Impact of enhanced sensory input on treadmill step frequency: infants born with myelomeningocele

Can Optic Flow Further Stimulate Treadmill-Elicited Stepping in Newborns?

Typically developing 3-day-old newborns take significantly more forward steps on a moving treadmill belt than on a static belt. The current experiment examined whether projecting optic flows that specified forward motion onto the moving treadmill surface (black dots moving on the white treadmill surface) would further enhance forward stepping. Twenty newborns were supported on a moving treadmill without optic flow (No OF), with optic flow matching the treadmill’s direction and speed (Congruent), with optic flow in the same direction but at a faster speed (Faster), and in a control condition with an incoherent optic flow moving at the same speed as in the Congruent condition but in random directions (Random). The results revealed no significant differences in the number or coordination of forward treadmill steps taken in each condition. However, the Faster condition generated significantly fewer leg pumping movements than the Random control condition. When highly aroused, newborns made significantly fewer single steps and significantly more parallel steps and pumping movements. We speculate the null findings may be a function of the high friction material that covered the treadmill surface.

Exploring the Unmet Need for Technology to Promote Motor Ability in Children Younger Than 5 Years of Age: A Systematic Review

Objective

To (1) identify types of technology that promote motor ability in children younger than 5 years of age, (2) report on the type of support these devices provide, and (3) evaluate their potential for use in the community (outside of the laboratory or clinic).

Data Sources

A literature search of PubMed was conducted in February 2019 using specific terms, including child, rehabilitation, movement, and instrumentation.

Study Selection

The search yielded 451 peer-reviewed articles, which were screened by multiple reviewers. Articles that described the use of devices for the purpose of motor rehabilitation and/or assistance (regardless of device type or body part targeted) in the age range of 0-5 years were eligible for inclusion.

Data Extraction

In conformity with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, final stage data extraction consisted of full text readings where each article was reviewed twice by 3 independent reviewers.

Data Synthesis

About half of the devices available (46%) for children younger than 5 years of age are orthotics and corrective casting devices. There are more facilitative (ie, power mobility devices) than inhibitive (ie, casting) technologies being used. Approximately 60% of the devices are designed for use by a single body part. Walking is the most common motor skill addressed. Although most of the devices were used to some degree outside of the laboratory or clinic, most of the devices available are considered investigative and are not available for commercial purchase.

Conclusions

Many types of pediatric devices to assist movement exist, but the current scope of employed devices is limited. There is a need for developing technology that allows for, if not supports, high-dosage, early, and variable motor practice that can take place in community settings.

The development of visually guided stepping

Adults use vision during stepping and walking to fine-tune foot placement. However, the developmental profile of visually guided stepping is unclear. We asked (1) whether children use online vision to fine-tune precise steps and (2) whether precision stepping develops as part of broader visuomotor development, alongside other fundamental motor skills like reaching. With 6-(N = 11), 7-(N = 11), 8-(N = 11)-year-olds and adults (N = 15), we manipulated visual input during steps and reaches. Using motion capture, we measured step and reach error, and postural stability. We expected (1) both steps and reaches would be visually guided (2) with similar developmental profiles (3) foot placement biases that promote stability, and (4) correlations between postural stability and step error. Children used vision to fine-tune both steps and reaches. At all ages, foot placement was biased (albeit not in the predicted directions). Contrary to our predictions, step error was not correlated with postural stability. By 8 years, children’s step and reach error were adult-like. Despite similar visual control mechanisms, stepping and reaching had different developmental profiles: step error reduced with age whilst reach error was lower and stable with age. We argue that the development of both visually guided and non-visually guided action is limb-specific.

Early Treadmill Practice in Infants Born With Myelomeningocele: A Pilot Study

PURPOSE

To determine the feasibility of an early treadmill training program for infants with myelomeningocele (MMC) and to measure changes in overt infant motor development and control, including mechanisms underlying the overt changes.

METHODS

Ten infants with MMC were initially enrolled: 8 infants completed 12 consecutive months of training, and 2 completed 6 months of training. Training consisted primarily of home-based, parent-administered treadmill stepping practice 5 days per week, 10 minutes per day starting within 6 months postbirth. We measured motor milestones, treadmill steps, spinal-level reflexes, and body composition.

