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Background: Postural stability depends on the integration of multisensory inputs to drive motor outputs. When visual and somatosensory input is available and reliable, this reduces the postural control system’s reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction (1,2). Training one or more of the three sensory systems can alter sensory weighting and change postural behavior. Vestibular activation exercises, including horizontal and vertical headshaking, influence vestibular-ocular and -motor responses and have been showed to be effective in vestibular rehabilitation (3–8). Purpose/Hypothesis: To assess sensory reweighting of postural control processing and vestibular-ocular and -motor responses after concurrent vestibular activation with postural training. It was hypothesized that the effect of this training would significantly alter the pattern of sensory weighting by changing the ratio of visual, somatosensory and vestibular dependence needed to maintain postural stability, and significantly decrease vestibular responses. Methods: Forty-two young healthy individuals (22 females; 23.0+3.9 years; 1.6+0.1 meters) were randomly assigned into four groups: 1) visual feedback weight shift training (WST) coupled with an active horizontal headshake (HHS), 2) same WST with vertical headshake (VHS), 3) WST with no headshake (NHS) and 4) no training/headshake control (CTL) groups. The headshake groups performed an intensive body WST together with horizontal or vertical rhythmic headshake at 80 to 120 beats/minute. The NHS group performed the WST with no headshake while the controls did not perform any training. Five 15-minute training sessions were performed on consecutive days for one week with the weight shift exercises involving upright limits of stability activities on a flat surface, foam or rocker board (Fig. 1). All groups performed baseline- and post-assessments including sensory organization test (SOT) and force platform ramp perturbations, coupled with electromyographic (EMG) recordings. A video head impulse test was also used to record horizontal vestibulo-ocular reflex (VOR) gain. A between- and within-group repeated measures ANOVA was used to analyze five COP sway variables, the equilibrium and composite scores and sensory ratios of the SOT as well as EMG signals and horizontal VOR gain. Similarly, COP variables, EMG, as well as vestibular reflex data (vertical VOR, vestibulo-collic reflex [VCR] and vestibulo-spinal [VSR] gains) during ramp perturbations were analyzed. Alpha level was set at p

Background Functional outcomes with early rehabilitation in the acute care setting have improved; however, an improved understanding of muscle fatigue using surface electromyography (sEMG) is warranted to better guide patient-centered exercise prescription. Objectives The objectives of this study were to assess the safety and feasibility of collecting sEMG at the acute care bedside and to determine differences in muscle fatigue during isometric and dynamic submaximal contractions among patients in the hospital, healthy younger participants, and healthy older participants. Design The study used an observational cohort design. Methods There were 37 participants. Median frequency (Fmed) of the myoelectric signal of the quadriceps femoris muscles and time to task failure (TTTF) were measured using sEMG during an isometric and dynamic fatiguing contraction. Primary analysis compared TTTF between groups for both types of contractions. Secondary analysis compared Fmed at initiation and termination of fatiguing contraction. Results High-quality sEMG measures were safe and feasible to collect at the acute care bedside with no adverse events. There was a statistically significant difference in TTTF between groups after isometric and dynamic contractions; hospitalized patients fatigued faster than healthy younger and healthy older participants after both contractions. With the exception of the vastus lateralis during a dynamic contraction in healthy younger and hospitalized patients, there was a statistically significant difference between Fmed at initiation and termination of contraction, indicating that subjects’ muscles did truly fatigue. Limitations A limitation of the study was the small sample size of patients who were hospitalized without matched controls. Conclusions sEMG is a lab quantitative technique that was found to be safe and feasible to assess muscle fatigue in the acute care environment. The protocol yielded similar results to previously published literature for healthy younger and healthy older people. Further research is needed to better understand how to integrate sEMG findings into patient-centered exercise prescriptions.

The presence of visual dependence as an influential factor on the development of functional stability in ambulatory individuals with cerebral palsy (CP) was studied in 22 adults with spastic bilateral CP, 11 of whom were considered visually dependent, and 18 healthy adults. Participants stood upright during pitch plane disturbances of the visual field and support surface. Intersegmental coordination behaviors were assessed by fitting trajectories of adjacent body segments to an ellipse. Mixed-model repeated measures ANOVAs were performed on ellipse orientation angle and area. Dissimilar stabilizing strategies adopted by the two groups with CP imply that visual dependence impacts postural control. Postural reorganization in response to visual flow in all groups indicates that we cannot ignore perceptual aspects of postural control when designing therapeutic interventions.

The current study aimed to explore the impact of visual dependence on sensorimotor coupling of postural sway and visual motion in adults and teens with spastic cerebral palsy (CP). We hypothesized that individuals with CP would exhibit greater magnitudes of sway than healthy individuals, and the presence of visual dependence (VD) would produce instability in the direction of visual motion. Participants stood in a virtual environment in which the visual scene remained static or continuously rotated 30 degree/second in pitch-up or pitch-down. Increased center of pressure and center of mass responses were observed in the direction of visual scene motion in those with CP. Those with VD exhibited reduced frequency responses in anterior-posterior direction than those who were visually independent. VD suggests deficient sensorimotor integration that could contribute to postural instability and reduced motor function. Individuals with CP who are visually dependent may benefit from more sensory focused rehabilitation strategies.AP, anterior-posterior; CP, cerebral palsy; COM, center of mass; COP, center of pressure; MDF, median frequency; ML, mediolateral; PD, pitch down (nose down) rotation; PU, pitch up (nose up) rotation; RFT, rod and frame test; RMS, root mean square; SLP, slope of the fitted line; TD, typical development; VD, visual dependence; VI, visual independence; VOR, vestibulo-ocular reflex; VPI, visual perceptual impairment.

