Use of endoscopic transorbital and endonasal approaches for 360° circumferential access to orbital tumors

OBJECTIVE

Orbital tumors are often surgically challenging because they require an extensive fronto-temporo-orbital zygomatic approach (FTOZ) and a multidisciplinary team approach to provide the best outcomes. Recently, minimally invasive endoscopic techniques via a transorbital superior eyelid approach (ETOA) or endoscopic endonasal approach (EEA) have been proposed as viable alternatives to transcranial approaches for orbital tumors. In this study, the authors investigated the feasibility of 360° circumferential access to orbital tumors via both ETOA and EEA.

METHODS

Between April 2014 and June 2019, 16 patients with orbital tumors underwent either ETOA or EEA at the authors' institution. Based on the neuro-topographic "four-zone model" of the orbit with its tumor epicenter around the optic nerve in the coronal plane, ETOA (n = 10, 62.5%) was performed for tumors located predominantly superolateral to the nerve and EEA (n = 6, 37.5%) for those located predominantly inferomedial to the nerve. Eight patients (50%) presented with intraconal tumors and 8 (50%) with extraconal ones. The orbital tumors included orbital schwannoma (n = 6), cavernous hemangioma (n = 2), olfactory groove meningioma (n = 1), sphenoorbital meningioma (n = 1), chondrosarcoma (n = 1), trigeminal schwannoma (n = 1), metastatic osteosarcoma (n = 1), mature cystic teratoma (n = 1), sebaceous carcinoma (n = 1), and ethmoid sinus osteoma (n = 1). The clinical outcomes and details of surgical techniques were reviewed.

RESULTS

Gross-total resection was achieved in 12 patients (75%), near-total resection in 3 (18.8%), and subtotal resection in 1 (6.2%). Eight (88.9%) of the 9 patients with preoperative proptosis showed improvement after surgery, and 4 (66.7%) of the 6 patients with visual symptoms demonstrated improvement. Four (40%) of the 10 patients treated with ETOA experienced partial third nerve palsy immediately after surgery (3 transient and 1 persistent). There have been no postoperative CSF leaks or infections in this series.

CONCLUSIONS

Without transcranial approaches requiring temporalis muscle dissection and orbitozygomatic osteotomy, the selection of ETOA or EEA based on a concept of a four-zone model with its epicenter around the optic nerve successfully provides a minimally invasive 360° circumferential access to the entire orbit with acceptable morbidity.

Using fixed anatomical landmarks to avoid medial rectus injury: a radiographic analysis in patients with and without Graves' disease

BACKGROUND

Injury to the medial rectus (MR) is a potentially devastating complication of orbital and sinus surgery. Precise knowledge of the MR relative to the lamina papyracea (LP) is important during endoscopic surgery for both Graves' ophthalmopathy and inflammatory disease. The objective of this study is to determine the location of the MR in relation to easily identified and frequently encountered intranasal landmarks in patients with and without Graves' disease.

METHODS

High-resolution computed tomography scans were analyzed in 100 controls and 63 patients with Graves' disease. The MR position was recorded relative to the maxillary sinus ostium (MSO), anterior ethmoid artery (AEA), and posterior ethmoid artery (PEA)/horizontal basal lamella (BL). Clinically relevant variables recorded at each level included the Keros stage, AEA position, MR height, and distance of the MR to orbital floor, skull base, and LP.

RESULTS

The mean distances between the MR and LP were statistically different for both groups. Controls at the MSO, AEA, and PEA/BL were 2.92, 1.69, and 1.06mm; for Graves' patients measurements at these sites were 2.12, 1.20, and 0.029mm. When comparing the two groups, each of these distances were statistically significant (p<0.02). There was no difference in ethmoid cavity width (p>0.05) between controls (9.66mm) and Graves' patients (9.70mm). Sex, age, and skull base depth were not statistically significant factors.

CONCLUSION

This study illustrates the position of the MR from the perspective of an endoscopic surgeon utilizing fixed intranasal landmarks. Knowledge of the position of MR is critical to safely perform decompression surgery and when operating adjacent to the LP during endoscopic surgery.

