Endoscopic Orbital Surgery: The Neurosurgeon’s Perspective

Neurosurgical approaches to the orbit are often done with the aid of ophthalmologist or otolaryngologist, to address intraorbital lesions invading intracranial spaces or, more recently, to gain skull base exposure. Dandy first reported use of a frontotemporal craniotomy to resect lesions from the orbit that then grew intracranial. The approach Dandy described has now evolved into the skull base workhorse approaches now commonly used for lesions of the orbit as well as anterior and middle cranial fossa. The development by Yasargil of the pterional craniotomy allowed for easy exposure of lesions in the anterior and middle fossa. Orbital pathology along the lateral edge of the orbit and the superior orbital fissure could be approached from the traditional version of this exposure. Later addition of a supraorbital craniotomy to the pterional approach created the orbitozygomatic craniotomy, which allowed for further exposure of the orbit. The purpose of the orbital removal with this exposure was not only to treat intraorbital pathology but to gain skull base exposure regardless of orbital involvement. Lesions of the superolateral area of the orbit as well as lesions extending into the anterior and middle cranial fossa could safely be resected from this approach. However, there are downsides of traditional craniotomies, including a large scar, temporalis atrophy, cerebrospinal fluid leak (CSF), and infection.

Subfrontal craniotomies are another commonly used approach to lesions of the orbit and anterior cranial fossa. These approaches usually include a variation of a bicoronal incision with removal of a portion of the frontal bar bilaterally or unilaterally depending on the pathology. Subfrontal retraction then allows for views of the superior orbit along with extended views of the superolateral or superomedial orbit. The required cranial exposure and retraction of a bifrontal craniotomy can be extensive. Therefore attempts have also been made to decrease the amount of craniotomy needed to expose the anterior fossa. One of these more minimal approaches includes the supraorbital craniotomy, which allows for anterior fossa exposure while minimizing frontal lobe retraction. Visualization offered with the supraorbital craniotomy has greatly been expanded with use of the endoscope and combining the supraorbital approach with endonasal approaches.

Endoscopic endonasal approaches were developed in the late 1990s by Jho, first for approaches to sellar pathology. Later, expanded approaches were able to expose the inferomedial orbital apex as well as the anterior cranial fossa. The first attempt to use the endoscope through the orbit was completed in the 1980s, but this technique was not advanced because of the lack of high-quality imaging and navigational capability. The potential of transorbital surgery as a corridor to intracranial pathology would not be advanced again until 2010. This transorbital corridor was developed in large part because of the tools developed for endonasal approaches, the advancement in imaging, and neuronavigation. The use of the endoscope allowed for small orbital craniotomies with more direct routes to surgical pathology of the anterior and middle cranial fossa, leading to minimization of brain retraction. Transorbital approaches have now opened the orbit as an extensive intracranial corridor.

Transorbital Approaches

Transorbital approaches have a classification based on the surgical target. Orbital endoscopic surgery is for access to the orbit and optic nerve within the orbit; transorbital endoscopic surgery or transorbital neuroendoscopic surgery (TONES) is for targeting intracranial pathology. These approaches offer a corridor to the lateral aspect of the anterior and middle fossa, as opposed to the direct approach to the central anterior fossa provided by endoscopic endonasal approaches. The choice of transorbital approach depends on the targeted anatomical region. Endoscopic orbital approaches include the superior eyelid crease approach (SLC), the precaruncular approach (PC), lateral retrocanthal approach (LRC), and preseptal lower eyelid (PS) approach ( Fig. 3.1 ). All these approaches have been tested in both clinical and preclinical settings for different pathologies.

Fig. 3.1

Overview of four quadrants of the orbit. The superior quadrant is the area covered by the superior eyelid crease approach. The lateral quadrant ( yellow ) is covered by the lateral retrocanthal approach with some overlap with the superior eyelid crease. The inferior quadrant is covered by the preseptal lower eyelid approach. The medial quadrant ( red ) is covered by the precaruncular approach.

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.

Table 3.1

Clinical Use of Endoscopic Transorbital Approaches

Author Year Approach Pathology Treated No. of Cases Type of Multiport Access
Moe et al. 2010 SLC CSF leak, frontal sinus mucocele, decompression of orbit 9
LRC Decompression of orbit apex, CSF leak repair 2
PC Tumor debulking, CSF leak repair, foreign body removal 10
PS Decompression orbit apex, CSF leak repair, metastatic squamous cell debulking 2
Moe et al. 2011 SLC CSF leak, orbital wall fractures, frontal sinus fracture 6
LRC CSF leak, orbital wall fracture 1
PC CSF leak, orbital wall fracture 5
PS CSF leak, orbital wall fracture 1
Lim et al. 2012 SLC Orbital abscess, epidural abscess, frontal sinus mucopyocele 9
PC Orbital apex syndrome, orbital abscess, fronto-orbital mucocele, 4
Raza et al. 2012 PC CSF leak repair, Paget disease, adjunct juvenile angiofibroma, and esthesioneuroblastoma resection 6 Endonasal
Rajappa et al. 2014 SLC Epidural abscess 1
Bly et al. 2014 SLC Tension pneumocephalus 1 Endonasal
Dallan et al. 2015 SLC Adjunct resection spheno-orbital meningioma 3 Endonasal
PS Malignant schwannoma 1
Tham et al. 2015 SLC Fibrous dysplasia of orbit and ethmoid 1 Endonasal
Chen 2015 SLC Amygdalohippocampectomy 2
Ramakrishna et al. 2016 SLC CSF leak repair, mucocele resection, orbital hematoma evacuation, evacuation of mucopyocele, optic nerve decompression, orbital fracture repair, sinonasal melanoma resection, fibroxanthoma resection, frontal sinus fracture repair 13
SLC/PS CSF leak repair, ORIF orbit fracture, epidural abscess drainage 6
LRC Esthesioneuroblastoma resection, melanoma resection, CSF leak repair 4
PC CSF leak repair, esthesioneuroblastoma resection, meningocele repair, osteoma resection, orbital fracture repair, osteoblastoma resection, fibrous dysplasia resection, squamous cell carcinoma resection, encephalocele resection, meningioma resection 17
Almeida 2017 SLC Resection spheno-orbital meningioma 2
Kong 2018 SLC Spheno-orbital meningioma, osteosarcoma, plasmacytoma, sebaceous gland carcinoma, intraconal schwannoma, cystic teratoma, and fibrous dysplasia resection 18

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Jan 3, 2021 | Posted by in OPHTHALMOLOGY | Comments Off on Endoscopic Orbital Surgery: The Neurosurgeon’s Perspective

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