Therese E. Johnston

Energy cost of walking in children with cerebral palsy: relation to the Gross Motor Function Classification System.

This study compared the energy cost of walking in children with cerebral palsy (CP) classified at different levels of the Gross Motor Function Classification System (GMFCS) with that in children with typical development. Sixteen female and 14 male children with CP (mean age 9 years 6 months, SD 2 years 4 months, range 6 years 4 months to 13 years 4 months) and 14 male and 13 female typically developing children (mean age 10 years, SD 1 year 6 months, range 7 years 1 month to 12 years 11 months) participated. Children with CP were classified at GMFCS level I, n=5; level II, n=10; level III, n=9; and level IV, n=6. Energy cost was assessed by the gas dilution method as each child walked around an oval track wearing a dilution mask. Significant differences were found across GMFCS levels (p < 0. 0001) and between adjacent levels (p < 0.013). Children with CP displayed a higher energy cost of walking than the typically developing children (p < 0.0001). A strong correlation (0.87) was found between the energy cost of walking and GMFCS level (p < 0.01) when children with typical development were assigned a GMFCS level of zero to allow statistical analysis. This indicates increasing energy cost of walking with increasing severity of functional involvement. These differences in energy cost across GMFCS levels provide another distinguishing factor between GMFCS levels and further emphasize the importance of considering metabolic demand in determining treatment options.

Effects of a supported speed treadmill training exercise program on impairment and function for children with cerebral palsy

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.

Implanted functional electrical stimulation: an alternative for standing and walking in pediatric spinal cord injury.

Study design: Post intervention, repeated measures design, comparing two interventions.Setting: Orthopedic pediatric hospital specializing in spinal cord injury.Methods: Nine subjects, ages 7–20 years, received an eight-channel implanted lower extremity functional electrical stimulation (FES) system for standing and walking. Electrodes were placed to stimulate hip and knee extension, and hip abduction and adduction. Standing and walking were achieved through constant stimulation to the implanted muscles, allowing a swing through gait pattern with an assistive device. After training with FES and long leg braces (LLB), subjects were tested in eight upright mobility activities, which were scored based upon completion time and level of independence.Results: Seven subjects completed data collection. These subjects completed four activities faster (P<0.02) and five activities more independently (P<0.025) with FES as compared to LLB. Transitions between sitting and standing, which were scored in isolation for two mobility activities, were achieved faster and with more independence with FES. In addition, subjects reported preferring FES for the majority of activities. No activity required more time or more assistance to complete with FES as compared to LLB.Conclusion: The implanted FES system provided these subjects with enhanced functional abilities over traditional LLB and decreased the need for physical assistance by a caregiver, suggesting that it is a realistic alternative for upright mobility in a pediatric population with spinal cord injury.Sponsorship: This study was funded by Shriners Hospitals for Children, Grant #8530.

Effects of cycling and/or electrical stimulation on bone mineral density in children with spinal cord injury

Study design:Randomized clinical trial.Objectives: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).Setting:Childrens hospital specializing in pediatric SCI.Methods: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.Results: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.Conclusion: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.

Technical Perspective Functional Electrical Stimulation For Augmented Walking In Adolescents With Incomplete Spinal Cord Injury

Abstract Background/Objective: This study evaluated the effects of functional electrical stimulation (FES) applied to the muscles acting on the pelvis, hip, and knee on muscle strength, energy cost of walking, maximum walking distance and speed, step length and cadence, and joint kinematics during gait in 3 ambulatory adolescents with incomplete spinal cord injury (SCI). Methods: Percutaneous FES was used to strengthen weakened muscles and to augment walking. After training, participants walked as desired at home with FES for 1 year. Data were collected at baseline (preintervention), and with FES on and FES off immediately following the training period and with FES on and FES off at 3, 6, and 12 months posttraining. Results: Voluntary strength improved in 12 out of 13 stimulated muscles. Decreased energy cost, increased maximum walking distance and speed, increased step length, and improved joint kinematics during gait were demonstrated with FES on and FES off Discussion: FES was able to achieve selective stimulation of key weakened muscles for augmented walking. The data suggest that FES had both direct and carryover effects.

