Very low peroneal nerve compound muscle action potential amplitude predicts poor outcome in patients with Guillain-Barré syndrome: a prospective cohort.

INTRODUCTION: Twenty percent of patients with Guillain-Barré syndrome (GBS) have poor outcomes despite proper management. The aim of the study was to characterize electrophysiological factors related to poor outcome in patients with GBS. METHODS: We conducted an observational study from a prospective cohort of 91 patients with GBS in a tertiary healthcare center in Mexico, from 2017 to 2019. Demographics and nerve conduction studies were performed on admission, and a 3-month follow-up for GBS disability score was ensued, allocating patients in good (GBS disability score ≤ 2) and poor outcome (GBS disability score ≥ 3) groups. A logistic regression analysis for independent walk at 3 months was performed. Kaplan-Meier estimator curves for independent walk in very low (< 20% LLN) and low-normal ( ≥20% LLN) peroneal nerve CMAPs are presented. RESULTS: From the 91 GBS patients included, 37 (40.6%) did not regain independent walk at 3 months. Axonal variants were more common in the poor outcome group (31.4% vs 59.4%, p = 0.01) as well as AIDP variants with motor conduction block (6.6% vs 42.4%, p = 0.018). Univariable analysis was statistically significant for very low median, ulnar, tibial, and peroneal CMAP amplitudes in poor outcome patients; however, multivariable analysis was only significant for very low peroneal nerve CMAP amplitude (OR 3.6 [1.1-11.5, p = 0.024]). Conversely, a greater proportion of GBS patients with low-normal CMAPs recovered independent walk at 90 days (75% vs 30%, p < 0.001). CONCLUSION: Severe axonal injury of the peroneal nerve, axonal, and AIDP with motor conduction block variants predicts worse functional outcome regarding independent walk at 3 months.

Electrophysiological subtypes and associated prognosis factors of Mexican adults diagnosed with Guillain-Barré syndrome, a single center experience.

BACKGROUND: The clinical characteristics of electrophysiological subtypes and prognostic factors of Mexican adults diagnosed with Guillain-Barré Syndrome (GBS) have not been described. MATERIALS AND METHODS: A single center, ambispective, cohort study was performed (2015-2019). GBS was defined following the Asbury and Cornblath criteria. Electrodiagnosis was made according to Hadden criteria. Clinical, biochemical and electrodiagnostic parameters were described, compared and analyzed using a multivariate model. Only patients who completed a 3-month follow-up were included. RESULTS: 137 GBS patients (92 males; mean age 46.6 ± 16.6).132 (96.3%) underwent an electrodiagnostic assessment.68 (51.5%) were classified as axonal GBS, with further classified into two groups: acute motor axonal neuropathy (AMAN) 45.4%, and acute motor and sensory axonal neuropathy (AMSAN) 8,6%. The following characteristics were lower in the AMAN group: Medical Research Counsel sumscore (MRC) 30.1 ± 16.3 vs 36.4 ± 14.4, unilateral facial palsy 10% vs 25.9% and albuminocytologic dissociation 41.3% vs. 71.7%.Multivariate analysis found AMAN as an independent predictor of an unfavorable outcome OR: 3.34 (p = 0.03) CONCLUSIONS: AMAN subtype is the most frequent presentation of GBS in Mexican adult patients and an independent predictor of inability to walk independently at 3 months after discharge.