RESULTS

Infants showed earlier acquisition of gross motor skills than previously reported. The number of alternating steps performed increased, indicating more complex neuromotor control and strength. Integrity of monosynaptic pathways and body composition were improved after controlling for chronological age.

CONCLUSIONS

This study demonstrates the feasibility of using early, home-based treadmill training for infants with MMC starting within 6 months postbirth.

Use of an In-Home Body Weight Support System by a Child With Spina Bifida

PURPOSE

To examine the feasibility of a new open-area body weight support system (BWSS) to act as both an "assistive" and a "rehabilitative" device within the home.

INTERVENTION

A 5-year-old boy with spina bifida used the BWSS during self-selected activities for 10 weeks. Feasibility, behavioral, and clinical assessments provided a quantification of his activity in and out of the BWSS.

OUTCOMES

On average, the child used the device on 2.7 days/week and for 67 minutes/day during intervention. When in the BWSS (assistive role), the child's locomotor activity and engagement in adapted sports activities increased. When not in the BWSS (rehabilitative role), the child's functional mobility and ambulatory ability increased.

WHAT THIS CASE ADDS

The use of the open-area in-home BWSS was feasible for regular home use and associated with an increase in functional mobility for a child with spina bifida.

Interventions for Gait Training in Children With Spinal Cord Impairments: A Scoping Review

PURPOSE

This is a scoping review of the literature on interventions for gait in individuals with pediatric spinal cord impairments.

SUMMARY OF KEY POINTS

Four categories of interventions were identified: orthoses/assistive devices, electrical stimulation, treadmill training, and infant treadmill stepping.

CONCLUSIONS

Studies on orthotic intervention, electrical stimulation, and treadmill training reported benefits for various components of gait. The majority of articles (77%) were classified as levels of evidence III and IV.

CLINICAL RECOMMENDATIONS

Each intervention targeted specific outcomes; therefore, it is important to identify individual patient characteristics and goals appropriate for each intervention to guide clinical practice. Determining the appropriate orthotic support for each child, and incorporating treadmill training or electrical stimulation, is recommended.

Treadmill interventions in children under six years of age at risk of neuromotor delay

BACKGROUND

Delayed motor development may occur in children with Down syndrome, cerebral palsy, general developmental delay or children born preterm. It limits the child's exploration of the environment and can hinder cognitive and social-emotional development. Literature suggests that task-specific training, such as locomotor treadmill training, facilitates motor development.

OBJECTIVES

To assess the effectiveness of treadmill interventions on locomotor development in children with delayed ambulation or in pre-ambulatory children (or both), who are under six years of age and who are at risk for neuromotor delay.

SEARCH METHODS

In May 2017, we searched CENTRAL, MEDLINE, Embase, six other databases and a number of trials registers. We also searched the reference lists of relevant studies and systematic reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that evaluated the effect of treadmill intervention in the target population.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted the data. Outcome parameters were structured according to the International Classification of Functioning, Disability and Health model.