Controlled laboratory study.To assess scapular kinematics and electromyographic signal amplitude of the shoulder musculature, before and after thoracic spine manipulation (TSM) in subjects with rotator cuff tendinopathy (RCT). Changes in range of motion, pain, and function were also assessed.There are various treatment techniques for RCT. Recent studies suggest that TSM may be a useful component in the management of pain and dysfunction associated with RCT.Thirty subjects between 18 and 45 years of age, who showed signs of RCT, participated in this study. Changes in scapular kinematics and muscle activity, as well as changes in shoulder pain and function, were assessed pre-TSM and post-TSM using paired t tests and repeated-measures analyses of variance.TSM did not lead to changes in range of motion or scapular kinematics, with the exception of a small decrease in scapular upward rotation (P = .05). The only change in muscle activity was a small but significant increase in middle trapezius activity (P = .03). After TSM, subjects demonstrated decreased pain during performance of the Jobe empty-can (mean ± SD change, 2.6 ± 1.1), Neer (2.6 ± 1.3), and Hawkins-Kennedy (2.8 ± 1.3) tests (all, P.001). Subjects also reported decreased pain with shoulder flexion (mean ± SD change, 2.0 ± 1.5; P.001) and improved shoulder function (force production, 2.5 ± 1.4 kg; Penn Shoulder Score, 7.7 ± 9.4; sports/performing arts module of the Disabilities of the Arm, Shoulder and Hand questionnaire, 16.4 ± 13.2) (all, P.001).Immediate improvements in shoulder pain and function post-TSM are not likely explained by alterations in scapular kinematics or shoulder muscle activity. For people with pain associated with RCT, TSM may be an effective component of their treatment plan to improve pain and function. However, further randomized controlled studies are necessary to better validate this treatment approach.Therapy, level 4.

Purpose The purpose of this study was to examine the relationship between spasticity and muscle volume in children with cerebral palsy (CP), using isokinetic dynamometry and magnetic resonance imaging. Methods A retrospective sample of 8 children with diplegic CP was analyzed. One set of 10 passive knee flexion movements was completed at a velocity of 180° per second with concurrent surface electromyography of the medial hamstrings (MH) and vastus lateralis (VL) to assess knee extensor spasticity. Magnetic resonance imaging was used to measure maximum cross-sectional area and muscle volume of the quadriceps femoris. Results The quadriceps femoris muscle volume was positively correlated with MH reflex activity, VL reflex activity, MH/VL co-contraction, and peak knee extensor passive torque (P Conclusion The present findings suggest that higher levels of knee extensor muscle spasticity are associated with greater quadriceps muscle volume in children with spastic diplegic CP.

Aim To compare the effects of a supported speed treadmill training exercise program (SSTTEP) with exercise on spasticity, strength, motor control, gait spatiotemporal parameters, gross motor skills, and physical function. Method Twenty-six children (14 males, 12 females; mean age 9y 6mo, SD 2y 2mo) with spastic cerebral palsy (CP; diplegia, n=12; triplegia, n=2; quadriplegia n=12; Gross Motor Function Classification System levels II–IV) were randomly assigned to the SSTTEP or exercise (strengthening) group. After a twice daily, 2-week induction, children continued the intervention at home 5 days a week for 10 weeks. Data collected at baseline, after 12-weeks’ intervention, and 4 weeks after the intervention stopped included spasticity, motor control, and strength; gait spatiotemporal parameters; Gross Motor Function Measure (GMFM); and Pediatric Outcomes Data Collection Instrument (PODCI). Results Gait speed, cadence, and PODCI global scores improved, with no difference between groups. No significant changes were seen in spasticity, strength, motor control, GMFM scores, or PODCI transfers and mobility. Post-hoc testing showed that gains in gait speed and PODCI global scores were maintained in the SSTTEP group after withdrawal of the intervention. Interpretation Although our hypothesis that the SSTTEP group would have better outcomes was not supported, results are encouraging as children in both groups showed changes in function and gait. Only the SSTTEP group maintained gains after withdrawal of intervention.

Background Poor control of postural muscles is a primary impairment in people with cerebral palsy (CP). Objective The purpose of this study was to investigate differences in the timing characteristics of trunk and hip muscle activity during walking in young children with CP compared with children with typical development (TD). Methods Thirty-one children (16 with TD, 15 with CP) with an average of 28.5 months of walking experience participated in this observational study. Electromyographic data were collected from 16 trunk and hip muscles as participants walked at a self-selected pace. A custom-written computer program determined onset and offset of activity. Activation and coactivation data were analyzed for group differences. Results The children with CP had greater total activation and coactivation for all muscles except the external oblique muscle and differences in the timing of activation for all muscles compared with the TD group. The implications of the observed muscle activation patterns are discussed in reference to existing postural control literature. Limitations The potential influence of recording activity from adjacent deep trunk muscles is discussed, as well as the influence of the use of an assistive device by some children with CP. Conclusions Young children with CP demonstrate excessive, nonreciprocal trunk and hip muscle activation during walking compared with children with TD. Future studies should investigate the efficacy of treatments to reduce excessive muscle activity and improve coordination of postural muscles in CP.

OBJECTIVE: To examine the relationship between passive torque, reflex activity, co-contraction, and age during the assessment of spasticity of knee flexors and extensors in children with spastic diplegic cerebral palsy (CP). DESIGN: Retrospective. SETTING: Pediatric orthopedic hospital. PARTICIPANTS: Children (N=36) with spastic diplegic CP. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Spasticity of the knee flexors and knee extensors (as measured by peak passive torque, mean passive torque, reflex activity of the medial hamstrings, reflex activity of vastus lateralis, and co-contraction) was assessed during passive movements completed using an isokinetic dynamometer with concurrent electromyography. RESULTS: A significant positive relationship was found between age and mean knee flexor passive torque (P

Johnston TE, Smith BT, Mulcahey MJ, Betz RR, Lauer RT. A randomized controlled trial on the effects of cycling with and without electrical stimulation on cardiorespi- ratory and vascular health in children with spinal cord injury. Arch Phys Med Rehabil 2009;90:1379-88. Objective: To examine the cardiorespiratory/vascular ef- fects of cycling with and without functional electrical stimula- tion (FES) in children with spinal cord injury (SCI). Design: Randomized controlled trial. Setting: Pediatric referral hospital. Participants: Children with SCI (N30), ages 5 to 13 years, with injury levels from C4 to T11, and American Spinal Injury Association grades A, B, or C. Interventions: Children were randomly assigned to 1 of 3 groups: FES leg cycling exercise, passive leg cycling, or non- cycling control group receiving electrical stimulation therapy. After receiving instruction on the use of the equipment, chil- dren exercised for 1 hour 3 times per week for 6 months at home with parental supervision. Main Outcome Measures: Oxygen uptake (VO2) during an incremental arm ergometry test, resting heart rate, forced vital capacity, and a fasting lipid profile. Results: There were no differences (P.05) between groups after 6 months of exercise when comparing pre- and postval- ues. However, there were differences between groups for some variables when examining percent change. The FES cycling group showed an improvement (P.035) in VO2 (16.2% 25.0%) as compared with the passive cycling group (-28.7% 29.1%). For lipid levels, the electrical stimulation-only group showed declines (P.032) in cholesterol levels (-17.1% 8.5%) as compared with the FES cycling group (4.4% 20.4%). Conclusions: Cycling with FES led to gains in VO2, whereas electrical stimulation alone led to improvements in cholesterol.

