Surgical Resection of an Optic Nerve Sheath Meningioma: Relevance of Endoscopic Endonasal Approaches to the Optic Canal

Intracranial meningioma: A review of recent and emerging data on the utility of preoperative imaging for management

Meningiomas are the most common neoplasms of the central nervous system, accounting for approximately 40% of all brain tumors. Surgical resection represents the mainstay of management for symptomatic lesions. Preoperative planning is largely informed by neuroimaging, which allows for evaluation of anatomy, degree of parenchymal invasion, and extent of peritumoral edema. Recent advances in imaging technology have expanded the purview of neuroradiologists, who play an increasingly important role in meningioma diagnosis and management. Tumor vascularity can now be determined using arterial spin labeling and dynamic susceptibility contrast-enhanced sequences, allowing the neurosurgeon or neurointerventionalist to assess patient candidacy for preoperative embolization. Meningioma consistency can be inferred based on signal intensity; emerging machine learning technologies may soon allow radiologists to predict consistency long before the patient enters the operating room. Perfusion imaging coupled with magnetic resonance spectroscopy can be used to distinguish meningiomas from malignant meningioma mimics. In this comprehensive review, we describe key features of meningiomas that can be established through neuroimaging, including size, location, vascularity, consistency, and, in some cases, histologic grade. We also summarize the role of advanced imaging techniques, including magnetic resonance perfusion and spectroscopy, for the preoperative evaluation of meningiomas. In addition, we describe the potential impact of emerging technologies, such as artificial intelligence and machine learning, on meningioma diagnosis and management. A strong foundation of knowledge in the latest meningioma imaging techniques will allow the neuroradiologist to help optimize preoperative planning and improve patient outcomes.

Exclusively endoscopic endonasal resection of benign orbital tumors: a systematic review and meta-analysis

BACKGROUND

The Cavernous Hemangioma Exclusively Endonasal Resection (CHEER) classification system was developed to standardize prospective outcome analysis following orbital cavernous hemangioma (OCH) resection. The goal of this study was to retroactively apply the CHEER system to all prior existing reports of endoscopic resection of primary benign orbital tumors (BOTs) to: (1) compare patient presentations, perioperative characteristics, and outcomes between OCH and other BOTs; and (2) determine whether the CHEER categorization regime could be expanded to other BOTs.

METHODS

A systematic review of studies reporting exclusively endoscopic resections of OCH and other BOTs (eg, solitary fibrous tumor, schwannoma, and meningioma) was performed. Patient, tumor characteristics, and operative outcomes were recorded. All tumors with adequate reporting were retrospectively assigned a CHEER stage. Outcomes were compared using chi-square or Fisher's exact tests.

RESULTS

Ninety-three studies met inclusion criteria, and sufficient data were available in 36 studies, comprising 105 tumors (n = 87 OCHs; n = 18 other BOTs). Baseline patient and tumor characteristics, as well as intraoperative and short-term postoperative outcomes were not significantly different between OCHs and other BOTs. Long-term outcomes (eg, visual deficits, diplopia, eye position, and recurrence) also did not differ when controlling for CHEER stage.

CONCLUSION

This review represents the largest collection of outcomes data following exclusively endoscopic endonasal resection of BOTs. Short-term and long-term outcomes appear similar between OCHs and other BOTs. These results suggest that exclusively endoscopic resection of orbital tumors may be effective in a range of benign pathologies. Furthermore, these results support a broader application of the CHEER system to other benign primary orbital tumors.

The Endoscopic Transnasal Approach to Orbital Tumors: A Review

Historically, surgical access to orbital tumors has required a transcutaneous, transconjunctival or transcranial approach. Resection of orbital tumors is notoriously challenging due to the surrounding dense network of critical structures in a confined bony cavity. Advances in endoscopic endonasal surgery, initially used for sinonasal and skull base conditions, have allowed for expansion of its applications beyond the sinorbital interface. In the past decade, the evolution of techniques has enabled a purely endoscopic, minimally invasive approach to medially located orbital pathology with good outcomes. With experience and multidisciplinary collaboration between orbit and rhinologic surgeons, this has expanded to allow for a safe and effective transnasal approach to nearly all regions of the orbit with or without assistance from the orbital side. This review summarizes the relevant anatomy, variations of surgical approaches, and literature regarding outcomes of the endoscopic endonasal approach to orbital tumors.

Primary and Secondary Optic Nerve Sheath Meningioma

Objective  This study was aimed to review issues relating to the recognition, radiographic diagnosis, monitoring, and management of primary and secondary optic nerve sheath meningioma (ONSM). Design  This study is a review of peer-reviewed literature combined with illustrative case studies. Participants and Methods  A literature search was conducted via the PubMed database using pertinent search terms. Selected articles were limited to those written or translated into English. Additional works cited within articles were also included. Individual cases were drawn from the experience of a tertiary academic neuroophthalmic and orbital practice. Tables summarize radiotherapeutic and surgical studies, excluding single case reports and studies focusing on meningioma of intracranial origin. Main Outcome Measurements  Review of reported surgical and radiotherapeutic series is the primary measurement. Results  The natural history of optic nerve sheath meningiomas is primarily characterized by progressive ipsilateral vision loss. Diagnosis is typically based on radiographic imaging findings, with biopsy remaining indicated in some patients. Management strategies may include observation, radiation, and/or surgical intervention, or a combination of these approaches. The role of surgery, especially with respect to primary ONSM (pONSM), remains controversial. Advancement of radiotherapy techniques has shifted modern treatment paradigms in pONSM toward radiation as primary treatment, as surgical outcomes are inferior in major studies. Although radiation remains the treatment of choice in many cases, selected patients may benefit from surgery, especially in the setting of secondary ONSM (sONSM). Conclusion  A wide variety of radiotherapeutic and surgical treatment modalities for ONSM exist. The specific indications for each management strategy continue to be redefined.

