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 precoronal 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 from the thela chorioidea and from the internal cerebral veins, adequate control of the posterior rim of the foramen of Monro and the roof of the 3rd ventricle is mandatory. Accordingly in other three cases a CT-guided biportal endoscopic technique was applied, which permitted radical removal of the entire cyst with maximum safety. CT-guidance is essential for optimal planning after careful study of the individual anatomy. In this way the rigid scopes are moved exclusively along their own axes throughout the procedure, the resulting brain damage thereby being minimal. With regard to all circumstances of the procedure, the use of flexible endoscopes appears to be inappropriate and biportal endoscopy offers itself as the method of choice.