oa Editorial [Hot Topic: Gliomas: Current Issues in Diagnosis and Treatment (Guest Editor: Stephan Ulmer)]

Forty Years of Technological Evolution in Image-Guided Neurosurgery: Past, Present and Future Aspects Although initial descriptions of neurosurgical procedures date back as early as into the 17th century BC in the ancient Egypt [1], modern neurosurgery - the juvenile medical field - changed tremendously within the past 40 years and nothing other than the fact of the craniotomy itself is similar to these initial reports. Neurosurgery ever since has been guided by anatomical structures such as the coronal suture as a reliable bony landmark or the Sylvian fissure. Surgical indications in those days were based on the patient's symptoms only and the approach was driven by neuroanatomical knowledge often based on observations of single cases suffering from strokes and postmortem analysis of patient's brains respectively Prior to the advent of imaging modalities, the first stereotactic procedures had been introduced in 1873 by Dittmar [2], however; the modern era of stereotaxy began in 1908 with the description of a stereotacic device for animal purposes only by Horsely and Clarke [3]. In 1918, Mussen introduced the first stereotacic device for human application [4]. This stereotactic apparatus, however, did not succeed into clinical application as surgeons did not believe in this technology. Spiegel and Wycis [5] were the first to use a stereotactic device in a patient in 1947, but this model was far from being applied in daily clinical routine as it was made out of a custom made plaster cast to fit the patient's individual head combined with a frame on top of it. Two years later, Talairach and Leksell introduced a stereotacic device [6], which modified “descendant” is still used today. Stereotactic procedures became very popular for biopsies as well as for the treatment of Parkinson's disease, the later becoming less frequent with the discovery of L-Dopa. First imaging modalities like ventriculography or pneumoencephalography [7, 8], which appear inconceivable nowadays, helped in the topographical orientation, but a milestone in the evolution was the invention of cranial computer tomography in 1973 by Hounsfield [9]. Since then, the entire neurological field changed and pathology in the brain became visible preoperatively. Procedures could be planned based on an individual anatomy. In 1979, the combination of cranial computer tomography and a stereotactic frame was introduced by Brown [10], while another imaging modality evolved contemporaneously. Based on the work of Bloch and Purcell [11, 12], magnetic resonance imaging was invented, but it was not before 1971, when Damadian [13] and Lauterbur [14] enabled the generation of first MR images. Clinical widespread took some time, but from today's perspective, MR imaging represents the Gold standard of high resolution medical imaging. Computer-based image-guided technology intraoperatively was invented by Kelly and colleagues in 1982 [15]. They were the first to use a computer-assisted stereotactic laser in the treatment of an intracranial lesion. Thus, the century of modern image- guided neurosurgery was born. In 1987, Watanabe and colleagues invented the principle of a frameless computer-guided neuronavigation based on the patient's individual images [16]. The improvement of MR imaging, newer neuronavigation technology and more recently the invention of intraoperative MRI [17] have further assisted the evolution of image-guided neurosurgery as we know it today. Within the past 40 years there was a tremendous jump technology-wise and neurosurgical procedures became more precise and safer for the patient. We're still not at the end of the rope. Higher field strengths, more detailed image resolution, more precise image-to-patient registration and the combination of various technologies like image fusion, integration of functional data, the use of intraoperative MRI and advanced technologies intraoperatively improve this field every day. This issue gives an overview on current state of the art treatment options starting with today's knowledge on the intracranial pathologies, preoperative mapping methods, imaging modalities, recent intraoperative technologies and long-term follow-up treatment options. After so many developments within the last 40 years, one can barely think of any further ground breaking technology to further improve image-guided neurosurgery, but now - looking back to the ancient Egypt and being astonished what was possible then - we might be amused in the near future how it was back then in the 21st century.