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

Spinal Muscular Atrophy With Severe Hyperlordosis: A Case Report

Spinal muscular atrophy (SMA) indicates a set of inherited autosomal recessive genetic disorders, where, specifically, the anterior horn cell motor neurons in the brain and spinal cord are affected, leading to a severe form of hypotonia and muscle weakness. The incidence is exceptionally rare, commonly manifesting as slowly progressive muscular weakness and atrophy of lower limbs. As per our existing knowledge, this is the first case of SMA associated with hyperlordosis in a patient. Hyperlordosis is a deformity in spinal curvature characterized by an excessive forward spinal curve in the region of the lower back, forming the characteristic C-shape curvature in the lumbar region, just above the buttocks. Parents brought an 11-year-old male child with complaints of inability to get up from a sitting position along with difficulty in walking for the past six months. Upon physical examination, deep tendon reflexes were absent; there was severe hyperlordosis, proximal limb weakness, and notable hypotonia. In our study, we aim to understand the clinical presentation, impact, and association of hyperlordosis in a child diagnosed with SMA. This case report describes the complaints and successful diagnosis of a patient of survivor motor neuron (SMN) gene-related SMA along with severe hyperlordosis backed by evidences of electrophysiology and neuropathology. However, a complete cure and normal lifestyle are not possible due to the lack of affordable and easily accessible therapies.

SMN deficiency perturbs monoamine neurotransmitter metabolism in spinal muscular atrophy

Beyond motor neuron degeneration, homozygous mutations in the survival motor neuron 1 (SMN1) gene cause multiorgan and metabolic defects in patients with spinal muscular atrophy (SMA). However, the precise biochemical features of these alterations and the age of onset in the brain and peripheral organs remain unclear. Using untargeted NMR-based metabolomics in SMA mice, we identify cerebral and hepatic abnormalities related to energy homeostasis pathways and amino acid metabolism, emerging already at postnatal day 3 (P3) in the liver. Through HPLC, we find that SMN deficiency induces a drop in cerebral norepinephrine levels in overt symptomatic SMA mice at P11, affecting the mRNA and protein expression of key genes regulating monoamine metabolism, including aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DβH) and monoamine oxidase A (MAO-A). In support of the translational value of our preclinical observations, we also discovered that SMN upregulation increases cerebrospinal fluid norepinephrine concentration in Nusinersen-treated SMA1 patients. Our findings highlight a previously unrecognized harmful influence of low SMN levels on the expression of critical enzymes involved in monoamine metabolism, suggesting that SMN-inducing therapies may modulate catecholamine neurotransmission. These results may also be relevant for setting therapeutic approaches to counteract peripheral metabolic defects in SMA.

Spinal muscular atrophy and anorexia nervosa: a case report

BACKGROUND

Spinal muscular atrophy (SMA) is an autosomal recessive condition affecting lower motor neurons causing progressive muscle atrophy. Anorexia nervosa (AN) is a psychiatric disorder characterised by intense fear of weight gain, restriction of energy intake, and preoccupation with body weight and shape. Low weight, gastrointestinal dysmotility, and respiratory infections are common in SMA but may mask AN. No paediatric cases of AN in SMA have been reported to date.

CASE PRESENTATION

A 14-year-old female with SMA2 presented with 12 months of declining body weight to a nadir of 24.8 kg (BMI 11). This was initially attributed to medical complications including pneumonia and gastroenteritis, and chronic gut dysmotility associated with SMA. Despite almost 2 years of dietetic input and nutritional supplementation due to the weight plateauing from age 11, no significant restoration or gain was achieved. The Eating Disorder Examination-Questionnaire (EDE-Q) indicated a possible eating disorder and psychiatric evaluation confirmed AN. Initial management prioritised close medical monitoring and outpatient weight restoration on an oral meal plan. Skin fold anthropometric measurement was conducted to determine a minimum healthy weight. Individual psychological therapy and family sessions were undertaken. The patient developed major depression and a brief relapse with weight loss to 28 kg. Since then, the patient has maintained a weight of around 35 kg with stable mood.