Aim Cycling using functional electrical stimulation (FES-cycling) is a well defined exercise method for adults with spinal cord injury (SCI). Although little studied thus far, FES-cycling also has the potential to offer a means of exercise to pediatric populations, such as SCI or cerebral palsy (CP), that presently have few alternative options. The primary aim of this study was to develop FES-cycling equipment and methods which can meet the differing needs of children with SCI and CP. Methods Design criteria were determined based on key considerations for pediatric FES-cycling. Two separate prototype systems for training/recreation and laboratory-based research were built to meet these specifications. To experimentally verify the equipment, FES-cycling tests involving one child with motor complete SCI and one child with diplegic spastic CP were performed using the laboratory system. Results Experimental verification indicated that FES-cycling experiments involving children with SCI and CP are feasible provided that accurate measurement of both propulsive and resistive torque is achieved. Specific seating and orthotic needs for each subject population were met by both systems. Conclusion The FES-cycling systems described here may assist in future investigations of pediatric FES-cycling performance and novel exercise regimes designed specifically for children.

To examine the role of reflex activity in spasticity and the relationship between peak passive torque, Ashworth Scale (AS), and Spasm Frequency Scale (SFS) of the knee flexors and extensors during the measurement of spasticity using an isokinetic dynamometer in children with spinal cord injury (SCI).Eighteen children with chronic SCI and 10 children of typical development (TD) participated. One set of 10 passive movements was completed using an isokinetic dynamometer at 15, 90, and 180 degrees per second (deg/s) while surface electromyographic data were collected from the vastus lateralis (VL) and medial hamstrings (MH). Spasticity was clinically assessed using the AS and SFS.There were no significant differences in peak passive torque of the knee flexors and extensors at any velocity for children with SCI compared to children with TD. Children with TD demonstrated significantly more reflex activity of the MH during the assessment of knee flexor spasticity at all movement velocities than did children with SCI. Children with TD demonstrated significantly more reflex activity of the VL during the assessment of knee-extensor spasticity with movements at 180 deg/s. The relationship between peak passive torque, AS, and SFS was significant during movements at a velocity of 90 deg/s only.The role of increased reflexes in spasticity needs further examination. Isokinetic dynamometry may be measuring a different aspect of spasticity than the AS and SFS do in children with SCI.

PURPOSE: To describe an upper extremity ergometer test for children with spinal cord injury (SCI) and examine differences based on injury level for peak heart rate (HR peak), oxygen uptake (VO 2 peak/kg), and peak power output per kilogram (W peak/kg). METHODS: Twenty-nine children with motor complete SCI participated. Nine had low cervical (C7, C8), 9 had upper thoracic (T1-T4), and 11 had mid/low thoracic (T5-T11) SCI. HR peak, VO2 peak/kg, and W peak/kg were compared based on these 3 injury level groupings. RESULTS: HR peak (p = 0.013), VO 2 peak/kg (p = 0.041), and W peak/kg (p = 0.001) differed between groups. The mid/low thoracic group had the highest values for each variable. CONCLUSIONS: The differences in HR peak, VO 2 peak/kg, and W peak/kg were consistent with exercise effects reported for adults with SCI. Further research is needed to develop an appropriate standardized ergometric test for children with SCI.

Children with spinal cord injury (SCI) are at risk for musculoskeletal and cardiovascular complications. Stationary cycling using functional electrical stimulation (FES) or passive motion has been suggested to address these complications. The purpose of this case series is to report the outcomes of a 6-month at-home cycling program for 4 children with SCI.Two children cycled with FES and 2 cycled passively at home for 1 hour, 3 times per week.Data collected included bone mineral density of the left femoral neck, distal femur, and proximal tibia; quadriceps and hamstring muscle volume; stimulated quadriceps and hamstring muscle strength; a fasting lipid profile; and heart rate and oxygen consumption during incremental upper extremity ergometry testing.The 2 children cycling with FES and 1 child cycling passively exhibited improved bone mineral density, muscle volume, stimulated quadriceps strength, and lower resting heart rate. For the second child cycling passively, few changes were realized. Overall, the lipid results were inconsistent, with some positive and some negative changes seen.This case series suggests that cycling with or without FES may have positive health benefits and was a practical home exercise option for these children with SCI.

Co-contraction is an impairment commonly reported in children with cerebral palsy. However, co-contraction has not been investigated during passive movements which may be used to assess spasticity in children with cerebral palsy. The purpose of this study was to examine the frequency of co-contraction and the relationship between reflex activity and co-contraction during passive movements of the knee joint in children with cerebral palsy.Twenty children with cerebral palsy participated in this study. One set of ten continuous passive movements from 90 degrees of knee flexion to 25 degrees of knee flexion and from 25 degrees of knee flexion to 90 degrees of knee flexion was completed at 15 degrees /s, 90 degrees /s, and 180 degrees /s. The mean percentage of the range of motion of each movement and mean percentage of the number of movements which exhibited electromyographic activity of the vastus lateralis, medial hamstrings, and co-contraction were calculated for each set of movements.The number of the movement repetitions and the percentage of the range of motion which exhibited co-contraction were considerable regardless of the direction and speed of motion. Significant positive correlations were found between the percentage of the passive range of motion with medial hamstrings activation, vastus lateralis activation, and co-contraction during passive movements into both knee flexion and knee extension at a velocity of 15 degrees /s, 90 degrees /s, and 180 degrees /s (P0.001).Co-contraction commonly occurs during passive movements of the knee in children with cerebral palsy. The presence of co-contraction may influence measurements of spasticity which use passive movements to assess spasticity.

