Confocal Laser Endomicroscopy in Neurosurgery: A New Technique with Much Potential

Technical innovations in brain tumour diagnostic and therapy have led to significant improvements of patient outcome and recurrence free interval. The use of technical devices such as surgical microscopes as well as neuronavigational systems have helped localising tumours as much as fluorescent agents, such as 5-aminolaevulinic acid, have helped visualizing pathologically altered tissue. Nonetheless, intraoperative instantaneous frozen sections and histological diagnosis remain the only method of gaining certainty of the nature of the resected tissue. This technique is time consuming and does not provide close-to-real-time information. In gastroenterology, confocal endoscopy closed the gap between tissue resection and histological examination, providing an almost real-time histological diagnosis. The potential of this technique using a confocal laser endoscope EndoMAG1 by Karl Storz Company was evaluated by our group on pig brains, tumour tissue cell cultures, and fresh human tumour specimen. Here, the authors report for the first time on the results of applying this new technique and provide first confocal endoscopic images of various brain and tumour structures. In all, the technique harbours a very promising potential to provide almost real-time intraoperative diagnosis, but further studies are needed to provide evidence for the technique’s potential. 1. Introduction Neurooncological diagnosis and treatment constitute a major part of neurosurgery. Obtaining histological diagnosis is frequently challenging. The resulting therapeutic options vary depending on the histological grade and the tumour type. The incidence of gliomas is expected to be around 5-6/100000 per year, with their survival rate depending heavily on their WHO grade. Even with today’s high medical standards consisting of surgical removal and postoperative combined radiochemotherapy, median survival shows 18–21 months at its best for glioblastomas [1]. While it is frequently noted that malignant gliomas cannot be cured by surgical resection, recent studies show an improved life expectancy associated with a more extended tumour resection [1–3]. Thus, currently, research is focussing on increasing the extent of resection through various additional techniques such as neuronavigation [4] or 5-aminolaevulinic acid (5-ALA) fluorescent marking of tumour cells. While neuronavigation suggests precise imaging of the tumour, this can be misleading due to brain shift occurring during surgery and therefore tumour borders are not depicted according to reality [5]. For 5-ALA, randomized clinical