CONCLUSIONS

Low body weight, feeding issues, gastrointestinal dysmotility, and respiratory infections are common in SMA and diagnostic overshadowing can lead to delayed recognition of anorexia nervosa. Change to growth trajectory and prolonged weight loss should prompt consideration of comorbid psychiatric issues. Screening measures such as the EDE-Q and DASS may be helpful in this population. Close liaison between the neurogenetics and psychiatry teams is helpful. Skin fold anthropometry can assist in identifying a minimum healthy weight range.

Patients with Spinal Muscular Atrophy Type 1 Achieve and Maintain Bulbar Function Following Onasemnogene Abeparvovec Treatment

BACKGROUND

Improvement and maintenance of bulbar function are goals of disease-modifying treatments for spinal muscular atrophy (SMA). Lack of standardized measures and a widely accepted definition of bulbar function represents a gap in SMA care.

OBJECTIVE

A multidisciplinary team conducted post-hoc analyses of pooled data from one phase 1 (START) and two phase 3 (STR1VE-US, STR1VE-EU) studies to define and evaluate bulbar function of infants with SMA type 1 after receiving one-time gene replacement therapy, onasemnogene abeparvovec.

METHODS

We defined bulbar function as the ability to meet nutritional needs while maintaining airway protection and the ability to communicate verbally. Four endpoints represented adequate bulbar function: (1) absence of clinician-identified physiologic swallowing impairment, (2) receiving full oral nutrition, (3) absence of adverse events indicating pulmonary instability, and (4) the ability to vocalize at least two different, distinct vowel sounds. We descriptively assessed numbers/percentages of patients who achieved each endpoint and all four collectively. Patients were followed until 18 months old (STR1VE-US and STR1VE-EU) or 24 months (START) post-infusion.

RESULTS

Overall, 65 patients were analyzed for swallowing, nutrition intake, and adverse events, and 20 were analyzed for communication. At study end, 92% (60/65) of patients had a normal swallow, 75% (49/65) achieved full oral nutrition, 92% (60/65) had no evidence of pulmonary instability, 95% (19/20) met the communication endpoint, and 75% (15/20) achieved all four bulbar function components in the composite endpoint.

CONCLUSIONS

In these three clinical trials, patients with SMA type 1 who received onasemnogene abeparvovec achieved and maintained the bulbar function criteria utilized within this investigation.

Open-labelled study to monitor the effect of an amino acid formula on symptom management in children with spinal muscular atrophy type I: The SMAAF pilot study

BACKGROUND

An increasing number of families with children who have spinal muscular atrophy (SMA) are incorporating a special amino acid diet into their child's feeding regimens. Characteristics of the diet include high-carbohydrate and low-fat content with added probiotics. However, because of insufficient evidenced-based research, clinicians are unable to prescribe or endorse this diet. Our aim was to assess the tolerability of an adapted version of the traditional amino acid diet in children with SMA type I.

METHODS

Children with SMA type I were recruited if they were enterally fed and experienced at least one gastrointestinal symptom (reflux, vomiting, constipation, and/or diarrhea). Children were transitioned to an amino acid formula (Neocate Syneo-Nutricia) for 8 weeks. Feeding tolerance was measured weekly by telephone consultation to monitor reflux, vomiting, stool consistency, and frequency.

RESULTS

Fourteen children were recruited, the mean age was 4.1 years (±1.2 SD), and 64% of participants were female. The mean resting energy expenditure determined by indirect calorimetry was 51.5 kcal/kg (±7 SD). The most common gastrointestinal complaint before switching to the amino acid formula was constipation, which was reported in 12 of 14 (85%) patients, of which 10 of the 12 (83%) children required daily stool softeners/laxatives to help regulate bowel function. After 8 weeks on the amino acid formula, 10 out of 12 (83%) children stopped or reduced constipation medication.

CONCLUSION

Children with SMA type I who display gastrointestinal symptoms such as constipation and reflux may benefit from an amino acid formula that is fortified with probiotics.

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.

