Endoscopic Third Ventriculostomy for Hydrocephalus with Interhypothalamic Adhesion: A Case Report and Literature Review.

Endoscopic third ventriculostomy (ETV) is a well-established treatment for obstructive hydrocephalus; however, anatomical variations, such as the interhypothalamic adhesion (IHA), may obscure critical third ventricular landmarks and complicate intraoperative orientation. IHA is a rare congenital band of neural tissue connecting the medial hypothalamic walls and may pose a technical challenge during ventricular endoscopy. A case of obstructive hydrocephalus in which IHA was encountered during ETV is presented, and a structured surgical approach to safely perform ventriculostomy without disrupting the adhesion is described. Preoperative magnetic resonance imaging was used to assess ventricular anatomy and to plan the trajectory. Intraoperative ultrasound guidance facilitated accurate ventricular access. After identification of the infundibular recess and mammillary bodies, the third ventricular floor was perforated anterior to the mammillary bodies using a blunt instrument. A balloon catheter was employed to dilate the fenestration while minimizing traction on the IHA. Adequate cerebrospinal fluid flow was confirmed endoscopically. Postoperative imaging demonstrated stoma patency, and the patient showed clinical improvement during follow-up. This case illustrates that the presence of IHA does not preclude successful ETV when critical landmarks are clearly visualized, and a methodical intraoperative strategy is followed. Preservation of the adhesion may enhance procedural safety, and ventriculoperitoneal shunting should remain a secondary option when anatomical constraints prevent safe fenestration.