title: Continuous monitoring of turning in Parkinson's disease: Rehabilitation potential.
abstract: BACKGROUND
  Difficulty turning during gait is a major contributor to mobility disability, falls and reduced quality of life in patients with Parkinson's disease (PD). Unfortunately, the assessment of mobility in the clinic may not adequately reflect typical mobility function or its variability during daily life. We hypothesized that quality of turning mobility, rather than overall quantity of activity, would be impaired in people with PD over seven days of continuous recording.
  
  
  METHODS
  Thirteen subjects with PD and 8 healthy control subjects of similar age wore three Opal inertial sensors (on their belt and on each foot) throughout seven consecutive days during normal daily activities. Turning metrics included average and coefficient of variation (CV) of: (1) number of turns per hour, (2) turn angle amplitude, (3) turn duration, (4) turn mean velocity, and (5) number of steps per turn. Turning characteristics during continuous monitoring were compared with turning 90 and 180 degrees in a observed gait task.
  
  
  RESULTS
  No differences were found between PD and control groups for observed turns. In contrast, subjects with PD showed impaired quality of turning compared to healthy control subjects (Turn Mean Velocity: 43.3 ± 4.8°/s versus 38 ± 5.7°/s, mean number of steps 1.7 ± 1.1 versus 3.2 ± 0.8). In addition, PD patients showed higher variability within the day and across days compared to controls. However, no differences were seen between PD and control subjects in the overall activity (number of steps per day or percent of the day walking) during the seven days.
  
  
  CONCLUSIONS
  We show that continuous monitoring of natural turning during daily activities inside or outside the home is feasible for patients with PD and the elderly. This is the first study showing that continuous monitoring of turning was more sensitive to PD than observed turns. In addition, the quality of turning characteristics was more sensitive to PD than quantity of turns. Characterizing functional turning during daily activities will address a critical barrier to rehabilitation practice and clinical trials: objective measures of mobility characteristics in real-life environments.
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Martina
authors.initials: M
authors.lastname: Mancini
authors.affiliation: APDM, Inc., Portland, OR, USA.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: El-Gohary
authors.affiliation: APDM, Inc., Portland, OR, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Pearson
authors.affiliation: APDM, Inc., Portland, OR, USA.
authors.forename: James
authors.initials: J
authors.lastname: McNames
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Schlueter
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Nutt
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA.
authors.forename: Laurie A
authors.initials: LA
authors.lastname: King
authors.affiliation: Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, OR, USA.|APDM, Inc., Portland, OR, USA.|VA Portland Health Care System VAPORHCS, Portland, OR, USA.
authors.forename: Fay B
authors.initials: FB
authors.lastname: Horak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000379:methods; D010300:Parkinson Disease / Q000503:physiopathology / Q000534:rehabilitation*; D016059:Range of Motion, Articular; D058998:Remote Sensing Technology / Q000379:methods*; D016138:Walking
keywords: Parkinson’s disease; continuous monitoring; functional mobility