Assessment of body composition, metabolism, and pulmonary function in patients with myotonic dystrophy type 1

Abnormal body composition in myotonic dystrophy type 1 (DM1) are affected by energy intake above resting energy expenditure (REE). We aim to investigate the characteristics and relationship between body composition, REE, and pulmonary function in patients with DM1, and to examine their changes in 1 year. The study design was a single-center, cross-sectional, and longitudinal study of body composition, REE characteristics, and pulmonary function. Twenty-one male patients with DM1 and 16 healthy volunteers were registered in the study. Body composition was measured using dual-energy X-ray absorptiometry (DEXA). Fat mass (FM) index (kg/m2), fat-FM index (kg/m2), and skeletal mass index (kg/m2) were calculated. The measurements were taken breath by breath with a portable indirect calorimeter. The REE was calculated using the oxygen intake (VO2) and carbon dioxide output (VCO2) in the Weir equation. Basal energy expenditure (BEE) was calculated by substituting height, weight, and age into the Harris-Benedict equation. The study enrolled male patients with DM1 (n = 12) and healthy male volunteers (n = 16). Patients with DM1 (n = 7) and healthy volunteers (n = 14) could be followed in 1 year. The body composition of patients with DM1 was significantly higher in the FM index and significantly lower in the fat-FM index and skeletal mass index. The REE of patients with DM1 was significantly lower and was not associated with body composition. Patients with DM1 had poor metabolism that was not related to body composition. FM was high and lean body mass was low.

Spinal muscular atrophy carrier frequency in Saudi Arabia

BACKGROUND

Spinal Muscular Dystrophy (SMA) is one of the leading causes of death in infants and young children from heritable diseases. Although no large-scale popultion-based studies have been done in Saudi Arabia, it is reported that the incidence of SMA is higher in the Saudi population partly because of the high degree of consanguineous marriages.

METHODS

The final analysis included 4198 normal volunteers aged between 18 and 25 years old, 54.7% males, and 45.3% females. Whole blood was spotted directly from finger pricks onto IsoCode StixTM and genomic DNA was isolated using one triangle from the machine. To discern the SMN1 copy number independently from SMN2, Multiplex PCR with Dral restriction fragment analysis was completed. We used the carrier frequency and population-level data to estimate the prevalence of SMA in the population using the life-table method.

RESULTS

This data analysis showed the presence of one copy of the SMN1 gene in 108 samples and two copies in 4090 samples, which resulted from a carrier frequency of 2.6%. The carrier frequency was twofold in females reaching 3.7% compared to 1.6% in males. 27% of participants were children of first-cousin marriages. We estimated the birth incidence of SMA to be 32 per 100,000 birth and the total number of people living with SMA in the Kingdom of Saudi Arabia to be 2265 of which 188 are type I, 1213 are type II, and 8,64 are type III.

CONCLUSION

The SMA carrier rate of 2.6% in Saudi control subjects is slightly higher than the reported global frequency of 1.25 to 2% with links to the high degree of consanguinity.

Association between serum zinc level and lipid profiles in children with spinal muscular atrophy

Background and aims

Children with spinal muscular atrophy (SMA) have a high rate of dyslipidaemia, which is a risk factor of vital importance for cardiovascular diseases in adulthood. Studies have demonstrated that the serum zinc level is associated with lipid profiles in the general population as well as in individuals diagnosed with obesity or diabetes. The purpose of this study was to evaluate the relationship between serum zinc level and lipid profiles in children with SMA.

Methods

This cross-sectional study was launched in a tertiary children's medical center in China and involved pediatric patients with SMA under the management of a multidisciplinary team of outpatient services from July 2019 to July 2021. Anthropometric information, general clinical data, serum zinc level, lipid profiles, and body composition data were collected. Multivariate analysis was used for a thorough inquiry on the association between the serum zinc level and lipid profiles.