Retrieval of ruptured medial rectus muscle with an endoscopic endonasal orbital approach. A case report and indication for surgical technique

INTRODUCTION

Rupture of the extraocular muscle is extremely rare, and a traumatic event is especially uncommon. Although retrieval of an injured MRM is usually performed by an anterior approach by an ophthalmologist, missing muscles in the orbital retrobulbar space are sometimes difficult to identify. This is the first report to demonstrate direct muscle to muscle anastomosis by an endoscopic endonasal orbital approach by a single otolaryngologist.

CASE REPORT

A 67-year-old man presented with left medial rectus muscle (MRM) rupture due to a traffic accident 4 months after injury. The MRM was completely ruptured, and the muscle was repaired by an endoscopic endonasal orbital approach. After surgery, his eye abduction was improved in the primary position, and adduction ability was markedly restored on right gaze without diplopia.

CONCLUSIONS

Our endonasal endoscopic approach provides excellent access to the MRM in the orbital retrobulbar space and avoids a facial scar. We could suture both ends of the muscle together by an endonasal endoscopic approach and could obtain a good result without any complications.

Anatomical analysis of intraorbital structures regarding sinus surgery using multiplanar reconstruction of computed tomography scans

OBJECTIVES

This study aimed to investigate the anatomy of the intraorbital structures regarding to endoscopic sinus surgery and external frontal sinus surgery analyzing computer tomography (CT) scans.

METHODS

The CT scans of 100 patients were retrospectively evaluated. The anatomic relationships between the intraorbital structures and paranasal structures were measured using multiplanar reconstruction of the CT scan.

RESULTS

The mean distances from the medial orbital floor (MOF) to the intraorbital structures were measured at the depth of the anterior ethmoid (AE), basal lamella (BL), and midportion of posterior ethmoid (PE) in the coronal planes respectively. The mean distances from the MOF to the medial rectus muscle and inferior rectus muscle at the depth of AE were approximately 8 mm and those distances in the BL and PE decreased rapidly. The mean distances from the MOF to the infraorbital nerve at the depth of the AE and BL were approximately more than 10 mm. The mean distances from the vertical axis, which passed through the MOF, to the superior oblique muscle and optic nerve at the depth of the PE were approximately 5 mm medially and 1 mm laterally. In addition, the mean distance from the midline to the trochlea of the superior oblique muscle was approximately 15 mm.

CONCLUSIONS

Those measurements provide spatial information on the placements of the extraocular muscles within the orbit. The measurements will contribute to the avoidance of orbital complications during sinus surgery.

The transmaxillary endoscopic approach to the orbit

OBJECTIVE

In this surgical-anatomical cadaveric study we investigate the feasibility of the transmaxillary endoscopic approach to the intraorbital space. Anatomical landmarks are defined, the endoscopic view in the orbital space is studied and complications that can occur are discussed.

METHODS

Nine formalin-fixed heads were used to study the transmaxillary endoscopic approach to the orbit. The approach was used twice on each head (once for each maxilla). Therefore, we report our results on 18 transmaxillary intraorbital approaches. For better differentiation of anatomical structures, the veins and arteries were injected with blue and red plastic respectively in six cadaveric heads.

RESULTS

The transmaxillary approach enables viewing the inferior intraconal structures without endangering the infraorbital nerve and its artery and without diversion of the inferior rectus muscle. The optic nerve was visualised more easily through the approach medial to the inferior rectus muscle instead of lateral to the muscle since the ciliary nerves are in the way in the lateral approach. The combination of the approaches medial and lateral to the inferior rectus muscle allows very good identification of all important anatomical structures in the inferior intraconal space.

CONCLUSION

The transmaxillary endoscopic approach to the orbit is a useful new approach in the surgical armamentarium for orbital lesions. The overview of the inferior part of the orbit is excellent, and the lateral part of the optic nerve can be visualised. Careful anatomical dissection allows visualisation of important anatomical structures in the orbit without damaging nerves or arteries.