Longitudinal changes in respiratory and upper limb function in a pediatric type III spinal muscular atrophy cohort after loss of ambulation

Secondary outcomes of scoliosis surgery in disease-modifying treatment-naïve patients with spinal muscular atrophy type 2 and nonambulant type 3

INTRODUCTION/AIMS

Available studies on scoliosis surgery in spinal muscular atrophy (SMA) have focused on the primary outcome of the procedure-the correction of the curve-whereas research focusing on secondary outcomes is scarce. We aimed to investigate postsurgical changes in respiratory function, motor function, weight, pain, and satisfaction.

METHODS

We retrospectively reviewed the clinical notes of 32 disease-modifying treatment-naïve patients (26 SMA2, 6 nonambulant SMA3). We also performed investigator-developed phone interviews and conducted a focus group with families on postsurgical satisfaction.

RESULTS

Mean annual rate of forced vital capacity percent decline improved in SMA2: -3.2% postsurgery versus -6.9% presurgery (p < .001), with similar trajectories in SMA3. Gross motor functional scores (Hammersmith Functional Motor Scale) available in 12/32 dropped immediately after surgery: median loss of 6.5 points, with relatively spared upper limb function. Weight z-scores postsurgery dropped in 16/32, requiring food supplements (5/16); one/16 lost >5% of total weight requiring gastrostomy. Postsurgical pain was frequently reported, especially hip pain (13/32). Overall, 10/10 patients/parents participating in the phone interview rated the procedure as very successful for posture and physical appearance. Nonetheless, 7/10 reported postsurgical pain, reduced mobility, and unmet care needs. The seven patients/parents attending the focus group highlighted lack of intensive physiotherapy programs, occupational therapy assistance, and psychological support as postsurgical unmet care needs.

DISCUSSION

This study reports a positive impact of scoliosis surgery on respiratory function and overall satisfaction with posture and physical appearance. The observed negative impact on the other outcomes highlights the importance of multidisciplinary approaches to improve postoperative management.

Impact of Wheelchair Seating Systems on Scoliosis Progression for Children With Neurologic and Neuromuscular Disorders: A Retrospective Study Of Custom-Contoured Wheelchair Seating and Modular Wheelchair Seating

OBJECTIVES

To retrospectively evaluate the comparative effect of 2 wheelchair seating systems, Custom-Contoured Wheelchair Seating (CCS) and Modular Wheelchair Seating (MWS), on scoliosis progression in children with neuromuscular and neurologic disorders and to determine any predictors for scoliosis progression.

DESIGN

Longitudinal, retrospective cohort study.

SETTING

A national health service regional posture and mobility service.

PARTICIPANTS

Nonambulant pediatric wheelchair users with neuromuscular and neurologic disorders (N=75; 36 men, 39 women; mean age at seating intervention, 10.50±3.97y) issued CCS and MWS by the South Wales Posture and Mobility Service from 2012-2022.

INTERVENTIONS

Two specialized wheelchair seating systems, CCS and MWS.

MAIN OUTCOME MEASURES

A generalized least squares model was used to estimate the effect of seat type on Cobb angle over time.

RESULTS

Of the 75 participants enrolled, 51% had cerebral palsy. Fifty were issued CCS and 25 were issued MWS. Baseline Cobb angle was 32.9±18.9° for the MWS group and 48.0±31.0° for the CCS group. The generalized least squares model demonstrated that time since seating intervention (χ2=122, P<.0001), seating type (χ2=52.5, P<.0001), and baseline scoliosis severity (χ2=41.6, P<.0001) were predictive of scoliosis progression. Condition was not a strong predictor (χ2=9.96, P =.0069), and sex (χ2=5.67, P=.13) and age at intervention (χ2=4.47, P=.35) were not predictive. Estimated contrasts of medical condition with seat type over time demonstrated smaller differences between MWS and CCS over time. Predicted scoliosis velocity was found to attenuate with use of CCS over time compared with MWS, although scoliosis deteriorated regardless of intervention.

CONCLUSIONS

Our findings showed pediatric wheelchair users with neurologic and neuromuscular disorders prescribed CCS showed greater mitigation of scoliosis progression over time compared with those issued MWS.

Sleep and sleep-related breathing disorders in patients with spinal muscular atrophy: a changing perspective from novel treatments?