MAIN RESULTS

This is an update of a Cochrane review from 2011, which included five trials. This update includes seven studies on treadmill intervention in 175 children: 104 were allocated to treadmill groups, and 71 were controls. The studies varied in population (children with Down syndrome, cerebral palsy, developmental delay or at moderate risk for neuromotor delay); comparison type (treadmill versus no treadmill; treadmill with versus without orthoses; high- versus low-intensity training); study duration, and assessed outcomes. Due to the diversity of the studies, only data from five studies were used in meta-analyses for five outcomes: age of independent walking onset, overall gross motor function, gross motor function related to standing and walking, and gait velocity. GRADE assessments of quality of the evidence ranged from high to very low.The effects of treadmill intervention on independent walking onset compared to no treadmill intervention was population dependent, but showed no overall effect (mean difference (MD) -2.08, 95% confidence intervals (CI) -5.38 to 1.22, 2 studies, 58 children; moderate-quality evidence): 30 children with Down syndrome benefited from treadmill training (MD -4.00, 95% CI -6.96 to -1.04), but 28 children at moderate risk of developmental delay did not (MD -0.60, 95% CI -2.34 to 1.14). We found no evidence regarding walking onset in two studies that compared treadmill intervention with and without orthotics in 17 children (MD 0.10, 95% CI -5.96 to 6.16), and high- versus low-intensity treadmill interventions in 30 children with Down syndrome (MD -2.13, 95% -4.96 to 0.70).Treadmill intervention did not improve overall gross motor function (MD 0.88, 95% CI -4.54 to 6.30, 2 studies, 36 children; moderate-quality evidence) or gross motor skills related to standing (MD 5.41, 95% CI -1.64 to 12.43, 2 studies, 32 children; low-quality evidence), and had a negligible improvement in gross motor skills related to walking (MD 4.51, 95% CI 0.29 to 8.73, 2 studies, 32 children; low-quality evidence). It led to improved walking skills in 20 ambulatory children with developmental delay (MD 7.60, 95% CI 0.88 to 14.32, 1 study) and favourable gross motor skills in 12 children with cerebral palsy (MD 8.00, 95% CI 3.18 to 12.82). A study which compared treadmill intervention with and without orthotics in 17 children with Down syndrome suggested that adding orthotics might hinder overall gross motor progress (MD -8.40, 95% CI -14.55 to -2.25).Overall, treadmill intervention showed a very small increase in walking speed compared to no treadmill intervention (MD 0.23, 95% CI 0.08 to 0.37, 2 studies, 32 children; high-quality evidence). Treadmill intervention increased walking speed in 20 ambulatory children with developmental delay (MD 0.25, 95% CI 0.08 to 0.42), but not in 12 children with cerebral palsy (MD 0.18, 95% CI -0.09 to 0.45).

AUTHORS' CONCLUSIONS

This update of the review from 2011 provides additional evidence of the efficacy of treadmill intervention for certain groups of children up to six years of age, but power to find significant results still remains limited. The current findings indicate that treadmill intervention may accelerate the development of independent walking in children with Down syndrome and may accelerate motor skill attainment in children with cerebral palsy and general developmental delay. Future research should first confirm these findings with larger and better designed studies, especially for infants with cerebral palsy and developmental delay. Once efficacy is established, research should examine the optimal dosage of treadmill intervention in these populations.

Conventional physical therapy and physical therapy based on reflex stimulation showed similar results in children with myelomeningocele

We aimed to investigate whether infants with myelomeningocele would improve their motor ability and functional independence after ten sessions of physical therapy and compare the outcomes of conventional physical therapy (CPT) to a physical therapy program based on reflex stimulation (RPT). Twelve children were allocated to CPT (n = 6, age 18.3 months) or RPT (n = 6, age 18.2 months). The RPT involved proprioceptive neuromuscular facilitation. Children were assessed with the Gross Motor Function Measure and the Pediatric Evaluation of Disability Inventory before and after treatment. Mann-Whitney tests compared the improvement on the two scales of CPT versus RPT and the Wilcoxon test compared CPT to RPT (before vs. after treatment). Possible correlations between the two scales were tested with Spearman correlation coefficients. Both groups showed improvement on self-care and mobility domains of both scales. There were no differences between the groups, before, or after intervention. The CPT and RPT showed similar results after ten weeks of treatment.

Effects of support surface and optic flow on step-like movements in pre-crawling and crawling infants

Step-like movements were examined in pre-crawling (n=9) and crawling (n=9) 6-13 month-old infants in the air and on a surface in response to a static pattern or optic flows that moved toward or away from the infant. Infants completed six 60-s trials. A significant interaction between locomotor status and support condition revealed that pre-crawling infants made more step-like movements in the air than on a rigid surface. In contrast, crawling infants made an equivalent number of step-like movements in the air and on the surface. Optic flow did not influence the number of step-like movements made by infants. The pre-crawling infant finding is consistent with a finding in a previous study in which two month-old infants were shown to step more in the air than on the ground. This finding is discussed relative to the idea that the infant stepping pattern disappears because the legs become too heavy to lift.

