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

Introduction/Aims: Spinal muscular atrophy (SMA) type III is a relatively mild form of SMA. Few studies have investigated the changes in both respiratory and upper limb function within this population after loss of ambulation. The aim of this study was to assess change in percentage of predicted forced vital capacity (FVC% predicted) and change in the Revised Upper Limb Module (RULM) score in these patients throughout a 24-month period after loss of ambulation. Effect of scoliosis and its surgical correction, disease duration since loss of ambulation, weight, and height were also investigated. / Methods: Retrospective analyses were performed on 24 nonambulant SMA III patients from data collected at two centers in the United Kingdom. / Results: The FVC% predicted score showed a significant progressive deterioration of 17% over the 24-month period. Respiratory deterioration correlated significantly with age, weight, disease duration since loss of ambulation, and spinal correctional surgery. Longitudinal RULM data were available for 16 patients; a significant deterioration was observed with a mean decrease in score of 3 over 24 months. Age correlated negatively with RULM score, as did height and time since loss of ambulation. A significant positive correlation between FVC% predicted and RULM was demonstrated. / Discussion: This study highlights how SMA type III patients have progressive deterioration of respiratory and upper limb function after loss of ambulation. Combining data from these assessments could provide insight into clinical progression, inform clinical trials, and provide assistance in managing disease progression expectations for patients

Development of an International SMA Bulbar Assessment for Inter-professional Administration

BACKGROUND: Progressive weakness can affect bulbar muscles in individuals with moderate to severe forms of spinal muscular atrophy (SMA). The paucity of standardized, valid bulbar assessments capturing clinically significant deficits in SMA impedes the ability to monitor function, facilitate intervention, or detect treatment response. OBJECTIVE: To fill this void, an international multidisciplinary team gathered to develop an agreed upon consensus-derived assessment of bulbar function in SMA for inter-professional administration to enhance our ability to monitor disease progression, support clinical management, and evaluate treatment effects. METHODS: Fifty-six international clinicians experienced in SMA were invited and engaged using the Delphi method over multiple rounds of web-based surveys to establish consensus. RESULTS: Serial virtual meetings occurred with 42 clinicians (21 speech and language therapists, 11 physical therapists, 5 neurologists, 4 occupational therapists, and 1 dentist). Seventy-two validated assessments of bulbar function were identified for potential relevance to individuals with SMA (32 accessible objective, 11 inaccessible objective, 29 patient-reported outcomes). Delphi survey rounds (n = 11, 15, 15) achieved consensus on individual items with relevance and wording discussed. Key aspects of bulbar function identified included: oral intake status, oral facial structure and motor strength, swallowing physiology, voice & speech, and fatigability. CONCLUSIONS: Multidisciplinary clinicians with expertise in bulbar function and SMA used Delphi methodology to reach consensus on assessments/items considered relevant for SMA across all age groups. Future steps include piloting the new scale moving towards validation/reliability. This work supports the advancement of assessing bulbar function in children and adults with SMA by a variety of professionals

Functional abilities, respiratory and cardiac function in a large cohort of adults with Duchenne muscular dystrophy treated with glucocorticoids

