Reliability of the Modified Hammersmith Functional Motor Scale in young children with spinal muscular atrophy

Feasibility and utility of in-home body weight support harness system use in young children treated for spinal muscular atrophy: A single-arm prospective cohort study

PURPOSE

This single-arm prospective cohort study aimed to evaluate the feasibility and utility of in-home body weight support harness system (BWSS) use in children treated for spinal muscular atrophy (SMA).

METHODS

Individuals with 2 or 3 copies of SMN2 who received pharmacotherapeutic treatment, had head control, and weight <50lbs were enrolled. Families were provided a BWSS and documented use. Motor outcome assessments were completed at baseline, month 3 and month 6. Families provided feedback in an end of study survey.

RESULTS

All 32 participants (2.9 (SD 1.9) yrs), improved or remained stable on all outcomes. Average reported frequency of use was 4.1(2.3) hrs/week. Controlling for other covariates, frequency of use explained over 70% of the variability in change scores. Family feedback was overwhelmingly positive.

CONCLUSION

Use of in-home BWSS is a safe, feasible and useful option to increase exercise dosage after treatment in SMA and may help optimize motor abilities.

TRIAL REGISTRATION

Study registered with: Clinicaltrials.gov Clinicaltrials.gov identifier: NCT05715749.

A Case Report of Pediatric Rehabilitation for Hypoxic Ischemic Encephalopathy Associated With Global Developmental Delay

Hypoxic ischemic encephalopathy (HIE) is a critical condition affecting neonates due to oxygen deprivation and insufficient flow of blood to the brain. It is associated with high neonatal mortality and the risk of developmental psychomotor disorders, including cerebral palsy. The global epidemiology of HIE reveals significant disparities, with more advanced healthcare systems reporting lower incidence rates. The aim of the study is to contribute to the understanding of effective rehabilitation strategies for children with HIE and global developmental delay (GDD), with the goal of improving outcomes and quality of life for these individuals. This case report focuses on an 11-month-old male child with a history of perinatal HIE, highlighting the developmental challenges and interventions undertaken. The child showed delayed gross and fine motor development, sensory awareness deficits, and postural coordination issues. A comprehensive physiotherapy intervention plan was implemented, resulting in significant improvements in post-treatment outcome measures. This case highlights the importance of early and holistic physiotherapy interventions in addressing HIE patients' developmental delays and improving their quality of life.

Criterion validity of the spatial exploration test of upper limb mobility to evaluate the active horizontal workspace of children with spinal muscular atrophy

PURPOSE

To determine the criterion validity of the SET-ULM (Spatial Exploration Test of Upper Limb Mobility), a functional workspace test.

MATERIALS AND METHODS

A prospective study from July 2017 to November 2018 in 30 children with SMA type 1 or 2. All children underwent assessment with the SET-ULM and the Motor Function Measure (MFM).

RESULTS

We included 30 children. Median (Q1; Q3) MFM D1 (standing ability, ambulation and transfers), D2 (axial and proximal motor function), D3 (distal motor function) scores, Total MFM and Total SET-ULM active score were respectively 2.6% (2.6-3.8); 45.8% (19.9-65.3); 57.7% (36.9-80.9); 35.4% (16.7-43.2) and 70.2% (49.7-97.9). Total SET-ULM active score was strongly correlated with the MFM D2 dimension score (rho 0.82; p < 001), with the D3 dimension (rho 0.86; p < 0.001) and with the Total MFM score (rho 0.89; p < 0.005). Total SET-ULM active score differed between SMA types (p < 0.01).

CONCLUSION

The SET-ULM has good criterion validity for the evaluation of available horizontal active upper limb workspace in children with SMA1 and SMA2. Future studies should evaluate reliability and sensitivity to change during a longitudinal follow-up study, as well as in a longitudinal trial of therapeutic effectiveness.

CLINICAL TRIALS

NCT03223051IMPLICATIONS FOR REHABILITATIONThe Spatial Exploration Test for Upper Limb Mobility is a useful adjunct to the Motor Function Measure.It provides a precise evaluation of horizontal reaching ability.The Spatial Exploration Test for Upper Limb Mobility will be of great clinical utility for the evaluation of the effects of treatments for spinal muscular atrophy.

