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

Assessing disease progression in spinal muscular atrophy, current gaps, and opportunities: a narrative review

Spinal Muscular Atrophy is a genetic disorder causing muscle atrophy and progressive weakness. People living with the condition can have a significant heterogenous phenotype ranging from arrest of motor development to mild impairment. Assessing disease severity has been done using a range of outcome measures that can be classified by body structure or function, by activities or by participation. Functional outocome measures can be generic measures, used to compare individuals or populations against general norms, or disease-specific measures designed to fit disease characteristics. Outcome measures assessing participation are primarily used to capture patients' perceptions of health-related quality of life, daily activity abilities, caregiver burden, and the impact of physical symptoms like fatigue or pain. When assessing disease progression, often the focus on functional abilities has served as an overall indicator of change. With the appearance of disease modifying therapies and the need to evaluate the impact that they had in the course of the disease, new requirements for the existing assessments measure had appeared. The current available toolkit is able to capture a significant spectrum of both, natural history and effect of new treatments but the increased survival, changes in fatigue, bulbar function and others will benefit from further assessment.

Research into the correlation between positional skull deformation and motor performance of infants aged under 4 months

OBJECTIVE

To investigate the correlation between positional skull deformation (PD) and motor performance of infants under 4 months of age.

METHODS

Infants aged under 4 months were enrolled in the children's healthcare and the premature infants follow-up Clinic of the Second Affiliated Hospital of Army Military Medical University. The cranial vault asymmetry (CVA) and cephalic index (CI) were calculated in all infants, and the infant motor performance test (TIMP) was used to evaluate the infant motor performance. The motor performances of infants with different types and degrees of PD were compared, so were the incidences of PD in infants with different motor performance levels.

RESULTS

Overall, 2118 infants were recruited and divided according to the types of PD and TIMP scores. The comparison of TIMP scores within different types of PD at different months of age showed that, regardless of the types of PD, TIMP scores of infants with PD were lower than those of normal infants. In particular, the difference in TIMP scores was statistically significant (P < 0.05) in infants with dolichocephaly, plagiocephaly,dolicho-plagiocephaly and brachy-plagiocephy. In addition, the comparison of CVA values of infants with different TIMP score levels at different months of age showed that the CVA values of the extremely low-level group were significantly higher than those of the medium-level and high-level group, especially in the 3-month-old and 4-month-old groups, which showed significant statistical differences (P < 0.05).

CONCLUSIONS

PD and motor performance of infants aged under 4 months seem to interact and influenc each other. The more serious the severity of PD were,the worse the motor performance of infants. Conversely, the incidence of PD increased in infants with poor motor performance.

Can items on the TIMP aide in determining the motor performance of children with severe cerebral palsy? A pilot study

BACKGROUND

Assessing the functional level of children with severe cerebral palsy (CP) requires sensitive tools. In this study, an 'assessment tool' was developed based on the Test of Infant Motor Performance (TIMP) for this population and the reliability and validity evaluated.

METHODS

Five physical therapists administered the 'assessment tool' to six children (3-6 years old with a diagnosis of CP, GMFCS Level V). Subtest I of the Gross Motor Function Measure (GMFM-88) was also administered. Intra- and inter-rater reliability were assessed, and the concurrent validity between the 'assessment tool' and GMFM-88 calculated.

RESULTS

The intra-rater reliability, a comparison of the total scores on the 'assessment tool' (live test) and the videotaped rescoring of the same test one month later showed consistency among four of the five therapists (ICC = 0.7545 to 0.979). The inter-rater reliability varied on some of the items but the total score on the 'assessment tool' showed good reliability (ICC_2,5 0.816). Scores of children with dyskinesia were less stable. The Spearman's rank correlation coefficient was not significant. Therapists provided recommendations for item revisions.

CONCLUSION

Further development of an 'assessment tool' appears justified; a larger study using a version with revised administration guidelines and items should be undertaken to re-verify the psychometrics properties of the 'assessment tool.'

