Muscle tone assessments for children aged 0 to 12 years: a systematic review

Biomechanical and clinical differences in muscle tone, stiffness, range of motion, and pain perception in children with cerebral palsy: a cross-sectional study

Introduction

Spasticity and altered muscle tone are key features in children with neurodevelopmental disorders, particularly cerebral palsy (CP). They impact movement, range of motion (ROM), and pain perception, influencing functional abilities and quality of life. Understanding the intrinsic muscle differences in children with CP can help improve clinical assessment and therapeutic interventions. This study aims to evaluate differences in muscle tone, stiffness, ROM, and pain perception between children with CP and typically developing peers using objective biomechanical measures.

Methods

An observational, cross-sectional study was conducted with 40 participants of both sexes (20 children with CP, 20 typically developing peers). Muscle tone and stiffness of the lower limb muscles were measured using the Myoton PRO device. ROM was assessed by goniometry, and pain perception was evaluated using the Visual Analog Scale during a Straight Leg Raise (SLR) test. A generalized linear mixed model was used to detect differences in myotonometry, ROM, and pain perception measurements. In participants with CP, the Pearson product-moment correlation coefficient analysis was used to explore possible associations between clinical features and muscle tone and stiffness.

Results

Children with CP exhibited reduced ROM, with a significant group effect for hip flexion (P < 0.001; η2 = 0.843), knee extension (P < 0.001; η2 = 0.355), and ankle flexion (P < 0.001; η2 = 0.959) and higher pain perception during the SLR test (P < 0.001; η2 = 0.831), compared to controls. Myotonometry revealed significantly increased muscle stiffness of the rectus femoris (P = 0.004; η2 = 0.112) and adductor muscles (P = 0.019; η2 = 0.074) in the CP group, with no differences in muscle tone between the groups. Sex-related differences were found for muscle tone and stiffness, with males showing higher values. Correlation analyses indicated that adductor muscles stiffness was associated with CP severity.

Conclusion

Children with CP demonstrate significant changes in ROM, pain perception, and muscle stiffness, emphasizing the need for targeted therapeutic interventions. These findings support the use of objective biomechanical tools for assessing muscle properties in clinical settings, contributing to better management strategies for spasticity-related impairments.

The Correlation Between Infant Head Shape in Craniometric Studies and Psychomotor Development Disorders

Objectives: The objective of this study was to analyze the correlation between muscle tone distribution disorders and asymmetry, with specific postnatal positional cranial deformities in infants. The study focused on assessing the level of unilateral occipital flattening and the extent of symmetrical occipital flattening. Methods: The study involved 60 infants aged between 1 and 5 months. Each infant was neurologically diagnosed and assigned to one of three groups: asymmetry, reduced muscle tone, or increased muscle tone. Each group consisted of 20 infants (10 girls and 10 boys). A MIMOS craniometer was used to measure the infants' head shapes, calculating the cranial vault asymmetry (mm) and cranial index (%). The data were analyzed and processed using Statistica software and appropriate statistical tests. Results: The results revealed a correlation between asymmetry and reduced muscle tone, increased muscle tone, and specific positional head deformities in infants up to the age of 5 months.

Clinical utility and psychometric properties of tools for early detection of developmental concerns and disability in young children: A scoping review

AIM

To explore the clinical utility and psychometric properties of standardized tools for the early detection of developmental concerns or disability in young children.

METHOD

Systematic reviews and clinical practice guidelines containing psychometric data on tools appropriate for use with children from birth to 5 years 11 months were searched for in MEDLINE, CINAHL, Embase, and PsycINFO for the years 2000 to 2023, with no language restrictions.

RESULTS

Eighty-six systematic reviews and six clinical practice guidelines guided identification of tools. A total of 246 tools were identified across domains of neurological, motor, cognition, communication/language, social-emotional, sensory processing, and/or specific diagnostic conditions of attention-deficit/hyperactivity disorder, autism spectrum disorder, cerebral palsy, developmental coordination disorder, and fetal alcohol spectrum disorder. After critical evaluation, 67 tools were included in the recommendations. Recommendations for screening and diagnostic assessment tools were based on best available evidence for predictive and discriminative validity, diagnostic accuracy, together with consideration of resource use and accessibility.

