Adiposity is increased among high-functioning, non-ambulatory patients with spinal muscular atrophy

Metabolic syndrome is common in adults with 5q-spinal muscular atrophy and impacts quality of life and fatigue

INTRODUCTION/AIMS

Spinal muscular atrophy (SMA) is a multisystem disorder. We assessed metabolic syndrome (MetS) prevalence in adults with SMA and its association with motor function, quality of life (QoL), fatigue, and depression.

METHODS

MetS was diagnosed using 2009 consensus criteria. Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), Fatigue Severity Scale (FSS), Beck Depression Inventory (BDI), and 36-Item Short Form Health Survey (SF-36) were recorded and correlations between muscle function, depression, fatigue, QoL, and MetS were analyzed.

RESULTS

We included 36 individuals (18 males; mean age: 38.7 ± 14.6 years). MetS was present in 25.0%. The most common component of MetS was central obesity (69.7%). Nearly half of the SMA individuals exhibited at least one abnormal lipid level result. Individuals with MetS more frequently were SMA type 3 (77.8% vs. 37.0%, p = .02) and had higher levels of fatigue (48.4 ± 6.7 vs. 39.5 ± 11.6, p = .03) than those without MetS. No associations of the presence of MetS with ambulatory status or HFMSE/RULM scores were observed. SMA individuals with MetS scored significantly lower in mental and social domains of QoL and total SF-36 score (p = .04). We observed weak to moderate correlations between the presence of MetS and SMA type, presence of comorbidities, QoL, and fatigue.

DISCUSSION

The frequency of MetS was modestly higher among adults with SMA than in the general population, particularly in SMA type 3. MetS was associated with reduced QoL and increased fatigue. Larger studies are needed to fully understand the significance of MetS in adults with SMA.

Serum leptin levels in children and adolescents with spinal muscular atrophy types 2 and 3✰

AIM

It has been reported that in patients with spinal muscular atrophy (SMA), lower levels of motor function are associated with hyperleptinemia. Additionally, hyperleptinemia has been found to be more frequent in underweight SMA patients. Therefore, we aimed to analyze serum leptin levels in patients with SMA.

METHOD

This was a cross-sectional study of pediatric patients (2-19 years old) with SMA types 2 and 3. The investigations included anthropometric measurements, assessment of pubertal status, motor function evaluation using the Hammersmith Functional Motor Scale - Expanded (HFMSE), and serum leptin levels.

RESULTS

In total, 37 patients (22 with type 2 and 15 with type 3 SMA) were included in the study. The male-to-female ratio was 1:1.3 and 62.2% of patients were prepubertal. No statistically significant correlation was found between the HFMSE score and leptin levels, r_s(35) = 0.24, p = 0.15. There was, however, a strong positive relationship between the body mass index (BMI) z-score and leptin levels, r_s(35) = 0.87, p < 0.001.

CONCLUSION

Serum leptin levels do not seem to be a useful marker of disease severity in children and adolescents with types 2 and 3 SMA. As in the general pediatric population, leptin levels are strongly correlated with BMI, which is a surrogate measure of body fat.

Distribution of weight, stature, and growth status in children and adolescents with spinal muscular atrophy: An observational retrospective study in the United States

Introduction/Aims

Data regarding weight, height/length, and growth status of patients with spinal muscular atrophy (SMA) who have received only supportive care are limited. This cross‐sectional study describes these measurements in patients with Type 1 and Types 2/3 SMA and compares them with reference values from typically developing children.

Methods

Retrospective baseline data from three sites in the Pediatric Neuromuscular Clinical Research Network (Boston, New York, Philadelphia) were used. Descriptive statistics for weight, height/length, body mass index‐for‐age, as well as weight‐for‐length and absolute and relative deviations from reference values (ie, 50th percentile from World Health Organization/Centers for Disease Control growth charts) were calculated. Furthermore, growth status was reported.

Results

A total of 91 genetically confirmed patients with SMA receiving optimal supportive care and without any disease‐modifying treatment were stratified into Types 1 (n = 28) and 2/3 SMA (n = 63). Patients with Type 1 SMA weighed significantly less (median = −7.5%) compared with reference values and patients with Types 2/3 SMA were significantly shorter (mean = −3.0%) compared with reference values. The median weight was considerably below the 50th percentile in both groups of patients, even if they received a high standard of care and proactive feeding support.

Discussion

More research is needed to understand which factors influence growth longitudinally, and how to accurately capture growth in patients with SMA. Further research should investigate the best time to provide feeding support to avoid underweight, especially in patients with Type 1, and how to avoid the risk of overfeeding, especially in patients with Types 2/3 SMA.

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.

