Audiovisual biofeedback amplifies plantarflexor adaptation during walking among children with cerebral palsy.

BACKGROUND: Biofeedback is a promising noninvasive strategy to enhance gait training among individuals with cerebral palsy (CP). Commonly, biofeedback systems are designed to guide movement correction using audio, visual, or sensorimotor (i.e., tactile or proprioceptive) cues, each of which has demonstrated measurable success in CP. However, it is currently unclear how the modality of biofeedback may influence user response which has significant implications if systems are to be consistently adopted into clinical care. METHODS: In this study, we evaluated the extent to which adolescents with CP (7M/1F; 14 [12.5,15.5] years) adapted their gait patterns during treadmill walking (6 min/modality) with audiovisual (AV), sensorimotor (SM), and combined AV + SM biofeedback before and after four acclimation sessions (20 min/session) and at a two-week follow-up. Both biofeedback systems were designed to target plantarflexor activity on the more-affected limb, as these muscles are commonly impaired in CP and impact walking function. SM biofeedback was administered using a resistive ankle exoskeleton and AV biofeedback displayed soleus activity from electromyography recordings during gait. At every visit, we measured the time-course response to each biofeedback modality to understand how the rate and magnitude of gait adaptation differed between modalities and following acclimation. RESULTS: Participants significantly increased soleus activity from baseline using AV + SM (42.8% [15.1, 59.6]), AV (28.5% [19.2, 58.5]), and SM (10.3% [3.2, 15.2]) biofeedback, but the rate of soleus adaptation was faster using AV + SM biofeedback than either modality alone. Further, SM-only biofeedback produced small initial increases in plantarflexor activity, but these responses were transient within and across sessions (p > 0.11). Following multi-session acclimation and at the two-week follow-up, responses to AV and AV + SM biofeedback were maintained. CONCLUSIONS: This study demonstrated that AV biofeedback was critical to increase plantarflexor engagement during walking, but that combining AV and SM modalities further amplified the rate of gait adaptation. Beyond improving our understanding of how individuals may differentially prioritize distinct forms of afferent information, outcomes from this study may inform the design and selection of biofeedback systems for use in clinical care.

Improving Ankle Muscle Recruitment via Plantar Pressure Biofeedback during Robot Resisted Gait Training in Cerebral Palsy.

Neurological impairment from stroke or cerebral palsy often presents with diminished ankle plantar flexor function during the propulsive phase of gait. This deficit often results in slow, energy-expensive walking patterns that limit community mobility. Robotic gait training interventions may prove effective in improving functional outcomes, including exoskeleton resistance used to provide targeted neuromuscular recruitment. However, these interventions to date have required regular verbal cues and coaching for proper plantar flexor engagement with resistance, particularly for pediatric applications. In this validation study, we sought to address the need for automating and improving the effectiveness of facilitating user engagement with robotic resistance. Specifically, our main goal was to compare changes in plantar flexor activity between walking with plantar flexor resistance alone vs plantar flexor resistance combined with plantar pressure biofeedback in individuals with cerebral palsy. We recruited 8 ambulatory adolescents with cerebral palsy between the ages of 11-18 years old to participate in this cross-sectional feasibility study. Supporting our hypothesis, we observed a 36 ± 36% and 46 ± 39% increase in mean and peak soleus activity, respectively, between resistance plus biofeedback vs resistance alone (both p < 0.05). Compared to other biofeedback sensing modalities like assessment of muscle activity via surface electrodes, integrating the plantar pressure-based system within the wearable robotic devices minimizes barriers to clinical implementation by reducing cost, complexity, and setup time. With these positive feasibility results, our future work will explore longer-term training effects of ankle resistance combined with plantar pressure biofeedback.