Six-minute walk test as outcome measure of fatigability in adults with spinal muscular atrophy treated with nusinersen.

INTRODUCTION/AIMS: Fatigue (subjective perception) and fatigability (objective motor performance worsening) are relevant aspects of disability in individuals with spinal muscular atrophy (SMA). The effect of nusinersen on fatigability in SMA patients has been investigated with conflicting results. We aimed to evaluate this in adult with SMA3. METHODS: We conducted a multicenter retrospective cohort study, including adult ambulant patients with SMA3, data available on 6-minute walk test (6MWT) and Hammersmith Functional Motor Scale-Expanded (HFMSE) at baseline and at least at 6 months of treatment with nusinersen. We investigated fatigability, estimated as 10% or higher decrease in walked distance between the first and sixth minute of the 6MWT, at baseline and over the 14-month follow-up. RESULTS: Forty-eight patients (56% females) were included. The 6MWT improved after 6, 10, and 14 months of treatment (p < 0.05). Of the 27 patients who completed the entire follow-up, 37% improved (6MWT distance increase ≥30 m), 48.2% remained stable, and 14.8% worsened (6MWT distance decline ≥30 m). Fatigability was found at baseline in 26/38 (68%) patients and confirmed at subsequent time points (p < 0.05) without any significant change over the treatment period. There was no correlation between fatigability and SMN2 copy number, sex, age at disease onset, age at baseline, nor with 6MWT total distance and baseline HFMSE score. DISCUSSION: Fatigability was detected at baseline in approximately 2/3 of SMA3 walker patients, without any correlation with clinical features, included motor performance. No effect on fatigability was observed during the 14-month treatment period with nusinersen.

Adults with spinal muscular atrophy: a large-scale natural history study shows gender effect on disease.

BACKGROUND: Natural history of spinal muscular atrophy (SMA) in adult age has not been fully elucidated yet, including factors predicting disease progression and response to treatments. Aim of this retrospective, cross-sectional study, is to investigate motor function across different ages, disease patterns and gender in adult SMA untreated patients. METHODS: Inclusion criteria were as follows: (1) clinical and molecular diagnosis of SMA2, SMA3 or SMA4 and (2) clinical assessments performed in adult age (>18 years). RESULTS: We included 64 (38.8%) females and 101 (61.2%) males (p=0.0025), among which 21 (12.7%) SMA2, 141 (85.5%) SMA3 and 3 (1.8%) SMA4. Ratio of sitters/walkers within the SMA3 subgroup was significantly (p=0.016) higher in males (46/38) than in females (19/38). Median age at onset was significantly (p=0.0071) earlier in females (3 years; range 0-16) than in males (4 years; range 0.3-28), especially in patients carrying 4 SMN2 copies. Median Hammersmith Functional Rating Scale Expanded scores were significantly (p=0.0040) lower in males (16, range 0-64) than in females (40, range 0-62); median revised upper limb module scores were not significantly (p=0.059) different between males (24, 0-38) and females (33, range 0-38), although a trend towards worse performance in males was observed. In SMA3 patients carrying three or four SMN2 copies, an effect of female sex in prolonging ambulation was statistically significant (p=0.034). CONCLUSIONS: Our data showed a relevant gender effect on SMA motor function with higher disease severity in males especially in the young adult age and in SMA3 patients.

Nusinersen safety and effects on motor function in adult spinal muscular atrophy type 2 and 3.

OBJECTIVE: To retrospectively investigate safety and efficacy of nusinersen in a large cohort of adult Italian patients with spinal muscular atrophy (SMA). METHODS: Inclusion criteria were: (1) clinical and molecular diagnosis of SMA2 or SMA3; (2) nusinersen treatment started in adult age (>18 years); (3) clinical data available at least at baseline (T0-beginning of treatment) and 6 months (T6). RESULTS: We included 116 patients (13 SMA2 and 103 SMA3) with median age at first administration of 34 years (range 18-72). The Hammersmith Functional Rating Scale Expanded (HFMSE) in patients with SMA3 increased significantly from baseline to T6 (median change +1 point, p<0.0001), T10 (+2, p<0.0001) and T14 (+3, p<0.0001). HFMSE changes were independently significant in SMA3 sitter and walker subgroups. The Revised Upper Limb Module (RULM) in SMA3 significantly improved between T0 and T14 (median +0.5, p=0.012), with most of the benefit observed in sitters (+2, p=0.018). Conversely, patients with SMA2 had no significant changes of median HFMSE and RULM between T0 and the following time points, although a trend for improvement of RULM was observed in those with some residual baseline function. The rate of patients showing clinically meaningful improvements (as defined during clinical trials) increased from 53% to 69% from T6 to T14. CONCLUSIONS: Our data provide further evidence of nusinersen safety and efficacy in adult SMA2 and SMA3, with the latter appearing to be cumulative over time. In patients with extremely advanced disease, effects on residual motor function are less clear.

Subjective Sleep Quality as it Relates to Cognitive and Physical Function in Spinal Muscular Atrophy Patients.

Sleep quality and its association with cognition has been widely studied in some neurodegenerative diseases, but less is known about this association in spinal muscular atrophy (SMA). In adult SMA (n = 21) patients and age-matched controls (n = 23), we assessed subjectively measured sleep quality and daytime somnolence. Cognition was assessed with a multi-domain neuropsychological battery. Further, we investigated the association between clinical functional scores and sleep questionnaire scores. Among SMA patients, better motor and limb function was associated with better subjective sleep quality (p's< 0.05). Clinicians should consider sleep quality in patient care and future studies are needed to better understand these relationships.

