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Abstract
Background
The endoscopic transorbital approach (ETOA) is being established as a new corridor for the lateral portion of the anterior and middle skull base. One of the main concerns is the risk of ophthalmological complications due to orbital retraction. Removal of the lateral orbital rim (LOR) is a simple measure that widens the corridor and may diminish injuries secondary to retraction. This study analyzes the impact of LOR removal on intraorbital pressure (IORP) during the stages of ETOA.
Methods
In this prospective cadaveric study, standard ETOA to the anterior and middle fossae were performed via a superior eyelid crease incision (Fig. 2). On one side, the LOR was preserved; on the other, it was removed. IORP was recorded with an intracranial pressure (ICP) probe during the entirety procedure (Fig. 3). All specimens underwent pre- and post-procedure CT to measure bone removal volume.
Results
Four specimens were used (8 sides, 4 with LOR removal, 4 without). Mean IORP was not statistically different between groups during periorbita detachment, which was prior to LOR removal (117.4 vs 91.5 mmHg, for the LOR removal group and LOR intact group respectively p = 0.217). IORP was consistently reduced in the LOR removal group in every subsequent step (Fig. 3): meningo-orbital band cutting (105.5 to 38.9 mmHg, p < 0.002), temporal fossa drilling (85.3 to 69.5 mmHg, p = 0.232), lateral greater sphenoid wing (GSW) drilling (99.8 to 49.9 mmHg, p < 0.001), medial GSW drilling (85.6 to 17.2 mmHg, p < 0.001), cavernous sinus peeling (85.6 to 3.0 mmHg, p < 0.001). LOR removal increased total bone removal volume from 6.2 cc to 9.4 cc (p = 0.05).
Conclusion
LOR removal decreased IORP, especially when working on the GSW and cavernous sinus, and significantly increased bone removal. These results support LOR removal to reduce orbital retraction stress and widen the working corridor during ETOA.
