Residual fatigue in Guillain-Barré syndrome is related to axonal loss

Objective: To determine the occurrence of residual loss of peripheral nerve axons by motor unit number estimation (MUNE) and conventional nerve conduction studies (NCS) in patients with and without severe fatigue. Methods: Thirty-nine patients at a median of 8 years (range 1-23 years) after diagnosis of Guillain-Barré syndrome were neurologically examined and divided in 2 subgroups based on the presence of severe fatigue (defined as a fatigue severity score ≥5). All patients were investigated with standard NCS and MUNE. Normal values for MUNE were collected in 14 healthy controls. Results: MUNE of the thenar muscles was lower in the 15 patients with severe fatigue (median 125, interquartile range 65-141) compared with the 24 patients without severe fatigue (median 258, interquartile range 120-345) (p = 0.002). In the healthy controls, MUNE was 358 (245-416). Severe fatigue was also related to lower sensory nerve action potential amplitude of the median (p = 0.01) and ulnar nerve (p = 0.03). The 2 subgroups did not differ regarding neurologic deficits, disability, and the remaining conventional motor NCS. Conclusion: This study demonstrates that severe fatigue after Guillain-Barré syndrome is related to more pronounced axonal loss, represented by lower MUNEs and lower sensory nerve action potentials.

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