Surface electromyography (sEMG) is part of an instrumented gait assessment, however, the interpretation of the data in a clinically meaningful manner is often limited to the extraction of individual sEMG characteristics. The purpose of this study was to develop an assessment methodology using sEMG time and frequency characteristics extracted using wavelet analyses to provide clinically relevant information in children with cerebral palsy (CP). A retrospective study was conducted with 37 children (16 children with typical development (TD) and 21 children with spastic CP). sEMG signals were examined from selected musculature of the lower extremities during level ground walking. Wavelet analysis techniques, along with functional principal component analyses, were employed to calculate a sEMG index. The data indicated a grouping in the EMG index based on the level of motor impairment and the clinical diagnosis of spastic hemiplegia or diplegia. Further analyses of the index exhibited moderate to high (r=-0.43 to -0.74 and r=0.62-0.65) correlations with the existing gait kinetics, kinematics, and clinical measures of motor impairment, and was sensitive to walking ability according to the Gross Motor Functional Classification Scale (GMFCS). Overall, this methodology may have the potential to provide additional insight into the outcome of a clinical intervention that was not available previously, and may find use as a predictive tool that can be utilized for clinical decision making.

To report on the bone mineral density (BMD) of the hip, distal femur, and proximal tibia in children with spinal cord injury (SCI) of at least 1-year duration and before skeletal maturity.BMD values were measured in 28 children (age, 9.6 +/- 2.5 years; range, 5-13 years) using dual-energy x-ray absorptiometry (DEXA) and were analyzed based on sex, injury, and time since injury. The hip values were compared with reported age- and sex-matched values in children without disability. No comparison was made at the knee because normative data were not available.Average BMD values were 0.48 +/- 0.17 g/cm2 for the total hip, 0.48 +/- 0.17 g/cm2 at the femoral neck, 0.41 +/- 0.17 g/cm2 at the greater trochanter, 0.47 +/- 0.17 g/cm2 at Ward's triangle, 0.38 +/- 0.10 g/ cm2 at the distal femur, and 0.37 +/- 0.07 g/cm2 at the proximal tibia. Trends were observed with respect to sex, level of injury, and time since injury. Z-scores for the femoral neck, greater trochanter, and Ward's triangle were -1.65 +/- 1.02, -1.83 +/- 1.30, and -1.78 +/- 0.78, respectively, representing a 40% lower BMD in comparison with children without disability.Children with a SCI seem to have a substantially lower BMD at the hip and knee in comparison with children without disability, placing them at the same risk for lower extremity fractures as adults with SCI, with potentially higher risks as they age given the lack of activity in a period of their life where exercise is essential for optimal bone health.

Increased knee flexion during stance is a common gait deviation in the child with cerebral palsy (CP), with distal hamstring lengthening surgeries being an accepted course of treatment. Post-operatively, improvements in gait kinematics have been reported, however little change is noted in the patterns of muscle activity as portrayed by onset and offset timing in the surface electromyographic (sEMG) signals. Similar analysis based on the frequency content of the sEMG signals has seldom been applied, yet may provide additional insight into changes in muscle activity in response to surgery. The purpose of this study was to determine if changes in the time-frequency characteristics of the sEMG, extracted using wavelet analysis techniques, corresponded to improved gait kinematics observed post-surgical intervention, and whether there existed a relationship between frequency characteristics of the sEMG signals and the type of surgery required to correct gait kinematics. Data were collected from 16 children with typical development (TD) and 17 children with CP pre- and post-surgery. Muscle activity was recorded from the medial hamstring (MH) and vastus lateralis (VL) muscles, processed using the wavelet transform, and analyzed using functional principal component analyses (PCA). Results indicated that frequency differences were present pre-operatively depending if surgery was to be performed bilaterally or involved bone modification. Post-operatively, frequency characteristics of the VL more closely approximated those observed in children with TD, agreeing with the improved gait kinematics. MH characteristics, however, for the surgical groups demonstrated a deviation away for TD reflecting the altered muscle structure.

Virtual environments are becoming popular as a tool for clinical assessment and intervention, but it is not clear whether motor behaviors within such environments are consistent and reliable. We have explored how exposure to a single velocity of optic flow is altered when also exposed to a faster or slower velocity in 23 young healthy adults during quiet standing. Two groups experienced pitch up and pitch down motion of the visual scene at 30 deg/s and either a faster visual scene at 45 deg/s and or a slower visual scene at 15 deg/s. No significant differences in postural sway to 30 deg/s were observed across groups in either the AP direction or the ML direction. This suggests that the postural behavior is velocity dependent and not reorganized as a result of concurrent exposure to differing visual velocities.

The objective of this study was to examine the use of the continuous wavelet transform (CWT) on surface electromyographic (sEMG) signals acquired from the lower extremity muscles during gait in children with typical development (TD) and cerebral palsy (CP). This was done to explore the possibility of developing a quantitative assessment scale of motor function based on time-frequency information. An initial study was conducted on retrospective gait data from three children, matched in gender and in anthropometric variables but with differing levels of walking ability. EMG data were extracted from five lower extremity muscles to assess the degrees of differentiation. The data were processed using the CWT to derive an average scalogram, from which the instantaneous mean frequency (IMNF) was calculated. Principal component analysis was used to assess the differences between the curves. Preliminary results indicated that for select lower extremity muscles, there was a significant deviation in the IMNF curves in the child with CP as compared to the child with TD. Furthermore, as motor impairment increased, total percent explained variance to the TD curves decreased. This suggests that it might be possible to derive a physiologically based quantitative index for assessing motor function and for assessing clinical treatments in CP using the wavelet analysis.

Pierce SR, Orlin MN, Lauer RT, Johnston TE, Smith BT, McCarthy JJ: Comparison of percutaneous and surface functional electrical stimulation during gait in a child with hemiplegic cerebral palsy. Am J Phys Med Rehabil 2004;83:798 – 805. The purpose of this brief report was to compare the immediate effects of surface functional electrical stimulation (S-FES) and percutaneous functional electrical stimulation (P-FES) of the tibialis anterior applied during gait in a child with hemiplegic cerebral palsy. A three-dimensional gait analysis was conducted while an 11-yr-old girl with right hemiplegia walked with S-FES, P-FES, and no stimulation. The results indicated that both P-FES and S-FES increased dorsiflexion at initial contact, peak dorsiflexion in swing, and mean dorsiflexion in swing compared with walking without stimulation. The increase in dorsiflexion was greater with P-FES as compared with S-FES. Ankle absorption work was improved with both types of stimulation, whereas ankle generation work increased only with P-FES. This report suggests that S-FES and P-FES may have different immediate effects on gait due to issues such as muscle contraction strength, sensory feedback, and control systems for stimulation.