Results

Among the 112 patients with SMA [median (IQR) age 5.54 years (2.75–8.29), 58.04% female], who fulfilled the inclusion criteria of the study, dyslipidaemia was detected in 60 patients (53.57%). Based on multivariable linear regression, serum zinc level was positively associated with high-density lipoprotein cholesterol (HDL-C; β = 1.63, 95% CI = 0.44–3.22) and apolipoprotein A1 (APO A1; β = 2.94, 95% CI = 0.03–5.85) levels, independently of age, sex, type, activity, percentage of body fat, and body mass index. As the serum zinc level increased by 10 μmol/L, the risk of low APO A1 levels decreased by 35% (OR = 0.65, 95% CI = 0.44–0.97) according to multivariable logistic regression analyses.

Conclusion

Serum zinc concentration was positively correlated with HDL-C and APO A1 levels among children with SMA. We suggest measures to correct the lower level of serum zinc to improve HDL-C and APO A1 levels.

Evolution of bulbar function in spinal muscular atrophy type 1 treated with nusinersen

AIM

To assess the evolution of bulbar function in nusinersen-treated spinal muscular atrophy type 1 (SMA1).

METHOD

This single-centre retrospective study identified 24 patients (14 females and 10 males) with SMA1, treated with nusinersen between 2017 and 2020. We adapted and validated the Paediatric Functional Oral Intake Scale (p-FOIS), which is an outcome measure to assess bulbar function. Analysis considered SMA1 subtype, nutritional support, and Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) and p-FOIS scores at initiation of nusinersen treatment (baseline) and at 6, 12, and 24 months after initiation.

RESULTS

The median age at baseline was 11 months (range 1 month-7 years 6 months). Median age at initiation of tube feeding was 8 months (range 0-2 years 2 months). Fourteen patients were tube fed at baseline. The median p-FOIS score was 3 at baseline and 2 at 12 and 24 months. Four patients, all with type 1c SMA, remained orally fed at 24 months. Median CHOP INTEND scores increased from 32 at baseline to 42 at 12 and 24 months.

INTERPRETATION

Impaired bulbar function persisted as a significant complication in most nusinersen-treated patients with SMA1, in contrast to the improvement in motor abilities demonstrated in the majority. p-FOIS allows for tracking of bulbar function progression and treatment response. Larger, prospective studies investigating the longer-term impacts of nusinersen on bulbar function are warranted.

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.

Features and diagnostic value of body composition in patients with late-onset multiple acyl-CoA dehydrogenase deficiency

OBJECTIVE

This study aims to analyse the body composition features and its changes after treatment in patients with late-onset multiple acyl-CoA dehydrogenase deficiency (MADD).

METHODS

Body composition was measured in patients with late-onset MADD, inflammatory myopathies, mitochondrial myopathy, and healthy controls. The correlation analyses between body composition and traditional parameters were performed. Comparisons between groups and receiver operating characteristic curve analyses were performed.

RESULTS

A total of 42 participants included 13 patients with late-onset MADD, 13 healthy controls, 10 with inflammatory myopathy, and 6 with mitochondrial myopathy. Bilateral grip strength and forced vital capacity (FVC) were moderate-strong correlated with skeletal muscle mass (right hand grip strength: r = 0.728, P < 0.001; left hand grip strength: r = 0.676, P < 0.001; FVC: r = 0.754, P < 0.001). Serum CK was moderately and negatively correlated with right hand grip strength (r = - 0.618, P = 0.005), left hand grip strength (r = - 0.630, P = 0.004), FVC (r = - 0.665, P = 0.002), manual muscle testing (MMT) (r = - 0.729, P = 0.000), and lean body mass skeletal muscle percentage (r = - 0.501, P = 0.029). Body composition features in patients with late-onset MADD were as follows: (1) obvious fat accumulation, (2) reduction of muscle mass, and (3) reduction of body water and intracellular water ratio. Some indicators of body composition were found to be valuable in diagnosis and eliminating differential diagnoses, such as visceral fat area (sensitivity 84.62%; specificity 92.31%; AUC 0.905) and fat mass (sensitivity 84.62%; specificity 75.00%; AUC 0.837). Seven patients were followed-up (2-9 months). Prior to treatment, the changes in body composition in these patients were conflicting.

