- Email: [email protected]
17.18 Postural sway complexity changes with recovery after stroke: Findings from dynamical analyses
Chapter 17. Sensorimotor deficits'following stroke
$110
Results: At their PWS patients walked on average for 120m, controls 374 m (P < 0.05), with no statistical difference at the matched pace. Discussion: Studies have assessed the aerobic capacity of stroke patients'; few have investigated overground walking. A 360% increase in VO2UDW is required for patients PWS over controls PWS. At the matched pace the patients require 169% VO2UDW over controls. Conclusion: The increased cost of walking in stroke survivors has significant functional implications.
References [1] Wade DT, Hewer RL. Functional abilities after stroke: measurement, natural history and prognosis. Journal of Neurology, Neurosurgery and Psychiatry 1987; 50:177 182. [2] Corcoran PJ. Brengelmann GL. Oxygen uptake in normal and handicapped subjects, in relation to speed of walking beside velocity-controlled cart. Archives of Physical Medicine & Rehabilitation 1970; 51(2): 78 87.
[•]
Longitudinal study of locomotor recovery up to two years after stroke
C.L. Richards 1'2, E Malouin 1'2, E Dumas 1'2, S. Wood-Dauphinee 3. 1 Department of Rehabilitation, Laval University, 2 CTRR/S Research
Cente~ sRehabilitation Institute of Quebec, Quebec City, and the School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada
We studied locomotor recovery post stroke by comparing values from healthy persons (age: 58.6±7.6; mean±l SD) walking slowly (68.3±6.7 cm/s). Methods: Gait analysis was performed at 6 weeks, 3, 6, 12 and 24 months after stroke in 11 persons (age range: 48 82 years, 5 women and 6 with left-sided hemiparesis). Movements (electrogoniometer), muscle activations (EMG: Quadriceps (Q), Triceps Surae (TS) and Tibialis Anterior (TA) muscles), footswitch signals and gait speed were concomitantly recorded as the subjects walked at free speed. Areas under functionally related muscle activation bursts during the gait cycle were compared for each muscle. Results: At 2 years post stroke the mean gait speed was double that at 6 weeks (31.8±19.9 vs 62.8±19.1 cm/s, n 11) and 5 persons with stroke attained a "normal" walking speed. The faster walkers (>60 cm/s at 6 weeks) displayed "more normal" movement and muscle activation patterns. The pattern of recovery varied among the muscles. The TA burst (60 80%) recovered progressively from 6 weeks-2 years, the Q burst (84 100%) recovered little until one year after stroke, while surprisingly, the TS "push-off" burst (20 50%) did not show significant recovery over time (ANOVA). Recovery in walking speed had a closer association with recovery in the TA (60 80%) than with the Q or TS. Discussion and Conclusion: This study provides new information on patterns of locomotor recovery over time in a cohort of subjects with stroke due to an ischaemic lesion of the middle cerebral artery. This work was supported by the National Health Research and Development Program of Canada and Laval University. Introduction:
•
Postural sway complexity changes with recovery after stroke: findings from dynamical analyses
M. Roerdink 1, M. de Haart 2'3, S. Donker 1'4, A.C.H. Geurts 5, R Beek 1. 1Institute for Fundamental and Clinical Human Movement
Sciences (IFKB), Amsterdam, The Netherlands'," 2Department of Rehabilitation, Amsterdam Medical Centre, University of Amsterdam, The Netherlands'; SSt. Maartenskliniek Research & Department of Rehabilitation Medicine, St. Maartenskliniek, Nijmegen, The Netherlands'," 4 Department of Otorhinolaryngolog,y, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands'," ~Department of Rehabilitation Medicine, University Medical Centre St. Radboud, Nijmegen, The Netherlands' Introduction: Centre of pressure (COP) trajectories often vary in a
complex and irregular manner. Standard averaging procedures generally mask the underlying dynamics, which requires the application of dynamical analyses dealing with spatial and temporal correlations. This study aims to: a) discover changes in the underlying dynamics involved in the recovery of postural control after stroke and b) determine how these dynamics are affected by changes in available sensory or cognitive information. Methods: CoP trajectories of 33 stroke patients were investigated longitudinally during rehabilitation for 3 conditions (eyes open; eyes open with concurrent arithmetic dual task; eyes closed) [1]. Regularity (sample entropy), complexity (correlation dimension) and scaling properties (Hurst exponent H) of CoP trajectories were determined. Results: CoP variability was structured rather than random, exhibiting anti-persistent scaling behavior (H <0.5). CoP regularity decreased with recovery (entropy increased). CoP dynamics was more complex (higher dimension) and less regular (higher entropy) when performing a dual task. Discussion and Conclusion: Successful recovery after stroke was associated with decreased regularity in postural sway, whereas its scaling behavior seemed to converge to 1/f noise (H near 0.25), as is typical for healthy, adaptive physiology. Also meaningful changes in CoP complexity with sensory and cognitive manipulations were identified. Dynamical analyses applied to CoP trajectories may thus reveal valuable information about the underlying postural control process.
