Extended endoscopic endonasal resection of a transinfundibular craniopharyngioma with third ventricular extension associated with superficial siderosis: Operative technique and technical nuances

Background: Craniopharyngiomas with third ventricular extension are difficult to resect safely given their proximity to the hypothalamus, pituitary stalk, and optic apparatus. Superficial siderosis, a rare consequence of chronic hemorrhage into the cerebrospinal fluid, has rarely been linked to craniopharyngiomas. When present, siderosis-related injury can progress independently of tumor mass effect. Case Description: A 63-year-old man presented with progressive sensorineural hearing loss, gait disturbance, urinary incontinence, and cognitive decline. His memory and executive dysfunction were considered consistent with hypothalamic involvement. Magnetic resonance imaging showed an enhancing suprasellar lesion arising from the infundibulo-tuberal region of the third ventricular floor with predominant extension into the third ventricle. Ventricular enlargement was present without evidence of obstructive hydrocephalus and was considered more consistent with impaired cerebrospinal fluid resorption associated with diffuse superficial siderosis. Endoscopic ventricular biopsy confirmed papillary craniopharyngioma, and a ventriculoperitoneal shunt was placed in the setting of ventricular enlargement. The tumor was considered the likely source of chronic bleeding into the cerebrospinal fluid. Due to its predominantly transinfundibular relationship, an extended endoscopic endonasal transplanum-transtuberculum approach was selected because it provided a direct inferior midline corridor into the third ventricle and hypothalamic-pituitary stalk interface while minimizing brain retraction. The tumor was identified beneath a thin-layer of pituitary stalk tissue, and careful dissection preserved the displaced hypothalamic walls. Gross-total resection was achieved without major postoperative complications. Despite anatomical preservation of the pituitary stalk, postoperative panhypopituitarism and vasopressin deficiency required hormonal replacement therapy. At 4-month follow-up, imaging showed no tumor recurrence and appropriate shunt function; however, ventricular drainage had not resulted in significant clinical improvement, and his hearing loss, gait dysfunction, and cognitive impairment persisted but remained clinically stable. Conclusion: Craniopharyngioma is an underrecognized cause of superficial siderosis. Resection of the suspected bleeding source may halt further decline, but neurological deficits related to siderosis can persist. In selected transinfundibular lesions, the extended endoscopic endonasal approach allows direct access to the third ventricle while preserving the hypothalamus and pituitary stalk. However, anatomical preservation of the pituitary stalk does not necessarily ensure preservation of hypothalamic-pituitary function.