Revised Hammersmith Scale for spinal muscular atrophy: Inter and intra-rater reliability and agreement

The Revised Hammersmith Scale (RHS) for Spinal Muscular Atrophy (SMA) was designed as a psychometrically robust clinical outcome assessment to assess physical abilities of patients with type 2 and 3 SMA. The reliability properties of the RHS have not yet been reported. A prospective RHS reliability study was undertaken in a UK cohort of experienced neuromuscular paediatric Physiotherapists. Reliability testing was conducted via a virtual survey platform two weeks apart. Through the virtual platform participants scored videos of two RHS assessments, one of a child with SMA 2 and one of a child with SMA 3. Inter and intra-rater reliability was analysed using a type 3 Intraclass Correlation Coefficient (ICC). Intra-rater agreement was further analysed using Bland Altman (BA) Limits of Agreement (LOA) and plots. The acceptable inter and intra-rater variability was set as a change of ± 2 by the international team of expert physiotherapists who developed the RHS. Inter-rater agreement, n = 22 raters, type 3 ICC was 0.989 (95% CI 0.944 to 1.00), 97.7% of scores were within the acceptable limits of ± 2 points. Intra-rater agreement, n = 21 raters, type 3 ICC ranged from 0.922 to 1.0, with 97.6% of scores within the acceptable limits of ± 2 points. The mean SMA 2 intra-rater difference was -0.10 (-0.6 to 0.4), with lower LOA -2.24 and upper LOA +2.04. Intra-rater difference between tests for SMA 3 intra-rater difference was -0.05 (-0.6 to 0.5), with lower LOA -2.48 and upper LOA +2.38. Intra-rater scoring precision fell within BA agreement limits of ±2 points. The results demonstrate that the RHS is highly reliable when used by experienced UK physiotherapists, and variability of test scores regarding inter and intra-rater reliability was confirmed to lie within ±2 points.

Systematic Review of Motor Function Scales and Patient-Reported Outcomes in Spinal Muscular Atrophy

ABSTRACT

Spinal muscular atrophy is a heterogeneous disease that results in loss of motor function. In an evolving treatment landscape, establishing the suitability and limitations of existing motor function scales and patient-reported outcomes used to monitor patients with this disease is important. A systematic review was conducted to examine utility of motor function scales and patient-reported outcomes in evaluating patients with spinal muscular atrophy. Published literature was reviewed up to June 2021 with no start date restriction. Of the reports screened, 122 were deemed appropriate for inclusion and are discussed in this review (including 24 validation studies for motor function scales or patient-reported outcomes). Fifteen motor function scales and patient-reported outcomes were identified to be commonly used (≥5 studies), of which 11 had available validation assessments. Each instrument has its strengths and limitations. It is imperative that the patient population (e.g., age, mobility), goals of treatment, and outcomes or endpoints of interest be considered when selecting the appropriate motor function scales and patient-reported outcomes for clinical studies.

Consensus Guidelines for Improving Quality of Assessment and Training for Neuromuscular Diseases

Critical components of successful evaluation of clinical outcome assessments (COAs) in multisite clinical trials and clinical practice are standardized training, administration, and documented reliability of scoring. Experiences of evaluators, alongside patient differences from regional standards of care, may contribute to heterogeneity in clinical center’s expertise. Achieving low variability and high reliability of COA is fundamental to clinical research and to give confidence in our ability to draw rational, interpretable conclusions from the data collected. The objective of this manuscript is to provide a framework to guide the learning process for COAs for use in clinics and clinical trials to maximize reliability and validity of COAs in neuromuscular disease (NMD). This is a consensus-based guideline with contributions from fourteen leading experts in clinical outcomes and the field of clinical outcome training in NMD. This framework should guide reliable and valid assessments in NMD specialty clinics and clinical trials. This consensus aims to expedite study start up with a progressive training pathway ranging from research naïve to highly experienced clinical evaluators. This document includes recommendations for education guidelines and roles and responsibilities of key stakeholders in COA assessment and implementation to ensure quality and consistency of outcome administration across different settings.

