The relationship of body habitus and respiratory function in Duchenne muscular dystrophy

Performance of upper limb entry item to predict forced vital capacity in dysferlin-deficient limb girdle muscular dystrophy

Dysferlin-deficient limb girdle muscular dystrophy (LGMD R2), also referred to as dysferlinopathy, can be associated with respiratory muscle weakness as the disease progresses. Clinical practice guidelines recommend biennial lung function assessments in patients with dysferlinopathy to screen for respiratory impairment. However, lack of universal access to spirometry equipment and trained specialists makes regular monitoring challenging. This study investigated the use of the Performance of Upper Limb (PUL) clinical scale entry item as a low-cost screening tool to identify patients with dysferlinopathy at risk of respiratory impairment. Using data from 193 patients from the Jain Foundation's International Clinical Outcomes Study, modelling identified a significant positive relationship between the PUL entry item and forced vital capacity (FVC). Eighty-eight percent of patients with the lowest PUL entry item score of 1 presented with FVC % predicted values of <60 %, suggestive of respiratory impairment. By contrast, only 10 % of the remainder of the cohort (PUL entry item of 2 or more) had an FVC of <60 %. This relationship also held true when accounting for ambulatory status, age, and sex as possible confounding factors. In summary, our results suggest that the PUL entry item could be implemented in clinical practice to screen for respiratory impairment where spirometry is not readily available.

Unveiling the Respiratory Muscle Strength in Duchenne Muscular Dystrophy: The Impact of Nutrition and Thoracic Deformities, Beyond Spirometry

BACKGROUND/OBJECTIVES

Duchenne muscular dystrophy (DMD) is the most prevalent progressive muscular dystrophy, and the guidelines recommend the regular assessment of respiratory muscle function. This study aimed to assess the relationship between maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP) and sniff nasal inspiratory pressure (SNIP) measurements and upright-supine spirometry parameters in children with DMD, the predictability of upright-supine spirometry in terms of diaphragm involvement, and the impact of nutrition on muscle strength.

METHODS

This prospective cross-sectional study examined patients with DMD by comparing upright and supine FVC, MIP, MEP, and SNIP measurements. The effects of the ambulatory status, kyphoscoliosis, chest deformity, and low BMI on respiratory parameters were investigated.

RESULTS

Forty-four patients were included in the study. The mean patient age was 10.8 ± 2.9 years. Twenty-five patients were ambulatory. A significant decrease in FVC, FEV1, and FEF25-75 values was detected in the supine position in both ambulatory and non-ambulatory patients (p < 0.05). All patients had low MIP, MEP, and SNIP measurements (less than 60 cm H2O). MIP, MEP, and SNIP values were significantly lower in patients with a low BMI than in those without (p < 0.05).

CONCLUSIONS

To accurately assess respiratory muscle strength, supine FVC should be combined with upright FVC, MIP, MEP, and SNIP measurements. It is crucial to regularly screen patients for nutrition, as this can significantly affect respiratory muscle function during pulmonology follow-up.

Disease-associated comorbidities, medication records and anthropometric measures in adults with Duchenne muscular dystrophy

We investigated the comorbidities, associated factors, and the relationship between anthropometric measures and respiratory function and functional abilities in adults with Duchenne muscular dystrophy (DMD). This was a single-centre cross-sectional study in genetically diagnosed adults with DMD (>16 years old). Univariate and multivariate analyses identified factors associated with dysphagia, constipation, Body Mass Index (BMI), and weight. Regression analysis explored associations between BMI, weight, and respiratory/motor abilities. We included 112 individuals (23.4 ± 5.2 years old), glucocorticoid-treated 66.1 %. The comorbidities frequency was 61.6 % scoliosis (61.0 % of them had spinal surgery), 36.6 % dysphagia, 36.6 % constipation, and 27.8 % urinary conditions. The use of glucocorticoids delayed the time to spinal surgery. The univariate analysis revealed associations between dysphagia and constipation with age, lack of glucocorticoid treatment, and lower respiratory and motor function. In the multivariate analysis, impaired cough ability remained as the factor consistently linked to both conditions. Constipation associated with lower BMI and weight. BMI and weight positively correlated with respiratory parameters, but they did not associate with functional abilities. Glucocorticoids reduce the frequency of comorbidities in adults with DMD. The ability to cough can help identifying dysphagia and constipation. Lower BMI and weight in individuals with DMD with compromised respiratory function may suggest a higher calories requirement.

Exploring caregivers' attitudes and beliefs about nutrition and weight management for young people with Duchenne muscular dystrophy

INTRODUCTION/AIMS

Obesity disproportionately affects children and adolescents with Duchenne muscular dystrophy (DMD) and with adverse consequences for disease progression. This study aims to: explore barriers, enablers, attitudes, and beliefs about nutrition and weight management; and to obtain caregiver preferences for the design of a weight management program for DMD.

