of the patient in the clinic, are inadequate. The small, unobtrusive device proposed in this project will enable the assessment of a patient's ability to walk over a 24-hour period in their home environment, improving diagnosis and treatment, and accordingly patient mobility and quality of life. ? ? ?