INTERPRETATION

This comprehensive scoping review provides recommendations on the best tools for primary care, medical, allied health professionals, nursing, and other health workers to detect and identify developmental concerns or disability in young children using evidence-based tools.

Central mechanisms of muscle tone regulation: implications for pain and performance

Muscle tone represents a foundational property of the motor system with the potential to impact musculoskeletal pain and motor performance. Muscle tone is involuntary, dynamically adaptive, interconnected across the body, sensitive to postural demands, and distinct from voluntary control. Research has historically focused on pathological tone, peripheral regulation, and contributions from passive tissues, without consideration of the neural regulation of active tone and its consequences, particularly for neurologically healthy individuals. Indeed, simplistic models based on the stretch reflex, which neglect the central regulation of tone, are still perpetuated today. Recent advances regarding tone are dispersed across different literatures, including animal physiology, pain science, motor control, neurology, and child development. This paper brings together diverse areas of research to construct a conceptual model of the neuroscience underlying active muscle tone. It highlights how multiple tonic drive networks tune the excitability of complex spinal feedback circuits in concert with various sources of sensory feedback and in relation to postural demands, gravity, and arousal levels. The paper also reveals how tonic muscle activity and excitability are disrupted in people with musculoskeletal pain and how tone disorders can lead to marked pain and motor impairment. The paper presents evidence that integrative somatic methods address the central regulation of tone and discusses potential mechanisms and implications for tone rehabilitation to improve pain and performance.

Intersession Intra-Rater and Inter-Rater Reliability of Myotonometer for Upper and Lower Extremity Muscles in Children with Spinal Muscular Atrophy

Background/Objectives: This study aimed to examine intra- and inter-rater reliability of a myotonometer (MyotonPRO) in measuring upper and lower extremity mechanical properties in children with spinal muscular atrophy types I and II. Methods: Biceps brachii, triceps brachii, rectus femoris, and gastrocnemius muscle tone and stiffness in children (n = 21) were measured using the MyotonPRO device. Examiner 1 performed two sets of measurements in 60 min to determine intra-rater reliability. Examiner 2 performed measurements between Examiner 1's sets. Intra-interclass correlation coefficient, minimal detectable change, and standard error of measurement values were calculated to assess intra- and inter-rater reliabilities in this cross-sectional study. Results: The results showed excellent intra- and inter-rater reliability analyses for frequency and stiffness values except for the stiffness value of the gastrocnemius muscle, which presented good reliability (ICC = 0.71). Minimal detectable change values ranged from 0.59 to 1.98 Hz for muscle tone and 16.08 to 124.74 N/m for stiffness (for both intra- and inter-rater reliabilities). Conclusions: Our findings indicate that MyotonPRO is a reliable tool for quantifying upper and lower extremity mechanical properties within one session in children with spinal muscular atrophy types I and II. Mechanical properties of the extremity muscle can be determined using this easily applied tool in future studies.

Shear modulus of lower limb muscles in school-aged children with mild hypotonia

The objective of this study is to compare shear modulus of lower limb muscles between children with hypotonia versus typical development (TD) or developmental disorders associated with altered tone. Nineteen children with mild hypotonia (mean age 9.4 ± 2.3y, 13 male) completed assessment of resting shear modulus of rectus femoris, biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL) at short and long lengths using shear wave elastography. Data was compared with previous data from TD children and a scoping review for children with developmental disorders. Data were collated according to Net-Longitudinal Tension Angle (Net-LTA), which is the muscle length expressed as the net proximal and distal joint angles. Effects of Net-LTA (e.g., short, neutral, long) were examined according to sex, age and body mass index (BMI). In children with hypotonia, shear modulus was: higher at longer versus shorter lengths for four muscles (p < 0.01); correlated with age for BF-short (r = 0.60, p < 0.03) and GL-short (r = -0.54, p < 0.03), with BMI for BF-short (r = 0.71, p < 0.05); and not different between sexes (p > 0.05). The shear modulus values for lower limb muscles for children with mild hypotonia were lower than those for children with Duchenne Muscular Dystrophy (TA-neutral), or Cerebral Palsy (GL-neutral), but not TD children (all four muscles). In conclusion, shear modulus increases with longer muscle length (i.e. higher Net-LTA) in mildly hypotonic children. Children with mild hypotonia have lower shear modulus than children with cerebral palsy and Duchenne muscular dystrophy.

