Fatigue in amyotrophic lateral sclerosis and correlated factors

Background Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to muscle weakness and paralysis. Fatigue is a disabling symptom, frequently reported in ALS, but remains under-investigated in this population. Thus, an accurate investigation of this symptom and possible associated factors in this clinical condition is needed to assist in the establishment of an adequate treatment approach. Objective To investigate the presence of fatigue in individuals with ALS and possible factors correlated with this symptom. Methods Sixty-five individuals with sporadic ALS participated in the present study. Demographic, clinical, and functional aspects were investigated. Evaluations involved the Fatigue Severity Scale (FSS), ALS Functional Scale (ALSRFS-R), and Quality of Life (QoL) questionnaire (ALSAQ-40). Descriptive and correlation analyses were performed with SPSS statistical program for Windows version 19.0 (IBM Corp., Armonk, NY, USA). Results Among the 65 individuals evaluated, 44.6% ( n = 29) presented fatigue based on the FSS. The mean fatigue intensity was 5.4 ± 1.2 and only 10.4% used a specific medication for fatigue. Differences between the groups with and without fatigue were found regarding sex ( p = 0.049), pain intensity ( p = 0.026), functioning ( p = 0.004), disease severity ( p = 0.029), and QoL ( p = 0.000). Fatigue was correlated with pain intensity (r = 0.425; p = 0.001), muscle strength (r = - 0.356; p = 0.004), functioning (r = - 0.363; p = 0.003), and QoL (r = 0.481; p = 0.000). No correlations were found with age, time since diagnosis, cramps, or other mobility parameters. Conclusions Fatigue is a common symptom among individuals with ALS and may be present in all stages of the disease. This symptom was correlated with worse functioning, poorer QoL, greater pain intensity, disease severity, muscle weakness, and the female sex in individuals with ALS.