The objective of this study was to develop and test the feasibility of a model that employs electromyographic (EMG) signals to predict the occurrence of gait events in the child with cerebral palsy (CP). This model could be the basis of a future functional electrical stimulation (FES) control system to assist gait. Two children were implanted with bifilar intramuscular electrodes into the quadriceps muscle bilaterally. Muscle activity and gait parameters were recorded, and a fuzzy inference system was used to correlate EMG to five distinct gait events. For nine of the 10 gait events evaluated, the model predicted gait events to within 82 ms on average, as referenced to the VICON motion analysis system. For eight of the 10 events, prediction errors were 0.3% or less. Results indicate that EMG from the proximal musculature could be used to predict the occurrence of gait events in these two children with CP.

Introduction The relationship between visual field motion and intersegmental behavior during postural destabilization was explored. Individuals with cerebral palsy (CP) were separated through a rod and frame test into those with visual dependence (VD) or independence (VI) to determine whether reliance upon an allocentric reference frame alters the postural organization. We hypothesized that VD reduces intersegmental motion so that whole body responses reflect visual flow direction and velocity; VI would reflect visual flow parameters only at the head. Material and methods Eleven individuals (31 ± 10.5 years) with spastic CP who were VD and 11 with VI, and 18 VI individuals (32 ± 11.5 years) with typical development (TD), stood on either a stationary or 3° dorsiflexion tilted force platform within an immersive, 3-wall virtual environment. Subjects stood quietly for 30 s with eyes closed while the visual scene remained stationary or rotated 15°/s and 30°/s in the pitch-up or pitch-down directions. Motion analysis data were collected and strategies of segmental stabilization were identified with an anchoring index. Group differences and visual and platform conditions were examined with a mixed model, repeated measures ANOVA and simple contrasts (corrected α = 0.01) to determine the effect of condition against stationary visual field motion. Results Either platform or visual motion produced a head locked to upper trunk stabilizing strategy across all subjects (P = 0.015). When the supporting surface was tilted, VI individuals stabilized the thorax to the hip (P = 0.02) whereas VD individuals stabilized the thorax to global space (P = 0.0125). Discussion Both biomechanical and sensory environment motion evoked head to trunk stabilization. CP individuals with visual dependence stabilized the upper trunk to an allocentric rather than egocentric reference frame, thus increasing their potential for instability. Possible causes of an increased reliance on an allocentric frame of reference could be a perceptual inability to suppress external feedback, or diminished signals from internal feedback.

Cortical signals might provide a potential means of interfacing with a neuroprosthesis. Guidelines regarding the necessary control features in terms of both performance characteristics and user requirements are presented, and their implications for the design of a first generation cortical control interface for a neuroprosthesis are discussed.

A device capable of simultaneously measuring the isometric moments generated about the metacarpophalangeal (MP), proximal interphalangeal (PTP), and distal interphalangeal (DIP) joints of all four fingers has been developed. The design utilizes a four-bar linkage to transmit moments, but not forces, to the device. This linkage allows the same device to fit a wide range of hand sizes without recalibration. The device was constructed out of aluminum bars which are strapped to each joint segment and to the back of the hand. Strain gauges mounted to the aluminum bars measure the bending moment on the device, which is directly related to the moment applied about the joint center of rotation. Because of the unique design of the device, it is not necessary to have accurate measurements of the joint center of rotation in order to get accurate moment information. A single device is capable of generating independent measurement of MP extension/flexion, PIP extension/flexion, and DIP extension/flexion. Four of these devices can be used to make simultaneous measurements of all the moments generated by all four fingers. The device also acts as a splint, allowing each joint to be positioned and locked at any angle through the range of motion of the joint. The device is accurate to within /spl plusmn/5.6% of each reading for moments from 10 N/spl middot/cm to 100 N/spl middot/cm and within /spl plusmn/2.0 N/spl middot/cm for moments of 10 N/spl middot/cm or less. If the device configuration is constrained, the accuracy can be improved to /spl plusmn/0.8% of full scale (100 N/spl middot/cm) and /spl plusmn/0.21 N/spl middot/cm for moments of 10 N/spl middot/cm or less. The device can measure both flexion and extension moments up to 100 N/spl middot/cm, and can allow the joints to be fixed at any angle from approximately 10 to 800.

We employed a virtual environment to examine the postural behaviors of adults with cerebral palsy (CP). Four adults with CP (22-32 years) and nine healthy adults (21-27 years) were tested with a Rod and Frame protocol. They then stood quietly on a platform within a three-wall virtual environment. The platform was either kept stationary or tilted 3(°) into dorsiflexion in the dark or with pitch up and down visual field rotations at 30(°)/s and 45(°)/s. While the visual field rotated, the platform was held tilted for 30 s and then slowly returned to a neutral position over 30 s. Center of pressure (CoP) was recorded and center of mass (CoM) as well as trunk and ankle angles were calculated. Electromyography (EMG) responses of the ankle and the hip muscles were recorded and analyzed using wavelets. Larger angular deviations from vertical and horizontal in the Rod and Frame test indicated that adults with CP were more visually dependent than healthy adults. Adults with CP had difficulty maintaining balance when standing on a stationary platform during pitch upward rotation of the visual scene. When the platform was tilted during visual field rotations, adults with CP took longer to stabilize their posture and had larger CoM oscillations than when in the dark. The inability to compensate for busy visual environments could impede maintenance of functional locomotion in adults with CP. Employing a visual field stimulus for assessment and training of postural behaviors would be more meaningful than testing in the dark.

To compare the effects of a supported speed treadmill training exercise program (SSTTEP) with exercise on spasticity, strength, motor control, gait spatiotemporal parameters, gross motor skills, and physical function.Twenty-six children (14 males, 12 females; mean age 9y 6mo, SD 2y 2mo) with spastic cerebral palsy (CP; diplegia, n=12; triplegia, n=2; quadriplegia n=12; Gross Motor Function Classification System levels II-IV) were randomly assigned to the SSTTEP or exercise (strengthening) group. After a twice daily, 2-week induction, children continued the intervention at home 5 days a week for 10 weeks. Data collected at baseline, after 12-weeks' intervention, and 4 weeks after the intervention stopped included spasticity, motor control, and strength; gait spatiotemporal parameters; Gross Motor Function Measure (GMFM); and Pediatric Outcomes Data Collection Instrument (PODCI).Gait speed, cadence, and PODCI global scores improved, with no difference between groups. No significant changes were seen in spasticity, strength, motor control, GMFM scores, or PODCI transfers and mobility. Post-hoc testing showed that gains in gait speed and PODCI global scores were maintained in the SSTTEP group after withdrawal of the intervention.Although our hypothesis that the SSTTEP group would have better outcomes was not supported, results are encouraging as children in both groups showed changes in function and gait. Only the SSTTEP group maintained gains after withdrawal of intervention.