Mathematical model that predicts isometric muscle forces for individuals with spinal cord injuries

The ideal functional electrical stimulation (FES) system requires a mathematical model to provide feedforward control of the stimulation parameters such that they are optimal for different individuals across a range of physiological conditions, muscles, and tasks. Recently we tested and validated such a model using able‐bodied subjects. The purpose of this study was to determine whether this model applied to persons with spinal cord injuries (SCI). To this end, the isometric force responses of the paralyzed quadriceps femoris muscles of 14 adolescents and young adults were tested. For each subject, the force responses to two six‐pulse stimulation trains were used to identify the parameter values of the model and then the model was used to predict the force responses to three train patterns across a range of frequencies in both a nonfatigued and fatigued condition. The intraclass correlation coefficients (ICCs) between the experimental and predicted force–time integrals and peak forces were above 0.90 for 12 of the 13 stimulation trains tested in the nonfatigued condition and all 13 trains tested in the fatigued condition. The success of our model with SCI subjects leads us to believe that our model may be useful for designing optimal stimulation parameters for standing and ambulation in patients who use FES. Muscle Nerve, 2005

Outcomes of a Home Cycling Program Using Functional Electrical Stimulation or Passive Motion for Children With Spinal Cord Injury: A Case Series

Abstract Background/Objective: 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. Methods: Two children cycled with FES and 2 cycled passively at home for 1 hour, 3 times per week. Outcome Measures: Data collected included bone mineral density of the left femoral neck, distal femur, and proximaltibia; 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. Results: 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. Conclusions: 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.

Use of Functional Electrical Stimulation to Augment Traditional Orthopaedic Surgery in Children With Cerebral Palsy

The purpose of this study was to compare the functional outcomes of traditional lower extremity orthopaedic surgery to more limited surgery augmented with functional electrical stimulation (FES) applied while walking. Seventeen ambulatory children with cerebral palsy participated in this prospective pretest–posttest control group study. The surgical group (nine subjects) underwent traditional orthopaedic procedures. The FES group (eight subjects) underwent placement of percutaneous intramuscular FES electrodes and limited orthopaedic surgical procedures. Postoperatively, they were provided with an FES home walking program. One year after intervention, all children (combined data) showed improvements in passive range of motion, gait spatiotemporal parameters, and gross motor function (P < 0.05). No differences were seen between groups before or after intervention. The FES group underwent 4.5 fewer ablative procedures per child than the surgical group. These results suggest that FES in combination with more limited surgery may provide similar functional gains with fewer ablative procedures than traditional orthopaedic surgery.

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 Childrens 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<.05) for quadriceps muscle volume and stimulated strength, with the ES group having greater changes in volume and the FESC group having greater changes in strength. Within-group analyses showed increased quadriceps volume and strength for the FESC group and increased quadriceps volume for the ES group. 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.

Switching stimulation patterns improves performance of paralyzed human quadriceps muscle.

The clinical efficacy of functional electrical stimulation (FES) is limited by the rapid onset of fatigue. Functional electrical stimulation applications typically stimulate skeletal muscles with constant‐frequency trains (CFTs). Our laboratory has identified trains that we call doublet‐frequency trains (DFTs) and that produce greater forces than CFTs, but more fatigue during repetitive activation than comparable CFTs. The purpose of this study was to see whether a series of CFTs followed by DFTs would reach a targeted isometric peak force more times than either train type alone during repetitive isometric activation of the paralyzed quadriceps muscles of subjects with spinal cord injuries (SCI). The combination of CFTs followed by DFTs reached the targeted isometric force 14% more often than the CFTs alone and 18% more often than the DFTs alone. These findings confirm that switching train types may be a useful strategy to offset the rapid fatigue of the functionally important quadriceps muscle that persons with SCI experience when using FES. Muscle Nerve, 2005