Body mass index in type 2 spinal muscular atrophy: a longitudinal study

The aim of this retrospective study was to review body mass index (BMI) in a large cohort of Italian pediatric type 2 spinal muscular atrophy (SMA) patients, aged between 0 and 20 years and to establish possible differences in relation to a number of variables such as ventilation, motor function, and survival motor neuron 2 gene copies. Cross-sectional data were collected from 102 patients for a total of 344 visits. Standard growth charts for height and weight were used as reference, with age adjusted BMI calculated using the Center for Disease and Prevention Children's BMI Tool. In the 344 visits, weight ranged between 3.90 and 83 kg, and the BMI between 8.4 and 31.6 with a BMI/age z-scores <  - 2SD present in 28% and BMI/age z-scores >  + 2SD in 9% of the measurements. The BMI/age z-scores were relatively stable < 5 years of age with an increasing number of patients <  - 2SD after the age of 5, and a wider range of BMI/age z-scores after the age of 13. A difference on the BMI/age z-scores was found among the different age subgroups (< 5, 5-12, ≥ 13 years). A multivariate analysis in 58 patients with longitudinal assessments showed that baseline BMI/age z-scores and gender were significantly contributing to the changes while other variables were not.

CONCLUSION

Our results confirm that careful surveillance of weight and BMI/age z-scores is needed in type 2 SMA. Further studies, including assessments of chewing and swallowing and of lean/fat body mass, will help to better understand the possible mechanisms underlying weight issues.

WHAT IS KNOWN

• Feeding difficulties have been reported in a few studies and were invariably found in patients with type 1 SMA. • Type 2 SMA patients often have low BMI with a relevant number of patients requiring tube feeding.

WHAT IS NEW

• Reduction in BMI/age z-score overtime appeared to depend on baseline BMI/age z-score and gender. • Patients with a low BMI/age z-score were at higher risk of developing further reduction.

Prolonged fasting-induced hyperketosis, hypoglycaemia and impaired fat oxidation in child and adult patients with spinal muscular atrophy type II

AIM

This study explored hypoglycaemia and metabolic crises, including hyperketosis, in patients with spinal muscular atrophy (SMA).

METHODS

The study comprised four adolescents aged 15-17 and six adults aged 19-37 with SMA type II and eight adult controls aged 21-41, who were recruited by the Rigshospitalet, Denmark, from May 1st to October 30th 2017. We used stable isotope technique and indirect calorimetry to investigate fat and glucose metabolism during a 24-h fast or until hypoglycaemia occurred.

RESULTS

All patients with SMA II developed moderate to severe hyperketosis and 60% had symptoms of hypoglycaemia or blood glucose levels below 3 mmol/L. None of the controls developed hyperketosis or hypoglycaemia. Plasma bicarbonate decreased, in line with increased ketone bodies, indicating the start of metabolic acidosis in patients with SMA II. Increased fat production and utilisation were seen in healthy controls during the fasting period, but were absent in patients with SMA II, indicating blunted fat oxidation.

CONCLUSION

Low skeletal muscle mass was the best explanation for why patients with SMA II had an increased risk of hypoglycaemia, hyperketosis, metabolic acidosis and disturbed fat and glucose metabolism during fasting. These risks have implications for children facing surgery and those with severe illnesses.

Association Between Body Mass Index and Disability in Children With Charcot-Marie-Tooth Disease

BACKGROUND AND OBJECTIVES

This study examined the association between body mass index (BMI) and disability in children with Charcot-Marie-Tooth disease (CMT).

METHODS

We conducted a cross-sectional analysis of 477 patients with CMT who were 3 to 20 years of age from the Inherited Neuropathy Consortium and 316 age- and sex-matched healthy children from the 1,000 Norms Project. BMI was categorized according to the International Obesity Task Force (IOTF) criteria, and BMI categorization was compared with healthy children. IOTF categories (adult equivalent BMI cut points) were severely underweight (BMI <17 kg/m2), underweight (BMI ≥17-<18.5 kg/m2), healthy weight (BMI ≥18.5-<25 kg/m2), overweight (BMI ≥25-<30 kg/m2), and obese (BMI ≥30 kg/m2). Scores on the 0 to 44-point CMT Pediatric Scale (CMTPedS), a well-validated measure of disability, were examined in relation to BMI.

RESULTS

There was a higher proportion of children with CMT categorized as severely underweight (5.7% vs 0.3%), underweight (10.3% vs 5.1%), and obese (7.3% vs 3.8%) (p < 0.05). Fewer children with CMT were categorized as healthy weight (61.8% vs 74.4%) (p < 0.05), and the proportion of overweight (14.9% vs 16.5%) between groups was similar. CMTPedS scores (mean ± SD) for weight categories were as follows: severely underweight 27 ± 9, underweight 20 ± 8, healthy weight 17 ± 9, overweight 17 ± 9, and obese 22 ± 10. Compared to children with a healthy weight with CMT, being severely underweight was associated with being more disabled (p < 0.001), as was being obese (p = 0.015).

DISCUSSION

The proportion of children with CMT who are underweight or obese is higher compared to age- and sex-matched healthy children. In children with CMT, being underweight or obese is associated with greater disability, when compared to children with CMT of healthy weight.

Growth patterns in children with spinal muscular atrophy

Background

Spinal muscular atrophy (SMA) is a neuromuscular disorder characterized by muscle atrophy and weakness. SMA type 1 (SMA1) is the most severe form: affected infants are unable to sit unaided; SMA type 2 (SMA2) children can sit, but are not able to walk independently. The Standards of Care has improved quality of life and the increasing availability of disease-modifying treatments is progressively changing the natural history; so, the clinical assessment of nutritional status has become even more crucial. Aims of this multicenter study were to present the growth pattern of treatment-naïve SMA1 and SMA2, and to compare it with the general growth standards.