Validity and Reliability of the Neuromuscular Gross Motor Outcome

BACKGROUND

Approved treatments in spinal muscular atrophy (SMA) have resulted in unprecedented gains for many individuals. Use of available outcomes, typically developed for a specific type of SMA, do not cover the range of progression, often resulting in a battery of functional testing being completed at visits. Our objective was to validate the Neuromuscular Gross Motor Outcome (GRO) as a tool to quantify function in SMA across the span of abilities.

METHODS

Patients with genetically confirmed SMA completed functional testing at each visit including the Neuromuscular GRO and other appropriate gross motor outcomes.

RESULTS

We enrolled 91 patients with SMA types 1 to 3 between 8 days and 32.1 years. The GRO utilizes a 0- to 2-point scale with scores in our cohort ranging from 1 to 95 points with no floor or ceiling effect. GRO scores were significantly different across functional categories (P < 0.001) and treatment status (P = 0.01) and correlated to other functional assessments (P ≤ 0.001). All patients were measured using the GRO, whereas traditional outcomes were only appropriate on 36% to 59% of our cohort.

CONCLUSION

The Neuromuscular GRO quantifies function across the span of age and abilities included in our cohort, allowing for continuous longitudinal monitoring on one scale to reduce the burden of testing in our heterogeneous clinic population.

Motor Function of Children with SMA1 and SMA2 Depends on the Neck and Trunk Muscle Strength, Deformation of the Spine, and the Range of Motion in the Limb Joints

The purpose of this study was to investigate the functional relationships between selected ranges of motion of the neck, upper and lower limbs, the strength of the neck and trunk muscles, postural parameters, and the motor function of children with SMA1 and SMA2—27 children, aged 6 months-15 years, with genetically confirmed spinal muscular atrophy type 1 (19 children) and 2 (8 children) undergoing pharmacological treatment. All children were examined, according to the methodology, including the motor function evaluation, measurement of selected ranges of motion, assessment of postural parameters, and measurement of neck and trunk muscle strength. The functional status of 15 children was assessed with the CHOP INTEND (CHOP group) scale and of 12 children with the HFMSE (HFMSE group). The results obtained showed that, in children examined with the CHOP scale, greater limitation of flexion in the shoulder joints was observed. As the deformation of the chest increased, the functional abilities of children deteriorated. In participants examined with the CHOP group, the ranges of neck rotation decreased with the increase of the chest deformity. In the HFMSE group, the ranges of head rotation showed a strong relationship with some parameters of muscle strength and the sum of the R coefficients. Participants showed many significant relationships between the range of motion in the neck and joints of the limbs, with more significant relationships in the CHOP group. The following conclusions were made: motor skills of children with SMA depend on muscle strength, range of motion, and deformities of the spine and chest; the development of scoliosis adversely affects the motor function, ranges of motion, and muscle strength; and movement ranges are related to motor skills and strength values.

Clinical outcome assessments in Duchenne muscular dystrophy and spinal muscular atrophy: past, present and future

Scores and scales used in pediatric motor development for neuromuscular disorders have evolved greatly since the beginning of their development. In this review we provide a brief history of scales used in pediatric patients with neuromuscular disorders and an update regarding the advancement of the scales commonly used in patients with spinal muscular atrophy and Duchenne muscular dystrophy. We focus on the collaborative effort that has led to the development of outcomes and speak to the possible future of Clinical Outcome Assessments.

Gross Motor Function Disorders in Patients with Alternating Hemiplegia of Childhood

Background

Alternating hemiplegia of Childhood (AHC) is a rare disease manifested by transient episodes of hemiplegia and other neurological disorders. Delayed motor development has been reported in patients with AHC, but detailed features of the motor impairment have not been described so far.

Aim

The aim of the study was to evaluate gross motor function between attacks in a group of Polish patients with AHC.

Materials and methods

The interictal gross motor function was assessed using the Gross Motor Function AHC scale, which consisted of 41 motor tasks. The study group consisted of 10 patients with AHC older than 2 years of age. The control group consisted of 30 age- and gender-matched subjects. The results achieved in each of the 41 tasks by the study subjects were compared to the results obtained with controls using the non-parametric Mann-Whitney U-test. In tasks 38-41, mean times were compared between the study subjects and controls.