METHODS

We surveyed caregivers of young people with DMD from four Australian pediatric neuromuscular clinics. Survey questions were informed by the Theoretical Domains Framework and purposefully designed to explore barriers and enablers to food and weight management. Caregivers were asked to identify their preferred features in a weight management program for families living with DMD.

RESULTS

Fifty-three caregivers completed the survey. Almost half (48%) perceived their son as above healthy weight. Consequences for those children were perceived to be self-consciousness (71%), a negative impact on self-esteem (64%) and movement (57%). Preventing weight gain was a common reason for providing healthy food and healthy eating was a high priority for families. Barriers to that intention included: time constraints, selective food preferences, and insufficient nutrition information. Caregivers preferred an intensive six-week weight management program addressing appetite management and screen time.

DISCUSSION

Managing weight is an important issue for caregivers of sons with DMD; yet several barriers exist. Individualized 6 week programs are preferred by caregivers to improve weight management for DMD.

The Relationship between Obesity and Clinical Outcomes in Young People with Duchenne Muscular Dystrophy

Background: Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder. Young people with DMD have high rates of obesity. There is emerging evidence that a higher BMI may negatively affect clinical outcomes in DMD. This study aimed to explore the relationship between obesity and clinical outcomes in DMD. Methods: This was a retrospective clinical audit of young people (two–21 years) with DMD. Height and weight were collected to calculate BMI z-scores to classify obesity, overweight and no overweight or obesity (reference category). Cox proportional hazards models determined the impact of obesity at five to nine years on clinical milestones including time to: loss of ambulation, timed function test cut-offs, obstructive sleep apnoea (OSA) diagnosis and first fracture. Results: 158 young people with DMD were included; most (89.9%) were steroid-treated. Mean follow-up was 8.7 ± 4.7 years. Obesity prevalence increased from age five (16.7%) to 11 years (50.6%). Boys with obesity at nine years sustained a fracture earlier (hazard ratio, HR: 2.050; 95% CI: 1.038–4.046). Boys with obesity at six to nine years were diagnosed with OSA earlier (e.g., obesity nine years HR: 2.883; 95% CI: 1.481–5.612). Obesity at eight years was associated with a 10 m walk/run in 7–10 s occurring at an older age (HR: 0.428; 95% CI: 0.207–0.887), but did not impact other physical function milestones. Conclusions: Although 50% of boys with DMD developed early obesity, the impact of obesity on physical function remains unclear. Obesity puts boys with DMD at risk of OSA and fractures at a younger age. Early weight management interventions are therefore important.

Methods and Applications in Respiratory Physiology: Respiratory Mechanics, Drive and Muscle Function in Neuromuscular and Chest Wall Disorders

Individuals with neuromuscular and chest wall disorders experience respiratory muscle weakness, reduced lung volume and increases in respiratory elastance and resistance which lead to increase in work of breathing, impaired gas exchange and respiratory pump failure. Recently developed methods to assess respiratory muscle weakness, mechanics and movement supplement traditionally employed spirometry and methods to evaluate gas exchange. These include recording postural change in vital capacity, respiratory pressures (mouth and sniff), electromyography and ultrasound evaluation of diaphragmatic thickness and excursions. In this review, we highlight key aspects of the pathophysiology of these conditions as they impact the patient and describe measures to evaluate respiratory dysfunction. We discuss potential areas of physiologic investigation in the evaluation of respiratory aspects of these disorders.

Obesity and loss of ambulation are associated with lower extremity oedema in Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy have multiple risk factors for lower extremity oedema. This study sought to define the frequency and predictors of oedema. Patients aged 15 years and older were screened by patient questionnaire, and the presence of oedema was confirmed by subsequent physical exam. Twenty-four of 52 patients (46%) had oedema, 12 of whom had swelling extending above the foot and two with sores/skin breakdown. There was no significant difference in age, frequency, or duration of glucocorticoid use, non-invasive respiratory support use, forced vital capacity, cardiac medication use, or ejection fraction between patients with and without oedema (all p > 0.2). Those with oedema had a greater time since the loss of ambulation (8.4 years versus 3.5 years; p = 0.004), higher body mass index (28.3 versus 24.8; p = 0.014), and lower frequency of deflazacort use (67% versus 89%; p = 0.008). Multivariate analysis revealed a longer duration of loss of ambulation (p = 0.02) and higher body mass index (p = 0.009) as predictors of oedema. Lower extremity oedema is common in Duchenne muscular dystrophy but independent of cardiac function. Interventions focused on minimising body mass index increases over time may be a therapeutic target.

The association between dietary factors and body weight and composition in boys with Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is a X-linked neuromuscular disorder. Boys with DMD have high rates of obesity, but little is known about dietary factors that may contribute to weight gain in this population. This study aimedto explore the relationship between dietary factors, body mass index (BMI) z-score, body composition and motor function and to describe dietary intake in boys with DMD.

