Endoscopic third ventriculostomy in adults: a technique for dealing with the neural (opaque) floor.

Object: An opaque (neural) floor of the third ventricle is considered an obstacle to safe penetration of the floor of the third ventricle in endoscopic third ventriculostomy (ETV). The direct technique of endoscopic coring ("cookie cut") of the opaque (neural) floor of the third ventricle is described in 41 cases among a total of 101 consecutive adult ETVs.

Methods: A 0° endoscope in a 4.6-mm irrigating sheath was used to press and core ("cookie cut") a section of the tuber cinereum, thereby exposing the underlying membranes and vasculature. Thereafter, the endoscopic apparatus was used to penetrate the membrane into the prepontine space.

Results: Among 101 consecutive ETVs performed in adults, there were 41 instances of an opaque floor in which the coring technique was used. The basilar artery (BA) complex was in the intended path of penetration in 13 cases. There were no perioperative deaths or vascular injuries. No cases were aborted because of the opaque floor or the configuration of the BA complex. The clinical success rate in the opaque floor group was 80% (33 of 41 patients).

Conclusions: An opaque (neural) floor is frequently seen in adults during ETV. Removing the floor by the core ("cookie cut") method is a safe means of revealing the underlying BA complex and membranous structures prior to penetration into the prepontine cistern. On occasion, the BA complex may be in the path of penetration, and one can maneuver the endoscope to displace the vasculature to successfully accomplish the ETV.