Early gait development in human infants: Plasticity and clinical applications

In this paper we focus on how a developmental perspective on plasticity in the control of human movement can promote early therapy and improve gait acquisition in infants with developmental disabilities. Current knowledge about stepping development in healthy infants across the first year of life highlights strong plasticity, both in behavioral outcome and in underlying neuro-muscular activation. These data show that stepping, like other motor skills, emerges from the interaction between infant's maturation and the environment. This view is reinforced by showing that infants with different internal resources (like genetic disorder or neural tube defect) show unique developmental trajectories when supported on a treadmill, yet do respond. Moreover, we will show that their behavior can be improved by context manipulations (mostly sensory stimulation) or practice. Overall, plasticity in the neural, skeletal, and muscle tissues create new opportunities for optimizing early intervention by creatively tapping into the same developmental processes experienced by healthy infants.

Why does infant stepping disappear and can it be stimulated by optic flow?

Two independent experiments (n = 22 and n = 22) showed that 2-month-old infants displayed significantly more stepping movements when supported upright in the air than when supported with their feet contacting a surface. Air- and surface-stepping kinematics were quite similar (Experiment 2). In addition, when data were collapsed across both experiments, more air steps and more donkey kicks were seen when infants were exposed to optic flows that specified backward compared to forward translation. The findings challenge the currently accepted heavy legs explanation for the disappearance of stepping at 2 months of age and raise new questions about the visual control of stepping.

Treadmill training after surgical removal of a spinal tumor in infancy

BACKGROUND AND PURPOSE

Step training on a treadmill is a common intervention for adult and pediatric patients with spinal cord injuries (SCI). Treadmill training has not been used as an intervention for infants and toddlers with SCI before walking onset. This case report describes the intervention and stepping behaviors on a treadmill and overground of a toddler after the surgical removal of a rare spinal tumor resulting in SCI.

CASE DESCRIPTION

The toddler presented with an inability to step on the left, rare stepping on the right, and an apparent lack of sensation in the lower extremities. After spinal tumor excision at 5.5 weeks of age, step training on a treadmill and overground occurred once per week from 15 to 35 months of age in addition to traditional physical therapy.

OUTCOMES

Independent symmetrical stepping emerged both on and off the treadmill over 20 months. Improvements in the number and pattern of steps occurred with training. Walking speed increased, and milestones important to overground walking developed.

DISCUSSION

Independent steps developed during the intervention with little motor development of the lower extremities during the first year of life. Furthermore, improvements in stepping alternation, standing, and walking occurred despite no evidence of sensation in the lower extremities.

Treadmill training for a child with spina bifida without functional ambulation

PURPOSE

To describe and report the effect of an 8-week individualized, progressive, treadmill training program on the ambulatory ability of a 4-year-old child with myelomeningocele without functional ambulation.

SUMMARY OF KEY POINTS

Heart rate and speed on the 2-minute walk test (2MWT) were used to individualize training. Ambulatory outcome measures taken at baseline, postintervention, and 6 weeks postintervention included the 2MWT and the Timed "Up and Go" (TUG). The Pediatric Evaluation of Disability Index was used to measure functional mobility. Improvements were noted in ambulatory ability after training (2MWT, 64.10%; TUG, 34.66%) and at the 6-week follow-up (2MWT, 58.97%; TUG, 34.24%). The Pediatric Evaluation of Disability Index showed no significant difference.

CONCLUSION AND RECOMMENDATIONS

Use of an individualized treadmill training program may have improved the ambulatory skills of a preschooler with myelomeningocele. More rigorous studies are needed to determine the effects of treadmill training with the spina bifida population and identify optimal training parameters.

Air stepping in response to optic flows that move Toward and Away from the neonate

To shed further light on the perceptual regulation of newborn stepping, we compared neonatal air stepping in response to optic flows simulating forward or backward displacement with stepping forward on a surface. Twenty-two 3-day-olds performed four 60 s trials in which they stepped forward on a table (Tactile) or in the air in response to a pattern that moved toward (Toward) or away (Away) from them or was static (Static). Significantly more steps were taken in the Tactile and Toward conditions than the Static condition. The Away condition was intermediate to the other conditions. The knee joint activity across the entire trial was significantly greater in the Toward than the Away condition. Within-limb kinematics and between-limb coordination were very similar for steps taken in the air and on the table, particularly in the Toward and Tactile conditions. These findings highlight that visual and tactile stimulation can equally elicit neonatal stepping.