References [1] de Haart M, Geurts AC, Huidekoper SC, Fasotti L, van Limbeek J. Recovery of standing balance in postacute stroke patients: a rehabilitation cohort study. Arch Phys Med Rehabil 2004; 85: 886 95.
~
Balance during obstacle crossing following stroke
C. Said 1'2'3, R Goldie2, A.E. Patla4, M.E. Morris 2, W. Sparrow 5, E. Culham 6. 1Austin Health, Melbourne, Australia; 2La Trobe
University, Melbourne, Australia; s University of Melbourne, Australia; 4 University off Waterloo, Canada; 5 Deakin University, Melbourne, Australia; °Queens University, Canada
Introduction: Difficulty negotiating obstacles may contribute to the high falls rate following stroke [1]. This study examined the impact of stroke on balance during obstacle crossing. Method: Centre of mass (CoM) and centre of pressure (COP) were measured as 12 stroke subjects and 12 healthy subjects stepped over a 4 cm high obstacle at self-selected speed. Healthy subjects also walked at speeds matched to their yoked stroke subject. Results: Compared with healthy subjects at matched speed, CoM anterior posterior (AP) velocity was reduced at affected lead toe off in stroke subjects (p < 0.0125). At unaffected lead toe clearance, AP separation between CoM and CoP increased (p < 0.0125). Step lengths before and after the obstacle were reduced. Compared with healthy subjects at self-selected speed, the CoM and CoP were positioned more posteriorly during affected lead toe clearance (p < 0.0125). Discussion and Conclusion: Balance during obstacle crossing was impaired following stroke, as evidenced by excessive separation of the
$110
Results: At their PWS patients walked on average for 120m, controls 374 m (P < 0.05), with no statistical difference at the matched pace. Discussion: Studies have assessed the aerobic capacity of stroke patients'; few have investigated overground walking. A 360% increase in VO2UDW is required for patients PWS over controls PWS. At the matched pace the patients require 169% VO2UDW over controls. Conclusion: The increased cost of walking in stroke survivors has significant functional implications.
References [1] Wade DT, Hewer RL. Functional abilities after stroke: measurement, natural history and prognosis. Journal of Neurology, Neurosurgery and Psychiatry 1987; 50:177 182. [2] Corcoran PJ. Brengelmann GL. Oxygen uptake in normal and handicapped subjects, in relation to speed of walking beside velocity-controlled cart. Archives of Physical Medicine & Rehabilitation 1970; 51(2): 78 87.
