Daniel A. Martínez-Piña, Department of Neurology, National Institute of Neurology and Neurosurgery Dr. Manuel Velasco Suarez, Mexico City, Mexico
Victor Medina-Gómez, Department of Neurology, National Institute of Neurology and Neurosurgery Dr. Manuel Velasco Suarez, Mexico City, Mexico
José F. García-Hernández, Department of Neurology, National Institute of Neurology and Neurosurgery Dr. Manuel Velasco Suarez, Mexico City, Mexico
Edwin S. Vargas-Cañas, Clinic of Neuromuscular Diseases, National Institute of Neurology and Neurosurgery Dr. Manuel Velasco Suarez, Mexico City, Mexico
Arturo Violante-Villanueva, Department of Neurological Emergencies, National Institute of Neurology and Neurosurgery Dr. Manuel Velasco Suarez, Mexico City, Mexico
Juan C. López-Hernández, Department of Neurological Emergency, Instituto Nacional de Neurología y Neurocirugía, Ciudad de México, México

Introduction: Hyponatremia occurs in 21-48% of patients with Guillain-Barre syndrome (GBS). However, little is known about the clinical implications in GBS. Materials and methods: In this observational, cross-sectional study, of patients diagnosed with GBS was conducted. Information used included: demographic clinical variables, cerebrospinal fluid (CSF) results, and nerve conduction studies. Patients with sodium levels < 135 meq/L in laboratory studies on admission and before treatment were considered to have hyponatremia. We defined good functional prognosis as the presence of independent gait (Hughes ≤ 2 points) at 3 months of follow-up. Results: Two hundred and twelve patients were initially screen and 31 (14.6%) presented hyponatremia; male gender was predominant with 72%, mean age was 45.9 ± 16 years, mean Modified Medical Research Council (MRC) score was 30.1 ± 17 points, invasive mechanical ventilation requirement was 32%, and the presence of dysautonomia 32%. One hundred and eighty-two nerve conduction studies, and 165 CSF cytochemical samples were collected. In the comparative analyses between the patients with hyponatremia versus without hyponatremia, we observed significant differences in mean age (50.4 ± 14.9 vs. 43.8 ± 16.3, p = 0.03), days of hospitalization (median) (16 [IQR = 7-51] vs. 7 [IQR = 5-12] p = 0.03), dysautonomia (54.8% vs. 28.2%, p = 0.006), protein levels (mgs/dL) in CSF (median) (105 [IQR = 59-165] vs. 39 [IQR = 28-57], p ≤ 0.001), and acute inflammatory demyelinating polyneuropathy (AIDP) variant (70.4% vs. 42%, p = 0.011). There was no significant finding in recovery of independent gait at 3 months (34.6% vs. 42.6%, p = 0.51). Conclusion: About 14% of patients with GBS presented with hyponatremia in our series and is associated with presence of dysautonomia, AIDP variant, elevated CSF protein levels and a greater number of days of hospital stay but did not impact functional prognosis.

Keywords: Guillain-Barre syndrome. Hyponatremia. Clinical presentation. Functional prognosis.