Background Efficacy of nusinersen in adult 5q-spinal muscular atrophy (SMA) patients regarding motor function has recently been demonstrated. However, additional outcome measures are needed to capture non-motor improvements. Fatigue is a common and disabling symptom in neurologic diseases, but little is known about its frequency, characteristics and associated factors in SMA. Objective To characterize fatigue in SMA patients receiving nusinersen, identify associated factors and evaluate fatigue as potential patient-reported outcome measure (PRO). Methods We assessed fatigue in adults with genetically confirmed 5q-SMA in a prospective longitudinal monocentric study using the Fatigue Severity Scale (FSS) and the Multidimensional Fatigue Inventory (MFI). Factors associated with fatigue including health-related quality of life (HRQOL) were evaluated. Results 75% of participants were abnormally fatigued with highest scores in the dimensions physical, followed by general fatigue and reduced activity. 53% agreed that fatigue was among their three most disabling symptoms. Reduced activity was reported more extensively by participants with ≥ 4 copies of the survival of motor neuron 2 gene and better motor function. General and mental fatigue correlated positively with age and disease duration. HRQOL was inversely correlated with physical fatigue, which was not associated with disease or participant characteristics. During 14 months of nusinersen treatment, fatigue measures remained mostly stable with a trend towards improvement in reduced activity, general and physical fatigue. Conclusion Fatigue is a frequent and relevant complaint in adult SMA patients. Fatigue should be taken into consideration as additional outcome measure, but needs further evaluation in a larger patient cohort over a longer observation period.

Motor neuron diseases, such as spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), share several clinical similarities while differing substantially in etiology, disease onset and progression. Cognitive dysfunction, a clinically relevant non-motor feature in a substantial proportion of ALS patients, has been less frequently investigated in SMA. In this prospective multicenter cross-sectional study, cognitive function was assessed by the Edinburgh Cognitive (and Behavioural) ALS Screen (ECAS) and a German vocabulary test (Wortschatztest, WST) in 34 adult patients with SMA types 2–4 and in 34 patients with ALS. Demographic and clinical parameters were assessed to identify factors that potentially influence cognitive function. While SMA and ALS patients were comparable in the vocabulary test, on average, SMA patients performed better than ALS patients in the cognitive domains of memory, language and executive function. Better cognitive abilities in SMA patients seemed to be related to the early onset, rather than the extent or the duration, of their physical handicap. Future studies should focus on disease-specific cognitive functions in SMA.

Objective Fatigue is a common and burdensome symptom of spinal muscular atrophy. Given its complex interactions, different dimensions of fatigue need to be investigated. The Multidimensional Fatigue Inventory is a widely used instrument that captures five distinct dimensions. The aim of this study was to investigate the validity and reliability of the German Multidimensional Fatigue Inventory in spinal muscular atrophy and to evaluate the presence of clinically relevant fatigue. Methods One hundred and forty adult spinal muscular atrophy patients completed the Multidimensional Fatigue Inventory in a nationwide, multicenter, cross‐sectional study. Structural validity was explored using principal component analysis. Cronbach’s α was calculated to evaluate internal consistency. Convergent validity was assessed by correlation with a Visual Analog Scale for fatigue and the EuroQol‐Five Dimension‐Five Level Scale as a measure of quality of life. Results The original five‐component model of the questionnaire constituted an acceptable fit. Internal consistency and convergent validity of general, physical, mental fatigue, and reduced activity were good. We observed a floor effect for mental fatigue. While physical fatigue exceeded the cutoff for clinically relevant fatigue, all dimensions but reduced motivation correlated negatively with quality of life. Age, depression, and ≥4 copies of the survival motor neuron 2 gene were associated with higher general/physical fatigue; unemployed participants reported higher scores for reduced activity/motivation. Interpretation The Multidimensional Fatigue Inventory is a valid and reliable instrument to assess different dimensions of fatigue in spinal muscular atrophy. Fatigue is a relevant problem in spinal muscular atrophy and its assessment should be incorporated into standard care.

Real-world data have shown mild improvement of overall motor function in adult patients treated with nusinersen, the first approved therapy for 5q-spinal muscular atrophy (SMA). However, knowledge about preferably targeted muscle functions is sparse. The aim of this study was to evaluate strength of distinct muscles and body regions in adult SMA patients in the early course of nusinersen therapy. 72 muscles of 15 patients were tested on the Medical Research Council (MRC) 0–10 scale (translated into MRC %) from nusinersen start to 14 months of treatment. The whole body muscular strength improved slightly or remained stable in 80% of SMA patients with a median improvement of + 2%. However, relevant increases of muscle strength of distinct regions were identified in the proximal upper limbs and shoulder girdle (median + 8%) and in muscle groups with a preserved function pre-treatment, even in more advanced diseased SMA patients. MRC grading was additionally performed in seven patients enrolled during ongoing treatment. Here, further improvement of muscle strength until month 18–26 was seen with the highest increases in the proximal upper and lower limbs. Our findings suggest that sole evaluation of the overall muscle strength might underestimate nusinersen therapy benefits.