The effect of continuous visual flow on the ability to regain and maintain postural orientation was examined. Fourteen young (20–39 years old) and 14 older women (60–79 years old) stood quietly during 3° (30°/s) dorsiflexion tilt of the support surface combined with 30° and 45°/s upward or downward pitch rotations of the visual field. The support surface was held tilted for 30 s and then returned to neutral over a 30-s period while the visual field continued to rotate. Segmental displacement and bilateral tibialis anterior and gastrocnemius muscle EMG responses were recorded. Continuous wavelet transforms were calculated for each muscle EMG response. An instantaneous mean frequency curve (IMNF) of muscle activity, center of mass (COM), center of pressure (COP), and angular excursion at the hip and ankle were used in a functional principal component analysis (fPCA). Functional component weights were calculated and compared with mixed model repeated measures ANOVAs. The fPCA revealed greatest mathematical differences in COM and COP responses between groups or conditions during the period that the platform transitioned from the sustained tilt to a return to neutral position. Muscle EMG responses differed most in the period following support surface tilt indicating that muscle activity increased to support stabilization against the visual flow. Older women exhibited significantly larger COM and COP responses in the direction of visual field motion and less muscle modulation when the platform returned to neutral than younger women. Results on a Rod and Frame test indicated that older women were significantly more visually dependent than the younger women. We concluded that a stiffer body combined with heightened visual sensitivity in older women critically interferes with their ability to counteract posturally destabilizing environments.

Randomized clinical trial. To determine the effect of cycling and/or electrical stimulation on hip and knee bone mineral density (BMD) in children with spinal cord injury (SCI). Children's hospital specializing in pediatric SCI. A total of 30 children, aged 5–13 years, with chronic SCI were randomized to one of three interventions: functional electrical stimulation cycling (FESC), passive cycling (PC), and non-cycling, electrically stimulated exercise (ES). Each group exercised for 1 h, three times per week for 6 months at home. The hip, distal femur and proximal tibia BMD were examined via dual-energy X-ray absorptiometry (DXA) pre- and post-intervention. In all, 28 children completed data collection. The FESC group exhibited increases in hip, distal femur and proximal tibia BMD of 32.4, 6.62 and 10.3%, respectively. The PC group exhibited increases at the hip (29.2%), but no change at the distal femur (1.5%) or proximal tibia (−1.0%). The ES group had no change at the hip (−0.24%) and distal femur (3.3%), but a loss at the proximal tibia (−7.06%). There were no differences between groups or within groups over time. Significant negative correlations were found between baseline BMD and the amount of BMD change. Although not achieving statistical significance, hip BMD changes observed were greater than the reported 0.9–10% gains after exercise for children with and without disability. Thus, cycling with and without electrical stimulation may be beneficial for skeletal health in pediatric SCI, but further research is needed with a larger sample size.

Johnston TE, Modlesky CM, Betz RR, Lauer RT. Muscle changes following cycling and/or electrical stimulation in pediatric spinal cord injury. Objective To determine the effect of cycling, electrical stimulation, or both, on thigh muscle volume and stimulated muscle strength in children with spinal cord injury (SCI). Design Randomized controlled trial. Setting Children's hospital specializing in pediatric SCI. Participants Children (N=30; ages, 5–13y) with chronic SCI. Interventions Children were randomly assigned to 1 of 3 interventions: functional electrical stimulation cycling (FESC), passive cycling (PC), and noncycling, electrically stimulated exercise (ES). Each group exercised for 1 hour, 3 times per week for 6 months at home. Main Outcome Measures Preintervention and postintervention, children underwent magnetic resonance imaging to assess muscle volume, and electrically stimulated isometric muscle strength testing with the use of a computerized dynamometer. Data were analyzed via analyses of covariance (ANCOVA) with baseline measures as covariates. Within-group changes were assessed via paired t tests. Results All 30 children completed the training. Muscle volume data were complete for 24 children (8 FESC, 8 PC, 8 ES) and stimulated strength data for 27 children (9 per group). Per ANCOVA, there were differences between groups ( P Conclusions Children receiving either electrically stimulated exercise experienced changes in muscle size, stimulated strength, or both. These changes may decrease their risk of cardiovascular disease, insulin resistance, glucose intolerance, and type 2 diabetes. Clinical Trials Registration Number NCT00245726.

The purpose of using time-series analyses is to provide interpretation of information on curves or functions, such as dynamic, biomechanical data. We evaluated the application of one method of time-series analysis for assessing changes in postural responses when exposed to a continuously rotating visual field combined with a tilted support surface. Functional Principal Component Analysis (fPCA) was applied to center of mass (CoM) trajectories collected from 22 young adults (20–39 y.o.) on a fixed surface or following a 3 degree (30°/s) dorsiflexion tilt of the support surface combined with continuous upward or downward pitch rotation of the visual field at 30 and 45°/s. The usefulness of this analytical tool is that each curve is treated as a distinct observation by itself, allowing for traditional PCA to be applied to the analysis of curves. Results of the fPCA highlighted 5 distinct time periods in the CoM curves that explained 91% of the variability in the data. These periods in which the young adults altered their CoM in response to visual field motion would not have been identified if we had relied on the onset and offset of the transient disturbance to distinguish responses. Young adults significantly displaced their CoM in response to visual motion over both the period of support surface tilt and while the support surface returned to a neutral position. Our results indicate that fPCA is a viable method when applied to the small but complex changes that emerge in postural data and might allow for a better understanding of time dependent processes occurring with pathology and intervention.

