Cerebral Palsy Archives - Page 4 of 16 - Neuromechanics & Mobility Lab

BC Conner, AM Spomer, KM Steele, ZF Lerner (2022) “Factors influencing neuromuscular responses to gait training with a robotic ankle exoskeleton in cerebral palsy”

Yusuke Maruo JournalArticle, Publications February 7, 2023August 9, 2023AFO, Cerebral Palsy, Exoskeleton

Journal Article in Assistive Technology:

Our findings underscored the importance of monitoring how users change their gait kinematics when walking with the resistive device, with a specific emphasis on stance-phase lower limb extension. We also highlight the necessity of considering an individual’s functional status and amount of practice with the device, as well as more obvious factors, like device parameters. BART can be used early in the development of robotic gait training interventions to better understand complex and multifactorial user-device interactions.

Aim: Although ankle exoskeletons offer a promising means of augmenting gait training and enhancing independent mobility among individuals with neuromuscular disorders, response to existing paradigms is highly heterogeneous. In this study we aimed to identify factors which may affect how individuals with cerebral palsy (CP) interact with a resistive ankle exoskeleton during multi-day training to inform future device design and individualized tuning.

Method:We evaluated the gait mechanics (kinematics and muscle activity) of eight individuals with CP as they walked with bilateral ankle exoskeletons – designed to promote increased plantar flexor recruitment – during a seven-day training paradigm. These data along with pertinent device and participant parameters were input into a Bayesian Additive Regression Trees (BART) machine learning model to identify factors which were most associated with increased plantar flexor recruitment.

Results: Four themes emerged: 1) AFO provision is a confusing and lengthy process, 2) participants want more information during AFO provision, 3) AFOs are uncomfortable and difficult to use, and 4) AFOs can benefit mobility and independence. Caregivers and individuals with CP recommended ideas such as 3D printing orthoses and education for caregivers on design choices to improve AFO design and provision.

Interpretation: Individuals with CP and their caregivers found the AFO provision process frustrating but highlight that AFOs support mobility and participation. Further opportunities exist to support function and participation of people with CP by streamlining AFO provision processes, creating educational materials, and improving AFO design for comfort and ease of use.

NL Zaino, M Yamagami, DJ Gaebler-Spira, KM Steele, KF Bjornson, HA Feldner (2022) “‘That’s frustrating’: Perceptions of ankle foot orthosis provision, use, and needs among people with cerebral palsy and caregivers”

Yusuke Maruo JournalArticle, News, Publications January 24, 2023February 23, 2024Accessibility, AFO, Cerebral Palsy, Orthosis

Journal Article in Prosthetics and Orthotics International:

This research provides insights into the lived experiences of individuals with CP and their caregivers regarding the process of obtaining and using an AFO. Further opportunities exist to support function and participation of people with CP by streamlining AFO provision processes, creating educational materials, and improving AFO design for comfort and ease of use.

Aim: The study objective was to evaluate the lived experiences of individuals with CP and their caregivers regarding AFO access, use, and priorities. We examined experiences around the perceived purpose of AFOs, provision process, current barriers to use, and ideas for future AFO design.

Method: Secondary data analysis was performed on semistructured focus groups that included 68 individuals with CP and 74 caregivers. Of the focus group participants, 66 mentioned AFOs (16 individuals with CP and 50 caregivers). De-identified transcripts were analyzed using inductive coding, and the codes were consolidated into themes.

BC Conner, AM Spomer, SSPA Bishe, KM Steele, ZF Lerner (2022) “Soleus H-reflex modulation in cerebral palsy and its relationship with neural control complexity: a pilot study”

Katie Landwehr JournalArticle, MotorControl, News, Publications June 25, 2022June 11, 2024Cerebral Palsy, Exoskeleton, H-reflex, Muscle synergy

Journal Article in Experimental Brain Research

Individuals with cerebral palsy (CP) display motor control patterns that suggest decreased supraspinal input, but it remains unknown if they are able to modulate lower-limb reflexes in response to more complex tasks, or whether global motor control patterns relate to reflex modulation capacity in this population.

Aim: To further elucidate the multifaceted effects of CP on inhibitory and faciliatory supraspinal pathways and global measures of motor control, providing novel information for improving targeted neuromuscular interventions in this patient population.

Methods: Eight ambulatory individuals with CP (12–18 years old) were recruited to complete a task complexity protocol, where soleus H-reflex excitability was compared between bilateral (baseline) and unilateral (complex) standing. We also investigated the relationship between each participant’s ability to modulate soleus H-reflex excitability and the complexity of their walking neural control pattern determined from muscle synergy analysis. Finally, six of the eight participants completed an exoskeleton walking protocol, where soleus H-reflexes were collected during the stance phase of walking with and without stance-phase plantar flexor resistance.