Results

Body Weight (BW, kg) and Supine Length (SL, cm) were collected using a published standardized procedure. SMA-specific growth percentiles curves were developed and compared to the WHO reference data. We recruited 133 SMA1 and 82 SMA2 (48.8% females). Mean ages were 0.6 (0.4–1.6) and 4.1 (2.1–6.7) years, respectively. We present here a set of disease-specific percentiles curves of BW, SL, and BMI-for-age for girls and boys with SMA1 and SMA2. These curves show that BW is significantly lower in SMA than healthy peers, while SL is more variable. BMI is also typically lower in both sexes and at all ages.

Conclusions

These data on treatment-naïve patients point toward a better understanding of growth in SMA and could be useful to improve the clinical management and to assess the efficacy of the available and forthcoming therapies not only on motor function, but also on growth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02015-9.

Nutritional, Gastrointestinal and Endo-Metabolic Challenges in the Management of Children with Spinal Muscular Atrophy Type 1

The management of patients with spinal muscular atrophy type 1 (SMA1) is constantly evolving. In just a few decades, the medical approach has switched from an exclusively palliative therapy to a targeted therapy, transforming the natural history of the disease, improving survival time and quality of life and creating new challenges and goals. Many nutritional problems, gastrointestinal disorders and metabolic and endocrine alterations are commonly identified in patients affected by SMA1 during childhood and adolescence. For this reason, a proper pediatric multidisciplinary approach is then required in the clinical care of these patients, with a specific focus on the prevention of most common complications. The purpose of this narrative review is to provide the clinician with a practical and usable tool about SMA1 patients care, through a comprehensive insight into the nutritional, gastroenterological, metabolic and endocrine management of SMA1. Considering the possible horizons opened thanks to new therapeutic frontiers, a nutritional and endo-metabolic surveillance is a crucial element to be considered for a proper clinical care of these patients.

Predictive fat mass equations for spinal muscular atrophy type I children: Development and internal validation

BACKGROUND

Body composition assessment is paramount for spinal muscular atrophy type I (SMA I) patients, as weight and BMI have proven to be misleading for these patients. Despite its importance, no disease-specific field method is currently available, and the assessment of body composition of SMA I patients requires reference methods available only in specialized settings.

OBJECTIVE

To develop predictive fat mass equations for SMA I children based on simple measurements, and compare existing equations to the new disease-specific equations.

DESIGN

Demographic, clinical and anthropometric data were examined as potential predictors of the best candidate response variable and non-linear relations were taken into account by transforming continuous predictors with restricted cubic splines. Alternative models were fitted including all the dimensions revealed by cluster analysis of the predictors. The best models were then internally validated, quantifying optimism of the obtained performance measures. The contribution of nusinersen treatment to the unexplained variability of the final models was also tested.

RESULTS

A total of 153 SMA I patients were included in the study, as part of a longitudinal observational study in SMA children conducted at the International Center for the Assessment of Nutritional Status (ICANS), University of Milan. The sample equally represented both sexes (56% females) and a wide age range (from 3 months to 12 years, median 1.2 years). Four alternative models performed equally in predicting fat mass fraction (fat mass/body weight). The most convenient was selected and further presented. The selected model uses as predictors sex, age, calf circumference and the sum of triceps, suprailiac and calf skinfold thicknesses. The model showed high predictive ability (optimism corrected coefficient of determination, R² = 0.72) and internal validation indicated little optimism both in performance measures and model calibration. The addition of nusinersen as a predictor variable did not improve the prediction. The disease-specific equation was more accurate than the available fat mass equations.

CONCLUSIONS

The developed prediction model allows the assessment of body composition in SMA I children with simple and widely available measures and with reasonable accuracy.

Glucose and lipid metabolism disorders in children and adolescents with spinal muscular atrophy types 2 and 3

We aimed to estimate the prevalence of glucose and lipid metabolism disorders in children and adolescents with spinal muscular atrophy (SMA) types 2 and 3. A cross-sectional study was conducted. Medical history, anthropometric measurements, pubertal status, blood chemistry (glucose and insulin levels, lipid profile, aminotransferases, and hemoglobin A1c [HbA1c]), and liver ultrasound were obtained in all patients. Oral glucose tolerance test was performed in those with body mass index (BMI) >25th percentile or glucose or HbA1c levels in the prediabetic range. A total of 37 patients with SMA (22 type 2, 15 type 3) with a median age of 8.5 years (range 2-18.9 years) were included. Eleven patients (29.7%) met the criteria for prediabetes, but none had overt type 2 diabetes. Dyslipidemia was detected in 11 patients (29.7%), and 4 (10.8%) had hepatic steatosis on ultrasound. Sixteen patients (43.2%) had at least one abnormal finding (prediabetes, dyslipidemia, or hepatic steatosis); all but one were non-ambulatory and 12 (75%) had BMI ≥85th percentile. One young child developed fasting hypoglycemia. Our results suggest that non-ambulatory overweight/obese SMA patients are particularly prone to abnormalities in glucose and lipid metabolism. Young underweight patients might develop fasting hypoglycemia.

