N euroendoscopy is a relatively new technique in neurosurgery that cannot yet be definitively judged on the basis of scientific evidence. Large-scale, randomized controlled studies and metaanalyses are currently in progress, but no conclusive findings have yet been reported regarding the potential advantages, for various indications, of this new technique over other, established ones. In this article, neuroendoscopic techniques and their indications and results will be described and discussed in the light of the current literature. The literature search terms used were "neuroendoscopy," "hydrocephalus," "colloid cysts," "cystic brain lesions," "endoscopic pituitary surgery," and "spinal endoscopy." History of neuroendoscopy In 1910, Victor de l'Espinasse, a Chicago urologist, performed an endoscopic operation on the ventricular system of a neonate with hydrocephalus. He is therefore considered the father of neuroendoscopy. It was not until February 6, 1923, however, that William J. Mixter, a neurosurgeon, performed the first endoscopic ventriculostomy in a child with congenital obstructive hydrocephalus. The instruments available at that time were not very suitable for use in the brain, and the endoscopic treatment of hydrocephalus was thus only rarely practiced. The situation changed in the latter half of the 1980's with the development of miniaturized endoscopes and endoscopic instruments (1). Today, endoscopic procedures for certain well-defined indications belong to the standard repertoire of neurosurgical operative techniques (2). Instruments and planning of the neuroendoscopic approach Neuroendoscope Many different types of neuroendoscope with good optical properties are now available, and little improvement seems to be needed in this area (3). A neuroendoscope should have two working channels to enable the surgeon to work with both hands (as in conventional, non-endoscopic microsurgery), as well as a channel for irrigation and suction. A compromise must be struck, so that the parenchymal trauma due to the insertion of the device is minimized Dtsch Arztebl 2007; 104(4): A 185–91  www.aerzteblatt.de 1 MEDICINE SUMMARY Introduction: There is currently no randomized controlled trial evidence of benefit for neuroendoscopy versus conventional neurosurgical treatment across a variety of indications. Methods: Medline review using search terms: neuroendoscopy, hydrocephalus, colloid cysts, cystic brain lesions, endoscopic pituitary surgery, spinal endoscopy. Results: The standard indications for neuroendoscopy are the treatment of hydrocephalus, intracerebral cysts and intraventricular tumors. The advantages of neuroendoscopy-assisted microsurgery as an adjuvant technique are self evident. Whether endoscopy of the sellar region will gain is as yet uncertain. Endoscopic interventions on the vertebral column and spinal cord are now routine, but controversial. The endoscopic carpal tunnel surgery is established and widely practised. Discussion: The increasingly close links between neuroendoscopy and neuronavigation, and robotics, may bring promising developments. In future, virtual neuroendoscopy may aid the planning and execution of surgical interventions. Dtsch Arztebl 2007; 104(4): A 185–91. Key words: neuroendoscopy, hydrocephalus, intracerebral cyst, brain tumor, lumbar disc prolapse, carpal tunnel syndrome Neurochirurgische Klinik Universitätsklinikum Gießen und Marburg, Standort Marburg (Prof. Dr. med. Hellwig, Dr. med.Tirakotai, Dr. med. Heinze, Dr. med. Riegel, Prof. Dr. med. Bertalanffy) REVIEW ARTICLE Endoscopy in Neurosurgery Dieter Hellwig, Wuttipong Tirakotai, Thomas Riegel, Stefan Heinze, Helmut Bertalanffy