[Neuroendoscopic management of a colloid cyst at the third ventricle using the high-definition flexible neuroendoscopic system: report of two cases].

Colloid cysts are benign intracranial lesions located at the anterior roof of the third ventricle, which can result in the obstruction of the foramen of Monro and subsequent hydrocephalus or sudden death. Colloid cysts have been treated by microsurgical resection or by stereotactic aspiration. More recently, the use of rigid neuroendoscopy for colloid cysts has been attempted, but the efficacy of the flexible neuroendoscopic system is undetermined except for limited reports. A 40-year-old man and a 52-year-old man were presented with obstructive hydrocephalus owing to colloid cysts in the third ventricle, who were diagnosed by the typical findings of pre-operative CT scan and MRI. In the first case, endoscopic resection of the cyst was attempted using a high-definition flexible neuroendoscopic system with a CCD camera at the tip of the endoscope. The procedure relieved his symptoms. Hydrocephalus was improved after surgery, and postoperative MRI revealed the disappearance of the third ventricle lesion. Histological examination confirmed the diagnosis of colloid cyst. In the second case, endoscopic removal of the cyst wall and the evacuation of the cyst content were attempted using a high-definition flexible endoscopic system which resulted in the improvement of hydrocephalus and marked shrinkage of the third ventricle lesion observed in postoperative MRI. There was no recurrence in either patient. We recommend endoscopic treatment for colloid cysts using the high-definition neuroendoscopic system, which enables safe and thorough manipulation of the lesion and surrounding structures.