EE Bulter, KM Steele, L Torburn, JG Gamble, J Rose (2016) “Clinical motion analyses over eight consecutive years in a child with crouch gait: a case report.” Journal of Medical Case Reports

Sagittal-plane images of child from 6-13 years of age.

Journal article in the Journal of Medical Case Reports:

A case study of crouch gait over 8-years in a child with no surgical interventions.

Sagittal-plane images of child from 6-13 years of age.

Background: This case report provides a unique look at the progression of crouch gait in a child with cerebral palsy over an 8-year time period, through annual physical examinations, three-dimensional gait analyses, and evaluation of postural balance. Our patient received regular botulinum toxin-A injections, casting, and physical therapy but no surgical interventions.

Case presentation: A white American boy with spastic diplegic cerebral palsy was evaluated annually by clinical motion analyses, including physical examination, joint kinematics, electromyography, energy expenditure, and standing postural balance tests, from 6 to 13 years of age. These analyses revealed that the biomechanical factors contributing to our patient’s crouch gait were weak plantar flexors, short and spastic hamstrings, moderately short hip flexors, and external rotation of the tibiae. Despite annual recommendations for surgical lengthening of the hamstrings, the family opted for non-surgical treatment through botulinum toxin-A injections, casting, and exercise. Our patient’s crouch gait improved between ages 6 and 9, then worsened at age 10, concurrent with his greatest body mass index, increased plantar flexor weakness, increased standing postural sway, slowest normalized walking speed, and greatest walking energy expenditure. Although our patient’s maximum knee extension in stance improved by 14 degrees at 13 years of age compared to 6 years of age, peak knee flexion in swing declined, his ankles became more dorsiflexed, his hips became more internally rotated, and his tibiae became more externally rotated. From 6 to 9 years of age, our patient’s minimum stance-phase knee flexion varied in an inverse relationship with his body mass index; from 10 to 13 years of age, changes in his minimum stance-phase knee flexion paralleled changes in his body mass index.

Conclusions: The motor deficits of weakness, spasticity, shortened muscle-tendon lengths, and impaired selective motor control were highlighted by our patient’s clinical motion analyses. Overall, our patient’s crouch gait improved mildly with aggressive non-operative management and a supportive family dedicated to regular home exercise. The annual clinical motion analyses identified changes in motor deficits that were associated with changes in the child’s walking pattern, suggesting that these analyses can serve to track the progression of children with spastic cerebral palsy.

MH Schwartz, A Rozumalski, KM Steele (2016) “Dynamic motor control is associated with treatment outcomes for children with cerebral palsy.” Developmental Medicine & Child Neurology

MH Schwartz, A Rozumalski, KM Steele (2016) “Dynamic motor control is associated with treatment outcomes for children with cerebral palsy.” Developmental Medicine & Child Neurology

Journal article in Developmental Medicine & Child Neurology

Kat Steele partnered with Michael Schwartz from Gillette Children’s Specialty Healthcare to investigate the impact of dynamic motor control on varying treatments in children with cerebral palsy.

Aim

To estimate the impact of dynamic motor control on treatment outcomes in children with cerebral palsy.

Method

We used multiple regression on a retrospective cohort of 473 ambulatory children with cerebral palsy who underwent conservative treatment, single-level orthopaedic surgery, single-event multi-level orthopaedic surgery, or selective dorsal rhizotomy. Outcomes included gait pattern, gait speed, energy cost of walking, and the Pediatric Outcomes Data Collection Instrument. Explanatory variables considered were pre-treatment levels of each outcome, treatment group, prior treatment, age, and dynamic motor control computed from surface electromyography using synergy analysis. Effect sizes were estimated from the adjusted response.

Results

Pre-treatment levels had effect sizes 2 to 13 times larger than the next largest variable. Individuals with milder pre-treatment involvement had smaller gains or actual declines. Dynamic motor control was significant in all domains except energy cost. The effect size of dynamic motor control was second only to pre-treatment level, and was substantially larger than the effect size of treatment group for outcomes where both were significant (gait pattern 2:1, gait speed 4:1). The effect of dynamic motor control was independent of treatment group.

Interpretation

Dynamic motor control is an important factor in treatment outcomes. Better dynamic motor control is associated with better outcomes, regardless of treatment. PDF

BR Shuman, M Goudriaan, L Bar-On, MH Schwartz, K Desloovere, KM Steele (2016) “Repeatability of muscle synergies within and between days for typically developing children and children with cerebral palsy.” Gait & Posture.

BR Shuman, M Goudriaan, L Bar-On, MH Schwartz, K Desloovere, KM Steele (2016) “Repeatability of muscle synergies within and between days for typically developing children and children with cerebral palsy.” Gait & Posture.

Journal article in Gait and Posture:

Filtering parameters impact the results from muscle synergy analyses.

