Endoscopic Orbital Surgery: The Neurosurgeon’s Perspective

Superior Eyelid Crease Approach

The SLC approach involves a superior eyelid incision with careful dissection along the superior orbital rim. Initial clinical use of this exposure was used to repair CSF leaks, fractures, and orbital compression as described by Moe et al. ( Table 3.1 ). With this exposure, a large portion of the superior and lateral orbit can be visualized. With drilling of the posterior orbit, the anterior and middle cranial fossa can be reached through this exposure. The SLC approach limits include the superomedial limit defined by the superior orbital fissure, the inferior limit defined by the inferior orbital fissure, and the lateral limit defined by the temporalis muscle ( Fig. 3.2 ). Preclinical cadaver studies have thoroughly evaluated the potential of this approach ( Table 3.2 ). The first use of this approach for intracranial pathology was described as a theoretical approach for an amygdalohippocampectomy. By drilling of the orbit adjacent to the inferior orbital fissure, the temporal pole was exposed and intradural exposure of the mesial temporal lobe was completed. Further cadaver studies have shown that the lateral cavernous sinus, including the cavernous carotid, gasserian ganglion, ophthalmic division of trigeminal nerve (V1), maxillarydivision of trigeminal nerve (V2), and mandibular nerves division of trigeminal nerve (V3), could all be reached through the SLC approach by more lateral dissection along the orbital rim. Using a combination of the SLC and endonasal approach, an almost 360-degree decompression of the optic nerve could be completed. The sylvian fissure has also been dissected through this route with exposure of the middle cerebral artery. More posterior exposure of the middle cranial fossa has also allowed for dissection and drilling of the petrous apex with the ability to visualize the cerebellopontine angle and internal auditory canal.

Despite multiple preclinical studies showing theoretical exposures and applications, practical clinical use of the SLC approach has remained limited. The first clinical cases used the SLC approach to repair CSF leaks, drain cerebral abscesses, decompress pneumocephalus, and repair orbital fractures. ^a

a References .

Decompression of the optic nerve and repair of difficult CSF leaks from trauma remain the most clinically used applications of the SLC approach. Because of the trajectory, SLC is particularly helpful in repair of anterior cranial fossa CSF leaks originating from the orbital roof, as well as CSF leaks from the frontal sinus. Orbital abscesses and cranial epidural abscesses have also been a common target of the SLC approach. In one case report, the SLC approach was chosen for a patient with a prior cranioplasty after bifrontal craniotomies and an isolated supraorbital epidural abscess. Because of the localized approach, the epidural abscess was able to be evacuated without hardware removal. One of the first reported nontraumatic applications of the SLC approach was a successful completion of two amygdalohippocampectomies. Tumor resection transorbitally with the SLC approach was first described by Dallan et al., who reported its use in three spheno-orbital meningioma cases. In these cases, subtotal resection was accomplished using the SLC approach in conjunction with transpterygoid and transmaxillary approaches for local control. Separate groups have also used the SLC approach as both a solo and combined approach for multiple types of mass lesions. Indications for SLC approach have included biopsy and resection of fibrous dysplasia, resection of sinonasal melanoma, and resection of fibroxanthoma. SLC as a solo approach was used by Almeida et al. for resection of two spheno-orbital meningiomas in patients with predominantly hyperostosis and proptosis. By using the SLC approach to drill out the bone of the hyperostotic orbital roof and lateral wall, the proptosis cold be relieved, even though gross total resection was not possible. The SLC approach is the most widely used transorbital approach in the literature. It was the approach chosen in the largest cohort of patients with mass lesions treated using the transorbital route. This cohort consisted of a total of 18 patients. Twelve of the patients had a diagnosis of spheno-orbital meningioma, and the other patients had diagnoses of osteosarcoma, plasmacytoma, sebaceous gland carcinoma, intraconal schwannoma, cystic teratoma, and fibrous dysplasia. Several of the tumors also had an intradural component, which was resected and the dural defect was repaired using a double-button technique. Only two of the patients with resections had a temporary CSF leak, but no long-term CSF leaks were reported.