Introduction: Hydrocephalus is not usually part of Down syndrome (DS). Fourth ventricle outlet obstruction is a rare cause of obstructive hydrocephalus, difficult to diagnose, because tetraventricular dilatation may suggest a communicant/nonobstructive hydrocephalus.
Case presentation: We describe the case of a 6-year-old boy with obstructive tetraventricular hydrocephalus, caused by Luschka and Magen-die foramina obstruction and diverticular enlargement of Luschka foramina (the so-called fourth ventricle outlet obstruction) associated with DS. He was treated with endoscopic third ventriculostomy (ETV) without complications, and a follow-up MRI revealed reduction of the ventricles, disappearance of the diverticula, and patency of the ventriculostomy.
Conclusion: Diverticular enlargement of Luschka foramina is an important radiological finding for obstructive tetraventricular hydrocephalus. ETV is a viable option in tetraventricular obstructive hydrocephalus in DS.
Keywords: Down syndrome; Endoscopic third ventriculostomy; Fourth ventricle outlet obstruction; Hydrocephalus; Ventricular diverticulum.
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