Post-Thyroidectomy Development of Posterior Reversible Encephalopathy Syndrome (PRES) Due to Calcium Over-Replacement

Posterior reversible encephalopathy syndrome (PRES) represents a distinct neurological entity characterized by a range of neurological signs and symptoms (seizures, headache, visual abnormalities, altered consciousness, and/or focal neurological signs) and typical neuroimaging findings reflecting reversible subcortical vasogenic edema, usually in the setting of blood pressure fluctuations, cytotoxic drugs, autoimmune disorders, and eclampsia. Here we present a case of a 61-year-old woman, with a history of recent total thyroidectomy and postoperative hypoparathyroidism, who was admitted to the Emergency Department with generalized seizures. Although in this clinical setting, hypocalcemia is expected as the most possible underlying pathogenic factor for triggering seizures, the patient was diagnosed with iatrogenic hypercalcemia and milk-alkali syndrome. A brain magnetic resonance imaging (MRI) demonstrated cortical swelling and fluid-attenuated inversion recovery (FLAIR) signal abnormalities in both occipital, parietal, and right frontal lobes, consistent with PRES. The patient's encephalopathy resolved after resolution of hypercalcemia; she had no neurological deficits on discharge, while she was restarted on lower doses of calcium for hypoparathyroidism. This case illustrates the challenges imposed by postoperative hypoparathyroidism and highlights that PRES is a rare but serious complication of hypercalcemia of which endocrinologists should be aware.