Chemical Meningitis and Syndrome of Inappropriate Antidiuretic Hormone Release (SIADH): A Rare Presentation of Pituitary Adenoma Apoplexy.

Pituitary apoplexy is an uncommon condition typically resulting from a sudden haemorrhage within a pituitary adenoma. This bleed can present clinically with a wide array of signs and symptoms. This report documents the case of a 62-year-old male who presented to the Lebanese Hospital Geitaoui University Medical Center with signs and symptoms of meningeal irritation. He was initially thought to have meningitis, and was started on antibiotics; he was then found to have pituitary adenoma apoplexy that was complicated by syndrome of inappropriate antidiuretic hormone release (SIADH). The patient was successfully treated with antibiotics, and fluid restriction and hypertonic saline after ruling out other more common causes for his hyponatraemia, before undergoing a transsphenoidal resection of the pituitary adenoma. A three-month follow-up evaluation of the patient demonstrated the absence of hormonal imbalances and the absence of residual tumours on imaging. LEARNING POINTS: Pituitary apoplexy has as a wide clinical presentationPituitary apoplexy should be ruled out in patients with aseptic chemical meningitis with a history of pituitary adenomasSIADH can complicate chemical meningitis due to pituitary apoplexy.