Functional movement assessment with the Test of Infant Motor Performance

The purpose of this article is to review research on the Test of Infant Motor Performance, a functional assessment of movement capabilities with age standards for infants from 34 weeks postmenstrual age through 17 weeks post term (corrected age). The Test of Infant Motor Performance was normed on a U.S. population-based sample to support its use as a tool for diagnosing delayed motor development in early infancy. The test is one of the preferred methods for parents of babies in special care nurseries to learn about their infant's development. The test was used in a variety of clinical trials to document effects of early therapy and can be used as a short-term outcome measure for other interventions expected to impact functional motor performance.

Update on Biomarkers in Spinal Muscular Atrophy

The availability of disease modifying therapies for spinal muscular atrophy (SMA) has created an urgent need to identify clinically meaningful biomarkers. Biomarkers present a means to measure and evaluate neurological disease across time. Changes in biomarkers provide insight into disease progression and may reveal biologic, physiologic, or pharmacologic phenomena occurring prior to clinical detection. Efforts to identify biomarkers for SMA, a genetic motor neuron disease characterized by motor neuron degeneration and weakness, have culminated in a number of putative molecular and physiologic markers that evaluate biological media (eg, blood and cerebrospinal fluid [CSF]) or nervous system function. Such biomarkers include SMN2 copy number, SMN mRNA and protein levels, neurofilament proteins (NFs), plasma protein analytes, creatine kinase (CK) and creatinine (Crn), and various electrophysiology and imaging measures. SMN2 copy number inversely correlates with disease severity and is the best predictor of clinical outcome in untreated individuals. SMN mRNA and protein are commonly measured in the blood or CSF of patients receiving SMA therapies, particularly those aimed at increasing SMN protein expression, and provide insight into current disease state. NFs have proven to be robust prognostic, disease progression, and pharmacodynamic markers for SMA infants undergoing treatment, but less so for adolescents and adults. Select plasma proteins are altered in SMA individuals and may track response to therapy. CK and Crn from blood correlate with motor function and disease severity status and are useful for predicting which individuals will respond to therapy. Electrophysiology measures comprise the most reliable means for monitoring motor function throughout disease course and are sensitive enough to detect neuromuscular changes before overt clinical manifestation, making them robust predictive and pharmacodynamic biomarkers. Finally, magnetic resonance imaging and muscle ultrasonography are non-invasive techniques for studying muscle structure and physiology and are useful diagnostic tools, but cannot reliably track disease progression. Importantly, biomarkers can provide information about the underlying mechanisms of disease as well as reveal subclinical disease progression, allowing for more appropriate timing and dosing of therapy for individuals with SMA. Recent therapeutic advancements in SMA have shown promising results, though there is still a great need to identify and understand the impact of biomarkers in modulating disease onset and progression.

Psychometric properties of the PEDI-CAT for children and youth with spinal muscular atrophy

PURPOSE

The purpose of this study was to examine the psychometric properties of the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT) in children and youth with Spinal Muscular Atrophy (SMA).

METHODS

In this prospective cross-sectional study, caregivers of children and youth with SMA completed the PEDI-CAT Daily Activities and Mobility domains. A subset of caregivers completed a questionnaire about the measure.

RESULTS

Mean ranks of scaled scores for Daily Activities (n = 96) and Mobility (n = 95) domains were significantly different across the three SMA types and across the three motor classifications. Normative scores indicated that 85 participants (89.5%) had limitations in Mobility and 51 in Daily Activities (53.1%). Floor effects were observed in≤10.4% of the sample for Daily Activities and Mobility. On average, caregivers completed the Mobility domain in 5.4 minutes and the Daily Activities domain in 3.3 minutes. Most caregivers reported that they provided meaningful information (92.1%), were willing to use the PEDI-CAT format again (79%), and suggested adding content including power wheelchair mobility items.

CONCLUSION

Convergent validity was demonstrated for the Daily Activities and Mobility domains. Normative scores detected limitations in Mobility and Daily Activity performance for most participants with SMA. The PEDI-CATwas feasible to administer and caregivers expressed willingness to complete the PEDI-CAT in the future.

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.

Maximum bite force in patients with spinal muscular atrophy during the first year of nusinersen therapy - A pilot study

Objectives

Spinal muscular atrophy is a monogenic disease characterized by progressive spinal and bulbar muscle weakness and atrophy. It is caused by the degeneration of alpha-motoneurons. The recent approval of the antisense oligonucleotide nusinersen highlights the need for reliable clinical tools to evaluate motor function in patients with neuromuscular disorders. Measurement of the bulbar neuromuscular function (e.g., bite force) could be an extension to existing motor scales, sensitive to more nuanced changes, especially in symptomatic patients with severely reduced functional abilities.

