Sternberg canal defect and intracranial hypertension: a synergistic etiopathology in spontaneous cerebrospinal fluid rhinorrhea. Illustrative case.

backgroundSpontaneous CSF rhinorrhea is an uncommon but potentially serious condition. It may arise from skull base defects and anatomical variations, often combined with triggers such as idiopathic intracranial hypertension (IIH). The proximity of these defects to critical neurovascular structures and the complexity of endoscopic repair pose surgical challenges. Distinguishing congenital skull base defects, such as a persistent Sternberg canal (SC), from pressure-induced bony erosion is challenging, and both may coexist. OBSERVATIONS: A 35-year-old woman presented with a 4-month history of spontaneous CSF rhinorrhea. Imaging revealed a lateral sphenoid meningoencephalocele, an SC defect, and superior sagittal sinus thrombosis. Lumbar puncture opening pressure and venous manometry were normal. Spontaneous sinus recanalization occurred without anticoagulation. The patient underwent successful endoscopic repair via an endonasal transmaxillary approach. Transient elevations in intracranial pressure (ICP) were observed twice: the first resolved spontaneously alongside concurrent management of iron deficiency, while the second was treated as IIH with acetazolamide. LESSONS: This case highlights the interplay between skull base defects and ICP, including subclinical IIH, in spontaneous CSF rhinorrhea. Surgical repair unmasked symptomatic IIH and dynamic venous sinus stenosis secondary to elevated ICP. Recognizing this pathophysiology enables accurate diagnosis, avoids unnecessary intervention, and guides appropriate management. https://thejns.org/doi/10.3171/CASE25775.