QUANTITATIVE AND QUALITATIVE ANALYSIS OF THE WORKING AREA OBTAINED BY ENDOSCOPE AND MICROSCOPE IN VARIOUS APPROACHES TO THE ANTERIOR COMMUNICATING ARTERY COMPLEX USING COMPUTED TOMOGRAPHY-BASED FRAMELESS STEREOTAXY: A CADAVER STUDY

OBJECTIVE: Surgical treatment of aneurysms of the anterior communicating artery complex is challenging, owing to its intricate vascular anatomy. Endoscopy is a recently rediscovered neurosurgical technique that could lend itself well to overcoming some of the vascular Visualization challenges associated with this procedure. The purpose of this study was to quantify and compare the working area afforded by the microscope and the endoscope to the anterior communicating artery complex in different surgical approaches and using image guidance. METHODS: We performed a total of 9 dissections, including mini-supraorbital, pterional, and orbitozygomatic approaches bilaterally in 5 whole, fresh cadaver heads. We used computed tomography-based image guidance for intraoperative navigation as well as for quantitative measurements. We estimated the working area of the anterior communicating artery complex region, using both a rigid endoscope (4.0 mm in diameter and 18 cm long with 0- and 30-degree lenses) and an operating microscope. Operability was qualitatively assessed by the senior authors. RESULTS: In microscopic exposure, the orbitozygomatic approach provided the greatest working area (204.5 +/- 33.9 mm(2)), as compared with the mini-supraorbital approach (114.8 +/- 26.9 mm(2)) and pterional approach (170 +/- 20.4 mm(2); P < 0.05). Evaluation of the endoscopic working area showed that the supraorbital approach, using both 0- and 30-degree endoscopes, provided a working area greater than that of a conventional pterional approach (P < 0.05) and comparable to that of an orbitozygomatic approach (P > 0.05). CONCLUSION: In our model, use of the endoscope, in an assistive manner to microscopic surgery, provided a working area advantage without loss of microneurosurgical techniques of dissection or of depth perception in the surgical field. This advantage was most prominent when smaller craniotomies were used.