Participation measures that evaluate attendance and involvement for young people aged 15 to 25 years with cerebral palsy: a systematic review

PURPOSE

To identify participation-focused measures used for young people with cerebral palsy (CP), evaluate their psychometric evidence, and map item content to the International Classification of Functioning, Disability, and Health (ICF), and family of Participation-Related Constructs (fPRC) frameworks.

METHODS

Four databases (PubMed, Embase, Web of Science, CINAHL) were searched for papers that involved young people with CP aged 15 to 25 years and reported original data from a participation measure. Each measure was examined for validity, reliability, responsiveness (using the COSMIN checklist), clinical utility, the inclusion of accessible design features, self- and/or proxy-report from people with communication support needs, and item content according to ICF and fPRC.

RESULTS

Of 895 papers, 80 were included for review. From these, 26 measures were identified. Seven measures (27 papers/resources) were participation-focused, capable of producing a score for participation Attendance and/or Involvement. Of these, all measured Attendance (n = 7) but fewer than half measured Involvement (n = 3). Few included studies (37%) reported including some self-report of people with communication support needs.

CONCLUSIONS

Participation measures for young people with CP are evolving but require more: (i) emphasis on measurement of involvement; (ii) investigation of psychometric properties; and (iii) adaptation to enable self-report by young people with communication support needs.

Identifying and Evaluating Young Children with Developmental Central Hypotonia: An Overview of Systematic Reviews and Tools

Children with developmental central hypotonia have reduced muscle tone secondary to non-progressive damage to the brain or brainstem. Children may have transient delays, mild or global functional impairments, and the lack of a clear understanding of this diagnosis makes evaluating appropriate interventions challenging. This overview aimed to systematically describe the best available evidence for tools to identify and evaluate children with developmental central hypotonia aged 2 months to 6 years. A systematic review of systematic reviews or syntheses was conducted with electronic searches in PubMed, Medline, CINAHL, Scopus, Cochrane Database of Systematic Reviews, Google Scholar, and PEDro and supplemented with hand-searching. Methodological quality and risk-of-bias were evaluated, and included reviews and tools were compared and contrasted. Three systematic reviews, an evidence-based clinical assessment algorithm, three measurement protocols, and two additional measurement tools were identified. For children aged 2 months to 2 years, the Hammersmith Infant Neurological Examination has the strongest measurement properties and contains a subset of items that may be useful for quantifying the severity of hypotonia. For children aged 2-6 years, a clinical algorithm and individual tools provide guidance. Further research is required to develop and validate all evaluative tools for children with developmental central hypotonia.

Intra-Rater and Inter-Rater Reliability Analysis of Muscle-Tone Evaluation Using a Myotonometer for Children with Developmental Disabilities

Assessing muscle tone is an essential component of the diagnosis, prognosis, and treatment planning of developmental disabilities (DD) in children and is of great help in developing clinical diagnosis patterns. The purpose of this study was to investigate intra-rater and inter-rater reliability using the myotonometer, which is an assessment tool to measure muscle tone in children with DD. This study included 26 children diagnosed with DD. Two physical therapists measured the children's muscle tone using a myotonometer. For all the muscles measured, reliability was determined using the intra-class correlation coefficient (ICC), the standard measurement error (SEM), and the minimal detectable change (MDC). The intra-rater reliability for all muscles was excellent (ICC = 0.75~0.78), except for the biceps brachii (ICC = 0.68). The inter-rater reliability was also excellent for all muscles (ICC = 0.75~0.95), and the SEM and MDC showed small measurement errors. Therefore, the intra-rater and inter-rater reliability of measurements by the myotonometer was found to be good or excellent. This suggests that the myotonometer is a tool that can objectively assess muscle tone, and it can be utilized in clinical practice to quickly and conveniently measure muscle tone in children with DD.

International Delphi Recommendations for Pediatric Lower Limb Neurological Test Protocols for Muscle Strength, Reflexes, and Tactile Sensitivity

PURPOSE

To gain consensus from physical therapists on pediatric lower limb neurological tests of muscle strength, tactile sensitivity, and reflexes.

