Unusual Presentation of Hypopituitarism Caused by Internal Carotid Artery Aneurysm

Hypopituitarism is most commonly caused by pituitary or parasellar tumors, while vascular lesions such as intracranial aneurysms are exceedingly rare etiologies. We report a unique case of a 42-year-old woman with a long-standing history of hypothyroidism who presented with generalized edema, hypotension, amenorrhea, and recurrent hypoglycemia. Biochemical assessment revealed panhypopituitarism-secondary hypothyroidism [free thyroxine (FT4) <0.88 pmol/L, thyroid-stimulating hormone (TSH) 3.36 µIU/mL] and secondary adrenal insufficiency, with extremely low serum cortisol (<0.16 µg/dL) and adrenocorticotropic hormone (ACTH) 9 pg/mL. Gonadotropins were also reduced [luteinizing hormone (LH) 1.49 mIU/mL, follicle-stimulating hormone (FSH) 5.12 mIU/mL]. Magnetic resonance imaging (MRI) of the brain demonstrated an empty sella with a left supraclinoid internal carotid artery (ICA) saccular aneurysm extending into the suprasellar region. Digital subtraction angiography confirmed the diagnosis, and the patient underwent successful endovascular coiling. Following the intervention, her electrolyte abnormalities resolved, and she remained stable on hydrocortisone and thyroxine supplementation. This case highlights the importance of considering ICA aneurysm in the differential diagnosis of hypopituitarism, as its presentation can mimic pituitary adenoma. In contrast to prior reports where visual disturbances predominated, this case presents isolated endocrine dysfunction without visual or neurological symptoms. Additionally, the coexistence of an empty sella and supraclinoid ICA aneurysm-induced panhypopituitarism is exceptionally rare. Early recognition with neuroimaging and timely intervention are crucial to prevent life-threatening endocrine crises and neurological complications.