Poor control of postural muscles is a primary impairment in cerebral palsy (CP), yet core trunk and hip muscle activity has not been thoroughly investigated. Frequency analysis of electromyographic (EMG) signals provides insight about the intensity and pattern of muscle activation, correlates with functional measures in CP, and is sensitive to change after intervention. The objective of this study was to investigate differences in trunk and hip muscle activation frequency in children with CP compared to children with similar amounts of walking experience and typical development (TD). EMG data from 31 children (15 with CP, 16 with TD) were recorded from 16 trunk and hip muscles bilaterally. A time–frequency pattern was generated using the continuous wavelet transform and instantaneous mean frequency (IMNF) was calculated at each interval of the gait cycle. Functional principal component analysis (PCA) revealed that IMNF was significantly higher in the CP group throughout the gait cycle for all muscles. Additionally, stride-to-stride variability was higher in the CP group. This evidence demonstrated altered patterns of trunk and hip muscle activation in CP, including increased rates of motor unit firing, increased number of recruited motor units, and/or decreased synchrony of motor units. These altered muscle activation patterns likely contribute to muscle fatigue and decreased biomechanical efficiency in children with CP.

Purpose Investigating gait characteristics during the early stages of walking in CP may contribute to the understanding of the development of impaired gait. The objective of this study was to investigate differences in the variability and symmetry of spatiotemporal gait characteristics during the early years of walking in children with bilateral spastic CP compared to children with similar amounts of walking experience and typical development (TD). Methods The spatiotemporal gait parameters of 31 children (15 with spastic CP, 16 with TD) who had an average of 28.5 (18.1 SD) months of walking experience were collected using an instrumented walkway. Results All primary spatiotemporal parameters were reduced in the CP group, who also demonstrated greater stride-to-stride variability, compared to the TD group. There were no statistically significant differences in side-to-side symmetry between groups. Implications Clinical trials investigating gait interventions during the early years of walking in children with CP should be conducted to determine if treatment can reduce the functional limitations that are present during the emergence of walking skills. Further investigation should examine variability and symmetry in the kinematics, kinetics, and muscle activity patterns of early walkers with CP, and the effect of treatment on the variability and symmetry of walking characteristics.

Background: Hip subluxation is common in children with spinal cord injury, especially in those younger than 10 years. The effects of standing with functional electrical stimulation (FES) on hip subluxation have been studied in these children. However, FES cycling is now available to children with spinal cord injury, but the effect of this intervention on hip subluxation has not been studied. Methods: Hip migration indices were measured before and after a 6-month program of FES cycling, passive cycling, or electrical stimulation exercise without cycling performed 3 times per week. During cycling, children were positioned to avoid hip adduction and internal rotation to decrease potential stress on the hip. Results: There were no changes in the hip migration indices for children in any group after participating in the study. Conclusions: These findings suggest that the 3 interventions used in this study may be safe for the hip, provided that the hips are positioned to avoid adduction and internal rotation while cycling. Level of Evidence: Randomized controlled trial, level 2.

The use of surface electromyography (sEMG) recorded during ambulation has provided valuable insight into motor development and changes with age in the pediatric population. However, no studies have reported sEMG differences with age in the children with cerebral palsy (CP). In this study, data from 50 children were divided retrospectively into four groups, representing either an older (above the age of seven years) or younger (below the age of seven years) age group with either typical development (TD) or CP. Data were analyzed from 16 children in the younger age group with TD, and eight in the older age group with TD. Data were also available from 14 in the younger age group with CP, and 12 in the older age group with CP. SEMG signals from the rectus femoris (RF) and medial hamstring (MH) were analyzed using wavelet techniques to examine time-frequency content. RF muscle activity was statistically different between all groups (p0.001), with an elevated instantaneous mean frequency (IMNF) in the older TD group than the younger TD group, an elevated IMNF in the younger CP group than the older CP group, and elevated IMNF in both CP groups compared to both TD groups. Activity for the MH muscle followed the same pattern except for the CP young and old group comparison, which indicated no difference. The results indicate that differences in neuromuscular activation exist between younger and older groups of children with both TD and CP, and may provide new insight into muscle activity pattern changes during the development of walking.

Johnston TE, Lauer RT, Lee SC. The effects of a shank guide on cycling biomechanics of an adolescent with cerebral palsy: a single-case study. Arch Phys Med Rehabil 2008; 89:2025-30. Objective: To examine 3-dimensional lower-extremity joint kinematics and muscle activity during cycling with and without a shank guide for a single subject with spastic diplegic cerebral palsy (CP). Design: Single case. Setting: Pediatric referral hospital. Participant: A 13-year-old adolescent with spastic diplegic CP and limited ambulation abilities. Interventions: Not applicable. Main Outcome Measures: Kinematic data were collected for 6 joint motions and electromyographic data for 7 muscles during 10- to 15-second trials. Average variability in the kine- matic curves was calculated, and kinematic and electromyo- graphic data were analyzed descriptively. Results: With the guide, the subject cycled at 40.12.0rpm compared with 13.74.0rpm without it. In addition, there was less variability in the kinematic curves (P.03) and muscles tended to turn on sooner and off later. These results indicate that this subject could cycle faster with the guide, which is desirable for cardiovascular health, and that there was a pos- sible increase in motor control due to reduced needs to control excessive joint motions. Conclusions: Based on these findings, a shank guide may allow some people with CP to cycle faster and provide im- proved joint kinematics.

Background In individuals with cerebral palsy, adaptation and plasticity in the neuromuscular system can lead to detrimental changes affecting gait. Cycling may be an effective method to improve mobility. The biomechanics of cycling in adolescents with cerebral palsy have been studied, but further analysis of the frequency and amplitude characteristics of the electromyographic signals can assist with interpretation of the cycling kinematics. Methods Data were analyzed from 10 adolescents with typical development (mean = 14.9, SD = 1.4 years) and 10 adolescents with cerebral palsy (mean = 15.6, SD = 1.8 years) as they cycled at two different cadences. Analyses of the lower extremity electromyographic signals involved frequency and amplitude analysis across the cycling revolution. Findings Examination of cycling cadence revealed that adolescents with cerebral palsy had altered electromyographic characteristics in comparison to adolescents with typical development across the entire crank revolution for all muscles. Analyses of individual muscles indicated both inappropriate muscle activation and weakness. Interpretation A more comprehensive analysis of electromyographic activity has the potential to provide insight into how a task is accomplished. In this study, the control of the several muscles, especially the rectus femoris, was significantly different in adolescents with cerebral palsy. This, combined with muscle weakness, may have contributed to the observed deviations in joint kinematics. Interventions that increase muscle strength with feedback to the nervous system about appropriate activation timing may be beneficial to allow individuals with cerebral palsy to cycle more efficiently.