METHODS

A Delphi technique was used for 2 sequential questionnaire rounds to gain consensus from a panel of pediatric physical therapists (n = 28). Physical therapists rated their agreement to items from statements on pediatric lower limb neurological tests, their protocols, and interpretation using a 6-point Likert scale.

RESULTS

Ninety percent of items gained consensus: 80% on pediatric lower limb neurological tests, 88% on test protocols, and 92% on test interpretation. Fifty-one percent of items had high agreement and high importance.

CONCLUSION

There is variability in pediatric neurological tests used, their protocols, and interpretation. Identification of items with high agreement and importance is the first step to develop a standardized lower limb neurological assessment for pediatric clients of varying ages and diagnoses.

Factor Analysis of the Einstein Neonatal Neurobehavioral Assessment Scale in Infants with Congenital Heart Disease and Healthy Controls

Background: Administration of the Einstein Neonatal Neurobehavioral Assessment Scale (ENNAS) can be time-consuming, and items can be highly correlated. We aimed to determine: (1) its factor analytic structure; (2) the validity of the factor structure; and (3) the associations of physiologic measures with factor scores. Methods: A factor analysis reduced 21 ENNAS items into 5 factors in 57 congenital heart disease (CHD) and 35 healthy infants. Multiple linear regressions examined the association of factor scores with group, gestational age, and physiologic variables. Results: 5-factor solution: 1 (Orienting Reflex), 2 (Extensor Axial Tone), 3 (Primitive Reflexes), 4 (Flexor Tone), 5 (Reflexive Tone Around Extremity Joints). Moderate to strong evidence supported: face, discriminant, and construct validity of these factors, with Factor 2 having the strongest. Conclusions: Components of Factor 2 may provide similar information about neonatal development, thus reducing the time for and burden of administration for researchers and clinicians.

Assessment of Viscoelastic Parameters of Muscles in Children Aged 4-9 Months with Minor Qualitative Impairment of the Motor Pattern after Vojta Therapy Implementation

The aim of this study was to assess if there are any objective changes in the viscoelastic parameters of the erector spinae muscle after Vojta stimulation. The study involved 22 healthy children at an average age of 7 months and with an Apgar score of 8-10 points, who were referred for rehabilitation due to a slight delay in the phases of psychomotor development. The first group consisted of 11 children with increased muscle tone (IMT) and the second group consisted of 11 children with non-increased muscle tone (nonIMT). All study participants received a one-time Vojta therapy session, which was continued for 4 weeks by parents at home. The viscoelastic parameters of the dorsal extensor muscle were measured three times. In the first study group, changes in the viscoelastic parameters of the extensor muscles of the back occurred immediately after the therapy at the first examination, whereas changes in the supporting and extensor function of the limbs occurred in both groups at the second examination. Analysis featuring an objective assessment allows physiotherapists to diagnose local changes in the viscoelastic parameters after the implementation of therapy. These studies are the first pilot studies to be continued with a 30- or 60-day follow-up.

Classification of Congenital Zika Syndrome: Muscle Tone, Motor Type, Body Segments Affected, and Gross Motor Function

Aim: To identify abnormalities in muscle tone and motor function associated with congenital Zika syndrome (CZS).Method: A cross-sectional observational study involving 96 children (55 males) with CZS at a mean (SD) age 35.2 ± 2.9 months. Children's muscle tone was investigated using the pull to sit, scarf sign, shoulder suspension and ventral suspension tests and the modified Ashworth scale (MAS). Motor impairment was determined using the Gross Motor Function Classification System (GMFCS) and body segments most affected with motor impairment.Results: 58 (60,5%) children tested positive for ≥1 maneuver used to evaluate muscle tone, while 38 (39.5%) tested negative in all the tests. MAS score was >0 for at least one of the appendicular muscles in 91 children (94.8%). In 88 children (91.7%), all four limbs were affected.Conclusion: Findings suggestive of axial hypotonia and appendicular hypertonia associated with severe motor impairment were prevalent in children with CZS.