Functioning of peripheral Ia pathways in infants with myelomeningocele

The goal was to examine the accessibility of Ia-proprioceptive pathways to motoneurons of leg muscles associated with gait in infants with Myelomeningocele (MMC). Participants were 15 MMC infants, ages 2-10 months. We assessed over repeated trials, the tendon reflex (T-reflex), vibration-induced inhibition of T-reflex (VIM-T-reflex), and tonic vibration-induced reflex (VIR) when computer controlled stimuli were applied to the three gait muscles of each leg. Only one third of MMC infants exhibited motor responses following the mechanical stimuli with sufficient frequency to be judged functioning as in typically developing (TD) infants. Age and lesion level were not apparently associated with response frequency, but scores on the gross motor portion of the Bayley Scale was a reasonable predictor. For those in which responses were frequent, the pattern of reciprocal excitation was similar to that of age-matched TD infants. 4 of the 10 non-responders who were also tested for their responses to being supported on a pediatric treadmill in a companion study showed voluntary muscle activity in all three gait muscles and a vibration-induced contraction was observed for some of the non-responders. Ia-proprioceptive pathways to homonymous and heteronymous muscles are functioning in some MMC babies, but the gain setting of these pathways were generally depressed and for many there was no evidence that the pathways were intact, although for some group more functional stimuli may be needed to elicit responses and experience may be needed to enhance the gain on the sensitivity of these neural pathways. More research is needed to understand how to optimize outcomes via rehabilitation.

Infants with spina bifida: immediate responses to contextual and manual sensory augmentation during treadmill stepping

PURPOSE

This study examined the effect of combined sensory enhancements and manual assistance on the immediate motor responsiveness of infants with spina bifida during treadmill trials.

METHODS

Six infants with spina bifida, aged 4 to 9.5 months, with lesion levels ranging from L4 to S3 were tested in each of 3 randomly ordered sets of enhanced sensory conditions across 3 weekly visits to the laboratory. Sensory enhancements included visual flow, unloading, load, and friction, presented in single and combined applications, as well as a set of trials with manual assistance for stepping at 2 treadmill belt speeds. Dependent variables included step frequencies and overall infant activity.

RESULTS

Friction+load was the most salient of the contextual sensory enhancements. Manual assistance at the slower speed was also effective at increasing infant stepping.

CONCLUSIONS

Sensory enhancements that increase stance excursion and vertical clearance during swing need further study.

Muscle activation patterns in infants with myelomeningocele stepping on a treadmill

PURPOSE

To characterize how infants with myelomeningocele (MMC) activate lower limb muscles over the first year of life, without practice, while stepping on a motorized treadmill.

METHODS

Twelve infants with MMC were tested longitudinally at 1, 6, and 12 months. Electromyography was used to collect data from the tibialis anterior, lateral gastrocnemius, rectus femoris, biceps femoris.

RESULTS

Across the first year, infants showed no electromyographic activity for approximately 50% of the stride cycle with poor rhythmicity and timing of muscles, when activated. Single muscle activation predominated; agonist-antagonist coactivation was low. Probability of individual muscle activity across the stride decreased with age.

CONCLUSIONS

Infants with MMC show high variability in timing and duration of muscle activity, few complex combinations, and very little change over time.

Changes in muscle activation patterns in response to enhanced sensory input during treadmill stepping in infants born with myelomeningocele

Infants with myelomeningocele (MMC) increase step frequency in response to modifications to the treadmill surface. The aim was to investigate how these modifications impacted the electromyographic (EMG) patterns. We analyzed EMG from 19 infants aged 2-10 months, with MMC at the lumbosacral level. We supported infants upright on the treadmill for 12 trials, each 30 seconds long. Modifications included visual flow, unloading, weights, Velcro and lcriction. Surface electrodes recorded EMG from tibialis anterior, lateral gastrocnemius, rectus femoris and biceps femoris. We determined muscle bursts for each stride cycle and from these calculated various parameters. Results indicated that each of the five sensory conditions generated different motor patterns. Visual flow and friction which we previously reported increased step frequency impacted lateral gastrocnemius most. Weights, which significantly decreased step frequency increased burst duration and co-activity of the proximal muscles. We also observed an age effect, with all conditions increasing muscle activity in younger infants whereas in older infants visual flow and unloading stimulated most activity. In conclusion, we have demonstrated that infants with myelomeningocele at levels which impact the myotomes of major locomotor muscles find ways to respond and adapt their motor output to changes in sensory input.

