Impact of thyroid hormone replacement therapy on the course and functional outcome of aneurysmal subarachnoid hemorrhage

Background Thyroid hormones were reported to exert neuroprotective effects after ischemic stroke by reducing the burden of brain injury and promoting post-ischemic brain remodeling.Objective We aimed to analyze the value of thyroid hormone replacement therapy (THRT) due to pre-existing hypothyroidism on the clinical course and outcome of aneurysmal subarachnoid hemorrhage (SAH).Methods SAH individuals treated between January 2003 and June 2016 were included. Data on baseline characteristics of patients and SAH, adverse events and functional outcome of SAH were recorded. Study endpoints were cerebral infarction, in-hospital mortality and unfavorable outcome at 6 months. Associations were adjusted for outcome-relevant confounders.Results 109 (11%) of 995 individuals had THRT before SAH. Risk of intracranial pressure- or vasospasm-related cerebrovascular events was inversely associated with presence of THRT (p = 0.047). In multivariate analysis, THRT was independently associated with lower risk of cerebral infarction (adjusted odds ratio [aOR] = 0.64, 95% confidence interval [CI] = 0.41-0.99, p = 0.045) and unfavorable outcome (aOR = 0.50, 95% CI = 0.28-0.89, p = 0.018), but not with in-hospital mortality (aOR = 0.69, 95% CI = 0.38-1.26, p = 0.227).Conclusion SAH patients with THRT show lower burden of ischemia-relevant cerebrovascular events and more favorable outcome. Further experimental and clinical studies are required to confirm our results and elaborate the mechanistic background of the effect of THRT on course and outcome of SAH.