Nutrition status survey of type 2 and 3 spinal muscular atrophy in Chinese population

OBJECTIVE

To evaluate the nutritional status of children with SMA types II and III in a Chinese population.

METHODS

We performed a retrospective medical record review of prospectively collected data from children with SMA types II and III in a single centre. We analysed data including clinical parameters, anthropometrics, and 24-hour dietary intake records in our clinic.

RESULTS

We analysed the anthropometric data from 86 children with 69 (80%) SMAII and 17 (20%) SMAIII; 47 (55%) were female, mean age was 5.22 ± 3.73 years. The WAZ of the SMAII (n = 69) and SMAIII (n = 17) were -0.48 (IQR -1.69, 0.57) vs -0.53 (IQR -1.60, 0.55), P = 0.926; the HAZ were -0.62 (IQR -1.4, 0.3) vs -0.6 (IQR -1.61, 0.4), P=0.72; the BMIZ were -0.51 (IQR -1.53, 0.99) vs -0.08 (IQR -1.625, 1.125), P = 0.537.The dietary intake of 51 children was compared to the Chinese Dietary Reference Intakes (DRIs). The actual energy intake in SMAII was similar to the DRIs, but which in SMAIII was less than the DRIs (1312.4 ± 329.5 kcal vs. 1655 ± 640.1 kcal, P = 0.028). The protein intake in SMAII and SMAIII was higher than the DRIs (55 ± 16.3 g/d vs 30.2 ± 4.6 g/d, P < 0.05; 56.8 ± 18.1 g/d vs 41.5 ± 17.5 g/d, p = 0.22), and calcium intake was lower than the recommendation (507.7 ± 177.8 mg/d vs 731.7 ± 123.4 mg/d, P < 0.05; 478.4 ± 207.4 mg/d vs 478.4 ± 207.4 mg/d, P = 0.01). Swallowing on the Neuromuscular Disease Status Scale was 7.41 ± 0.5.

CONCLUSIONS

Children with SMAII and SMAIII were at risk for malnutrition and low calcium intake.

Feeding difficulties in children and adolescents with spinal muscular atrophy type 2

Disease course of feeding difficulties in spinal muscular atrophy type 2 is not well documented. Disease-modifying therapies rapidly change the trajectory of motor function and survival in spinal muscular atrophy, but effects on co-morbidities like bulbar function are unknown. We analysed data concerning feeding problems and their standard of care treatment in 146 patients with spinal muscular atrophy type 2. Data were collected from two separate cohorts: one single-centre retrospective chart review study from the United Kingdom (London), and one prospective questionnaire-based multicentre study from Italy. Cumulatively feeding difficulties were present in 88 patients (60%) in these 2 cohorts. Median age at onset of problems was 6.5years (range 0-16.5 years). Eighty-two patients (60%) showed periods of underweight according to age adjusted body mass index, and thirty-six patients (25%) showed malnourishment with a significant drop on their weight curves. Enteral feeding was indicated in 23 out of 72 patients in the UK cohort (32%) because of weight loss, oropharyngeal dysphagia or aspiration. Gastrostomy and its placement was generally well tolerated, uncomplicated in 96%, never reversed and performed without Nissen fundoplication in 66% of patients. After gastrostomy chest infections improved in 80% and nutritional status (e.g., Body Mass Index) in 84% of patients. These results show that feeding difficulties are a common problem in spinal muscular atrophy type 2. Treatment strategies should be tailor-made on the symptoms and needs of the individual patient.

Nutritional practices in pediatric patients with neuromuscular disorders

Children with neuromuscular disorders (NMDs) may experience a spectrum of nutritional issues with adverse health consequences. This review summarizes the current understanding of nutritional care in pediatric NMDs, recognizing disease-specific aspects of nutrition alongside the challenges and needs in dietetic care. General or disease-related nutritional issues for children with NMDs include being underweight, overweight, or obese and having swallowing difficulty, gastroesophageal reflux, diarrhea, and/or constipation. Specific challenges in NMD nutritional assessment include alterations in body composition and energy requirements and difficulties in measuring anthropometry. Multidisciplinary dietetic intervention focuses on optimizing nutrient intakes to avert growth failure or obesity and managing feeding difficulties and gastrointestinal problems. Care guidelines are disease specific and vary in approach and detail. To promote best clinical practice across diverse settings, a standardized approach to assessing growth and nutrition across all pediatric NMDs is needed to direct optimal care centered on individual requirements. Future studies should focus on determining the prevalence of specific nutritional issues and the effectiveness of specific interventions among various pediatric NMD populations.

Predictive energy equations for spinal muscular atrophy type I children

BACKGROUND

Knowledge on resting energy expenditure (REE) in spinal muscular atrophy type I (SMAI) is still limited. The lack of a population-specific REE equation has led to poor nutritional support and impairment of nutritional status.

OBJECTIVE

To identify the best predictors of measured REE (mREE) among simple bedside parameters, to include these predictors in population-specific equations, and to compare such models with the common predictive equations.

