The relation of early hypernatremia with clinical outcome in patients suffering from aneurysmal subarachnoid hemorrhage

Abstract

Objective: Sodium dysregulation in the course after aneurysmal subarachnoid hemorrhage (aSAH) has been identified as one contributor to adverse clinical outcome. However, the correlation of acute dysnatremia and early brain injury (EBI) remains unclear. We investigated the early course and prognostic relevance of changes in serum sodium concentrations and its relation to EBI after aSAH.

Methods: Retrospectively, the serum sodium concentration (SSC) of 264 patients with aSAH was analyzed. The first SSC was obtained within 8h after initial ictus and then repeatedly analyzed every 8h over the first five days. Incidence of hypernatremia (defined as SSC>145mmol/l) was correlated with initial neurological condition according to World Federation of Neurological Surgeons grade (WFNS), incidence of delayed cerebral ischemia (DCI) and clinical outcome at 12 month according to modified Rankin Scale (mRS).

Results: Within 56h, 82 patients (31.1%) developed hypernatremia which correlated significantly with initial neurological condition (p<0.001). Initial SSC within 8h after SAH did not correlate with patient outcome at 12 month (r=-0.026, p=0.694), however SSC obtained 56h after ictus did significantly (r=0.365, p<0.001; OR 4.14 95% CI (1.84-9.31)). A correlation with the incidence of DCI was not found (r=0.079, p=0.217).

Conclusion: The occurrence of hypernatremia within 56h after aSAH was shown to be an independent predictor for poor neurological outcome. Early serum sodium levels after aSAH can be considered as surrogate markers to predict outcome after aSAH irrespective to the occurrence of DCI. However, prospective studies are necessary to validate this concept.

Keywords: Early brain injury; Epidemiology; Hypernatremia; Outcome; Subarachnoid hemorrhage.