Bilateral Lateral Ventricle Cerebrospinal Fluid Diversion in a Rare Case of Foramen of Monro Occlusion: A Case Report.

Obstructive hydrocephalus in young adults is a rare and often misdiagnosed condition. Normal pressure hydrocephalus (NPH), typically affecting older adults, may resemble obstructive forms when bilateral foramen of Monro occlusion is present. Traditional cerebrospinal fluid (CSF) diversion may be insufficient in cases with isolated ventricles. We present a unique case of a 37-year-old patient with presumed NPH, a prior endoscopic third ventriculostomy (ETV), and persistent symptoms due to undiagnosed foraminal obstruction. The patient presented with progressive gait instability and memory impairment. Imaging demonstrated ventriculomegaly with lateral ventricular isolation. An initial right ventriculoperitoneal shunt (VPS) provided partial relief, but persistent symptoms prompted a second procedure. A left VPS was placed and connected to the original system using a single programmable valve via a novel suboccipital tunneling technique, referred to as the "neckband technique." This case illustrates the diagnostic challenges of differentiating NPH from obstructive hydrocephalus in young adults. It also demonstrates a safe, effective technique for bilateral ventricular drainage using a single valve system. This strategy reduces long-term hardware burden while ensuring effective CSF diversion in patients with bilateral ventricular isolation.