CONCLUSIONS

Hand grip strength and FVC were strongly associated with body composition. Body composition features in late-onset MADD are fat accumulation, muscle loss, decrease in total body water, and intracellular water ratio. Body composition features are valuable for diagnosis and assessment.

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.

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.

Evaluation of Metabolic Effects of Nusinersen in Patients with Spinal Muscular Atrophy

Nusinersen is the first disease-modifying therapy for spinal muscular atrophy (SMA), but there are few data on potential long-term endocrinological and metabolic systemic effects of this novel treatment as well as metabolic alterations in SMA itself. In this retrospective and multicentric study, we analyzed anthropometric, endocrinological, and motor function data of 81 pediatric and adult patients with SMA1 to 3 undergoing treatment with nusinersen. In 39 patients (51%), we observed a slight increase in body mass index (BMI) centiles under treatment with nusinersen, especially in patients with SMA2 and in pediatric patients between 3.1 and 12 years. A correlation to the SMN2 copy number or motor function was not found. Additionally, length centiles decreased significantly under treatment. The results of longitudinal endocrinological assessments were interpreted as not clinically significant in most patients; in three patients, the signs of an altered glucose metabolism were present. Our study indicates a putative effect of treatment with nusinersen on BMI, which might be due to a conjoint effect of weight gain and reduction of height velocity, without evidence of correlation to increased muscle function. Further studies need to address specific effects of targeted therapies such as nusinersen or onasemnogene abeparvovec on body composition including fat and muscle mass.

Nutritional Therapy in Children With Spinal Muscular Atrophy in the Era of Nusinersen

OBJECTIVES

Spinal muscular atrophy (SMA) is a genetic motor neuron disorder characterized by progressive muscle atrophy. Our aims were to evaluate the impact of nutritional intervention and nusinersen therapy on the nutritional status of SMA patients.

STUDY DESIGN

This prospective study included all children and young adults (<24 years of age) with SMA who attended our multidisciplinary SMA clinic, during January 2017-July 2019. We documented demographic, clinical, anthropometric, and nutritional data at baseline and follow-up. A nutritional intervention was implemented according to standards of the 2018 Consensus Statement of SMA Management.

RESULTS

The cohort included 51 SMA patients with a median age of 7.2 (interquartile range 2.1-15.3) years. Among them, 24 (47%) were SMA type 1, 16 (31.4%) SMA type 2, and 11 (21.6%) SMA type 3 patients. At baseline, 28 (54.9%) patients presented with malnutrition, 20 (71.4%) of whom with severe malnutrition. A decline in the frequency of severe malnutrition of SMA type 1 patients was observed at follow-up. The body mass index of patients who started nusinersen therapy after the nutritional intervention increased significantly compared with patients that started nusinersen therapy before the nutritional intervention (P = 0.042). There was also a significant increase in total energy and protein consumption in the former group (P = 0.043).

CONCLUSIONS

Malnutrition is frequent among children with SMA, and the nutritional status of patients that started nusinersen therapy after implementation of a nutritional intervention underwent a more significant improvement. The importance of combining adequate nutritional management with disease-modifying treatment is highlighted.

Metabolic Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder leading to paralysis, muscle atrophy, and death. Significant advances in antisense oligonucleotide treatment and gene therapy have made it possible for SMA patients to benefit from improvements in many aspects of the once devastating natural history of the disease. How the depletion of survival motor neuron (SMN) protein, the product of the gene implicated in the disease, leads to the consequent pathogenic changes remains unresolved. Over the past few years, evidence toward a potential contribution of gastrointestinal, metabolic, and endocrine defects to disease phenotype has surfaced. These findings ranged from disrupted body composition, gastrointestinal tract, fatty acid, glucose, amino acid, and hormonal regulation. Together, these changes could have a meaningful clinical impact on disease traits. However, it is currently unclear whether these findings are secondary to widespread denervation or unique to the SMA phenotype. This review provides an in-depth account of metabolism-related research available to date, with a discussion of unique features compared to other motor neuron and related disorders.

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.

