LAUSR

INTRODUCTION The parasellar region is one of the most complex of the skull base. In this study, we review the anatomy and approaches to this region through a 360-degree perspective, correlating microsurgical and endoscopic anatomical nuances of this area. METHODS Endoscopic endonasal approach (EEA) and microsurgical dissections were performed. The parasellar anatomy is reviewed and common areas of tumor extensions are assessed. Surgical approaches are discussed based on the anatomical nuances of those regions. RESULTS The cavernous sinus (CS) can be divided in two spaces: posterosuperior, above and behind the internal carotid artery (ICA); and anterior, in front of the cavernous ICA. Those can be approached through the CS walls: anterior and/ or medial wall via EEA; or superior and/or lateral wall via transcranial approaches. The relationship of Meckel's cave, adjacent to the lateral and posterior wall of the CS, is relevant for surgical planning. Areas often affected by tumor extension can be divided into 6 regions: superior (cisternal), superolateral (parapeduncular), posterolateral (Meckel's cave and petrous bone), medial (sella), anterior (SOF) and anterior inferior (pterygopalatine fossa). Anatomical and technical nuances of each of those regions should be taken into consideration when dealing with tumors in the parasellar space. CONCLUSION Transcranial and EEA provide effective access to the parasellar region. Management of cavernous sinus and Meckel's cave tumors requires familiarity with those approaches. Understanding of the surgical anatomy of the parasellar region, from "above and below", is therefore necessary for adequate surgical planning and execution.