Endoscope-assisted skull base surgery

The direct endonasal transsphenoidal approach to the sella with the operating microscope was first described over 20 years ago. Over the last decade, this minimally invasive technique has evolved into an effective skull base approach for pituitary adenomas and many other parasellar tumors. This expansion of the endonasal technique has resulted largely from development of refined instrumentation and greater use of endoscopy. By taking advantage of the expanded panoramic vision provided by the endoscope, one can visualize areas of the skull base not possible with the operating microscope. Our use of endoscopy has increased over time, particularly for extended endonasal transsphenoidal cases. In a total of 900 endonasal microscopic approaches performed since 1998, endoscopic assistance was utilized in 20% of all cases and in 66% of the last 100 cases. In 129 extended endonasal procedures for parasellar pathology, endoscopy was used in 63% of cases overall and in 84% of the last 25 cases. In 109 extended procedures for tumor removal in 97 patients (including 22 pituitary adenomas, 18 meningiomas, 17 craniopharyngiomas, 14 clival chordomas, and 26 other lesions), endoscopic assistance was used in 64% of these procedures. Total or near-total (>90%) tumor removal was achieved in 70% of patients operated with endoscopic assistance compared to only 41% of those operated without endoscopic assistance (p = 0.003); other factors including prior surgery, prior radiotherapy and cavernous sinus invasion were also strongly associated with subtotal tumor removal (p < 0.01). From our experience and that of others, it is becoming increasingly clear that endoscopy is essential for achieving maximal and safe endonasal removal of parasellar tumors that extend beyond the confines of the sella. Herein we describe the technique of endoscopic- assisted endonasal skull base surgery, its advantages, clinical applications and potential pitfalls.