Cognitive profiles and clinical factors in type III spinal muscular atrophy: a preliminary study.

Cognitive abilities are often affected in progressive neurodegenerative disorders, but there is a lack of understanding about whether spinal muscular atrophy (SMA) patients experience cognitive deficits and, if so, whether they are associated with clinical factors. A sample of 22 type III SMA patients and 22 healthy controls completed a comprehensive neuropsychological battery, including tests in memory, executive function, language, visuospatial, and global cognitive functioning. Clinical severity was assessed using the Hammersmith Functional Motor Scale, the Revised Upper Limb Module and the Six Minute Walk Test. SMA patients showed poorer performance in visuospatial abilities, executive functions and language as compared to healthy controls. In the SMA sample, patients with greater motor difficulties had lower performance in attention, but higher performance in measures of language, verbal fluency, and memory. In men, but not women, cognitive test performance was associated with motor functioning. Our findings showing cognitive changes in SMA type III may reflect the presence of intrinsic brain pathology and cognitive adaptation mechanisms following physical dysfunction, which may be mediated by other factors, such as sex.

Quality of life assessment in adult spinal muscular atrophy patients treated with nusinersen.

OBJECTIVE: To retrospectively evaluate quality of life (QoL) in a large multicenter cohort of adult patients affected by spinal muscular atrophy (SMA) during nusinersen treatment. METHODS: We included adult (≥ 18 years) patients clinically and genetically defined as SMA2, SMA3 and SMA4, who started nusinersen treatment in adulthood. QoL was rated by the Individualized Neuromuscular Quality of Life (INQoL) questionnaire. Concurrent motor function evaluation included the Hammersmith Functional Motor Scale Expanded (HFMSE), the Revised Upper Limb Module (RULM), the 6 min walking test (6MWT). RESULTS: 189 completed questionnaires were collected during a 14 months' treatment period. 78 patients were included (7 SMA2 and 69 SMA3 and 2 SMA4) with mean disease duration at first nusinersen administration of 33.2 years (± 12.5 years). All the scores for each INQoL domain (weakness, fatigue, activities, independence, social relationship, emotions, body images) and the derived QoL total score, significantly improved during the observation period, except the muscle locking and pain items. Exploratory analyses suggested that emotions and social relationships were more relevant issues for females compared to males. Social relationships were affected also by a longer disease duration (> 30 years). In SMA3 non-walker patients, activities ameliorate better compared to walkers. The HFMSE and RULM significantly improved from baseline; however, no associations with QoL total score and weakness, activities or independence were demonstrated. CONCLUSION: In our cohort, adult SMA patients showed a global improvement at the INQoL assessment over 14 months of nusinersen treatment. QoL assessment is relevant to SMA multidisciplinary evaluation.

Muscle MRI and functional outcome measures in Becker muscular dystrophy.

Becker muscular dystrophy (BMD) is a neuromuscular disorder allelic to Duchenne muscular dystrophy (DMD), caused by in-frame mutations in the dystrophin gene, and characterized by a clinical progression that is both milder and more heterogeneous than DMD. Muscle magnetic resonance imaging (MRI) has been proposed as biomarker of disease progression in dystrophinopathies. Correlation with clinically meaningful outcome measures such as North Star Ambulatory Assessment (NSAA) and 6 minute walk test (6MWT) is paramount for biomarker qualification. In this study, 51 molecularly confirmed BMD patients (aged 7-69 years) underwent muscle MRI and were evaluated with functional measures (NSAA and 6MWT) at the time of the MRI, and subsequently after one year. We confirmed a pattern of fatty substitution involving mainly the hip extensors and most thigh muscles. Severity of muscle fatty substitution was significantly correlated with specific DMD mutations: in particular, patients with an isolated deletion of exon 48, or deletions bordering exon 51, showed milder involvement. Fat infiltration scores correlated with baseline functional measures, and predicted changes after 1 year. We conclude that in BMD, skeletal muscle MRI not only strongly correlates with motor function, but also helps in predicting functional deterioration within a 12-month time frame.

Functional changes in Becker muscular dystrophy: implications for clinical trials in dystrophinopathies.

We performed a 1-year longitudinal study of Six Minute Walk Test (6MWT), North Star Ambulatory Assessment (NSAA), and timed function tests in Becker muscular dystrophy (BMD). Skeletal muscle dystrophin was quantified by immunoblot. We grouped deletions ending on exon 45 ("del 45-x", n = 28) or 51 ("del x-51", n = 10); isolated exon 48 deletion ("del 48", n = 10); and other mutations (n = 21). Only patients in the "del 45-x" or "other" groups became non-ambulatory (n = 5, log-rank p = n.s.) or unable to run (n = 22, p < 0.001). All measures correlated positively with dystrophin quantity and negatively with age, and were significantly more impaired in the "del 45-x" and "other" groups. After one year, NSAA score decreased significantly (-0.9 ± 1.6, p < 0.001); in the "del 45-x" group, both NSAA (-1.3 ± 1.7, p = 0.001) and 6MWT (-12 ± 31 m, p = 0.059) decreased. We conclude that patients with "del x-51" or "del 48" mutations have mild or asymptomatic BMD, while "del 45-x" mutations cause comparatively severe weakness, and functional deterioration in 1 year. Furthermore, exon 51 skipping could be more effective than exon 45 skipping in Duchenne muscular dystrophy.