Literature ReviewLow Tri-Iodothyronine Syndrome in Neurosurgical Patients: A Systematic Review of Literature

BackgroundIntracranial neurosurgical disorders are important causes of mortality and disability worldwide. Low tri-iodothyronine (T3) syndrome is a common complication in critically ill patients and is associated with a poor prognosis.MethodsWe performed a systematic review of clinical studies analyzing the prevalence of low T3 syndrome and the association of serum T3 concentrations with disease severity and outcomes in patients with traumatic brain injury (TBI), hydrocephalus, aneurysmal subarachnoid hemorrhage (SAH), and brain tumors.ResultsThe greatest prevalence rate of low T3 syndrome was reported in severe TBI patients (up to 67%), followed by patients with brain tumors (54%), aneurysmal SAH (up to 43%), and hydrocephalus (33%). A lower than normal serum T3 concentration was associated with greater disease severity, worse health status, complicated clinical course, and worse hospital discharge outcomes for TBI, aneurysmal SAH, and brain tumor patients. Lower T3 concentrations were also associated with greater long-term mortality and increased disability in TBI and aneurysmal SAH patients.ConclusionsLow T3 syndrome is a common complication in patients suffering from intracranial neurosurgical disorders and is associated with greater disease severity, complicated clinical course, and greater mortality and handicap rates. However, it remains unclear if low T3 syndrome can impact the findings of currently available clinical prognostic models and if management of low T3 syndrome can improve outcomes in neurosurgical patients.