The anterior skull base (ASB) is a complex anatomical region with regard to intricacy of bony, neurological and soft tissue structures. This region is a confluence of multiple interacting systems including high level neurological function and sinonasal physiology, in addition to vision, olfaction and complex eye movements. Traditional open cranial approaches to the ASB have been pioneered by neurological surgeons, otolaryngologists/head and neck surgeons, plastic surgeons and ophthalmologists. Over the past several decades, minimally invasive cranial approaches to the ASB have changed the clinical decision-making paradigm for approaching many pathological subtypes encountered in this region. The rapid evolution of endonasal endoscopic techniques has pushed the frontiers of minimally invasive neurosurgery. Whereas open, transcranial approaches have been used for decades to approach lesions of the ASB, the development of endonasal access to the same regions has rapidly expanded the neurosurgeon’s armamentarium. This text is a cornerstone reference for all surgical corridors involving the ASB, an area that has to date not been exclusively or adequately addressed. Main sections include descriptions of surgical ASB anatomy via open approaches and minimally invasive, endoscopic approaches; indications and technical steps for approaching each region (i.e., frontal sinus, cribriform plate, planum sphenoidale, tuberculum, and the sellar/parasellar/suprasellar region) of the ASB via open and minimally invasive approaches; and illustrated cases exemplifying treatment of commonly encountered ASB pathologies, including intra- and extra-axial tumors, cerebrospinal fluid leaks, and nasal- and oro-pharyngeal pathology with intracranial extension. Full-color photographs and selected video segments enhance the presentation and provide real-world context for the cases.