METHODOLOGY

A cross-sectional analysis of 3-day food diaries from ambulant and steroid treated boys with DMD aged 5-13 years was conducted. Correlation analysis explored the relationship between dietary factors, BMI z-score, fat mass % (FM%) and lean mass (LM%).

RESULTS

Themedian agewas 8.5 years [interquartile range (IQR) 7.2, 10.5]. Median energy/kg/day in those within a healthy weight range (n=11) was316 kJ/kg/day [IQR 276, 355] and greater than estimated requirements; and forthose above a healthy weight (n=26) energy intake was 185kJ/kg/day [IQR 143, 214] and lower than estimated requirements. Energy/kg/day was negatively associatedwith BMI z-score (r=-0. 650) and FM% (r=-0.817)but positively associated with LM% (r=0.805, all analyses p =<0.01). Younger age was associated (r=-0.609 p=<0.01) with a higher energy/kg/day. For all participants vegetable, grains, meat/alternatives and dairy intake was sub-optimal.

PRINCIPAL CONCLUSIONS

Younger boys with DMD within a healthy weight range are overconsuming energy dense nutrient poor foods. A focus on improving diet quality during early childhood may prove a useful strategy to reduce excess weight gain and support healthier eating habits in this vulnerable clinical population. This article is protected by copyright. All rights reserved.

Early NIV is associated with accelerated lung function decline in Duchenne muscular dystrophy treated with glucocorticosteroids

Background

Use of non-invasive ventilation (NIV) in adolescents with Duchenne muscular dystrophy (DMD) has increased with concomitant extended survival.

Aim

To describe lung function (LF) changes with NIV in adolescents with DMD and to assess differences between Steroid Users and Steroid Naïve subjects.

Method

A retrospective cohort of adolescents with DMD initiating NIV over 10 years was conducted. Serial LF before and after NIV initiation was collated. Use of systemic glucocorticosteroids, adherence to NIV and presence of cardiac disease were assessed.

Results

Twenty-nine men started NIV, median age 14.66 years (IQR 2.35, 10.47–17.96). Nine were Steroid Users and eight were Steroid Naïve. Indications for NIV were apnoea–hypopnoea index >5 and/or nocturnal hypoventilation. LF is better (forced vital capacity (FVC) z-score −3.26 vs −5.41, p < 0.02) and decline slower (FVC z-score −0.58 per annum (pa) vs −0.68 pa, p<0.001) in Steroid Users compared with Steroid Naïve subjects. Following NIV initiation, FVC z-score decline slowed for the whole (−0.72 pa (95% CI −0.79 to 0.64) to −0.46 pa (95% CI −0.54 to 0.38) p < 0.001) and Steroid Naïve groups (−0.74 (95% CI −0.85 to 0.63) to −0.44 pa (95% CI −0.56 to 0.32) p < 0.001) but accelerated in the Steroid User group (−0.56 (95% CI −0.70 to 0.42) to −0.75 pa (95% CI −0.89 to 0.61) p < 0.001). Adherence to NIV and cardiac disease did not impact decline.

Conclusion

Overall, LF decline is reduced on NIV. Steroid Naïve patients have lower LF and faster decline, which slows following NIV initiation. An accelerated LF decline was seen on NIV in Steroid Users which requires further prospective research.

Nutritional status, swallowing disorders, and respiratory prognosis in adult Duchenne muscular dystrophy patients

Malnutrition and swallowing disorders are common in Duchenne muscular dystrophy (DMD) patients. We assessed, in adult DMD with home mechanical ventilation (HMV) and cough assist device, its prevalence and the relationships with respiratory muscle strength and long-term respiratory prognosis. We reviewed the patients (n = 117, age 18-39 years [median 24]), followed in a reference center, from 2006 to 2015, to obtain clinical baseline, nutritional status, vital capacity (VC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). The median body mass index (BMI) was low (15.6 kg/m²). Included patients had severe restrictive respiratory function with a median VC of 10.5% [7-17] of the predicted value. All patients were on HMV. Prevalence of malnutrition, swallowing disorders, and gastrostomy were respectively 62%, 34%, and 11%. BMI and serum albumin level were significantly associated with MIP, MEP, and VC. The 1-year/5-years cumulative incidences of respiratory events (pulmonary sepsis and acute respiratory distress) were, respectively, 20.7%/44.5%. Using univariate analysis, predictive factors for respiratory events were swallowing disorders (p = .001), transthyretinemia (p = .034), MIP (p = .039), and MEP (p = .03) but not BMI or albuminemia. Using multivariate analysis, only swallowing disorders remained significantly associated with respiratory events (OR = 4.2, IC 95% 1.31-12.2, p = .01). In conclusion, this study highlights the interrelationships between nutritional intake, swallowing function, airway clearance, and respiratory function in adult DMD. A multidisciplinary approach focusing on these previous factors is essential to optimize DMD patient health.

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.