Figure 3: A 7‑year‑old female child presented with cognitive decline and weakness for 3 years. The preoperative symptoms were completely relieved after she underwent cystoventriculostomy by endoscopy. (a) T2‑weighted MRI showed that a large cystic lesion located in the intraventricle and the homolateral ventricle was enlarged and that the mid‑line shifted to the left side. (b) The area of the shin wall without the blood vessels was clearly observed by endoscopy. (c) Fistula surgery was performed by single‑pole coagulation. (d) The choroid plexus of the third ventricle was observed after cystoventriculostomy. (e) The enlarged lateral ventricle decreased in size, the shifted mid‑line retreated to the normal site, and the small subdural hygroma was observed in the CT scan during the 2‑year follow‑up period. (f) The pathological result of the arachnoid cyst was confirmed