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245 DETECTING FALLERS WITH PARKINSON'S DISEASE USING CENTRE OF MASS MOTION DURING GAIT
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Posters / Parkinsonism and Related Disorders 16S1 (2010) S11–S86
control group (r = 0.85, p = 0.002), suggests that the central nervous system may preset postural response parameters based on voluntary maximum limits of stability. The farther a subject leaned backward voluntarily, the greater their stability during platform translations. This relationship between limits of stability and postural responses is disrupted by PD (r = 0.3, p = 0.5) and improved with levodopa medication (r = 0.72, p = 0.05), consistent with a dopaminergic mechanism for this central representation of postural stability limits. 245 DETECTING FALLERS WITH PARKINSON’S DISEASE USING CENTRE OF MASS MOTION DURING GAIT M. Morris1 , B. Galna2 , A. Murphy3 . 1 Health Sciences, 2 Physiotherapy, The University of Melbourne, Carlton, 3 Kingston Centre, Cheltenham, Australia Background and Aims: Identifying people with PD at a risk of falls is important for cost-effective patient-specific treatment. This
study examined whether mediolateral motion of the CoM during level-ground walking and obstacle crossing could distinguish fallers and non-fallers in people with mild to moderate PD. Methods: 20 people with mild to moderate PD were tested at the peak dose of their levodopa medication (4 females; age m: 65.6 yr, s: 7.7; UPDRS-III m: 12.6, s: 5.1; H&Y stage range 1–3, 8 reported falling in the past year). Mediolateral CoM excursion relative to the centre of pressure (inclination angle), was calculated during the swing phase of level-ground walking and lead and trail limb obstacle crossing steps (obstacle height 10% of leg length × 600 mm × 10 mm). ROC curve analysis was used to determine whether CoM-CoP excursions could distinguish PD fallers from non-fallers. Results: Greater mediolateral CoM motion during level-ground walking and obstacle crossing distinguished PD fallers from nonfallers better than chance (Figure 1). Conclusions: CoM motion during gait could help identify people with PD at risk of falling. Larger prospective studies are required to verify these findings. Acknowledgements: This project was assisted by NHMRC Australia #466630, the University of Melbourne and the Kingston Centre. 246 A WEARABLE TECHNOLOGY FOR MEASURING CENTER OF MASS AND EXAMINING THE RECIPROCAL COORDINATION BETWEEN LOWER-LIMBS AND TORSO WHILE STANDING D. Horn, J. Wrobel, B. Najafi. Scholl’s Center for Lower Extremity Ambulatory Research (CLEAR), Rosalind Franklin University of Medicine & Science, North Chicago, IL, USA Background: The goals of this study were to explore the validity of a new biosensor technology to quantify postural control and examine the impact of two major sensory feedbacks: visual and somatosensory in postural-compensatory strategy. Method: We designed a biosensor system using a 2-link model for assessing the postural-anticipatory-strategy. This novel tool enables measuring 3D movements of body segments in real-time. Postural control of 21 healthy-subjects was assessed under various conditions: eyes-open and eyes-closed, while standing on a hard or a soft surface. Using this sensor-based technology, we estimated: the area of sway for center of mass (COM) as well as reciprocal coordination between lower-limbs and torso. A pressure-platform (Emed® ) was used as a gold-standard to examine the validity of the biosensor technology. Results: Results demonstrated a relatively high agreement between pressure-platform and biosensor technology over all conditions (r > 0.9, p < 10−6 ). In addition, excellent test–retest reliability was observed for both COP and COM measurement for all conditions [ICC(1,1) > 0.85]. As expected the area of sway was significantly increased by closing the eyes as well as by challenging the somatosensory feedback by using a soft surface support (EO COM = 32.69 cm2 , EO foam COM = 66.34 cm2 , EC COM = 68.76 cm2 , EC foam COM = 197.5 cm2 ). The average area of dispersion of the COM was approximately 12 times higher than the COP. Conclusion: The suggested technology is wearable and can be used for assessing postural instability in free-condition, while standing on different surfaces. It may also be a more sensitive indicator of postural instability v. the COP. 247 DOES THE TYPE OF FOOTWEAR IMPACT THE NUMBER OF STEPS REQUIRED FOR REACHING GAIT STEADY-STATE?