METHODS

Demographic, clinical, anthropometric, and treatment variables were examined as potential predictors of mREE by indirect calorimetry (IC) in 122 SMAI children consecutively enrolled in an ongoing longitudinal observational study. Parameters predicting REE were identified, and prespecified linear regression models adjusted for nusinersen treatment (discrete: 0 = no; 1 = yes) were used to develop predictive equations, separately in spontaneously breathing and mechanically ventilated patients.

RESULTS

In naïve patients, the median (25th, 75th percentile) mREE was 480 (412, 575) compared with 394 (281, 554) kcal/d in spontaneously breathing and mechanically ventilated patients, respectively (P = 0.009).In nusinersen-treated patients, the median (25th, 75th percentile) mREE was 609 (592, 702) compared with 639 (479, 723) kcal/d in spontaneously breathing and mechanically ventilated patients, respectively (P = 0.949).Both in spontaneously breathing and mechanically ventilated patients, the best prediction of REE was obtained from 3 models, all using as predictors: 1 body size related measurement and nusinersen treatment status. Nusinersen treatment was correlated with higher REE both in spontaneously breathing and mechanically ventilated patients. The population-specific equations showed a lower interindividual variability of the bias than the other equation tested, however, they showed a high root mean squared error.

CONCLUSIONS

We demonstrated that ventilatory status, nusinersen treatment, demographic, and anthropometric characteristics determine energy requirements in SMAI. Our SMAI-specific equations include variables available in clinical practice and were generally more accurate than previously published equations. At the individual level, however, IC is strongly recommended for assessing energy requirements. Further research is needed to externally validate these predictive equations.

Health, wellbeing and lived experiences of adults with SMA: a scoping systematic review

BACKGROUND

Spinal muscular atrophy (SMA) is a neurodegenerative disease that has a substantial and multifaceted burden on affected adults. While advances in supportive care and therapies are rapidly reshaping the therapeutic environment, these efforts have largely centered on pediatric populations. Understanding the natural history, care pathways, and patient-reported outcomes associated with SMA in adulthood is critical to advancing health policy, practice and research across the disease spectrum. The aim of this study was to systematically review research investigating the healthcare, well-being and lived experiences of adults with SMA.

METHODS

In accordance with the Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines, seven electronic databases were systematically searched until January 2020 for studies examining clinical (physical health, natural history, treatment) and patient-reported (symptoms, physical function, mental health, quality of life, lived experiences) outcomes in adults with SMA. Study risk of bias and the level of evidence were assessed using validated tools.

RESULTS

Ninety-five articles met eligibility criteria with clinical and methodological diversity observed across studies. A heterogeneous clinical spectrum with variability in natural history was evident in adults, yet slow declines in motor function were reported when observational periods extended beyond 2 years. There remains no high quality evidence of an efficacious drug treatment for adults. Limitations in mobility and daily activities associated with deteriorating physical health were commonly reported, alongside emotional difficulties, fatigue and a perceived lack of societal support, however there was no evidence regarding effective interventions.

CONCLUSIONS

This systematic review identifies the many uncertainties regarding best clinical practice, treatment response, and long-term outcomes for adults with SMA. This comprehensive identification of the current gaps in knowledge is essential to guide future clinical research, best practice care, and advance health policy with the ultimate aim of reducing the burden associated with adult SMA.

Evaluation of body composition as a potential biomarker in spinal muscular atrophy

INTRODUCTION

We aimed to investigate the correlation between body composition (BC) and spinal muscular atrophy (SMA)-specific motor function assessments.

METHODS

Patients with SMA types I or II, aged 1 to 10 years, were recruited in this cross-sectional study. The protocol included anthropometric measurements, and dual-energy X-ray absoprtiometry to assess fat mass (FM), lean mass (LM), fat-free mass (FFM), FM and FFM indexes (FMI, FFMI), and motor function assessments (Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders scale for SMAI, and Hammersmith Functional Motor Scale-Expanded for SMAII).

RESULTS

Eighty-eight children were included. All had a higher FM percentage than reference values. Motor function was moderately correlated with body mass index (BMI), FFMI, and LMI in SMAI, and weakly correlated with FFMI, LMI, and LM:FM ratio in SMAII.

DISCUSSION

BC shows promise as a potential biomarker for SMA, but further studies are needed.

Comprehensive nutritional and metabolic assessment in patients with spinal muscular atrophy: Opportunity for an individualized approach

Optimal nutrition support is recommended for patients with spinal muscular atrophy (SMA). In a prospective study, we performed comprehensive nutritional assessments with the aim to guide best nutritional strategies for patients with SMA types II and III. We recorded a) anthropometry; b) macro- and micronutrient intakes; c) measured resting energy expenditure by indirect calorimetry; and d) body composition including dual X-ray absorptiometry. We enrolled a cohort of 21 patients aged 3 to 36 years of which 13 were female; 19 had SMA type II and 2 had SMA type III. The body mass index z-score ranged from -3 to 2.4. Forty-five percent of the cohort was either underfed or overfed, based on the difference between actual energy intake and measured resting energy expenditure. Vitamin D, E, K, folate and calcium intakes were low in a majority of the cohort. Forty-five percent of the cohort was either hypometabolic or hypermetabolic. Fat mass index (kg/m²) was significantly higher and lean body mass index (kg/m²) was significantly lower in the study cohort compared to population normalized values. Bone mineral density was low in 13 of 17 patients. In summary, we have described the prevalence of malnutrition, suboptimal feeding and alterations in body composition in children with SMA. A comprehensive nutritional assessment could guide individualized nutrition therapy in this vulnerable population.

