Endoscopic management of a choroid plexus cyst of the third ventricle: case report and documentation of dynamic behavior

The aim of this study is to document the dynamic behavior of a choroid plexus cyst of the third ventricle. Although these lesions may float freely within the ventricle leading to intermittent obstruction of the cerebrospinal fluid (CSF) circulation at variable points in a single patient, such a phenomenon has only been documented using cranial ultrasonography and was never observed intraoperatively. We endoscopically treated a case of third ventricular choroid plexus cyst in a 9-year-old boy who presented with headaches and disturbed conscious level. He underwent a transventricular approach through a single burr hole. During the procedure, the cyst was noted to intermittently herniate into the lateral ventricle and recede back through the foramen of Monro. Endoscopic ablation of the cyst was achieved and followed by endoscopic third ventriculostomy (ETV). The patient made an excellent recovery after the procedure. We were able to endoscopically observe the dynamic behavior displayed by a choroid plexus cyst of the third ventricle. To the best of our knowledge, intraoperative documentation of the obstruction of the CSF pathway by a single choroid plexus cyst that intermittently herniates through the foramen of Monro and back into the third ventricular cavity has not been previously demonstrated neither microsurgically nor endoscopically.