Colloid cysts are benign space-occupying lesions, which arise from the velum interpositum or the choroid plexus of the third ventricle and are able to produce symptomatic obstruction of the foramina of Monro with resultant
hydrocephalus. In our department, we have operated on
colloid cysts routinely in an
endoscope-assisted microsurgical manner via a key-hole approach. During a period of 10 years, 28 microsurgical resections of
colloid cysts of the third ventricle were performed. Seven patients demonstrated
colloid cysts inside the third ventricle with obstruction of the right foramen Monro, two patients demonstrated
cysts with obstruction of the left foramen Monro. Twelve patients suffered from
cysts inside the third ventricle with obstruction of both foramina Monro and five patients demonstrated
cysts lying into the third ventricle without obstruction of the foramina. In 21 patients no preoperative
therapy was performed outside. Three patients had received shunt systems before in other hospitals, two patients received aspiration of the
cysts under stereotactic conditions and two patients received external ventricular drains. Total removal of the
cyst was achieved in all patients (100%). No patient received a second operation, because none had a recurrent
cyst. All
cysts were removed with the
cyst wall. Overall clinical improvement was achieved in a long-standing period between 6 and 83 months in 27 (96%) patients. In one patient (4%) the psychomotor disturbance was unchanged and no patient deteriorated. From the microsurgical point of view, the combination of keyhole surgery under endoscopic visual control using preexisting anatomical windows offers an effective minimally invasive approach.