Spinal Muscular Atrophy, types I and II: What are the differences in body composition and resting energy expenditure?

Background & aims

Different neuromuscular functional domains in types I and II Spinal Muscular Atrophy (SMAI and SMAII) could lead to differences in body composition (BC) and resting energy expenditure (REE). Their identification could provide the key to defining appropriate strategies in clinical dietary management, but data comparing SMAI and SMAII in terms of BC and REE are not yet available. We measured total and regional fat (FM), lean (LBM), mineral (BMC) masses, body water (total, intra- and extra-cellular, TBW, ICW, ECW) and REE in a sample of SMAI and II children, matched for age and sex, and also adjusting for body size to compare these features of the two SMA phenotypes.

Methods

15 SMAI and 15 SMAII children, (M/F = 9/6 vs 9/6, age 3.6 ± 1.9 vs 3.5 ± 1.8 years, p = 0.99), confirmed genetically, were measured as follows: Anthropometric measurements [Body Weight (BW), Supine Length (SL), Arm Length (AL), Femur Length (FL), Tibia Length (TL)], Dual x-ray Energy Absorptiometry (DEXA) [total and segmental FM, LBM, FFM, and BMC], Bioelectrical impedance (BIA) [TBW, ICW, ECW] and Indirect Calorimetry (REE, respiratory quotients) were collected by the same trained dietician. BW, SL and Body Mass Index (BMI) Z-scores were calculated according to CDC Growth Charts (2000).

Results

SMA children had high percentages of FM and a lower percentage of TBW and ECW compared to the respective reference values for sex and age, whereas the BMC percentages did not differ, even splitting the two phenotypes. SMA I children had a lower BW and BMI-Z score compared to children with SMA II, but similar total and segmental FM. On the contrary, total FFM and LBM were significantly lower in SMAI (7290.0 ± 1729.1 g vs 8410.1 ± 1508.4 g; 6971.8 ± 1637.1 g vs 8041.7 ± 1427.7 g, p = 0.039, p = 0.037, respectively), particularly at the trunk level. Arm BMC also resulted significantly lower in SMAI. The measured REE values were similar (684 ± 143 kcal/day vs 703 ± 122 Kcal/day p = 0.707) whereas REE per FFM unit was higher in SMA I children than in SMA II (95 ± 12 kcal/FFMkg vs 84 ± 11 kcal/FFMkg p = 0.017).

Conclusions

This study has shown that BW and BMI Z-score measurements alone can be misleading in assessing nutritional status, particularly in SMAI. The differences between SMAI and II in total and regional BC are related only to FFM, LBM and BMC, and seem to be more linked to the magnitude of neurofunctional impairment rather than to the nutritional status derangement. SMA I and SMA II children can have different energy requirements in relation to their specific BC and hypermetabolism of FFM. Based on these results, our recommendation is to use direct BC and REE measurements in the nutritional care process until SMA-specific predictive equations become available.

Spinal Muscular Atrophy

Spinal muscular atrophy is an autosomal-recessive disorder characterized by degeneration of motor neurons in the spinal cord and caused by mutations in the survival motor neuron 1 gene, SMN1. The severity of SMA is variable. The SMN2 gene produces a fraction of the SMN messenger RNA (mRNA) transcript produced by the SMN1 gene. There is an inverse correlation between SMN2 gene copy number and clinical severity. Clinical management focuses on multidisciplinary care. Preclinical models of SMA have led to an explosion of SMA clinical trials that hold great promise of effective therapy in the future.

Describing nutrition in spinal muscular atrophy: A systematic review

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease of variable severity. Progressive muscle wasting and impairment in functional ability in SMA have a profound influence on nutritional outcomes. This systematic review summarises the existing evidence on nutrition in SMA. The search strategy was conducted across five databases in August 2014, and updated in March 2016, using key terms relating to growth, nutrition requirements, dietary intake and nutrition management. Studies were selected for inclusion using a two pass method, and data systematically extracted using standardised forms. Thirty-nine studies met eligibility criteria. Body composition is abnormal in patients with SMA, and feeding and swallowing issues are prevalent among sufferers of SMA types I and II. Nutritional management practices vary internationally. There is a paucity of literature regarding nutrition requirements in SMA, although it appears that energy expenditure may be reduced. Children with SMA require individualised nutritional management in order to address their growth and nutrition requirements. There is an urgent need for larger, coordinated, prospective intervention studies of nutrition in SMA.

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.