Results

The study revealed gross motor function impairment in patients with AHC. The greatest differences compared to controls concerned such skills as standing on toes, walking on toes, walking on heels, as well as running and hopping on one leg and on alternate legs. Significant impairment of the motor function of the upper limbs was also found.

Conclusions

The study confirmed motor function impairment between attacks in patients with AHC. The study findings may indicate the need to introduce individualised physiotherapy management of patients with AHC.

Stander Use in Spinal Muscular Atrophy: Results From a Large Natural History Database

PURPOSE

The purpose of this study was to describe stander use in a natural history cohort of drug therapy-naïve children with spinal muscular atrophy (SMA) who are not walking and identify factors associated with consistent stander use.

METHODS

Data from 397 children with SMA types 1 and 2 characterized the prevalence and frequency of stander use. Predictors of consistent stander use explored were SMA type, survival motor neuron 2 gene (SMN2) copy number, respiratory support, and motor performance.

RESULTS

Prevalence of consistent stander use was 13% in type 1 and 68% in type 2. SMA type, SMN2 copy number, respiratory support, and head rotation control each predicted consistent stander use.

CONCLUSIONS

Findings characterize stander use in children with SMA who are not walking, address important safety considerations, identify factors that may inform physical therapists' clinical decision-making related to standing program prescription, and provide guidance for future prospective studies.

Efficacy and Safety of Valproic Acid for Spinal Muscular Atrophy: A Systematic Review and Meta-Analysis

BACKGROUND

Spinal muscular atrophy (SMA) is a neuromuscular disorder classified into four types based on the age of onset of the disease. Early onset is correlated with a higher mortality rate, mainly due to respiratory complications. Valproic acid (VPA) is a histone deacetylase (HDAC) inhibitor that has shown positive results on SMA both in experimental and cohort studies.

OBJECTIVES

This systematic review and meta-analysis aimed to investigate the efficacy and safety of VPA in patients with SMA.

METHODS

Eleven databases were systematically searched on 30 May 2017 for clinical trials that reported the efficacy and safety of VPA in SMA patients. The primary outcome was the efficacy of VPA in terms of gross motor function and expression of both full-length spinal motor neuron (SMN) gene (FL-SMN) and exon 7-lacking SMN. The secondary outcome was the safety of VPA in terms of reported adverse effects. The protocol was registered at PROSPERO (CRD42017067203).

RESULTS

Five of the ten included studies were used in the meta-analysis (n = 126). The overall effect estimate, comparing pre- and post-VPA treatment, regardless of carnitine co-administration and design of the studies, showed significant improvement in gross motor function (standard mean difference [SMD] = 0.302, 95% confidence interval [CI] 0.048-0.556, P = 0.02) using the Hammersmith Functional Motor Scale (HFMS), Modified Hammersmith Functional Motor Scale (MHFMS), and MHFMS-Extend, with no significant heterogeneity. Similarly, in non-randomized controlled studies, the results indicated that there was a significant improvement detected (SMD = 0.335, 95% CI 0.041-0.628, P = 0.025), with no significant heterogeneity. Meanwhile, our results suggest that there was no significant improvement in treatment with co-administered carnitine (SMD = 0.28, 95% CI - 0.02 to 0.581, P = 0.067). No significant differences were found between pre- and post-VPA treatment co-administered with carnitine, in terms of the change in FL-SMN and exon 7-lacking SMN. Qualitative synthesis showed that other motor functions were not improved, while respiratory function test results were contradictory. Regarding the safety of the treatment, a double-blind, randomized, placebo-controlled trial reported no statistically significant differences for adverse events (AEs) between groups. Moreover, most of the included studies reported no serious AEs related to VPA use, although weight gain, gastrointestinal symptoms and respiratory symptoms were notable problems.

CONCLUSIONS

Our study suggests that VPA treatment results in an improvement in gross motor functions for SMA patients, but not in other assessments of motor function or, possibly, in respiratory function. Furthermore, VPA appears to be a relatively safe drug, although treatment may be associated with a wide range of AEs (including body weight increase, fatigue, fever, flu-like symptoms, irritability, and pain). Double-blind, randomized, controlled trials are required to confirm these findings.

