Motor and Cognitive Fatigue in Chronic Inflammatory Demyelinating Polyneuropathy

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is the most prevalent dysimmune disease of sensorimotor nerves. However, based on various non-sensorimotor symptoms (NSMS), the concept of a purely peripheral condition has recently been challenged. Against this background, we aimed to differentiate motor and cognitive components of fatigue as the most prominent NSMS in CIDP.

Cognitive and motor fatigue constructs were assessed in 47 CIDP patients and 31 healthy controls (HC) using the Fatigue Scale for Motor and Cognitive Functions (FSMC). The results were referred to score data for sensorimotor disability as well as for depressiveness, sleep quality, and alertness, describing functional levels potentially related to fatigue. Further, they were analyzed with respect to serum neurofilament light chain (sNfL), a biomarker of disease progression and potentially central involvement in CIDP.

CIDP patients reported significantly higher scores of total (p < 0.001), motor (p < 0.001), and cognitive (p = 0.005) fatigue compared to HC. Within the CIDP group, motor fatigue was more pronounced than cognitive fatigue compared to HC (p < 0.001). Although alertness levels did not differ significantly between the groups, poorer alertness correlated with cognitive fatigue in the CIDP cohort (p = 0.02). Notably, only functional disability and depressiveness served as predictors for both fatigue components (p < 0.05). sNfL levels showed no significant association with fatigue.

These findings show that the burden of CIDP is not sufficiently described by sensorimotor disability. A clinically relevant NSMS aspect of the disease is fatigue in motor as well as cognitive dimensions.