Dissemination of newborn behavior observation skills after Newborn Individualized Developmental Care and Assessment Program (NIDCAP) implementation

Aim

To assess nurses’ ability to observe newborn behaviour after in situ training provided by caregivers with advanced practice certification in the Newborn Individualized Developmental Care and Assessment Program (NIDCAP).

Design

Prospective observational study.

Methods

Twelve nurses viewed 20‐min films showing the behaviour of 10 premature newborns before, during and after the usual caregiving. The behaviour was rated on an observation sheet with 88 items distributed into six systems. The responses were compared to the reference ratings established by two professionals certified for this programme.

Results

Despite less accurate observations during care and for some components, the nurses generally showed a satisfactory ability to observe newborn behaviour after training by NIDCAP expert professionals. The dissemination of observation skills among caregivers may result in an improved quality of patient care and better communication among professionals in a department of neonatology.

Development and Validation of a Probe Word List to Assess Speech Motor Skills in Children

Purpose The aim of the study was to develop and validate a probe word list and scoring system to assess speech motor skills in preschool and school-age children with motor speech disorders. Method This article describes the development of a probe word list and scoring system using a modified word complexity measure and principles based on the hierarchical development of speech motor control known as the Motor Speech Hierarchy (MSH). The probe word list development accounted for factors related to word (i.e., motoric) complexity, linguistic variables, and content familiarity. The probe word list and scoring system was administered to 48 preschool and school-age children with moderate-to-severe speech motor delay at clinical centers in Ontario, Canada, and then evaluated for reliability and validity. Results One-way analyses of variance revealed that the motor complexity of the probe words increased significantly for each MSH stage, while no significant differences in the linguistic complexity were found for neighborhood density, mean biphone frequency, or log word frequency. The probe word list and scoring system yielded high reliability on measures of internal consistency and intrarater reliability. Interrater reliability indicated moderate agreement across the MSH stages, with the exception of MSH Stage V, which yielded substantial agreement. The probe word list and scoring system demonstrated high content, construct (unidimensionality, convergent validity, and discriminant validity), and criterion-related (concurrent and predictive) validity. Conclusions The probe word list and scoring system described in the current study provide a standardized method that speech-language pathologists can use in the assessment of speech motor control. It can support clinicians in identifying speech motor difficulties in preschool and school-age children, set appropriate goals, and potentially measure changes in these goals across time and/or after intervention.

A profile of reference data for shear modulus for lower limb muscles in typically developing children

BACKGROUND

Shear wave elastography can measure shear wave speed in muscles, which is used to estimate shear modulus. Normative values and standardized methodology are needed for children. Study aims were to: estimate shear modulus behavior of lower limb muscles of typically developing children; and establish a profile of reference data and recommendations for clinical assessment.

METHODS

Forty-one typically developing children (mean 9.7 y, SD 1.9 y) completed assessment of resting shear modulus of rectus femoris, biceps femoris, gastrocnemius lateralis and tibialis anterior at short and long lengths using shear wave elastography. Effects of muscle length, age, sex and BMI were examined. Then, our data and data from a scoping review for typical individuals were collated according to Net-Longitudinal Tension Angle (net proximal and distal joint angles).

FINDINGS

Shear modulus was: higher at long versus short muscle lengths for all four muscles (P < 0.001); correlated with increasing age for tibialis anterior at short (r = 0.39) and long lengths (r = 0.42) (both P = 0.01); but not related to sex or BMI. Shear modulus: tended to increase with increasing Net-Longitudinal Tension Angle for 18 lower limb muscles; and was higher for children than adults for some muscles (e.g. tibialis anterior and gastrocnemius lateralis, both P < 0.001).

INTERPRETATION

In typically developing children, shear modulus of lower limb muscles increases with increasing Net-Longitudinal Tension Angle. Recommendations enable comparison of values across different test positions and populations. Some relation between shear modulus and age was identified, but more research is needed.

Patterns of atypical muscle tone in the general infant population - Prevalence and associations with perinatal risk and neurodevelopmental status

BACKGROUND

Muscle tone is an indispensable element in motor development. Its assessment forms an integral part of the infant neurological examination. Knowledge on the prevalence of atypical tone in infancy is lacking.

AIM

To assess the prevalence of atypical muscle tone in infancy and of the most common atypical muscle tone patterns, and associations between atypical tone and perinatal risk and neurodevelopmental status.