3D Facial morphology in children affected by spinal muscular atrophy type 2 (SMAII)

OBJECTIVES

The main objective of this study was to assess the three-dimensional facial characteristics of children affected by spinal muscular atrophy (SMA), a severe muscular disorder characterized by hypotonia, areflexia, weakness, and respiratory impairment.

MATERIALS/METHODS

Stereophotogrammetric facial scans from 22 SMA type II patients aged 2-7 years were obtained. Data were analysed using both inter-landmark distances and principal component analysis and compared with data collected from matched control subjects.

RESULTS

Patients had wider transverse facial diameters, but smaller biocular width. Middle and lower anterior face heights were increased, whereas the mandibular ramus was shorter, with a reduced posterior-to-anterior face height ratio. Facial width-to-length ratio was reduced. In the sagittal plane, mandibular body length, and facial divergence were increased, whereas the gonial angles were decreased. In the horizontal plane, lower facial convexity was greater in patients, whereas mandibular convexity was smaller. Patients had smaller and down-slanted eye fissures, with a larger and more vertically developed nose.

LIMITATIONS

This study assessed a relatively small number of patients, due to the rare frequency of SMA type II.

CONCLUSIONS/IMPLICATIONS

SMA type II children possess peculiar facial alterations that may be due to the altered muscular activity. As feeding problems may derive also by malocclusion and masticatory muscular alterations, a detailed assessment of the craniofacial individual alterations should be considered in the standards of care of these patients.

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.

The Relationship between Body Composition, Fatty Acid Metabolism and Diet in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive condition that results in pathological deficiency of the survival motor neuron (SMN) protein. SMA most frequently presents itself within the first few months of life and is characterized by progressive muscle weakness. As a neuromuscular condition, it prominently affects spinal cord motor neurons and the skeletal muscle they innervate. However, over the past few decades, the SMA phenotype has expanded to include pathologies outside of the neuromuscular system. The current therapeutic SMA landscape is at a turning point, whereby a holistic multi-systemic approach to the understanding of disease pathophysiology is at the forefront of fundamental research and translational endeavours. In particular, there has recently been a renewed interest in body composition and metabolism in SMA patients, specifically that of fatty acids. Indeed, there is increasing evidence of aberrant fat distribution and fatty acid metabolism dysfunction in SMA patients and animal models. This review will explore fatty acid metabolic defects in SMA and discuss how dietary interventions could potentially be used to modulate and reduce the adverse health impacts of these perturbations in SMA patients.

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.

Spinal muscular atrophy: Broad disease spectrum and sex-specific phenotypes

Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% of cases of SMA result from deletions of or mutations in the Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, does not compensate for the loss of SMN1 due to predominant skipping of exon 7. The spectrum of SMA is broad, ranging from prenatal death to infant mortality to survival into adulthood. All tissues, including brain, spinal cord, bone, skeletal muscle, heart, lung, liver, pancreas, gastrointestinal tract, kidney, spleen, ovary and testis, are directly and/or indirectly affected in SMA. Accumulating evidence on impaired mitochondrial biogenesis and defects in X chromosome-linked modifying factors, coupled with the sexual dimorphic nature of many tissues, point to sex-specific vulnerabilities in SMA. Here we review the role of sex in the pathogenesis of SMA.

Metabolic and Nutritional Issues Associated with Spinal Muscular Atrophy

Spinal muscular atrophy (SMA), the main genetic cause of infant death, is a neurodegenerative disease characterized by the selective loss of motor neurons in the anterior horn of the spinal cord, accompanied by muscle wasting. Pathomechanically, SMA is caused by low levels of the survival motor neuron protein (SMN) resulting from the loss of the SMN1 gene. However, emerging research extends the pathogenic effect of SMN deficiency beyond motor neurons. A variety of metabolic abnormalities, especially altered fatty acid metabolism and impaired glucose tolerance, has been described in isolated cases of SMA; therefore, the impact of SMN deficiency in metabolic abnormalities has been speculated. Although the life expectancy of these patients has increased due to novel disease-modifying therapies and standardization of care, understanding of the involvement of metabolism and nutrition in SMA is still limited. Optimal nutrition support and metabolic monitoring are essential for patients with SMA, and a comprehensive nutritional assessment can guide personalized nutritional therapy for this vulnerable population. It has recently been suggested that metabolomics studies before and after the onset of SMA in patients can provide valuable information about the direct or indirect effects of SMN deficiency on metabolic abnormalities. Furthermore, identifying and quantifying the specific metabolites in SMA patients may serve as an authentic biomarker or therapeutic target for SMA. Here, we review the main epidemiological and mechanistic findings that link metabolic changes to SMA and further discuss the principles of metabolomics as a novel approach to seek biomarkers and therapeutic insights in SMA.