Motor Function Test Reliability During the NeuroNEXT Spinal Muscular Atrophy Infant Biomarker Study

BACKGROUND

The NeuroNEXT SMA Infant Biomarker Study, a two year, longitudinal, multi-center study of infants with SMA type 1 and healthy infants, presented a unique opportunity to assess multi-site rater reliability on three infant motor function tests (MFTs) commonly used to assess infants with SMA type 1.

OBJECTIVE

To determine the effect of prospective MFT rater training and the effect of rater experience on inter-rater and intra-rater reliability for the Test of Infant Motor Performance Screening Items (TIMPSI), the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) and the Alberta Infant Motor Scale (AIMS).

METHODS

Training was conducted utilizing a novel set of motor function test (MFT) videos to optimize accurate MFT administration and reliability for the study duration. Inter- and intra-rater reliability of scoring for the TIMPSI and inter-rater reliability of scoring for the CHOP INTEND and the AIMS was assessed using intraclass correlation coefficients (ICC). Effect of rater experience on reliability was examined using ICC. Agreement with 'expert' consensus scores was examined using Pearson's correlation coefficients.

RESULTS

Inter-rater reliability on all MFTs was good to excellent. Intra-rater reliability for the primary MFT, the TIMPSI, was excellent for the study duration. Agreement with 'expert' consensus was within predetermined limits (≥85%) after training. Evaluator experience with SMA and MFTs did not affect reliability.

CONCLUSIONS

Reliability of scores across evaluators was demonstrated for all three study MFTs and scores were reproducible on repeated administration. Evaluator experience had no effect on reliability.

Revised Hammersmith Scale for spinal muscular atrophy: A SMA specific clinical outcome assessment tool

Recent translational research developments in Spinal Muscular Atrophy (SMA), outcome measure design and demands from regulatory authorities require that clinical outcome assessments are 'fit for purpose'. An international collaboration (SMA REACH UK, Italian SMA Network and PNCRN USA) undertook an iterative process to address discontinuity in the recorded performance of the Hammersmith Functional Motor Scale Expanded and developed a revised functional scale using Rasch analysis, traditional psychometric techniques and the application of clinical sensibility via expert panels. Specifically, we intended to develop a psychometrically and clinically robust functional clinician rated outcome measure to assess physical abilities in weak SMA type 2 through to strong ambulant SMA type 3 patients. The final scale, the Revised Hammersmith Scale (RHS) for SMA, consisting of 36 items and two timed tests, was piloted in 138 patients with type 2 and 3 SMA in an observational cross-sectional multi-centre study across the three national networks. Rasch analysis demonstrated very good fit of all 36 items to the construct of motor performance, good reliability with a high Person Separation Index PSI 0.98, logical and hierarchical scoring in 27/36 items and excellent targeting with minimal ceiling. The RHS differentiated between clinically different groups: SMA type, World Health Organisation (WHO) categories, ambulatory status, and SMA type combined with ambulatory status (all p < 0.001). Construct and concurrent validity was also confirmed with a strong significant positive correlation with the WHO motor milestones rs = 0.860, p < 0.001. We conclude that the RHS is a psychometrically sound and versatile clinical outcome assessment to test the broad range of physical abilities of patients with type 2 and 3 SMA. Further longitudinal testing of the scale with regards change in scores over 6 and 12 months are required prior to its adoption in clinical trials.

Patterns of disease progression in type 2 and 3 SMA: Implications for clinical trials

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The paper reports for the first time patterns of progression in type 2 and 3 SMA.

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Different trajectories can be identified in ambulant and non-ambulant patients.

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Age appears to be an important factor in determining trajectories of progression.

The aim of the study was to establish 12-month changes in the Hammersmith Functional motor scale in a large cohort of SMA patients, to identify patterns of disease progression and the effect of different variables. 268 patients were included in this multicentric study. Their age ranged between 2.5 and 55.5 years at baseline, 68 were ambulant and 200 non-ambulant. The baseline scores ranged between 0 and 66 (mean 23.91, SD 20.09). The 12-month change was between −14 and +9 (mean −0.56, SD 2.72). Of the 268 patients, 206 (76.86%) had changes between −2 and +2 points. Ambulant and non-ambulant subjects had a different relationship between baseline values and age (p for age X ambulation interaction = 0.007). There was no association with age in ambulant subjects, while there was a significant heterogeneity at different age for non-ambulant patients (p < 0.001). The 12-month change (adjusted for baseline) was not associated with age in ambulant patients (p = 0.34), but it was significantly different among various age groups in non-ambulant patients. Our results suggest that there are different profiles of progression in ambulant and non-ambulant patients, and that age may play an important role in the progression of non-ambulant patients.

