Imaging of endoscopic approaches to the anterior and central skull base

Sinonasal endoscopy for treatment of benign sinonasal diseases is a well-established procedure. Recent advances in endoscope technology have substantially expanded its application with many institutions now offering resection of skull base lesions and sinonasal malignancies via the endoscopic approach. Its minimally invasive nature leads to faster recovery time, better cosmetic results, and fewer complications. Unfortunately, not all lesions involving the sinonasal region and skull base are accessible to sinonasal endoscopy. In addition, many of these disease processes are not directly visible on clinical examination. Therefore, the surgeon relies upon imaging to (1) determine the extent and possible nature of the disease; (2) provide guidance for surgical planning purposes, in particular, if a lesion is accessible to endoscopic surgery or if an open surgical approach is indicated. The radiologist, on the other hand, needs to be familiar with the technical limitations and contraindications of sinonasal endoscopy to provide a meaningful radiology report to the surgeon. The relative and absolute contraindications to endoscopic surgery can be categorised into technical factors, extent of a lesion, tumour vascularity, and anatomical variations and are discussed in this review article.