Endoscopic endonasal surgery for anterior cranial fossa meningiomas

Meningiomas along the anterior skull base arise from the midline but have historically been resected via open cranial approaches with lateral to medial trajectories. The endoscopic endonasal approach (EEA) offers a direct, inferomedial approach which has demonstrated several superior qualities for their resection. These meningiomas include tuberculum sellae, planum sphenoidale, and olfactory groove meningiomas. While early gross total resection (GTR) was lower than open approaches, EEA has currently achieved comparable rates of GTR and significantly improved postoperative visual outcomes. Rate of cerebrospinal fluid (CSF) leak was one of the early complicating features preventing widespread use of EEA. However, CSF leak rates have dramatically fallen into a tolerable range with introduction of the vascularized nasoseptal flap. Olfactory groove meningiomas often present with anosmia which is persistent after endonasal approach. Rates of other complications have proven similar between EEA and open approaches and include: vascular injury, infection, morbidity, and mortality. With the appropriate team and experience, EEA for anterior skull base meningiomas is increasingly becoming the standard for resection of these lesions. However, there are certain anatomic considerations, patient features, and other aspects which may favor the open approach over EEA, and vice versa; these must be carefully and judiciously evaluated preoperatively. Overall, resection and recurrence rates are comparable, complication rates fall within a very acceptable range, and patients experience superior cosmesis and improved visual outcome with this approach.

Endoscopic Endonasal Removal of Primary/Recurrent Meningiomas in the Medial Optic Canal: Surgical Technique and Long-Term Visual Outcome

BACKGROUND

Tuberculum sellae meningiomas frequently extend into the optic canals, which leads to a progressive longitudinal visual loss. Therefore, in addition to tumor removal, unroofing and exploration inside the optic canal are important procedures.

OBJECTIVE

To perform endoscopic endonasal tumor removal with optic canal decompression for small primary or recurrent meningiomas associated with a progressive visual loss at the inferior-medial optic canal, which corresponded to a blind corner in the ipsilateral pterional/subfrontal approach.

METHODS

We retrospectively reviewed 2 cases of primary meningiomas that arose in the inferior-medial optic canal and 4 recurrent cases from the remnant inside the medial optic canal that had previously undergone craniotomy for tuberculum sellae meningiomas, and were treated by the endoscopic endonasal approach.

RESULTS

All tumors were detectable and could be removed without manipulation of the affected optic nerve. The average maximum diameter of the tumor was 8.4 mm (range: 5-12 mm). Two patients who had a long history of progressive visual disturbance and papillary atrophy did not recover from severe visual disturbances postoperatively. However, others showed considerable improvement, maintaining postoperative visual function during follow-up. There were no postoperative complications.

CONCLUSION

Endoscopic endonasal approach has several advantages for meningiomas in the medial optic canal and associated with progressive visual disturbance. In surgery of tuberculum sellae meningiomas, optic canal decompression and exploration inside the optic canal are important procedures to avoid symptomatic recurrence, which may be facilitated by the endoscopic endonasal approach. Papillary atrophy and duration of visual deterioration are predictive factors for postoperative visual outcomes.

Optic nerve sheath meningioma endoscopic endonasal surgical management

Background:

Meningiomas of the optic sheath have been traditionally treated with radiotherapy, among other reasons, because of the poor results in terms of visual preservation of the open surgical approaches.

Case Description:

Two cases of optic nerve meningioma were operated through an endoscopic endonasal expanded approach due to rapidly progressing visual deterioration and doubtful diagnosis. In the first case an exclusively bone decompression was performed. In the second one a partial resection of the intradural portion and complete opening of the dural sheath was undertaken. In both cases visual acuity remained stable without further treatment for the 2 years follow up.

Conclusions:

Endoscopic endonasal decompression of the optic nerve by removal of the optic canal and opening of the optic sheath is safe. This approach is feasible for optic sheath meningioma. This treatment might be considered as an option in patients with rapidly deteriorating visual acuity.

The Role of Endonasal Endoscopic Optic Nerve Decompression as the Initial Management of Primary Optic Nerve Sheath Meningiomas

Background  The management of optic nerve sheath meningiomas (ONSMs) remains controversial. Surgical decompression through traditional resective techniques has been associated with significant morbidity. While radiation therapy, the current modality of choice is not exempt of risks. Transnasal endoscopic optic nerve decompression (EOND) offers a direct route to the orbit, optic canal, and orbital apex, providing a minimally invasive alternative. Objective  The main objective of this article is to assess EOND as the initial management of symptomatic patients with primary ONSM. Methods  Patients with ONSMs without a history of radiotherapy who underwent EOND were retrospectively reviewed. Postoperative imaging, duration of follow-up, and visual outcomes at the last ophthalmology visit were assessed. Results  Four women (age range 25-63 years) with primary ONSMs that underwent EOND were identified. All patients displayed subjective and objective baseline signs of vision loss. Additionally, baseline proptosis, diplopia, optic nerve atrophy, and ocular pain were identified. In none of the cases, the optic nerve sheath was breached. Following EOND, all patients deferred treatment with adjuvant radiotherapy. At a mean postoperative follow-up of 14 months, all patients were clinically stable without evidence of disease progression on imaging or physical examination. At last ophthalmologic evaluation, three out of four showed objective improvements from baseline visual acuity and visual field (remaining patient had baseline optic nerve atrophy). Conclusion  These results suggest that EOND could be a viable initial treatment modality of selected primary ONSM cases. Further studies are warranted to determine long-term efficacy and its role in a stepwise progression of management, preceding radiotherapy.