Results: Participants displayed a significant reduction in soleus H-reflex excitability (− 26 ± 25%, p = 0.04) with unilateral standing, and a strong positive relationship was observed between more refined neural control during walking and an increased ability to modulate reflex excitability (R = 0.79, p = 0.04). There was no difference in neuromuscular outcome measures with and without the ankle exoskeleton (p values all > 0.05), with variable reflex responses to walking with ankle exoskeleton resistance.

Interpretation: These findings provide evidence that ambulatory individuals with CP retain some capacity to modulate lower-limb reflexes in response to increased task complexity, and that less refined neural control during walking appears to be related to deficits in reflex modulation.

KM Steele, MH Schwartz (2022) “Causal Effects of Motor Control on Gait Kinematics After Orthopedic Surgery in Cerebral Palsy: A Machine-Learning Approach”

Katie Landwehr JournalArticle, MotorControl, News, Publications June 3, 2022June 11, 2024Cerebral Palsy, Electromyography, EMG, Gait, Machine Learning, Motor Control, Spasticity

Journal Article in Frontiers in Human Neuroscience

Altered motor control is common in cerebral palsy (CP). Understanding how altered motor control affects movement and treatment outcomes is important but challenging due to complex interactions with other neuromuscular impairments. While regression can be used to examine associations between impairments and movement, causal modeling provides a mathematical framework to specify assumed causal relationships, identify covariates that may introduce bias, and test model plausibility.

Aim: The goal of this research was to quantify the causal effects of altered motor control and other impairments on gait, before and after single-event multi-level orthopedic surgery (SEMLS).

Methods: We evaluated the impact of SEMLS on change in Gait Deviation Index (ΔGDI) between gait analyses. We constructed our causal model with a Directed Acyclic Graph that included the assumed causal relationships between SEMLS, ΔGDI, baseline GDI (GDIpre), baseline neurologic and orthopedic impairments (Imppre), age, and surgical history. We identified the adjustment set to evaluate the causal effect of SEMLS on ΔGDI and the impact of Imppre on ΔGDI and GDIpre. We used Bayesian Additive Regression Trees (BART) and accumulated local effects to assess relative effects.

Results: We prospectively recruited a cohort of children with bilateral CP undergoing SEMLS (N = 55, 35 males, age: 10.5 ± 3.1 years) and identified a control cohort with bilateral CP who did not undergo SEMLS (N = 55, 30 males, age: 10.0 ± 3.4 years). There was a small positive causal effect of SEMLS on ΔGDI (1.70 GDI points). Altered motor control (i.e., dynamic and static motor control) and strength had strong effects on GDIpre, but minimal effects on ΔGDI. Spasticity and orthopedic impairments had minimal effects on GDIpre or ΔGDI.

Interpretation: Altered motor control did have a strong effect on GDIpre, indicating that these impairments do have a causal effect on a child’s gait pattern, but minimal effect on expected changes in GDI after SEMLS. Heterogeneity in outcomes suggests there are other factors contributing to changes in gait. Identifying these factors and employing causal methods to examine the complex relationships between impairments and movement will be required to advance our understanding and care of children with CP.

EC Kuska, N Mehrabi, MH Schwartz, KM Steele (2022) “Number of synergies impacts sensitivity of gait to weakness and contracture”

Katie Landwehr JournalArticle, MotorControl, News, Projects, Publications February 15, 2022June 12, 2024Cerebral Palsy, Machine Learning, Modeling, Motor Control, Muscle synergy, musculoskeletal modeling, Simulation

Journal Article in Journal of Biomechanics

Muscle activity during gait can be described by a small set of synergies, weighted groups of muscles, that are theorized to reflect underlying neural control. For people with neurologic injuries, like cerebral palsy or stroke, even fewer synergies are required to explain muscle activity during gait. This reduction in synergies is thought to reflect altered control and is associated with impairment severity and treatment outcomes. Individuals with neurologic injuries also develop secondary musculoskeletal impairments, like weakness or contracture, that can impact gait. Yet, the combined impacts of altered control and musculoskeletal impairments on gait remains unclear.

Aim: In this study, we use a two-dimensional musculoskeletal model constrained to synergy control to simulate unimpaired gait.

Methods: We vary the number of synergies, while simulating muscle weakness and contracture to examine how altered control impacts sensitivity to musculoskeletal impairment while tracking unimpaired gait.

Results: Results demonstrate that reducing the number of synergies increases sensitivity to weakness and contracture for specific muscle groups. For example, simulations using five-synergy control tolerated 40% and 51% more knee extensor weakness than those using four- or three-synergy control, respectively. Furthermore, when constrained to four- or three-synergy control, the model was increasingly sensitive to contracture and weakness of proximal muscles, such as the hamstring and hip flexors. Contrastingly, neither the amount of generalized nor plantarflexor weakness tolerated was affected by the number of synergies.

Interpretation: These findings highlight the interactions between altered control and musculoskeletal impairments, emphasizing the importance of measuring and incorporating both in future simulation and experimental studies.