Intraoperative Central Diabetes Insipidus during Aneurysmal Clipping Surgery: An Unusual Phenomenon

Abstract Central diabetes insipidus (DI) is a known complication associated with pituitary surgeries occurring in postoperative period. However, development of DI following aneurysmal subarachnoid hemorrhage (SAH) is rarely reported. We describe here a case of intraoperative DI in a patient undergoing aneurysmal clipping surgery that posed a challenge for both diagnosis and management. A 55-year-old female, diagnosed with SAH due to ruptured left middle cerebral artery (MCA) aneurysm, was posted for aneurysmal clipping. A preoperative sudden rebleeding led to neurological deterioration and patient was taken up for the evacuation of hematoma and aneurysmal clipping. Intraoperatively, 2 hours into surgery, polyuria (700–1,000 mL/hour) was noted. Arterial blood gas analysis revealed severe hypernatremia with increased serum osmolality and urine-specific gravity showed hypo-osmolar urine. Possibility of mannitol induced diuresis, overzealous administration of intravenous fluid, and other causes of DI were ruled out. Medical management of DI was initiated and after 45 minutes, urine output was reduced and serum sodium measurements showed decreasing trend indicating responsiveness to treatment. Postoperatively noncontrast computed tomography head showed temporal bleeding with MCA infarct, infarct in thalamic, and hypothalamic region with hydrocephalus. Intraoperative development of central DI was attributed to the evolving ischemic injury to the hypothalamus at the time of rebleeding that was not apparent in preoperative scan. DI resolved postoperatively after 18 hours of medical management. Development of DI during aneurysmal surgery was unexpected and unanticipated. The cause of intraoperative DI was found to be pre-existing ischemic injury of hypothalamic region that subsequently evolved to infarct which was not evident in preoperative scan. A careful observation of preoperative scans and vigilant monitoring may help in early diagnosis and management of such complication in perioperative period.