Endoscopic Transseptal Transcaval Interforniceal Approach to the Posterior Third Ventricle in the Presence of Cavum Septum Pellucidum

Background Posterior third ventricular lesions often cause obstructive hydrocephalus. Thus, a combined endoscopic third ventriculostomy (ETV) and endoscopy biopsy are often the first treatment. However, the trajectories for both procedures can differ significantly, necessitating 2 entry points or a combined rigid-flexible technique. Methods We describe the use of a large cavum septum pellucidum as a route for performing the biopsy. Results Using a rigid endoscope and a single trajectory, we were able to perform a transforaminal ETV and a transseptal, transcaval, interforniceal biopsy of the tumor. Conclusion Although described as a route to reach the anterior third ventricle endoscopically, we describe the use of the transseptal, transcaval, interforniceal approach to reach the posterior part of the third ventricle.