To compare reports of the child's quality of life (QOL) between children with spinal cord injury (SCI) and their parents using the Pediatric Quality of Life 4.0 Generic Scales (PedsQL), and assess agreement between parent and child responses. To examine the influence of level of injury on QOL and internal consistency reliability of the PedsQL in pediatric SCI.Twenty-eight children (17 male children and 11 female children) between five and 13 years and their parents completed the PedsQL.Children rated their QOL better than their parents; however, there was good to excellent parent-child agreement. No differences were noted between children with tetraplegia and paraplegia. Low internal consistency reliability was obtained for various domains.In addition to using summary scores, specific ratings may raise important points for clinical decision-making. Results on internal consistency reliability suggest the need for condition-specific questionnaires for children with SCI.

Pierce SR, Lauer RT, Shewokis PA, Rubertone JA, Orlin MN. Test-retest reliability of isokinetic dynamometry for the assessment of spasticity of the knee flexors and knee extensors in children with cerebral palsy. Objective To assess test-retest reliability of the peak resistance torque and slope of work methods of spasticity measurement of the knee flexors and extensors in children with cerebral palsy (CP). Design Test-retest reliability study. Setting Pediatric orthopedic hospital. Participants Fifteen children with CP. Intervention Knee extensor and flexor spasticity was assessed with an isokinetic dynamometer using passive movements at 15°, 90°, and 180°/s taken 1 hour apart. Main Outcome Measures Peak resistive torque and work were calculated. The relative and absolute test-retest reliability was calculated by using intraclass correlation coefficients (ICCs) and Bland-Altman plots, respectively. Results Relative reliability was good (ICC>.75) for slope-of-work and peak resistance torque measurements at a velocity of 180°/s, whereas reliability of peak torque measurements was decreased (ICC Conclusions The measurement of spasticity of the knee extensors and flexors in children with CP using peak-resistance torque at 180°/s and the slope of work method has acceptable relative test-retest reliability. However, the absolute reliability of spasticity data should be considered cautiously.

The effects of electrical stimulation (ES) applied to the ankle musculature while walking on lower limb coordination and on muscle activation were assessed in a child with cerebral palsy (CP) when walking without ES. Three-dimensional lower extremity joint motion and surface electromyographic (EMG) data from the lower extremity muscles were collected before and after a 20-week gait training protocol with surface stimulation of the left dorsiflexors. Results of this preliminary investigation demonstrated carry-over effects of ES on joint coordination and muscle activity, with patterns approaching those of children with typical development (TD). Further, the use of ES appeared to affect the antagonistic muscle to which the ES was applied, which may have important implications for future training programs with ES

Accurate determination of the onset and offset of muscle activity in relation to the gait cycle is essential for understanding the pathology of certain neuromuscular disorders and for evaluating the effectiveness of treatment. This study examined the use of the discrete wavelet transform as an automated method for the detection of EMG activity. Comparisons of the wavelet method to a root mean squared algorithm and visual observation indicate that the wavelet method could be ideal for the detection of EMG activity during gait, but further studies are required.

A device for measuring torques generated about the joints of the fingers has been developed. The design utilizes a parallelogram construction that allows the device to fit different sizes of hands. The device has the capability to measure isometric moments generated about the MP, PIP and DIP joints of a single digit. Four of these devices can be used to make simultaneous measurements of all the moments generated about all three joints of the four fingers. The device also acts as a splint, allowing each joint to be positioned and locked at any angle through the range of motion of the joint. This device will be utilized in the synthesis of grasp patterns using functional electrical stimulation. >

The feasibility of using the EEG signal to operate a hand grasp neuroprosthesis was investigated. Two able-bodied subjects and one neuroprosthesis user were trained to control the amplitude of the beta rhythm recorded over the frontal areas. After 6 months, all subjects exhibited a high level of control, being able to use this signal to move a cursor to targets on a computer screen with a high (>90%) accuracy rate. Control over the EEG signal was unaffected by upper extremity movement or electrical activation of the muscles, indicating that this signal would be adequate for neuroprosthetic use. To test this concept, the neuroprosthesis user operated his system with the cortical signal, and was able to effectively manipulate several objects.

Disclosure: None disclosed. Objective: Determine the effect of cycling with and without functional electrical stimulation (FES) on bone mineral density (BMD), muscle volume, and stimulated strength in pediatric spinal cord injury (SCI). Design: Randomized controlled trial. Setting: Pediatric referral hospital. Participants: Thirty children, ages 5 to 13 years, with motor complete SCI. Interventions: Children were randomized to FES cycling (FESC), passive cycling (PC), or electrically-stimulated exercise (ES) and exercised one hour, three times/week for 6 months. Main Outcome Measures: BMD via dual-energy x-ray absorptiometry (DXA), muscle volume via magnetic resonance imaging (MRI), and isometric stimulated strength on a computerized dynamometer. Results: The FESC group increased hip, distal femur, and proximal tibia BMD by 32.4%, 6.62% and 10.3%, respectively. The PC group increased at the hip (29.2%), but not at the distal femur (1.5%) or proximal tibia ( 1.0%). The ES group had no change at the hip ( 0.24%) or distal femur (3.3%) and declined at the proximal tibia ( 7.06%). For quadriceps volume and stimulated strength, ES led to greater changes in volume and FESC to greater changes in strength. Within groups, quadriceps volume and strength increased following FESC, and quadriceps volume increased following ES. Average percent changes were: quadriceps volume (FESC 24.4%, PC 7%, 27%), hamstrings volume (FESC 19.8%, PC 3.1%, ES 12.5%), quadriceps stimulated strength (FESC 137.1%, PC 33.0%, ES 96.2%), and hamstrings stimulated strength (FESC 1.2%, PC 20.5%, ES 27.3%). Conclusions: Positive effects were seen on muscle for groups using electrical stimulation and possibly bone for children who cycled, which may reduce the risk of cardiovascular disease and fractures. Some BMD gains made were greater than anticipated due to growth, and muscle volume changes are not anticipated following strengthening in children without disability, suggesting that changes were clinically meaningful.