Neuroendoscopic Diagnosis and Treatment of Adolescent-Onset Aqueductal Stenosis: A Report of Two Cases Demonstrating the Utility of Endoscopic Third Ventriculostomy.

Neuroendoscopic evaluation and endoscopic third ventriculostomy (ETV) are important in the management of adolescent-onset aqueductal stenosis, a condition often treated with a ventriculoperitoneal shunt (VPS). This condition is relatively rare, and treatment based on an accurate morphological assessment is desirable to provide less invasive and more precise therapy. We report two cases of adolescent-onset aqueductal stenosis (late-onset aqueductal membranous occlusion (LAMO) and late-onset idiopathic aqueductal stenosis (LIAS)) in which a definitive diagnosis was made by direct neuroendoscopic observation, leading to successful ETV and positive clinical outcomes. The clinical courses, imaging findings, intraoperative endoscopic findings, and postoperative courses of the two cases were retrospectively analyzed and compared with a review of the literature. Case 1 was a 16-year-old female patient with LAMO who presented with diplopia. Brain magnetic resonance imaging (MRI) suggested hydrocephalus and a membranous structure within the cerebral aqueduct. The preoperative Endoscopic Third Ventriculostomy Success Score (ETVSS) was 90. After confirming membranous occlusion endoscopically, ETV was performed. Her neurological symptoms completely resolved, and she was discharged with a modified Rankin scale (mRS) score of 0. No recurrence has been observed at 12 months after surgery. Case 2 was a 39-year-old male patient with LIAS who presented with a Glasgow Coma Scale score of 10. He had a history of VPS placement for aqueductal stenosis at age 17. A head computed tomography (CT) revealed acute hydrocephalus due to shunt malfunction. The preoperative ETVSS was 80. The aqueductal stenosis was confirmed endoscopically, diagnosed as LIAS, and ETV was performed. His consciousness improved, and he was transferred to another facility with an mRS score of 1. However, neurological deficits that developed during the acute hydrocephalic episode preceding ETV, such as a constricted visual field and cognitive dysfunction, persisted after surgery. No recurrence has been observed at three months after surgery. No procedure-related complications were observed in either case. In adolescent-onset aqueductal stenosis causing hydrocephalus, a treatment strategy of performing ETV after a definitive neuroendoscopic diagnosis appears safe and effective. This approach may avoid the lifelong risk of shunt-related complications and improve the patient's quality of life.