Complete removal of colloid cyst via CT-guided stereotactic biportal neuroendoscopy

Four patients harbouring a colloid cyst of the 3rd ventricle were operated on endoscopically. With the "classical" monoportal technique, through a pre coronal burr hole only partial removal could be achieved in the first case. As the crucial point of the procedure is the safe dissection of the cyst f rom the thela chorioidea and from the internal cerebral veins, adequate con trol of the posterior rim of the foramen of Monro and the roof of the 3rd v entricle is mandatory. Accordingly in other three cases a CT-guided biporta l endoscopic technique was applied, which permitted radical removal of the entire cyst with maximum safety. CT-guidance is essential for optimal plann ing after careful study of the individual anatomy. In this way the rigid sc opes are moved exclusively along their own axes throughout the procedure, t he resulting brain damage thereby being minimal. With regard to all circums tances of the procedure, the use of flexible endoscopes appears to be inapp ropriate and biportal endoscopy offers itself as the method of choice.