Transventricular fenestration of the lamina terminalis: the value of a flexible endoscope: technical note.

BACKGROUND: Recently, the authors demonstrated the technical feasibility of a transventricular translaminar terminalis ventriculostomy with a rigid endoscope. A major problem with this technique remains the contusion of the fornix at the foramen of Monro. Here, the authors evaluated alternative approaches and techniques, including the use of a flexible endoscope. MATERIAL AND METHODS: Feasibility of two approaches-anterior and posterior of the coronal suture-was evaluated on magnetic resonance images and in cadaveric brains. Two different trajectories were selected. Lamina terminalis (LT) fenestration was performed with a rigid and a flexible endoscope using two approaches in 10 fixed cadaver brains. RESULTS: Using the posterior approach 2 cm behind the coronal suture with the two endoscopes caused moderate to severe damage to foramen and fornix. Using the standard approach (Kocher point) with the flexible endoscope avoided damage of these structures. After completion of the anatomical investigation, the authors successfully performed a transventricular fenestration of the LT with the flexible endoscope in one clinical case. CONCLUSION: Rigid scopes provide brilliant optics and safe manipulation with the instruments. However, with the rigid scope, a transventricular opening of the LT is only possible with acceptance of structural damage to the foramen of Monro and the fornix. In contrast, opening of the LT via a transventricular route with preservation of the anatomical structures can be achieved with a flexible steerable endoscope even via a standard burr hole. Thus, if a standard third ventriculostomy is not feasible, endoscopic opening of the LT might represent an alternative, particularly with a flexible scope in experienced hands.