Endoscopic-Assisted Ommaya Reservoir Placement: Technical Note.

Ommaya reservoir placement has been an option for patients requiring cerebrospinal fluid (CSF) access since the 1960s. It is preferred to repeat lumbar punctures, both in terms of patient comfort and the consistency of intrathecal drug concentration. Technological developments have advanced the placement technique, allowing for better accuracy and reduced complications. Freehand placement was first augmented with pneumoencephalograms and intraoperative computerized tomography (CT), then with optical-based navigation, and finally by utilizing electromagnetic neuronavigation. We outline a method of placement using electromagnetic neuronavigation and intraoperative endoscopic visualization, which allows for both real-time guidance and the confirmation of placement while maintaining tract patency for the entirety of the procedure. We make our incision and burr hole near Kocher's point. The neuronavigation stylet is placed in a peel-away sheath (Cook Medical, Bloomington, Indiana, US), which allows us to advance into the ventricle under real-time neuronavigation guidance. After the ventricle is entered, the stylet may be withdrawn and an endoscope advanced down the sheath. The intraventricular anatomy and catheter placement are confirmed. The burr hole reservoir is attached to a ventricle catheter that has been trimmed based on trajectory measurement on preoperative imaging. The reservoir-catheter construct can then be placed and the sheath removed from around it. This method provides a high level of confidence in appropriate catheter placement.