Instruments for the evaluation of motor abilities for children with severe multiple disabilities: A systematic review of the literature

Based on a systematic review, psychometric characteristics of currently available instruments on motor abilities of children with disabilities were evaluated, with the aim to identify candidates for use in children with severe multiple (intellectual and motor) disabilities. In addition, motor abilities are essential for independent functioning, but are severely compromised in these children. The methodological quality of all studies was evaluated with the Consensus Based Standards for the Selection of Health Status Measurement Instruments (COSMIN) Checklist; overall levels of evidence per instrument were based on the Cochrane Back Review Group strategy. As a result, 18 studies with a total of eight instruments, developed for children with cerebral palsy (CLA, GMFM-88 and LE85), spinal muscular atrophy (MHFMS), neuromuscular diseases (MFM), disabilities 0-6 years (VAB, WeeFIM), and one developed specifically for children with severe multiple disabilities (TDMMT) were found. Strong levels of evidence were found for construct validity of LE85 and MFM and for responsiveness of WeeFIM, but reliability studies of these instruments had a limited methodological quality. Up to now studies of the TDMMT resulted in limited and unknown evidence for structural validity due to the poor methodological quality of reliability studies. In a next step, the clinical suitability of the instruments for children with severe multiple disabilities will be evaluate.

Upper limb module in non-ambulant patients with spinal muscular atrophy: 12 month changes

Recent studies have suggested that in non-ambulant patients affected by spinal muscular atrophy the Upper Limb Module can increase the range of activities assessed by the Hammersmith Functional Motor Scale Expanded. The aim of this study was to establish 12-month changes in the Upper Limb Module in a cohort of non-ambulant spinal muscular atrophy patients and their correlation with changes on the Hammersmith Functional Motor Scale Expanded. The Upper Limb Module scores ranged between 0 and 17 (mean 10.23, SD 4.81) at baseline and between 1 and 17 at 12 months (mean 10.27, SD 4.74). The Hammersmith Functional Motor Scale Expanded scores ranged between 0 and 34 (mean 12.43, SD 9.13) at baseline and between 0 and 34 at 12 months (mean 12.08, SD 9.21). The correlation betweeen the two scales was 0.65 at baseline and 0.72 on the 12 month changes. Our results confirm that the Upper Limb Module can capture functional changes in non-ambulant spinal muscular atrophy patients not otherwise captured by the other scale and that the combination of the two measures allows to capture changes in different subgroups of patients in whom baseline scores and functional changes may be influenced by several variables such as age.

The motor neuron response to SMN1 deficiency in spinal muscular atrophy

INTRODUCTION

The purpose of this study was to measure and analyze motor unit number estimation (MUNE) values longitudinally in spinal muscular atrophy (SMA).

METHODS

Sixty-two children with SMA types 2 and 3 were observed prospectively for up to 42 months. Longitudinal electrophysiological data were collected, including compound motor action potential (CMAP), single motor unit action potential (SMUP), and MUNE.

RESULTS

Significant motor neuron loss and compensatory collateral reinnervation were noted at baseline. Over time, there was a significant mean increase in MUNE (4.92 units/year, P = 0.009), a mean decrease in SMUP amplitude (-6.32 μV/year, P = 0.10), and stable CMAP amplitude.

CONCLUSIONS

The unexpected longitudinal results differ from findings in amyotrophic lateral sclerosis studies, perhaps indicating that compensatory processes in SMA involve new motor unit development. A better understanding of the mechanisms of motor unit decline and compensation in SMA is important for assessing novel therapeutic strategies and for providing key insights into disease pathophysiology.

Rasch analysis of clinical outcome measures in spinal muscular atrophy

INTRODUCTION

Trial design for SMA depends on meaningful rating scales to assess outcomes. In this study Rasch methodology was applied to 9 motor scales in spinal muscular atrophy (SMA).

