Comparative Analysis of Microsurgical Techniques for the Exposure of Internal Maxillary Artery: A Cadaver Study of a Major Donor for Cerebral Revascularization

Background: Internal maxillary artery (IMAX) has been used as a donor vessel in extracranial-to-intracranial bypass surgery. In literature, four different approach methods have been described as techniques of exposing different segments of IMAX: anterior medial infratemporal fossa (AMITF), middle infratemporal fossa (MITF), anterior lateral middle fossa (ALMF), and lateral middle fossa (LMF) approaches. However, the advantages and limitations between these techniques were not compared. We aimed to compare the anatomical measurements of these four effective techniques for exposing IMAX as a bypass donor vessel and also measurements of AMITF and MITF methods without zygomatic bone.

Methods: Each approach technique was performed on 10 cadaveric specimens. The length, branches, caliber of targeted segments of IMAX, and depth from operating plane to IMAX were recorded. The surgical area of each technique was measured by assessing surrounding landmark with a navigation system. The time of surgical dissection of each technique has been calculated in five specimens. The downward reflected length of temporal muscle after zygomatic bone dissection was also recorded in 10 specimens. All data were analyzed by SPSS statistic software.

Results: The method of MITF provided the greatest operating area of exposure (3.88 ± 0.97 cm²), while the ALMF method provided the smallest one (1.08 ± 0.34 cm²). The method of LMF and MITF provided the largest caliber of IMAX (3.1 ± 0.4 mm, 3.0 ± 0.3 mm). The method of ALMF provided the shortest road from the operating plane to the exposed segment and the least time for exposure (21.8 minutes). The method of MITF exposed the longest segment of IMAX (18.8 ± 3.5 mm). The MITF method without zygomatic bone provided significantly longer segment than MITF method (19.5 ± 3.8 mm).

Conclusion: The AMITF and MITF methods can make the whole anastomosis procedure easier than ALMF and LMF methods with advantages such as less complex structure, less skull base drilling, and less muscle dissection. Identification of the pattern of IMAX is important before decision of the approach method in bypass operation. Our research can provide evidence for neurosurgeon to decide which one method would be better for their surgeries, plan their procedures preoperatively, and also to understand better the advantages and limitations of these methods.