\ua9 2024 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.Background and purpose: The transition to adult services, and subsequent glucocorticoid management, is critical in adults with Duchenne muscular dystrophy. This study aims (1) to describe treatment, functional abilities, respiratory and cardiac status during transition to adulthood and adult stages; and (2) to explore the association between glucocorticoid treatment after loss of ambulation (LOA) and late-stage clinical outcomes. Methods: This was a retrospective single-centre study on individuals with Duchenne muscular dystrophy (≥16 years old) between 1986 and 2022. Logistic regression, Cox proportional hazards models and survival analyses were conducted utilizing data from clinical records. Results: In all, 112 individuals were included. Mean age was 23.4 \ub1 5.2 years and mean follow-up was 18.5 \ub1 5.5 years. At last assessment, 47.2% were on glucocorticoids; the mean dose of prednisone was 0.38 \ub1 0.13 mg/kg/day and of deflazacort 0.43 \ub1 0.16 mg/kg/day. At age 16 years, motor function limitations included using a manual wheelchair (89.7%), standing (87.9%), transferring from a wheelchair (86.2%) and turning in bed (53.4%); 77.5% had a peak cough flow <270 L/min, 53.3% a forced vital capacity percentage of predicted <50% and 40.3% a left ventricular ejection fraction <50%. Glucocorticoids after LOA reduced the risk and delayed the time to difficulties balancing in the wheelchair, loss of hand to mouth function, forced vital capacity percentage of predicted <30% and forced vital capacity <1 L and were associated with lower frequency of left ventricular ejection fraction <50%, without differences between prednisone and deflazacort. Glucocorticoid dose did not differ by functional, respiratory or cardiac status. Conclusion: Glucocorticoids after LOA preserve late-stage functional abilities, respiratory and cardiac function. It is suggested using functional abilities, respiratory and cardiac status at transition stages for adult services planning

Clinical variability in spinal muscular atrophy type III

Objective: We report natural history data in a large cohort of 199 patients with spinal muscular atrophy (SMA) type III assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE). The aim of the study was to establish the annual rate and possible patterns of progression according to a number of variables, such as age of onset, age at assessment, SMN2 copy number, and functional status. Methods: HFMSE longitudinal changes were assessed using piecewise linear mixed‐effects models. The dependency in the data due to repeated measures was accounted for by a random intercept per individual and an unstructured covariance R matrix was used as correlation structure. An additional descriptive analysis was performed for 123 patients, for a total of 375 12‐month assessments. Results: A break point at age 7 years was set for the whole cohort and for SMA IIIA and IIIB. Age, SMA type, and ambulatory status were significantly associated with changes in mean HFMSE score, whereas gender and SMN2 copy number were not. The increase in response before the break point of age 7 years is significant only for SMA IIIA (β = 1.79, p < 0.0001). After the break point, the change in the rate of HFMSE score significantly decrease for both SMA IIIA (β = −1.15, p < 0.0001) and IIIB (β = −0.69, p = 0.002). Interpretation: Our findings contribute to the understanding of the natural history of SMA type III and will be helpful in the interpretation of the real‐world data of patients treated with commercially available drugs. ANN NEUROL 2020;88:1109–111

Respiratory trajectories in type 2 and non-ambulant 3 Spinal muscular atrophy in the iSMAC cohort study

OBJECTIVE: To describe the respiratory trajectories and their correlation with motor function in an international paediatric cohort of patients with type 2 and non-ambulant type 3 spinal muscular atrophy (SMA). METHODS: Eight-year retrospective observational study of patients in the iSMAc natural history study. We retrieved anthropometrics, forced vital capacity (FVC) absolute, FVC% predicted (FVC%P.), Non-Invasive ventilation (NIV) requirement. Hammersmith functional motor scale (HFMS) and Revised performance of upper limb (RULM) were correlated with respiratory function. We excluded patients in interventional clinical trials and on Nusinersen commercial therapy. RESULTS: There were 437 patients with SMA: 348 type 2, 89 non-ambulant type 3. Mean age at first visit was 6.9(±4.4) and 11.1(±4) years. In SMA type 2 FVC%P declined by 4.2%/year from 5 to 13 years, followed by a slower decline (1.0%/year). In type 3 FVC%P declined by 6.3%/year between 8 and 13 years, followed by a slower decline (0.9%/year). 39% SMA type 2 and 9% type 3 required NIV at median age 5.0(1.8-16.6) and 15.1(13.8-16.3) years. 84% SMA type 2 and 80% type 3 had scoliosis, 54% and 46% required surgery, which did not significantly affect respiratory decline. FVC%P positively correlated with HFMS and RULM in both subtypes. CONCLUSIONS: In SMA type 2 and non-ambulant type 3 lung function declines differently, with a common levelling after age 13 years. Lung and motor function correlated in both subtypes. Our data further defines the milder SMA phenotypes and provides novel information to benchmark the long-term efficacy of new treatments for SMA