METHODS

Data from all 3 SMA types were provided by research groups for 9 commonly used scales. Rasch methodology assessed the ordering of response option thresholds, tests of fit, spread of item locations, residual correlations, and person separation index.

RESULTS

Each scale had good reliability. However, several issues impacting scale validity were identified, including the extent that items defined clinically meaningful constructs and how well each scale measured performance across the SMA spectrum.

CONCLUSIONS

The sensitivity and potential utility of each SMA scale as outcome measures for trials could be improved by establishing clear definitions of what is measured, reconsidering items that misfit and items whose response categories have reversed thresholds, and adding new items at the extremes of scale ranges.

Correlation between motor performance scales, body composition, and anthropometry in patients with Duchenne muscular dystrophy

The aim of this study is to investigate the relationship between body composition, anthropometry, and motor scales in patients with Duchenne muscular dystrophy (DMD). Twenty six patients with DMD were evaluated by Expanded Hammersmith Functional Motor Scale (HFMSE), gross motor function classification system (GMFCS), multifrequency bioelectrical impedance analysis, and anthropometric measurements. Seventeen healthy children served as control group. There were 26 patients with a mean age of 9.5 ± 4.8 years. Ages and anthropometric measurements did not differ between groups. Of the 26 patients, nine were level I, seven were level II, two were level III, seven were level IV, and one was level V, according to the GMFCS. Despite the similar percentage of total body water, extracellular water/intracellular water ratio was significantly elevated in DMD patients (p = 0.001). Increased values of fat percentage and body fat mass index (BFMI) correlated positively with elevated GMFCS levels (r = 0.785 and 0.719 respectively). Increased fat-free mass index (FFMI) correlated negatively with elevated GMFCS levels (r = -0.401). Increased fat percentage and BFMI correlated negatively with HFMSE scores (r = -0.779 and -0.698, respectively). Increased values of FFMI correlated positively with HFMSE scores. There was also a negative correlation between increased skin fold measurements from triceps and scapula and HFMSE scores (r = -0.618 and -0.683, respectively). Increased skin fold values from the same regions correlated positively with elevated GMFCS levels (r = 0.643 and 0.712, respectively). Significant body composition changes occur in patients with DMD. Anthropometric and multifrequency bioelectrical impedance analyses measurements show good correlation between motor function scales. These results may also be helpful to evaluate the effects of new treatment strategies.

Motor and cognitive assessment of infants and young boys with Duchenne Muscular Dystrophy: results from the Muscular Dystrophy Association DMD Clinical Research Network

Therapeutic trials in Duchenne Muscular Dystrophy (DMD) exclude young boys because traditional outcome measures rely on cooperation. The Bayley III Scales of Infant and Toddler Development (Bayley III) have been validated in developing children and those with developmental disorders but have not been studied in DMD. Expanded Hammersmith Functional Motor Scale (HFMSE) and North Star Ambulatory Assessment (NSAA) may also be useful in this young DMD population. Clinical evaluators from the MDA-DMD Clinical Research Network were trained in these assessment tools. Infants and boys with DMD (n = 24; 1.9 ± 0.7 years) were assessed. The mean Bayley III motor composite score was low (82.8 ± 8; p ≤ .0001) (normal = 100 ± 15). Mean gross motor and fine motor function scaled scores were low (both p ≤ .0001). The mean cognitive comprehensive (p=.0002), receptive language (p ≤ .0001), and expressive language (p = .0001) were also low compared to normal children. Age was negatively associated with Bayley III gross motor (r = -0.44; p = .02) but not with fine motor, cognitive, or language scores. HFMSE (n=23) showed a mean score of 31 ± 13. NSAA (n = 18 boys; 2.2 ± 0.4 years) showed a mean score of 12 ± 5. Outcome assessments of young boys with DMD are feasible and in this multicenter study were best demonstrated using the Bayley III.

Reliability and validity of the TIMPSI for infants with spinal muscular atrophy type I

PURPOSE

This study examined the reliability and validity of the Test of Infant Motor Performance Screening Items (TIMPSI) in infants with type I spinal muscular atrophy (SMA).