Spinal muscular atrophies

Spinal muscular atrophies (SMAs) are hereditary degenerative disorders of lower motor neurons associated with progressive muscle weakness and atrophy. Proximal 5q SMA is caused by decreased levels of the survival of motor neuron (SMN) protein and is the most common genetic cause of infant mortality. Its inheritance pattern is autosomal recessive, resulting from mutations involving the SMN1 gene on chromosome 5q13. Unlike other autosomal recessive diseases, the SMN gene has a unique structure (an inverted duplication) that presents potential therapeutic targets. Although there is currently no effective treatment of SMA, the field of translational research in this disorder is active and clinical trials are ongoing. Advances in the multidisciplinary supportive care of children with SMA also offer hope for improved life expectancy and quality of life.

SMA valiant trial: a prospective, double-blind, placebo-controlled trial of valproic acid in ambulatory adults with spinal muscular atrophy

INTRODUCTION

An open-label trial suggested that valproic acid (VPA) improved strength in adults with spinal muscular atrophy (SMA). We report a 12-month, double-blind, cross-over study of VPA in ambulatory SMA adults.

METHODS

There were 33 subjects, aged 20–55 years, included in this investigation. After baseline assessment, subjects were randomized to receive VPA (10–20 mg/kg/day) or placebo. At 6 months, patients were switched to the other group. Assessments were performed at 3, 6, and 12 months. The primary outcome was the 6-month change in maximum voluntary isometric contraction testing with pulmonary, electrophysiological, and functional secondary outcomes.

RESULTS

Thirty subjects completed the study. VPA was well tolerated, and compliance was good. There was no change in primary or secondary outcomes at 6 or 12 months.

CONCLUSIONS

VPA did not improve strength or function in SMA adults. The outcomes used are feasible and reliable and can be employed in future trials in SMA adults.

[Respiratory treatments in neuromuscular disease]

In a previous article, a review was presented of the respiratory pathophysiology of the patient with neuromuscular disease, as well as their clinical evaluation and the major complications causing pulmonary deterioration. This article presents the respiratory treatments required to preserve lung function in neuromuscular disease as long as possible, as well as in special situations (respiratory infections, spinal curvature surgery, etc.). Special emphasis is made on the use of non-invasive ventilation, which is changing the natural history of many of these diseases. The increase in survival and life expectancy of these children means that they can continue their clinical care in adult units. The transition from pediatric care must be an active, timely and progressive process. It may be slightly stressful for the patient before the adaptation to this new environment, with multidisciplinary care always being maintained.

Neurodegeneration in spinal muscular atrophy: from disease phenotype and animal models to therapeutic strategies and beyond

Of the numerous inherited diseases known to afflict the pediatric population, spinal muscular atrophy (SMA) is among the most common. It has an incidence of approximately one in 10,000 newborns and a carrier frequency of one in 50. Despite its relatively high incidence, SMA remains somewhat obscure among the many neurodegenerative diseases that affect humans. Nevertheless, the last two decades have witnessed remarkable progress in our understanding of the pathology, underlying biology and especially the molecular genetics of SMA. This has led to a genuine expectation within the scientific community that a robust treatment will be available to patients before the end of the decade. The progress made in our understanding of SMA and, therefore, towards a viable therapy for affected individuals is in large measure a consequence of the simple yet fascinating genetics of the disease. Nevertheless, important questions remain. Addressing these questions promises not only to accelerate the march towards a cure for SMA, but also to uncover novel therapies for related neurodegenerative disorders. This review discusses our current understanding of SMA, considers the challenges ahead, describes existing treatment options and highlights state-of-the-art research being conducted as a means to a better, safer and more effective treatment for the disease.

Proximal spinal muscular atrophy: current orthopedic perspective

Spinal muscular atrophy (SMA) is a hereditary neuromuscular disease of lower motor neurons that is caused by a defective “survival motor neuron” (SMN) protein that is mainly associated with proximal progressive muscle weakness and atrophy. Although SMA involves a wide range of disease severity and a high mortality and morbidity rate, recent advances in multidisciplinary supportive care have enhanced quality of life and life expectancy. Active research for possible treatment options has become possible since the disease-causing gene defect was identified in 1995. Nevertheless, a causal therapy is not available at present, and therapeutic management of SMA remains challenging; the prolonged survival is increasing, especially orthopedic, respiratory and nutritive problems. This review focuses on orthopedic management of the disease, with discussion of key aspects that include scoliosis, muscular contractures, hip joint disorders, fractures, technical devices, and a comparative approach of conservative and surgical treatment. Also emphasized are associated complications including respiratory involvement, perioperative care and anesthesia, nutrition problems, and rehabilitation. The SMA disease course can be greatly improved with adequate therapy with established orthopedic procedures in a multidisciplinary therapeutic approach.

SMA-MAP: a plasma protein panel for spinal muscular atrophy

Objectives

Spinal Muscular Atrophy (SMA) presents challenges in (i) monitoring disease activity and predicting progression, (ii) designing trials that allow rapid assessment of candidate therapies, and (iii) understanding molecular causes and consequences of the disease. Validated biomarkers of SMA motor and non-motor function would offer utility in addressing these challenges. Our objectives were (i) to discover additional markers from the Biomarkers for SMA (BforSMA) study using an immunoassay platform, and (ii) to validate the putative biomarkers in an independent cohort of SMA patients collected from a multi-site natural history study (NHS).