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.

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.

Low-Intensity Running and High-Intensity Swimming Exercises Differentially Improve Energy Metabolism in Mice With Mild Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA), an autosomal recessive neurodegenerative disease characterized by the loss of spinal-cord motor-neurons, is caused by mutations on Survival-of-Motor Neuron (SMN)-1 gene. The expression of SMN2, a SMN1 gene copy, partially compensates for SMN1 disruption due to exon-7 excision in 90% of transcripts subsequently explaining the strong clinical heterogeneity. Several alterations in energy metabolism, like glucose intolerance and hyperlipidemia, have been reported in SMA at both systemic and cellular level, prompting questions about the potential role of energy homeostasis and/or production involvement in disease progression. In this context, we have recently reported the tolerance of mild SMA-like mice (Smn^Δ7/Δ7; huSMN2^+/+) to 10 months of low-intensity running or high-intensity swimming exercise programs, respectively involving aerobic and a mix aerobic/anaerobic muscular metabolic pathways. Here, we investigated whether those exercise-induced benefits were associated with an improvement in metabolic status in mild SMA-like mice. We showed that untrained SMA-like mice exhibited a dysregulation of lipid metabolism with an enhancement of lipogenesis and adipocyte deposits when compared to control mice. Moreover, they displayed a high oxygen consumption and energy expenditure through β-oxidation increase yet for the same levels of spontaneous activity. Interestingly, both exercises significantly improved lipid metabolism and glucose homeostasis in SMA-like mice, and enhanced oxygen consumption efficiency with the maintenance of a high oxygen consumption for higher levels of spontaneous activity. Surprisingly, more significant effects were obtained with the high-intensity swimming protocol with the maintenance of high lipid oxidation. Finally, when combining electron microscopy, respiratory chain complexes expression and enzymatic activity measurements in muscle mitochondria, we found that (1) a muscle-specific decreased in enzymatic activity of respiratory chain I, II, and IV complexes for equal amount of mitochondria and complexes expression and (2) a significant decline in mitochondrial maximal oxygen consumption, were reduced by both exercise programs. Most of the beneficial effects were obtained with the high-intensity swimming protocol. Taking together, our data support the hypothesis that active physical exercise, including high-intensity protocols, induces metabolic adaptations at both systemic and cellular levels, providing further evidence for its use in association with SMN-overexpressing therapies, in the long-term care of SMA patients.

Weight-Loss Cognitive-Behavioural Treatment and Essential Amino Acid Supplementation in a Patient with Spinal Muscular Atrophy and Obesity

Spinal muscular atrophy is a genetic neuromuscular disease characterised by muscle atrophy, hypotonia, weakness, and progressive paralysis. Usually, these patients display increased fat mass deposition and reductions in fat-free mass and resting energy expenditure—an unfavourable condition that facilitates the development of obesity. However, weight management of these patients remains poorly described. Hence, the aim of this case report was to describe the clinical presentation and weight management of a 31-year-old male patient with spinal muscular atrophy type III, class I obesity, and metabolic syndrome treated for 1 year by means of a personalised multistep cognitive-behavioural treatment for obesity. The treatment produced a weight loss of 7.2 kg (7.1%), which was associated with a marked improvement in both the patient's self-reported general conditions and obesity-related cardiometabolic profile, and no adverse effects in terms of spinal muscular atrophy (i.e., reductions in fat-free mass or resting energy expenditure).