STUDY DESIGN

Cross-sectional study.

SUBJECTS

1100 infants (585 boys; gestational age 39.4 weeks (27.3-42.4)), 6 weeks-12 months corrected age, representative of the Dutch population.

OUTCOME MEASURES

Muscle tone and neurodevelopmental status were assessed with the Standardized Infant NeuroDevelopmental Assessment (SINDA). Perinatal information was obtained by questionnaire and medical records. Univariable and multivariable statistics were applied.

RESULTS

Ninety-two infants (8%) had atypical muscle tone in 3-4 body parts (impaired pattern), while atypical muscle tone in 1-2 body parts was observed in 50%. Isolated leg hypotonia and isolated arm hypertonia were most common. Isolated arm hypertonia and the impaired pattern were most clearly but only moderately associated with perinatal risk. These patterns were also most clearly associated with lower neurological scores. Only the impaired pattern was associated with lower developmental scores.

CONCLUSION

Atypical muscle tone in one or two body parts is common in infancy and has in general little clinical significance. This finding corresponds to the well-known high prevalence of a typical but non-optimal neurological condition. Eight percent of infants show atypical muscle tone in 3-4 body parts. This clinically relevant pattern is associated with perinatal risk and less favourable neurodevelopmental status.

Systematic Review of Instrumented Measures of Skeletal Muscle Mechanical Properties: Evidence for the Application of Shear Wave Elastography with Children

The aim of this review was to identify instrumented devices that quantify skeletal muscle mechanical properties and to evaluate their potential clinical utility and clinimetric evidence with respect to children. Four databases were searched to identify articles reporting original clinimetric data for devices measuring muscle stiffness or elastic modulus, along a muscle's main fibre direction. Clinimetric evidence was rated using the Consensus-Based Standard for the Selection of Measurement Instruments (COSMIN) checklist. Sixty-five articles provided clinimetric data for two devices meeting our criteria: the Aixplorer and the Acuson. Both are shear wave elastography devices that determine the shear modulus of muscle tissue. The Aixplorer had strong construct validity and reliability, and the Acuson, moderate construct validity and reliability. Both devices have sound clinical utility with non-invasive application at various joint positions and data acquisition in real time, minimizing fatigue. Further research is warranted to evaluate utility for children with specific disorders of abnormal muscle structure or function.

High-level motor skills assessment for ambulant children with cerebral palsy: a systematic review and decision tree

AIM

To examine the psychometric evidence for high-level motor skills assessment tools for ambulant, school-aged children with cerebral palsy (CP).

METHOD

We searched five databases for population (children with CP aged 5-18y in Gross Motor Function Classification System levels I and II), assessment focus (high-level motor skills), and psychometric evidence. We evaluated evidence strength using the number of studies, quality, and conduct according to COnsensus-based Standards for the selection of health status Measurement INstruments checklists.

RESULTS

Eleven assessments (39 studies) met the criteria. Seven high-level motor skills assessment items (Muscle Power Sprint Test, 10m Shuttle Run Test, 10×5m Sprint Test, vertical jump, standing broad jump, seated throw, and Timed Up and Down Stairs) had strong validity and responsiveness evidence. Jumping items and seated throw lacked reliability data. Four high-level motor skills assessment batteries (Functional Strength Measure in CP, Gross Motor Function Measure-Challenge, Peabody Developmental Motor Scale, and Test of Gross Motor Development, Second Edition) had moderate-to-strong validity and/or reliability evidence. Responsiveness data were only available for the Gross Motor Function Measure-Challenge battery. The decision tree was developed with five levels: clinical feasibility, relevance, tool design, clinical utility, and psychometric properties.

INTERPRETATION

High-level motor skills assessment tools have strong psychometric evidence for ambulant, school-aged children with CP. The decision tree can assist clinicians and researchers in identifying appropriate tools to measure high-level motor skills.

WHAT THIS PAPER ADDS

An evidence-based decision tree guides the selection of appropriate high-level motor skills assessment tools. Seven high-level motor skills assessment items have strong psychometric evidence and clinical utility for ambulant children with cerebral palsy. Four high-level motor skills assessment batteries with recreation and mobility items have emerging psychometric evidence in this population.