Materials and methods

Maximum bite force measurement was used to quantify changes of the masticatory function in adult monozygotic female twins with SMA type II. Using piezoelectric transducers, 550 observations were recorded for each patient during the first year of nusinersen therapy.

Results

During the application of four loading doses of nusinersen, bite force levels steadily increased and reached a statistically significantly higher level compared to the initial state in both patients. Subsequent maintenance doses coincided with smaller or no statistically significant changes in maximum bite force.

Conclusions

This pilot study indicates that the measurement of maximum bite force may be a useful tool to detect changes of the bulbar function in SMA patients. As such, it may supplement existing scales to identify treatment-related changes in motor function.

Functional outcome measures for infantile Charcot-Marie-Tooth disease: a systematic review

A functional outcome measure for infants (aged 0-3 years) with Charcot-Marie-Tooth (CMT) disease is needed for upcoming disease-modifying trials. A systematic review of outcome measures for infants with neuromuscular disorders was completed to determine if validated measures were available for the CMT infant population. We assessed 20,375 papers and identified seven functional outcome measures for infants with neuromuscular disorders. Six were developed and validated for spinal muscular atrophy (SMA). There were no CMT-specific outcome measures identified; however, one (motor function measure) assessed a range of neuromuscular disorders including 13 infants and children with CMT. The included studies exhibited "good" face, discriminant, convergent and concurrent validity, and reported excellent intra- and inter-rater reliability. No outcome measure was subjected to item response theory. Studies reported outcome measures comprising of 51 different items assessing six domains of function: reflexive movement, axial movement, limb movement, positioning, gross motor, and fine-motor skills. Scoring of items ranged from 2- to 7-point rating scales; and none were scaled to normative reference values to account for changes in growth and development. The SMA focus of most items is likely to produce ceiling effects and lack sensitivity and responsiveness for within and between types of CMT in infants. Nevertheless, several items across scales assessing distal strength, gross- and fine-motor function, could be included in the development of a composite functional outcome measure for infants with CMT to assess disease-modifying interventions.

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.

Natural history of infantile-onset spinal muscular atrophy

OBJECTIVE

Infantile-onset spinal muscular atrophy (SMA) is the most common genetic cause of infant mortality, typically resulting in death preceding age 2. Clinical trials in this population require an understanding of disease progression and identification of meaningful biomarkers to hasten therapeutic development and predict outcomes.

METHODS

A longitudinal, multicenter, prospective natural history study enrolled 26 SMA infants and 27 control infants aged <6 months. Recruitment occurred at 14 centers over 21 months within the NINDS-sponsored NeuroNEXT (National Network for Excellence in Neuroscience Clinical Trials) Network. Infant motor function scales (Test of Infant Motor Performance Screening Items [TIMPSI], The Children's Hospital of Philadelphia Infant Test for Neuromuscular Disorders, and Alberta Infant Motor Score) and putative physiological and molecular biomarkers were assessed preceding age 6 months and at 6, 9, 12, 18, and 24 months with progression, correlations between motor function and biomarkers, and hazard ratios analyzed.

RESULTS

Motor function scores (MFS) and compound muscle action potential (CMAP) decreased rapidly in SMA infants, whereas MFS in all healthy infants rapidly increased. Correlations were identified between TIMPSI and CMAP in SMA infants. TIMPSI at first study visit was associated with risk of combined endpoint of death or permanent invasive ventilation in SMA infants. Post-hoc analysis of survival to combined endpoint in SMA infants with 2 copies of SMN2 indicated a median age of 8 months at death (95% confidence interval, 6, 17).

INTERPRETATION

These data of SMA and control outcome measures delineates meaningful change in clinical trials in infantile-onset SMA. The power and utility of NeuroNEXT to provide "real-world," prospective natural history data sets to accelerate public and private drug development programs for rare disease is demonstrated. Ann Neurol 2017;82:883-891.

