New method of bone reconstruction designed for skull base surgery

The direct endonasal or transoral transclival approaches to the skull base permit effective, minimally invasive surgery along the clivus. Developing long-term, effective techniques to prevent cerebrospinal fluid (CSF) leaks and their consequences (infection and delayed healing) remains a major challenge. In this study we describe a method of bone reconstruction newly developed by us, which uses a custom designed silicone plug for bone replacement after minimally invasive skull base surgery with a low incidence of postoperative CSF leaks. German Landrace pigs were used to test the efficiency of the new technique. Twelve craniotomies were performed in six pigs using a subtemporal approach and subsequently the dura was opened. After these preparations the craniotomy defects were occluded with a silicone ball, which had a near spherical shape. The ball elastically adapts to the bone defect. Each pig also received an intracranial pressure (ICP) catheter and a subdural catheter for later fluorescein injection. Then we increased ICP by infusion of artificial CSF and detected fluorescein leaks from the craniotomy using ultraviolet illumination and a photomacroscope equipped with appropriate filters and a charge-coupled device camera. In all pigs we increased ICP to 75–80 mmHg by infusing 25–30 mL saline containing 0.05% sodium fluorescein. For the first four craniotomies infusions were interrupted after CSF leaks occurred due to technical failures, which were subsequently rectified. The following eight craniotomies were watertight without CSF leakage. This novel medical device allows a leak-proof closure of bone defects after minimally invasive craniotomies; no additional surgery or other therapies were necessary. The application of the silicone plug, which is made of a cost-effective and biocompatible material, is easy and fast, making use of a specially developed toolkit.