Spinal Muscular Atrophy (SMA) is an inherited neuromuscular disorder characterized by progressive muscle weakness and atrophy, resulting from the degeneration of motor neurons in the spinal cord. A critical aspect of SMA is its impact on respiratory function. As the disease progresses, respiratory muscles, in particular intercostal muscles, become increasingly affected, leading to breathing difficulties and respiratory failure. Without intervention, many children with SMA type 1 die from respiratory failure before their second year of life. While assisted ventilation has improved survival, it often results in ventilator dependence. The development of new SMN-augmenting therapies has renewed optimism, but their long-term impact on respiratory function is uncertain, and non-invasive respiratory support remains an important part of SMA management. Despite the importance of respiratory support in SMA, knowledge regarding sleep disorders in this population is limited. This review aims to synthesize existing literature on sleep and sleep-related breathing disorders in patients with SMA, with a focus on SMA type 1. We summarize evidence of sleep-disordered breathing and respiratory failure in SMA, as well as outcomes and survival benefits associated with non-invasive or invasive ventilation with or without pharmacological therapies. We also discuss current knowledge regarding the effects of novel disease-modifying therapies for SMA on respiratory function and sleep. In conclusion, optimal care for children with SMA requires a multidisciplinary approach that includes neurology and respiratory specialists. This review highlights the importance of monitoring sleep and respiratory function in SMA, as well as the potential benefits and challenges associated with assisted ventilation combined with new therapies.

Assessment of the upper limb function, strength, and mobility in treatment-naive children with spinal muscular atrophy Types 2 and 3

INTRODUCTION/AIMS

Current upper limb assessments in pediatric spinal muscular atrophy (SMA) may not adequately capture change with disease progression. Our aim was to examine the relationship between motor function, strength, and hand/finger mobility of the upper limb in treatment-naïve children with SMA Types 2 and 3 to assess new methods to supplement current outcomes.

METHODS

The Revised Upper Limb Module (RULM), grip and pinch strength, and hand/finger mobility data were collected from 19 children with SMA Types 2 and 3 aged 5.2-16.9 years over a year.

RESULTS

A median loss between 0.5 and 2.5 points in the RULM was seen across all SMA subgroups with the biggest median loss recorded between 10 and 14 years of age. The grip strength loss was -0.06 kg (-4.69 to 3.49; IQR, 1.21); pinch improvement of 0.05 (-0.65 to 1.27; IQR, 0.48); hand/finger mobility test improvement of 4 points (-24 to 14; IQR, 6.75) for the whole cohort. Significant correlations were found between the RULM and grip strength (p < .001), RULM and pinch strength (p < .001), RULM and revised Brooke (p < .001), grip strength and pinch strength (p < .001).

DISCUSSION

The combined use of the RULM, dynamometry, and hand mobility provide insight about correlations between function and strength in children with SMA. The RULM and grip strength assessments captured a significant decline in upper limb function, whereas the pinch and finger/hand mobility showed an improvement over the course of 1 year and these results should be considered for future studies.

A Systematic Literature Review of the Natural History of Respiratory, Swallowing, Feeding, and Speech Functions in Spinal Muscular Atrophy (SMA)

Background

Respiratory and bulbar dysfunctions (including swallowing, feeding, and speech functions) are key symptoms of spinal muscular atrophy (SMA), especially in its most severe forms. Demonstrating the long-term efficacy of disease-modifying therapies (DMTs) necessitates an understanding of SMA natural history.

Objective

This study summarizes published natural history data on respiratory, swallowing, feeding, and speech functions in patients with SMA not receiving DMTs.

Methods

Electronic databases (Embase, MEDLINE, and Evidence-Based Medicine Reviews) were searched from database inception to June 27, 2022, for studies reporting data on respiratory and/or bulbar function outcomes in Types 1-3 SMA. Data were extracted into a predefined template and a descriptive summary of these data was provided.

Results

Ninety-one publications were included: 43 reported data on respiratory, swallowing, feeding, and/or speech function outcomes. Data highlighted early loss of respiratory function for patients with Type 1 SMA, with ventilatory support typically required by 12 months of age. Patients with Type 2 or 3 SMA were at risk of losing respiratory function over time, with ventilatory support initiated between the first and fifth decades of life. Swallowing and feeding difficulties, including choking, chewing problems, and aspiration, were reported in patients across the SMA spectrum. Swallowing and feeding difficulties, and a need for non-oral nutritional support, were reported before 1 year of age in Type 1 SMA, and before 10 years of age in Type 2 SMA. Limited data relating to other bulbar functions were collated.

