Extended endoscopic transorbital approach with superior-lateral orbital rim osteotomy: cadaveric feasibility study and clinical implications (SevEN-007)

Abstract

OBJECTIVE The endoscopic transorbital approach (ETOA) has been developed, permitting a new surgical corridor. Due to the vertical limitation of the ETOA, some lesions of the anterior cranial fossa are difficult to access. The ETOA with superior-lateral orbital rim (SLOR) osteotomy can achieve surgical freedom of vertical as well as horizontal movement. The purpose of this study was to confirm the feasibility of the ETOA with SLOR osteotomy. METHODS Anatomical dissections were performed in 5 cadaveric heads with a neuroendoscope and neuronavigation system. ETOA with SLOR osteotomy was performed on one side of the head, and ETOA with lateral orbital rim (LOR) osteotomy was performed on the other side. After analysis of the results of the cadaveric study, the ETOA with SLOR osteotomy was applied in 6 clinical cases. RESULTS The horizontal and vertical movement range through ETOA with SLOR osteotomy (43.8° ± 7.49° and 36.1° ± 3.32°, respectively) was improved over ETOA with LOR osteotomy (31.8° ± 5.49° and 23.3° ± 1.34°, respectively) (p < 0.01). Surgical freedom through ETOA with SLOR osteotomy (6025.1 ± 220.1 mm3) was increased relative to ETOA with LOR osteotomy (4191.3 ± 57.2 mm3) (p < 0.01); these values are expressed as the mean ± SD. Access levels of ETOA with SLOR osteotomy were comfortable, including anterior skull base lesion and superior orbital area. The view range of the endoscope for anterior skull base lesions was increased through ETOA with SLOR osteotomy. After SLOR osteotomy, the space for moving surgical instruments and the endoscope was widened. Anterior clinoidectomy could be achieved successfully using ETOA with SLOR osteotomy. The authors performed ETOA with SLOR osteotomy in 6 cases of brain tumor. In all 6 cases, complete removal of the tumor was successfully accomplished. In the 3 cases of anterior clinoidal meningioma, anterior clinoidectomy was performed easily and safely, and manipulation of the extended dural margin and origin dura mater was possible. There was no complication related to this approach. CONCLUSIONS The authors evaluated the clinical feasibility of ETOA with SLOR osteotomy based on a cadaveric study. ETOA with SLOR osteotomy could be applied to more diverse disease groups that do not permit conventional ETOA or to cases in which surgical application is challenging. ETOA with SLOR osteotomy might serve as an opportunity to broaden the indication for the ETOA.

Endoscopic transorbital extradural anterior clinoidectomy: A stepwise surgical technique and case series study [SevEN-013]

“…The ETOA surgery was performed as described previously in the literature ( 7 , 8 , 11 , 31 ). Skin incision was made using either trans eyelid or below-the-eyebrow techniques ( Figure 2 ).…”

“…In ETOA, moreover, the anatomical orientation around the ACP is confusing for neurosurgeons because of the unfamiliarity with the surgical view of the approach. Currently, there are only few studies of the surgical anatomy and technique for endoscopic transorbital anterior clinoidectomy, and no study about the clinical implication of this procedure in ETOA ( 2 , 11 , 43 ). To the best of our knowledge, this is the first technical study with clinical series suggesting this reproducible surgical technique and thus proving its clinical feasibility.…”

“…Surgeons should place the retractor cautiously and pay close attention to the intraorbital pressure. The extended ETOA with lateral orbital rim osteotomy or SLOR osteotomy can also help to reduce the retraction of the orbital contents ( 11 , 54 ).…”

“…Although using the ETOA for extra-axial lesions such as trigeminal schwannoma or sphenoid wing meningioma would be advantageous, efforts have also been made for intra-axial lesion tumors in the temporal lobe and insular along the ETOA trajectory ( 6 , 8 – 10 ). Additionally, recent attempts have been made to extend the use of the ETOA in the anterior or the posterior fossa ( 11 – 13 ). The anterior clinoid process (ACP) is an important landmark in anterior skull base surgeries ( 14 – 16 ).…”

Development of 3-dimensional printed simulation surgical training models for endoscopic endonasal and transorbital surgery

“…However, to the best of our knowledge, there are currently no simulation models for ETOS procedures. The pioneers of ETOS have demonstrated novel surgical techniques for ETOS procedures based on cadaveric studies and case descriptions (14)(15)(16)(17)(18)(19)(20)(21). A steep learning curve, technical expertise, and unfamiliar anatomy limit the opportunities for surgical training of the ETOS procedure.…”