Dose–Effect Relationship of Motor Nerve Inexcitability on Outcome in Guillain–Barré Syndrome: A Prospective Cohort Study

Abstract

Objective: One or more inexcitable motor (IM) nerves are common during electrodiagnostic (EDx) study in Guillain–Barré syndrome (GBS). This study assessed the dose–effect relationship of IM nerves on outcome in patients with acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor and/or sensory axonal neuropathy (AMAN and AMSAN). Materials and Methods: Eighty-eight GBS patients admitted during May 2018–June 2023 underwent detailed clinical evaluation and EDx study. Admission and follow-up disability were assessed on a 0–10 Clinical Grading Scale (CGS). Outcome was recovery at 6 months, defined as good (CGS <3) and poor (CGS ≥3). Binary multivariate logistic regression with backward elimination was used to calculate independent predictors of outcome. Results: Proportion of patients with complete recovery decreased significantly with increasing numbers of IM nerves (P < 0.01). Seventy-six patients were followed for 6 months. Among patients with IM nerves (n = 28), complete recovery was similar between AIDP and axonal GBS (70% vs. 50%, respectively; P = 0.40). However, in patients with recordable compound muscle action potentials (CMAPs) in all the motor nerves (n = 26), axonal GBS had significantly poor recovery compared to AIDP (75% vs. 9.1%; P = 0.01). Among patients receiving intravenous immunoglobulin (IVIg; n = 42), poor recovery was seen in 53.6% with IM nerves compared to 35.7% without (P = 0.28), while it was 37.5% versus 5.6% (P = 0.04), respectively, in those who did not receive IVIg (n = 34). However, only admission disability (odds ratio [OR] 0.88, 95% confidence interval [CI] 0.81–0.97; P = 0.007) was found to be an independent predictor of outcome. Conclusion: Although increasing numbers of IM nerves were associated with poor outcome on univariate analysis, they did not predict 6 months’ outcome independently. Outcome did not differ between axonal GBS and AIDP among those with IM nerves. IVIg improved outcome in patients with IM nerves.