Somatosensory deficits affect balance and motor function in children with cerebral palsy: stochastic resonance stimulation can modulate somatosensation to enhance balance

Lee, Samuel C. K.Traditional rehabilitation and motor learning approaches in Cerebral Palsy (CP) are generally motor-centric focusing on how to improve musculoskeletal and motor impairments, and are marginally effective. Less attention has been paid to deficits in sensory processing that could potentially shape motor behavior, especially in relation to dynamic control of upright stance. Recent neuroimaging evidence on disrupted thalamocortical connections and aberrant somatosensory cortical activation supports the presence of sensory dysfunction in children with CP. Yet, limited research has thus far explored somatosensory deficits in lower extremities (LE) and how they influence motor ability in CP. Additionally, there is not a universally accepted framework for the diagnosis and treatment of sensory information and processing impairments in this population. Hence, the purpose of this dissertation was to identify distal LE somatosensation deficits, delineate their relationship with balance and motor function, and investigate if they can be modulated by utilizing Stochastic Resonance (SR) stimulation to enhance balance control in CP. Our results indicated that children with spastic diplegia exhibited diminished plantar cutaneous and ankle proprioceptive ability that may influence their balance and motor control; therefore, contributing to their poor functional performance. Applying SR stimulation in the LE during quiet stance resulted in decreased postural sway suggesting enhanced stability and, thus, SR may be used as a therapeutic tool to improve balance performance by up-regulating somatosensory information in CP. From a clinical standpoint, these findings could lead to an improved therapeutic management in CP by: 1) recommending the use of an easy to administer and cost effective battery of sensory tests in daily practice to identify individuals with somatosensory impairments, 2) assisting clinicians to design more effective subject-specific plans by targeting not only motor but also sensory deficits, and 3) introducing SR stimulation as a novel sensory-oriented method for somatosensory facilitation and training balance control in CP. Specifically, combining afferent SR stimulation while performing daily activities may promote neuroplasticity and, as a result enhance motor and sensory function compared to traditional motor-centric protocols.Ph.D.University of Delaware. ǂb Program in Biomechanics and Movement Scienc

Stochastic resonance stimulation improves balance in children with cerebral palsy: a case control study

Abstract Background Stochastic Resonance (SR) Stimulation has been used to enhance balance in populations with sensory deficits by improving the detection and transmission of afferent information. Despite the potential promise of SR in improving postural control, its use in individuals with cerebral palsy (CP) is novel. The objective of this study was to investigate the immediate effects of electrical SR stimulation when applied in the ankle muscles and ligaments on postural stability in children with CP and their typically developing (TD) peers. Methods Ten children with spastic diplegia (GMFCS level I- III) and ten age-matched TD children participated in this study. For each participant the SR sensory threshold was determined. Then, five different SR intensity levels (no stimulation, 25, 50, 75, and 90% of sensory threshold) were used to identify the optimal SR intensity for each subject. The optimal SR and no stimulation condition were tested while children stood on top of 2 force plates with their eyes open and closed. To assess balance, the center of pressure velocity (COPV) in anteroposterior (A/P) and medial-lateral (M/L) direction, 95% COP confidence ellipse area (COPA), and A/P and M/L root mean square (RMS) measures were computed and compared. Results For the CP group, SR significantly decreased COPV in A/P direction, and COPA measures compared to the no stimulation condition for the eyes open condition. In the eyes closed condition, SR significantly decreased COPV only in M/L direction. Children with CP demonstrated greater reduction in all the COP measures but the RMS in M/L direction during the eyes open condition compared to their TD peers. The only significant difference between groups in the eyes closed condition was in the COPV in M/L direction. Conclusions SR electrical stimulation may be an effective stimulation approach for decreasing postural sway and has the potential to be used as a therapeutic tool to improve balance. Applying subject-specific SR stimulation intensities is recommended to maximize balance improvements. Overall, balance rehabilitation interventions in CP might be more effective if sensory facilitation methods, like SR, are utilized by the clinicians. Trial registration ClinicalTrials.gov identifier NCT02456376; 28 May 2015 (Retrospectively registered); https://clinicaltrials.gov/ct2/show/NCT02456376

Optimizing assessment of low frequency H-reflex depression in persons with spinal cord injury.

Considering the growing interest in clinical applications of neuromodulation, assessing effects of various modulatory approaches is increasingly important. Monosynaptic spinal reflexes undergo depression following repeated activation, offering a means to quantify neuromodulatory influences. Following spinal cord injury (SCI), changes in reflex modulation are associated with spasticity and impaired motor control. To assess disrupted reflex modulation, low-frequency depression (LFD) of Hoffman (H)-reflex excitability is examined, wherein the amplitudes of conditioned reflexes are compared to an unconditioned control reflex. Alternatively, some studies utilize paired-pulse depression (PPD) in place of the extended LFD train. While both protocols induce similar amounts of H-reflex depression in neurologically intact individuals, this may not be the case for persons with neuropathology. We compared the H-reflex depression elicited by PPD and by trains of 3-10 pulses to an 11-pulse LFD protocol in persons with incomplete SCI. The amount of depression produced by PPD was less than an 11-pulse train (mean difference = 0.137). When compared to the 11-pulse train, the 5-pulse train had a Pearson's correlation coefficient (R) of 0.905 and a coefficient of determination (R2) of 0.818. Therefore, a 5-pulse train for assessing LFD elicits modulation similar to the 11-pulse train and thus we recommend its use in lieu of longer trains

Combined Transcutaneous Spinal Stimulation and Locomotor Training to Improve Walking Function and Reduce Spasticity in Subacute Spinal Cord Injury: A Randomized Study of Clinical Feasibility and Efficacy

Locomotor training (LT) is intended to improve walking function and can also reduce spasticity in motor-incomplete spinal cord injury (MISCI). Transcutaneous spinal stimulation (TSS) also influences these outcomes. We assessed feasibility and preliminary efficacy of combined LT + TSS during inpatient rehabilitation in a randomized, sham-controlled, pragmatic study. Eighteen individuals with subacute MISCI (2–6 months post-SCI) were enrolled and randomly assigned to the LT + TSS or the LT + TSSsham intervention group. Participants completed a 4-week program consisting of a 2-week wash-in period (LT only) then a 2-week intervention period (LT + TSS or LT + TSSsham). Before and after each 2-week period, walking (10 m walk test, 2-min walk test, step length asymmetry) and spasticity (pendulum test, clonus drop test, modified spinal cord injury—spasticity evaluation tool) were assessed. Sixteen participants completed the study. Both groups improved in walking speed and distance. While there were no significant between-groups differences, the LT + TSS group had significant improvements in walking outcomes following the intervention period; conversely, improvements in the LT + TSSsham group were not significant. Neither group had significant changes in spasticity, and the large amount of variability in spasticity may have obscured ability to observe change in these measures. TSS is a feasible adjunct to LT in the subacute stage of SCI and may have potential to augment training-related improvements in walking outcomes