Fatigue and Its Association with Upper Limb Function in People with Multiple Sclerosis

<b>Background and Objectives:</b> This cross-sectional study investigates the association between fatigue and upper limb (UL) function in people with Multiple Sclerosis (PwMS). <b>Methods:</b> Adult PwMS were recruited from five Italian MS centers. Fatigue was evaluated using the Modified Fatigue Impact Scale (MFIS), while UL function was assessed through the Box and Block Test (BBT), Nine-Hole Peg Test (9HPT), and Hand-Grip Strength (HGS). Data analysis included Spearman rank correlations and Mann-Whitney U tests. <b>Results:</b> A total of 261 participants were involved. Significant correlations were found between fatigue severity, UL function, and patient-reported manual ability. Physical and cognitive aspects of fatigue were independently related to functional impairments. Participants with clinically relevant fatigue demonstrated lower subjective UL function, poorer BBT and HGS performance, and greater HGS asymmetry. <b>Discussion:</b> The study underscores the complex relationship between fatigue and functional impairments in MS. The findings suggest both strength and dexterity contribute to the perception of clinically relevant fatigue in PwMS, highlighting the importance of incorporating both domains to complement neurological assessment. <b>Conclusion:</b> Fatigue in PwMS is linked to both subjective and objective measures of UL function. Assessing strength and dexterity alongside fatigue may enhance clinical understanding and inform targeted rehabilitation strategies.