Oct 29, 2015 - On the Relationship between Spasticity and Gait. Variability. Arnaud Gouelle, PhD. Gait and Motion Analysis Unit. Robert Debré University ...
On the Relationship between Spasticity and Gait Variability Arnaud Gouelle, PhD Gait and Motion Analysis Unit Robert Debré University Hospital for Children Paris, France
Disclosure: No financial interest to disclose. nd Annualde 26ème la SOFMER, octobre - Nantes ACRM 92congrès Conference, 29th 14 October 20152011 – Dallas, TX, USA
Learning Objectives
What is gait variability and How quantified it
Different levels of influence of spasticity on variability
“Bad” and “Good” variability
Mid-term and long term effects
Impact of therapy against spasticity
What is gait variability?
Fluctuations in gait characteristics (kinematics, kinetics, spatiotemporal parameters) between strides or steps
Natural variability in healthy persons due to: Neuromuscular noise in the sensori-motor system Errors or deficits in the motor control system
Variability is affected in advanced age and various neurologically impaired populations (including CP, MS, Stroke, SCI….)
Key parameter of dynamic instability during walking Measure of motor ability Tool for assessing progressive changes or the efficacy of therapeutic interventions
Note: can arise too from external (e.g., environmental demands) and methodological (e.g., instrumentation) factors
How is gait variability quantified?
No gold standard and different analysis techniques depending on: Methods used to record data (accelerometers, gait mats, 3D mocap, etc.) Nature of the main variables (STP, angles, CoP, CoM, etc.) Pathological condition (treadmill, distance, etc.)
Fluctuation magnitude Distributional metrics such as standard deviation, coefficient of variation Conglomerate measure: Gait Variability Index (Gouelle et al., 2013) Most commonly used: more clinically applicable
Fluctuation dynamics (For a review, see Hausdorff, 2007) Temporal structuring of the signal Non linear metrics (e.g. DFA, approximate entropy, Lyapunov exponent)
Presenter’s images Gouelle et al. (2013). The Gait Variability Index: A new way to quantify fluctuation magnitude of spatiotemporal parameters during gait. Gait and Posture, 38, 461-465. Hausdorff (2007). Gait dynamics, fractals and falls finding meaning in the stride-tostride fluctuations of human walking. Human Movement Science, 26, 555-589.
Influence of spasticity
Direct noisy impact (“bad variability”) Abnormal muscle tone and loss of selective control Alteration in the outcome of descending motor command driving walking More variability in movement trajectories Spasticity
Stimulus
Central Nervous system
Musculoskeletal system
Trajectory
Influence of spasticity
Direct noisy impact (“bad variability”)
Bakir et al. (2013) Children (from 6 of age) with spastic bilateral CP compared to TD children Absence of contractures, Modified Ashworth Scale 1.5 ± 0.4 CV significantly higher in CP Prosser et al. (2010) Children (from 7 of age) with spastic bilateral CP Spasticity in hamstrings and hip adductors using modified Tardieu scale CV significantly higher in CP But not related to any Tardieu test value
WHY???
Bakir et al. (2013). Temporal but not spatial variability during gait Is reduced after selective dorsal rhizotomy in children with cerebral palsy. PLoS ONE, 8(7), e69500. Prosser et al. (2010). Variability and symmetry of gait in early walkers with and without bilateral cerebral palsy. Gait and Posture, 31, 522-526.
Influence of spasticity
Immediate adaptation to the perturbation (“good variability”) Required to preserve movement and prevent falling Depending on physiological and physical capacities
Difficult to clearly differentiate perturbation and regulation More visible in patients with a more affected/spastic side
Balasubramanian et al. (2009) Post-stroke with chronic hemiparesis, No control for spasticity SD swing time greater on the paretic side SD single phase time greater on the non-paretic side = more regulation
Balasubramanian et al. (2009). Variability in spatiotemporal step characteristics and its relationship to walking performance post-stroke. Gait and Posture, 29, 408-414.
Influence of spasticity
Immediate adaptation to the perturbation (“good variability”)
Femery et al. (2001), Descatoire et al. (2009) Children (15±3 years) with Cerebral Palsy hemiplegia Spasticity (hamstrings, rectus femoris, triceps surae) using Ashworth Scale Low spasticity group (mean 1) versus High spasticity group (mean 3) Spatiotemporal parameters + Foot pressure
Global variability is higher in the High spasticity group High spasticity: plegic limb more variable Low spasticity: non-plegic limb more variable
REGULATION STRATEGY
Femery et al. (2001). Spasticity and dynamic plantar pressure distribution measurements in hemiplegic spastic children. Annals of Physical and Rehabilitation Medicine, 44, 26-34.
Influence of spasticity
Mid- and long-term impact Primary effects of the original brain injury (spasticity) lead to… … Secondary anomalies (e.g. bones torsional misalignment, muscular contractures) … Tertiary compensation (e.g. vaulting in plantarflexor spasticity)
Dynamic theories of self-organization (task, organism, environment) Gait variability depending on the possibilities, the quality of coping strategies… … and WHAT is optimized? (energy, velocity, or stability)
High level of constraints Very reproducible walk with low gait variability Hide often inability to manage high perturbation
Changes in gait variability during spasticity therapy
Few articles with follow-up of the outcomes Gait variability is reduced after therapy
Bakir et al. (2013) Children (from 6 of age) with spastic bilateral CP, Dorsal Rhyzotomy Modified Ashworth Scale from 1.5 (±0.4) to 0.6 (±0.5) Temporal variability is reduced Gross et al. (2012) Case study on patient with Spinal Cord Injury, Motor nerve block in Rectus Femoris ICC for knee flexion/extension curves of the different gait cycles Reproducibility improved at 6 weeks after toxin
How does patient re-organize his gait? New degrees of freedom to manage Immediate improvement of the functional aspect of gait Increased gait variability that decreases with time
Bakir et al. (2013). Temporal but not spatial variability during gait Is reduced after selective dorsal rhizotomy in children with cerebral palsy. PLoS ONE, 8(7), e69500. Gross et al. (2012). Unstable gait due to spasticity of the rectus femoris: Gait analysis and motor nerve block. Annals of Physical Rehabilitation and Medicine, 55, 609622.
Conclusion
Combination of deficits contribute to gait
Not easy to assess which part is really due to spasticity
Which proportion of “Bad” and “Good” variability
Spasticity is commonly evaluated in a passive condition
Need of electromyography during spasticity testing
Thank you!