Conclusions

Natural history data demonstrate that untreated patients with SMA experience respiratory and bulbar function deterioration, with a more rapid decline associated with greater disease severity. This study provides a comprehensive repository of natural history data on bulbar function in SMA, and it highlights that consistent assessment of outcomes in this area is necessary to benefit understanding and approval of new treatments.

Spinal Muscular Atrophy: A (Now) Treatable Neurodegenerative Disease

Spinal muscular atrophy (SMA) is a progressive disease of the lower motor neurons associated with recessive loss of the SMN1 gene, and which leads to worsening weakness and disability, and is fatal in its most severe forms. Over the past six years, three treatments have emerged, two drugs that modify exon splicing and one gene therapy, which have transformed the management of this disease. When treated pre-symptomatically, many children show normal early motor development, and the benefits extend from the newborn period to adulthood. Similar treatment approaches are now under investigation for rare types of SMA associated with genes beyond SMN1.

Examination of Upper Limb Function and the Relationship with Gross Motor Functional and Structural Parameters in Patients with Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by the deletion or/and mutation in the survival motor neuron 1 (SMN1) gene on chromosome 5. Until now, only a few articles investigating the relationship between upper limb function and the gross motor function in untreated SMA patients have been published. However, there is still a lack of publications including the relationship between structural changes such as cervical rotation, trunk rotation and side trunk shortening, and upper limb function. The aim of the study was to examine the upper limb function in patients with spinal muscular atrophy and the relationship between the upper limb function, gross motor function, and structural parameters. We present an analysis of 25 SMA patients, divided into sitter and walker groups, undergoing pharmacological treatment (nusinersen or risdiplam), examined twice between the initial examination and evaluation after a 12-month period. The participants were tested using validated scales such as the Revised Upper Limb Module (RULM), the Hammersmith Functional Motor Scale-Extended (HFMSE), and the structural parameters. Our results showed that patients demonstrated greater improvement on the RULM scale than on the HFMSE scale. Moreover, persistent structural changes negatively affected both the upper limb function and gross motor skills.

The Association between the Respiratory System and Upper Limb Strength in Males with Duchenne Muscular Dystrophy: A New Field for Intervention?

Progressive, irreversible muscle weakness is the leading symptom of Duchenne muscular dystrophy (DMD), often resulting in death from respiratory muscle failure. Little is known about the relationship between the functioning of the respiratory system and the hand grip-a function which remains long preserved. This study aimed to investigate the interdependence between muscle strength and the function of both hand grip and the respiratory system in patients with DMD.

MATERIALS AND METHOD

The study included cohort patients, aged 6-17, with DMD, recruited from the Rare Disease Centre, Gdansk, Poland. Clinical status (Vignos scale, Brook scale), pulmonary function (respiratory muscle strength-MIP, MEP); spirometry (FEV1; FVC), as well as upper limb function (performance of the upper limb-PUL 2.0) and hand grip strength (HGS) (hand-held dynamometer) were evaluated in all participants.

RESULTS

Finally, 53 boys (mean age 11.41 ± 3.70 years, 25 non-ambulant) were included. Each of the participants presented a lower %pv of MIP (48.11 ± 27), MEP (38.11 ± 22), PUL (75.64 ± 27), and HGS (33.28 ± 18). There were differences between the ambulatory and non-ambulatory groups in values of MIP, MEP, FVC, PUL, HGS (p < 0.001 for all), and FEV1 (p < 0.013). There were correlations between PUL, HGS, and MIP (R = 0.56; R = 0.61, p < 0.001 both), MEP (R = 0.59; R = 0.62, p < 0.001), FVC (R = 0.77; R = 0.77, p < 0.001), and FEV1 (R = 0.77; R = 0.79; p < 0.001). These correlations were found for all participants, but non-ambulatory patients presented stronger relationships.

CONCLUSIONS

1. The pulmonary and upper limb functions were within the normal range in ambulatory and low in non-ambulatory patients with DMD, but the muscle strength of both systems was low, regardless of the stage of the disease. 2. There seems to be an interdependence between the respiratory system and upper limb strength in terms of muscle strength and function in DMD patients, which is stronger in non-ambulatory patients. This may be the basis for the creation of a new personalized plan in rehabilitation-the simultaneous rehabilitation of the respiratory and upper limb muscles. Further studies on this theory should be conducted.