Methods

BforSMA study plasma samples (N = 129) were analyzed by immunoassay to identify new analytes correlating to SMA motor function. These immunoassays included the strongest candidate biomarkers identified previously by chromatography. We selected 35 biomarkers to validate in an independent cohort SMA type 1, 2, and 3 samples (N = 158) from an SMA NHS. The putative biomarkers were tested for association to multiple motor scales and to pulmonary function, neurophysiology, strength, and quality of life measures. We implemented a Tobit model to predict SMA motor function scores.

Results

12 of the 35 putative SMA biomarkers were significantly associated (p<0.05) with motor function, with a 13^th analyte being nearly significant. Several other analytes associated with non-motor SMA outcome measures. From these 35 biomarkers, 27 analytes were selected for inclusion in a commercial panel (SMA-MAP) for association with motor and other functional measures.

Conclusions

Discovery and validation using independent cohorts yielded a set of SMA biomarkers significantly associated with motor function and other measures of SMA disease activity. A commercial SMA-MAP biomarker panel was generated for further testing in other SMA collections and interventional trials. Future work includes evaluating the panel in other neuromuscular diseases, for pharmacodynamic responsiveness to experimental SMA therapies, and for predicting functional changes over time in SMA patients.

Age at disease onset predicts likelihood and rapidity of growth failure among infants and young children with spinal muscular atrophy types 1 and 2

Growth failure is nearly universal in spinal muscular atrophy type 1 and common in type 2, although acuity is often underappreciated at initial diagnosis. We reviewed 44 consecutive spinal muscular atrophy patients (28 type 1, 16 type 2) under 3 years at initial presentation. Growth failure was conventionally defined: weight below the fifth percentile or dropping 2 major percentiles over 6 months. Growth failure differed among subjects stratified by age at disease onset using the Kaplan-Meier method (P = 0.011). Median time to growth failure among subjects with onset between 0 to 3 months of age was 5 months; Only 1 of 22 avoided failure by 22 months of age. Median time to failure with disease onset between 4 to 6 months was 15 months. Most late onset (> 6 months) subjects avoided growth failure. Early clinical symptoms predict feeding dysfunction and growth failure. Immediate, proactive nutritional intervention is indicated for patients with early symptom onset.

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.

Spinal muscular atrophy: a clinical and research update

Spinal muscular atrophy, a hereditary degenerative disorder of lower motor neurons associated with progressive muscle weakness and atrophy, is the most common genetic cause of infant mortality. It is caused by decreased levels of the "survival of motor neuron" (SMN) protein. Its inheritance pattern is autosomal recessive, resulting from mutations involving the SMN1 gene on chromosome 5q13. However, unlike many other autosomal recessive diseases, the SMN gene involves a unique structure (an inverted duplication) that presents potential therapeutic targets. Although no effective treatment for spinal muscular atrophy exists, the field of translational research in spinal muscular atrophy is active, and clinical trials are ongoing. Advances in the multidisciplinary supportive care of children with spinal muscular atrophy also offer hope for improved life expectancy and quality of life.

SMA CARNIVAL TRIAL PART II: a prospective, single-armed trial of L-carnitine and valproic acid in ambulatory children with spinal muscular atrophy

Background

Multiple lines of evidence have suggested that valproic acid (VPA) might benefit patients with spinal muscular atrophy (SMA). The SMA CARNIVAL TRIAL was a two part prospective trial to evaluate oral VPA and l-carnitine in SMA children. Part 1 targeted non-ambulatory children ages 2–8 in a 12 month cross over design. We report here Part 2, a twelve month prospective, open-label trial of VPA and L-carnitine in ambulatory SMA children.

Methods

This study involved 33 genetically proven type 3 SMA subjects ages 3–17 years. Subjects underwent two baseline assessments over 4–6 weeks and then were placed on VPA and L-carnitine for 12 months. Assessments were performed at baseline, 3, 6 and 12 months. Primary outcomes included safety, adverse events and the change at 6 and 12 months in motor function assessed using the Modified Hammersmith Functional Motor Scale Extend (MHFMS-Extend), timed motor tests and fine motor modules. Secondary outcomes included changes in ulnar compound muscle action potential amplitudes (CMAP), handheld dynamometry, pulmonary function, and Pediatric Quality of Life Inventory scores.

Results

Twenty-eight subjects completed the study. VPA and carnitine were generally well tolerated. Although adverse events occurred in 85% of subjects, they were usually mild and transient. Weight gain of 20% above body weight occurred in 17% of subjects. There was no significant change in any primary outcome at six or 12 months. Some pulmonary function measures showed improvement at one year as expected with normal growth. CMAP significantly improved suggesting a modest biologic effect not clinically meaningful.

Conclusions

This study, coupled with the CARNIVAL Part 1 study, indicate that VPA is not effective in improving strength or function in SMA children. The outcomes used in this study are feasible and reliable, and can be employed in future trials in SMA.

Trial Regsitration

Clinicaltrials.gov NCT00227266