Figure 1. ROC curve of sensitivity plotted against 1 − specificity using the mediolateral centre of mass inclination angle excursion during level-ground walking and obstacle crossing to distinguish people with PD who did (n = 8) and did not (n = 12) report having fallen in the past year
D. Miller1 , B. Jarrett2 , J. Wrobel1 , B. Najafi1 . 1 Scholl’s Center for Lower Extremity Ambulatory Research (CLEAR), 2 The Dr. William M. Scholl College of Podiatric Medicine, Rosalind Franklin University of Medicine & Science, North Chicago, IL, USA Background: The gait initiation phase is the transient period between upright posture and steady state gait. The central (CNS)
Posters / Parkinsonism and Related Disorders 16S1 (2010) S11–S86
control group (r = 0.85, p = 0.002), suggests that the central nervous system may preset postural response parameters based on voluntary maximum limits of stability. The farther a subject leaned backward voluntarily, the greater their stability during platform translations. This relationship between limits of stability and postural responses is disrupted by PD (r = 0.3, p = 0.5) and improved with levodopa medication (r = 0.72, p = 0.05), consistent with a dopaminergic mechanism for this central representation of postural stability limits. 245 DETECTING FALLERS WITH PARKINSON’S DISEASE USING CENTRE OF MASS MOTION DURING GAIT M. Morris1 , B. Galna2 , A. Murphy3 . 1 Health Sciences, 2 Physiotherapy, The University of Melbourne, Carlton, 3 Kingston Centre, Cheltenham, Australia Background and Aims: Identifying people with PD at a risk of falls is important for cost-effective patient-specific treatment. This
study examined whether mediolateral motion of the CoM during level-ground walking and obstacle crossing could distinguish fallers and non-fallers in people with mild to moderate PD. Methods: 20 people with mild to moderate PD were tested at the peak dose of their levodopa medication (4 females; age m: 65.6 yr, s: 7.7; UPDRS-III m: 12.6, s: 5.1; H&Y stage range 1–3, 8 reported falling in the past year). Mediolateral CoM excursion relative to the centre of pressure (inclination angle), was calculated during the swing phase of level-ground walking and lead and trail limb obstacle crossing steps (obstacle height 10% of leg length × 600 mm × 10 mm). ROC curve analysis was used to determine whether CoM-CoP excursions could distinguish PD fallers from non-fallers. Results: Greater mediolateral CoM motion during level-ground walking and obstacle crossing distinguished PD fallers from nonfallers better than chance (Figure 1). Conclusions: CoM motion during gait could help identify people with PD at risk of falling. Larger prospective studies are required to verify these findings. Acknowledgements: This project was assisted by NHMRC Australia #466630, the University of Melbourne and the Kingston Centre. 246 A WEARABLE TECHNOLOGY FOR MEASURING CENTER OF MASS AND EXAMINING THE RECIPROCAL COORDINATION BETWEEN LOWER-LIMBS AND TORSO WHILE STANDING D. Horn, J. Wrobel, B. Najafi. Scholl’s Center for Lower Extremity Ambulatory Research (CLEAR), Rosalind Franklin University of Medicine & Science, North Chicago, IL, USA Background: The goals of this study were to explore the validity of a new biosensor technology to quantify postural control and examine the impact of two major sensory feedbacks: visual and somatosensory in postural-compensatory strategy. Method: We designed a biosensor system using a 2-link model for assessing the postural-anticipatory-strategy. This novel tool enables measuring 3D movements of body segments in real-time. Postural control of 21 healthy-subjects was assessed under various conditions: eyes-open and eyes-closed, while standing on a hard or a soft surface. Using this sensor-based technology, we estimated: the area of sway for center of mass (COM) as well as reciprocal coordination between lower-limbs and torso. A pressure-platform (Emed® ) was used as a gold-standard to examine the validity of the biosensor technology. Results: Results demonstrated a relatively high agreement between pressure-platform and biosensor technology over all conditions (r > 0.9, p < 10−6 ). In addition, excellent test–retest reliability was observed for both COP and COM measurement for all conditions [ICC(1,1) > 0.85]. As expected the area of sway was significantly increased by closing the eyes as well as by challenging the somatosensory feedback by using a soft surface support (EO COM = 32.69 cm2 , EO foam COM = 66.34 cm2 , EC COM = 68.76 cm2 , EC foam COM = 197.5 cm2 ). The average area of dispersion of the COM was approximately 12 times higher than the COP. Conclusion: The suggested technology is wearable and can be used for assessing postural instability in free-condition, while standing on different surfaces. It may also be a more sensitive indicator of postural instability v. the COP. 247 DOES THE TYPE OF FOOTWEAR IMPACT THE NUMBER OF STEPS REQUIRED FOR REACHING GAIT STEADY-STATE?
Figure 1. ROC curve of sensitivity plotted against 1 − specificity using the mediolateral centre of mass inclination angle excursion during level-ground walking and obstacle crossing to distinguish people with PD who did (n = 8) and did not (n = 12) report having fallen in the past year
D. Miller1 , B. Jarrett2 , J. Wrobel1 , B. Najafi1 . 1 Scholl’s Center for Lower Extremity Ambulatory Research (CLEAR), 2 The Dr. William M. Scholl College of Podiatric Medicine, Rosalind Franklin University of Medicine & Science, North Chicago, IL, USA Background: The gait initiation phase is the transient period between upright posture and steady state gait. The central (CNS)