Fatigue in patients with spinal muscular atrophy types 2 and 3

*Correspondence: [e-mail].

Abstract

Background: Fatigue is a frequent disabling primary symptom in Spinal Muscular Atrophy (SMA) patients. It results in low levels of physical activity, significantly impairing patients' quality of life.

Objective: To evaluate perceived and physiological fatigue in individuals with SMA type 2 and 3, and to establish its relationship with other important aspects, such as muscle strength, motor and respiratory function.

Methods: We evaluated fatigue in children and adults with a confirmed genetic diagnosis for SMA, in a cross-sectional observational study, using the Fatigue Severity Scale (FSS, Portuguese version) and Multidimensional Fatigue Scale (PedsQL MFS, Portuguese version) to assessment of perceived fatigue and repeated nine hole peg test (r9HPT) and Endurance Shuttle Walk Test (ESWT) to assess physiological fatigue. Factors associated with fatigue, including muscle strength, motor function and vital capacity (VC) were also evaluated.

Results: In total, 28 participants with SMA types 2 and 3 were included, with a mean age of 20.6 ± 11.8 years. Participants' reports of perceived fatigue through the PedsQL MFS were similar to those of caregivers. Perceived fatigue was similar for SMA type 2 and 3 participants (PedsQL MFS self-report: 75.9; 70.5). Perceived fatigue was common in adult participants with 58.4% reporting abnormal or several fatigue (FSS > 4). Perceived fatigue was not associated with motor function, respiratory function and physiological fatigue. All correlations showed alpha levels of p > 0.05. In the evaluation of physiological fatigue through the r9HPT, it was observed that SMA type 2 participants showed significantly worse performance than participants with type 3. The results of the r9HPT were shown to be correlated with the VC and muscle strength of elbow flexors, with a value of p < 0.05. In ambulatory patients who performed the ESWT, none were able to complete the maximum time of 1200 seconds. The median time the test was interrupted was 186.9 seconds, which represents 16% of the maximum time.

Conclusion: Fatigue is a frequent and relevant complaint in SMA patients. The relationship between perceived and physiological fatigue is complex and requires a multifactorial approach that encompasses the various mechanisms involved in fatigue in SMA.

Publication History

Article published online:
12 May 2025