Infant visual attention and step responsiveness to optic flow during treadmill stepping

This study examined infant treadmill stepping in two groups of pre-locomotor infants in response to terrestrial optic flow. The optic flow was provided via the treadmill belt for flow translation that was directionally consistent with the forward stepping of the infants. Twelve 2-5-month-old and twelve 7-10-month-old infants participated. Visual attention (duration and direction) and step responsiveness (frequency and step types) were coded from digital video, and visuomotor coupling was examined by temporally juxtaposing the visual attention and step data. Longer durations of visual attention to the patterned belt with increased step frequencies during periods of visual attention were observed, suggesting that the visuotactile calibration afforded by the patterned treadmill belt, increased visuomotor coupling and enhanced the frequency and complexity of stepping in prelocomotor infants. The findings are discussed with regard to sensorimotor experiences that enhance treadmill stepping in infants and that may have application to clinical populations.

Vibration-induced motor responses of infants with and without myelomeningocele

BACKGROUND

The severity of myelomeningocele (MMC) stems both from a loss of neurons due to neural tube defect and a loss of function in viable neurons due to reduced movement experience during the first year after birth. In young infants with MMC, the challenge is to reinforce excitability and voluntary control of all available neurons. Muscle vibration paired with voluntary movement may increase motoneuron excitability and contribute to improvements in neural organization, responsiveness, and control.

OBJECTIVES

This study examined whether infants with or without MMC respond to vibration by altering their step or stance behavior when supported upright on a treadmill.

DESIGN

This was a cross-sectional study.

METHODS

Twenty-four 2- to 10-month-old infants, 12 with typical development (TD) and 12 with MMC (lumbar and sacral lesions), were tested. Infants were supported upright with their feet in contact with a stationary or moving treadmill during 30-second trials. Rhythmic alternating vibrations were applied to the right and left rectus femoris muscles, the lateral gastrocnemius muscle, or the sole of the foot. Two cameras and behavior coding were used to determine step count, step type, and motor response to vibration onset.

RESULTS

Step count decreased and swing duration increased in infants with TD during vibration of the sole of the foot on a moving treadmill (FT-M trials). Across all groups the percentage of single steps increased during vibration of the lateral gastrocnemius muscle on a moving treadmill. Infants with MMC and younger infants with TD responded to onset of vibration with leg straightening during rectus femoris muscle stimulation and by stepping during FT-M trials more often than older infants with TD.

CONCLUSIONS

Vibration seems a viable option for increasing motor responsiveness in infants with MMC. Follow-up studies are needed to identify optimal methods of administering vibration to maximize step and stance behavior in infants.

Approximate entropy values demonstrate impaired neuromotor control of spontaneous leg activity in infants with myelomeningocele

PURPOSE

One obstacle to providing early intervention to infants with myelomeningocele (MMC) is the challenge of quantifying impaired neuromotor control of movements early in life.

METHODS

We used the nonlinear analysis tool Approximate Entropy (ApEn) to analyze periodicity and complexity of supine spontaneous lower extremity movements of infants with MMC and typical development (TD) at 1, 3, 6, and 9 months of age.

RESULTS

Movements of infants with MMC were more regular and repeatable (lower ApEn values) than movements of infants with TD, indicating less adaptive and flexible movement patterns. For both groups ApEn values decreased with age, and the movements of infants with MMC were less complex than movements of infants with TD. Further, for infants with MMC, lesion level and age of walking onset correlated negatively with ApEn values.

CONCLUSIONS

Our study begins to demonstrate the feasibility of ApEn to identify impaired neuromotor control in infants with MMC.