Clinical trial of L-Carnitine and valproic acid in spinal muscular atrophy type I

INTRODUCTION

The aim of this study was to determine the safety and therapeutic potential of L-carnitine and valproic acid (VPA) in infants with spinal muscular atrophy (SMA).

METHODS

Our investigation was an open-label phase 2 multicenter trial of L-carnitine and VPA in infants with SMA type I with retrospective comparison to an untreated, matched cohort. Primary outcomes were: safety and adverse events; secondary outcomes were survival, time to death/>16 hours/day of ventilator support; motor outcomes; and maximum ulnar compound motor action potential amplitude.

RESULTS

A total of 245 AEs were observed in 35 of the 37 treated subjects (95%). Respiratory events accounted for 49% of all adverse events, resulting in 14 deaths. Survival was not significantly different between treated and untreated cohorts.

DISCUSSION

This trial provides evidence that, in infants with SMA type I, L-carnitine/VPA is ineffective at altering survival. The substantial proportion of infants reaching end-points within 6 months of enrollment underscores the urgent need for pre-symptomatic treatment in SMA type I. Muscle Nerve 57: 193-199, 2018.

Developmental milestones in type I spinal muscular atrophy

The aim of this retrospective multicentric study was to assess developmental milestones longitudinally in type I SMA infants using the Hammersmith Infant Neurological Examination. Thirty-three type I SMA infants, who classically do not achieve the ability to sit unsupported, were included in the study. Our results confirmed that all patients had a score of 0 out of a scale of 4 on items assessing sitting, rolling, crawling, standing or walking. A score of more than 0 was only achieved in three items: head control (n = 13), kicking (n = 15) and hand grasp (n = 18). In these items, the maximal score achieved was 1 out of a scale of 4, indicating only partial achievement of the milestone. Infants with symptom onset after 6 months of age had longer preservation of a score of 1 when compared to those with onset before 6 months of age. Our results suggest that even when current standards of care are applied, developmental milestones are rarely even partially achieved as part of natural history in type I SMA infants. No infants in this study achieved a major milestone such as rolling over, or sitting independently, which would therefore represent robust outcomes in future interventional trials.

Test-retest reliability of the Test of Infant Motor Performance Screening Items in infants at risk for impaired functional motor performance

OBJECTIVE

To examine test-retest reliability of the TIMPSI in infants at risk for impaired functional motor performance.

METHODS

The TIMPSI was administered twice to 51 infants from two different hospitals in Norway.

RESULTS

The intra-class correlation coefficient was 0.99.

CONCLUSION

Test-retest reliability of the TIMPSI was excellent.

Baseline results of the NeuroNEXT spinal muscular atrophy infant biomarker study

OBJECTIVE

This study prospectively assessed putative promising biomarkers for use in assessing infants with spinal muscular atrophy (SMA).

METHODS

This prospective, multi-center natural history study targeted the enrollment of SMA infants and healthy control infants less than 6 months of age. Recruitment occurred at 14 centers within the NINDS National Network for Excellence in Neuroscience Clinical Trials (NeuroNEXT) Network. Infant motor function scales and putative electrophysiological, protein and molecular biomarkers were assessed at baseline and subsequent visits.

RESULTS

Enrollment began November, 2012 and ended September, 2014 with 26 SMA infants and 27 healthy infants enrolled. Baseline demographic characteristics of the SMA and control infant cohorts aligned well. Motor function as assessed by the Test for Infant Motor Performance Items (TIMPSI) and the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) revealed significant differences between the SMA and control infants at baseline. Ulnar compound muscle action potential amplitude (CMAP) in SMA infants (1.4 ± 2.2 mV) was significantly reduced compared to controls (5.5 ± 2.0 mV). Electrical impedance myography (EIM) high-frequency reactance slope (Ohms/MHz) was significantly higher in SMA infants than controls SMA infants had lower survival motor neuron (SMN) mRNA levels in blood than controls, and several serum protein analytes were altered between cohorts.

INTERPRETATION

By the time infants were recruited and presented for the baseline visit, SMA infants had reduced motor function compared to controls. Ulnar CMAP, EIM, blood SMN mRNA levels, and serum protein analytes were able to distinguish between cohorts at the enrollment visit.