METHODS

After training, 12 evaluators scored 4 videos of infants with type I SMA to assess interrater reliability. Intrarater and test-retest reliability was further assessed for 9 evaluators during a SMA type I clinical trial, with 9 evaluators testing a total of 38 infants twice. Relatedness of the TIMPSI score to ability to reach and ventilatory support was also examined.

RESULTS

Excellent interrater video score reliability was noted (intraclass correlation coefficient, 0.97-0.98). Intrarater reliability was excellent (intraclass correlation coefficient, 0.91-0.98) and test-retest reliability ranged from r = 0.82 to r = 0.95. The TIMPSI score was related to the ability to reach (P ≤ .05).

CONCLUSION

The TIMPSI can reliably be used to assess motor function in infants with type I SMA. In addition, the TIMPSI scores are related to the ability to reach, an important functional skill in children with type I SMA.

Pathophysiological insights derived by natural history and motor function of spinal muscular atrophy

OBJECTIVE

To examine the natural history of spinal muscular atrophy (SMA) to gain further insight into the clinical course and pathogenesis.

STUDY DESIGN

Survival pattern, age of onset, and ambulatory status were retrospectively analyzed in 70 patients with SMA with deletions of the survival motor neuron 1 genes that presented to a specialized neuromuscular clinic. The Kaplan-Meier method was used to obtain survival curves. Hammersmith Functional Motor Scale-Expanded and abductor pollicis brevis compound muscle action potential amplitudes were assessed in 25 of the surviving cohort and correlated with survival motor neuron 2 copy number.

RESULTS

Survival probabilities at ages 1, 2, 4, 10, 20, and 40 years were 40%, 25%, 6%, and 0%, respectively, for patients with SMA type 1; 100%, 100%, 97%, 93%, 93%, and 52% for patients with SMA type 2 and all patients with SMA type 3 were alive (age range 7-33 years). There were significant associations between age of onset and long-term outcome, specifically survival in SMA type 1 (P < .01) and Hammersmith Functional Motor Scale-Expanded (P < .0001), and compound muscle action potential (P = .001) in SMA types 2 and 3. Motor function in patients with long-standing SMA reduced over prolonged periods or remained stable. Survival motor neuron 2 copy number related to continuing changes in motor function with age.

CONCLUSION

The natural history of SMA suggests considerable early loss of motor neurons, with severity related to differences in the number of remaining motor neurons. As the ensuing chronic course in milder phenotypes suggests relative stability of remaining motor neurons, the maximal therapeutic window presents early.

Childhood spinal muscular atrophy: controversies and challenges

Spinal muscular atrophy is an autosomal recessive disorder characterised by degeneration of motor neurons in the spinal cord and is caused by mutations of the survival of motor neuron 1 gene SMN1. The severity of spinal muscular atrophy is highly variable and no cure is available at present. Consensus has been reached on several aspects of care, the availability of which can have a substantial effect on prognosis, but controversies remain. The development of standards of care for children with the disorder and the identification of promising treatment strategies have changed the natural history of spinal muscular atrophy, and the prospects are good for further improvements in function, quality of life, and survival. A long-term benefit for patients will be the development of effective interventions (such as antisense oligonucleotides), some of which are in clinical trials. The need to be prepared for clinical trials has been the impetus for a remarkable and unprecedented cooperation between clinicians, scientists, industry, government, and volunteer organisations on an international scale.

New therapeutic approaches to spinal muscular atrophy

Bench to bedside progress has been widely anticipated for a growing number of neurodegenerative disorders. Of these, spinal muscular atrophy (SMA) is perhaps the best poised to capitalize on advances in targeted therapeutics development over the next few years. Several laboratories have achieved compelling success in SMA animal models using sophisticated methods for targeted delivery, repair, or increased expression of the survival motor neuron protein, SMN. The clinical community is actively collaborating to identify, develop, and validate outcome measures and biomarkers in parallel with laboratory efforts. Innovative trial design and synergistic approaches to maximize proactive care in conjunction with treatment with one or more of the promising pharmacologic and biologic therapies currently in the pipeline will maximize our chances to achieve meaningful outcomes for patients. This review highlights recent promising scientific and clinical advances bringing us ever closer to effective treatment(s) for our patients with SMA.