Top: Average tVAF for day 1 and day 2 in TD and CP calculated from all measured gait cycles. The LME model identified a significant difference in synergy complexity between TD and CP for n = 1–5 synergies. Bottom: Average tVAF for each of the three walking speeds in TD and CP from both days. Walking speed had a significant effect on synergy complexity for tVAF of 1–5 synergiesAbstract: Muscle synergies are typically calculated from electromyographic (EMG) signals using nonnegative matrix factorization. Synergies identify weighted groups of muscles that are commonly activated together during a task, such as walking. Synergy analysis has become an emerging tool to evaluate neuromuscular control; however, the repeatability of synergies between trials and days has not been evaluated. The goal of this study was to evaluate the repeatability of synergy complexity and structure in unimpaired individuals and individuals with cerebral palsy (CP). EMG data were collected from eight lower-limb muscles during gait for six typically developing (TD) children and five children with CP on two separate days, over three walking speeds. To evaluate synergy complexity, we calculated the total variance accounted for by one synergy (tVAF1). On a given day, the average range in tVAF1 between gait cycles was 18.2% for TD and 19.1% for CP. The average standard deviation in tVAF1 between gait cycles was 4.9% for TD and 5.0% for CP. Average tVAF1 calculated across gait cycles was not significantly different between days for TD or CP participants. Comparing synergy structure, the average (standard deviation) within day correlation coefficients of synergy weights for two or more synergies were 0.89 (0.15) for TD and 0.88 (0.15) for CP. Between days, the average correlation coefficient of synergy weights for two or more synergies was greater than 0.89 for TD and 0.74 for CP. These results demonstrate that synergy complexity and structure averaged over multiple gait cycles are repeatable between days in both TD and CP groups.

SSM Lee, D Gaebler-Spira, LQ Zhang, WZ Rymer, KM Steele, (2016) “Use of shear wave ultrasound elastography to quantify muscle properties in cerebral palsy.” Clinical Biomechanics

Sample ultrasound images from gastrocnemius and tibialis anterior showing greater shear wave velocity on more affected limb.

Journal article in Clinical Biomechanics:

Kat Steele partnered with Sabrina Lee from Northwestern University and the Rehabilitation Institute of Chicago to investigate shearwave ultrasound elastography as a new tool to quantify changes in muscle properties in cerebral palsy.

Sample ultrasound images from gastrocnemius and tibialis anterior showing greater shear wave velocity on more affected limb.Abstract: Individuals with cerebral palsy tend to have altered muscle architecture and composition, but little is known about the muscle material properties, specifically stiffness. Shear wave ultrasound elastography allows shear wave speed, which is related to stiffness, to be measured in vivo in individual muscles. Our aim was to evaluate the material properties, specifically stiffness, as measured by shear wave speed of the medial gastrocnemius and tibialis anterior muscles in children with hemiplegic cerebral palsy across a range of ankle torques and positions, and fascicle strains. Shear wave speed was measured bilaterally in the medial gastrocnemius and tibialis anterior over a range of ankle positions and torques using shear wave ultrasound elastography in eight individuals with hemiplegic cerebral palsy. B-mode ultrasound was used to measure muscle thickness and fascicle strain. Shear waves traveled faster in the medial gastrocnemius and tibialis anterior of the more-affected limb by 14% (P = 0.024) and 20% (P = 0.03), respectively, when the ankle was at 90°. Shear wave speed in the medial gastrocnemius increased as the ankle moved from plantarflexion to dorsiflexion (less affected: r2 = 0.82, P < 0.001; more-affected: r2 = 0.69, P < 0.001) and as ankle torque increased (less affected: r2 = 0.56,P < 0.001; more-affected: r2 = 0.45, P < 0.001). In addition, shear wave speed was strongly correlated with fascicle strain (less affected: r2 = 0.63, P < 0.001; more-affected: r2 = 0.53, P < 0.001). The higher shear wave speed in the more-affected limb of individuals with cerebral palsy indicates greater muscle stiffness, and demonstrates the clinical potential of shear wave elastography as a non-invasive tool for investigating mechanisms of altered muscle properties and informing diagnosis and treatment.

KM Steele, A Rozumalski, MH Schwartz (2015) “Muscle synergies and complexity of neuromuscular control during gait in cerebral palsy.” Developmental Medicine & Child Neurology

WalkDMC decreased with GMFCS level among individuals with cerebral palsy.

Journal article accepted in Developmental Medicine & Child Neurology:

Kat Steele partnered with Mike Schwartz and Adam Rozumalski of Gillette Children’s Specialty Healthcare to complete one of the largest studies to date of individuals with cerebral palsy. They quantified how neuromuscular control is altered among individuals with cerebral palsy and how this altered control can contribute to impaired function.

WalkDMC decreased with GMFCS level among individuals with cerebral palsy.

Abstract: Individuals with cerebral palsy (CP) have impaired movement due to a brain injury near birth. Understanding how neuromuscular control is altered in CP can provide insight into pathological movement. We sought to determine if individuals with CP demonstrate reduced complexity of neuromuscular control during gait compared with unimpaired individuals and if changes in control are related to functional ability. Muscle synergies during gait were retrospectively analyzed for 633 individuals (age range 3.9–70y): 549 with CP (hemiplegia, n=122; diplegia, n=266; triplegia, n=73; quadriplegia, n=88) and 84 unimpaired individuals. Synergies were calculated using non-negative matrix factorization from surface electromyography collected during previous clinical gait analyses. Synergy complexity during gait was compared with diagnosis subtype, functional ability, and clinical examination measures. Fewer synergies were required to describe muscle activity during gait in individuals with CP compared with unimpaired individuals. Changes in synergies were related to functional impairment and clinical examination measures including selective motor control, strength, and spasticity. InterpretationIndividuals with CP use a simplified control strategy during gait compared with unimpaired individuals. These results were similar to synergies during walking among adult stroke survivors, suggesting similar neuromuscular control strategies between these clinical populations. PDF

Also, make sure you look at the commentary from Diane Damiano. She provides perspective about the utility of synergies for evaluating neuromuscular control in children with cerebral palsy and future challenges.