[•]
Longitudinal study of locomotor recovery up to two years after stroke
C.L. Richards 1'2, E Malouin 1'2, E Dumas 1'2, S. Wood-Dauphinee 3. 1 Department of Rehabilitation, Laval University, 2 CTRR/S Research
Cente~ sRehabilitation Institute of Quebec, Quebec City, and the School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada
We studied locomotor recovery post stroke by comparing values from healthy persons (age: 58.6±7.6; mean±l SD) walking slowly (68.3±6.7 cm/s). Methods: Gait analysis was performed at 6 weeks, 3, 6, 12 and 24 months after stroke in 11 persons (age range: 48 82 years, 5 women and 6 with left-sided hemiparesis). Movements (electrogoniometer), muscle activations (EMG: Quadriceps (Q), Triceps Surae (TS) and Tibialis Anterior (TA) muscles), footswitch signals and gait speed were concomitantly recorded as the subjects walked at free speed. Areas under functionally related muscle activation bursts during the gait cycle were compared for each muscle. Results: At 2 years post stroke the mean gait speed was double that at 6 weeks (31.8±19.9 vs 62.8±19.1 cm/s, n 11) and 5 persons with stroke attained a "normal" walking speed. The faster walkers (>60 cm/s at 6 weeks) displayed "more normal" movement and muscle activation patterns. The pattern of recovery varied among the muscles. The TA burst (60 80%) recovered progressively from 6 weeks-2 years, the Q burst (84 100%) recovered little until one year after stroke, while surprisingly, the TS "push-off" burst (20 50%) did not show significant recovery over time (ANOVA). Recovery in walking speed had a closer association with recovery in the TA (60 80%) than with the Q or TS. Discussion and Conclusion: This study provides new information on patterns of locomotor recovery over time in a cohort of subjects with stroke due to an ischaemic lesion of the middle cerebral artery. This work was supported by the National Health Research and Development Program of Canada and Laval University. Introduction:
•
Postural sway complexity changes with recovery after stroke: findings from dynamical analyses
M. Roerdink 1, M. de Haart 2'3, S. Donker 1'4, A.C.H. Geurts 5, R Beek 1. 1Institute for Fundamental and Clinical Human Movement
Sciences (IFKB), Amsterdam, The Netherlands'," 2Department of Rehabilitation, Amsterdam Medical Centre, University of Amsterdam, The Netherlands'; SSt. Maartenskliniek Research & Department of Rehabilitation Medicine, St. Maartenskliniek, Nijmegen, The Netherlands'," 4 Department of Otorhinolaryngolog,y, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands'," ~Department of Rehabilitation Medicine, University Medical Centre St. Radboud, Nijmegen, The Netherlands' Introduction: Centre of pressure (COP) trajectories often vary in a
complex and irregular manner. Standard averaging procedures generally mask the underlying dynamics, which requires the application of dynamical analyses dealing with spatial and temporal correlations. This study aims to: a) discover changes in the underlying dynamics involved in the recovery of postural control after stroke and b) determine how these dynamics are affected by changes in available sensory or cognitive information. Methods: CoP trajectories of 33 stroke patients were investigated longitudinally during rehabilitation for 3 conditions (eyes open; eyes open with concurrent arithmetic dual task; eyes closed) [1]. Regularity (sample entropy), complexity (correlation dimension) and scaling properties (Hurst exponent H) of CoP trajectories were determined. Results: CoP variability was structured rather than random, exhibiting anti-persistent scaling behavior (H <0.5). CoP regularity decreased with recovery (entropy increased). CoP dynamics was more complex (higher dimension) and less regular (higher entropy) when performing a dual task. Discussion and Conclusion: Successful recovery after stroke was associated with decreased regularity in postural sway, whereas its scaling behavior seemed to converge to 1/f noise (H near 0.25), as is typical for healthy, adaptive physiology. Also meaningful changes in CoP complexity with sensory and cognitive manipulations were identified. Dynamical analyses applied to CoP trajectories may thus reveal valuable information about the underlying postural control process.
References [1] de Haart M, Geurts AC, Huidekoper SC, Fasotti L, van Limbeek J. Recovery of standing balance in postacute stroke patients: a rehabilitation cohort study. Arch Phys Med Rehabil 2004; 85: 886 95.
~
Balance during obstacle crossing following stroke
C. Said 1'2'3, R Goldie2, A.E. Patla4, M.E. Morris 2, W. Sparrow 5, E. Culham 6. 1Austin Health, Melbourne, Australia; 2La Trobe
University, Melbourne, Australia; s University of Melbourne, Australia; 4 University off Waterloo, Canada; 5 Deakin University, Melbourne, Australia; °Queens University, Canada
Introduction: Difficulty negotiating obstacles may contribute to the high falls rate following stroke [1]. This study examined the impact of stroke on balance during obstacle crossing. Method: Centre of mass (CoM) and centre of pressure (COP) were measured as 12 stroke subjects and 12 healthy subjects stepped over a 4 cm high obstacle at self-selected speed. Healthy subjects also walked at speeds matched to their yoked stroke subject. Results: Compared with healthy subjects at matched speed, CoM anterior posterior (AP) velocity was reduced at affected lead toe off in stroke subjects (p < 0.0125). At unaffected lead toe clearance, AP separation between CoM and CoP increased (p < 0.0125). Step lengths before and after the obstacle were reduced. Compared with healthy subjects at self-selected speed, the CoM and CoP were positioned more posteriorly during affected lead toe clearance (p < 0.0125). Discussion and Conclusion: Balance during obstacle crossing was impaired following stroke, as evidenced by excessive separation of the