Endoscopic Third Ventriculostomy for an Idiopathic Disproportionately Large Communicating Fourth Ventricle: A Case Report

A disproportionately large communicating fourth ventricle (DLCFV) is a rare condition. A 34-year-old man experienced severe headaches, nausea, vomiting, and gait disturbance. Initial brain computed tomography (CT) showed markedly dilated ventricles with prepontine cistern shrinkage. Following extraventricular drain (EVD) insertion, approximately 400 mL/d of cerebrospinal fluid (CSF) was removed over 8 days. During this time, no significant changes in ventricle size were observed on CT images or the facial pain scale (FPS). We then performed an endoscopic third ventriculostomy and changed the drainage catheter. Immediately after surgery, the patient’s symptoms were relieved, and the drainage volume gradually decreased. EVD was successfully removed on the eighth postoperative day. Our experiences suggest that neurosurgeons should consider the importance of a third ventriculostomy for the diagnosis and treatment of DLCFV.