Primary and Secondary Optic Nerve Sheath Meningioma

Treatment of Meningiomas Involving the Optic Canal with Endoscopic Transnasal Decompression of the Optic Nerve

BACKGROUND

Management of patients with optic nerve sheath meningiomas (ONSMs) is controversial and the treatment strategy in this patient group is still up for discussion. Transnasal endoscopic orbital and optic nerve decompression aims to reduce the pressure in the orbit and on the optic nerve and thereby prevent vision loss. This article presents material from 7 cases of transnasal endoscopic orbital decompression.

METHODS

The study design is a retrospective cohort study. The aim was to include all patients with a meningioma residing along the nerve sheath and who were operated using endoscopic transnasal decompression of the orbit and if needed the optic canal at Odense University Hospital. Data from the medical records were collected and pre- and postoperative eye examinations were compared. In addition, it was recorded whether there were complications to the procedure and whether additional treatments were given.

RESULTS

In total, 4 women and 3 men were included in the study. Four out of 7 patients experienced improvement in vision after the operation. One patient experienced unchanged vision and 2 patients experienced deterioration of vision after surgery.

CONCLUSIONS

The current report of 7 patients with ONSM shows promising results for this surgical procedure as 4 out of 7 patients experienced improvement in their vision at follow-up examinations. The 2 patients who experienced deterioration of vision already had severely reduced vision preoperatively, which indicates that surgery should be considered before the vision becomes significantly reduced.

Gross-total resection in optic nerve sheath meningiomas: minimally invasive and cosmetic pleasing

PURPOSE

The optic nerve sheath meningioma (ONSM) is one of the most challenging tumors in orbital surgery. From the perspective of mental health and patient needs, we analyzed the necessity and importance of the endoscopic transnasal approach (ETA) combined with optic nerve transection (ONT) in gross-total resection (GTR) in ONSM patients with residual vision and aim to broaden the use of ONT for specific people.

METHODS

The authors included patients with ONSMs who were treated between 2014 and 2022. We divided those cases into two groups named ETA group and lateral orbitotomy approach (LOA) group. We present the application of ETA and analyze the preoperative indication of the ONT and compared the advantages and disadvantages between ETA and LOA. The degree of tumor resection was based on imaging and surgical evaluation.

RESULTS

A total of 23 patients with ONSM were included. Sixteen patients underwent ETA, and seven underwent LOA. Among ETA cases, GTR was achieved in 14 patients with ONT and most patients maintained normal eye movement function (75%) and morphology (93.75%). In the ETA group, 14 patients experienced vision loss, while two other patients saw improvements in vision. And proptosis was alleviated (5.20 ± 2.34 vs 0.27 ± 0.46, p < 0.0001). Six patients with blindness and proptosis of the LOA group resulted in GTR with ONT and ophthalmectomy. Although intracranial extension and recurrence included no cases in the two groups, a significant psychological gap was presented due to cosmetic problems.

CONCLUSIONS

Under the premise of reducing damage and improving aesthetics, the selection of ETA combined with ONT to gross-total resect ONSMs successfully provides a minimally invasive access with acceptable complications. As an important adjunct to GTR in the surgical treatment of ONSM, the scope of ONT application should be expanded to relieve the patient's psychological burden.

Visual Outcomes Following Surgical Debulking in Exophytic Optic Nerve Sheath Meningiomas

PURPOSE

To report a case of a globular primary optic nerve sheath meningioma managed surgically with improvement in vision and review the literature for outcomes of purely intraorbital exophytic-globular primary optic nerve sheath meningiomas managed surgically.

METHODS

A literature review was conducted using Google Scholar and PubMed with the search terms "primary optic nerve sheath meningioma," "surgery," "exophytic," and "globular." Articles were included if they were available in English. Individual cases from the reviewed articles were included if the tumor was purely intraorbital with a globular or exophytic morphology, was managed with total or subtotal surgical excision, and visual outcomes were reported. Cases were excluded if the tumor extended intracanalicularly or intracranially, tumor morphology was unknown, or surgical management consisted of biopsy, optic nerve sheath decompression, or optic canal decompression rather than tumor debulking.

RESULTS

A total of 28 patients with intraorbital globular-exophytic primary optic nerve sheath meningiomas managed surgically have been reported in the literature. Vision improved in 29% (n = 8/28) and remained stable in 43% (n = 12/28) of patients. Furthermore, patients with good (Snellen notation ≥ 0.5) vision (n = 10) typically retained good vision postoperatively and at follow-up, with 1 patient experiencing a decline to poor (Snellen ≤0.1) vision at the last follow-up (92 months postoperatively). Similarly, patients with fair (Snellen notation >0.1 and <0.5) vision (n = 5) often improved to good vision (n = 3) or stayed at fair vision (n = 1), with 1 declining to poor vision at postoperative hospital discharge.

CONCLUSIONS

Surgical management of exophytic or globular optic nerve meningiomas does not universally lead to vision loss and may be appropriate in select patients.

A Patient With Exophytic Primary Optic Nerve Sheath Meningioma: Stratified Risk of Surgery Based on the Morphology

Primary optic nerve sheath meningioma (pONSM) is one of the most challenging tumors to manage. Although surgical excision may be considered a treatment option to maintain visual function, the safety of surgery remains debatable due to the non-negligible risk of optic nerve injury. pONSM often grows concentrically around the optic nerve; however, it can also demonstrate an exophytic growth from the optic nerve. The risk of surgical excision of pONSM may vary based on the tumor's growth pattern and area of contact with the optic nerve; however, there has been no detailed report on risk stratification to date. The authors present an illustrative case of an exophytic pONSM which was removed surgically without complications, suggesting that tumor morphology may also influence the surgical risk. In this report, the imaging and intraoperative features of exophytic pONSM are presented in detail, and the risk factors for complications are discussed.

Investigating variation of dose gradient index by different grid sizes in intensity-modulated radiation therapy of optic nerve sheath meningioma

In optic nerve sheath meningioma (ONSM) radiotherapy, vital organs with a low tolerance dose are very close to the target volume. Thus dose fall-off steepness around the target volume is the most critical parameter in intensity-modulated radiation therapy (IMRT) planning for this malignancy. We hypothesized that one of the parameters that can impact the dose fall-off steepness is dose calculation grid sizes. This study aimed to assess the impact of different dose calculation grid sizes on the newly introduced dose gradient indices (DGIs) for the steepness of dose fall-off around the target volume. Results showed that decreasing the dose calculation grid size in IMRT treatment planning of ONSM patients had a significant difference in the dosimetric parameters and DGIs of the target volume and at-risk organs. This study demonstrates that using a finer dose calculation grid size is preferred in treating ONSM patients.

Combined endoscopic transethmoid and transconjunctival en bloc resection of optic nerve tumors in patients lacking functional vision

Background

Surgical treatment of optic nerve tumors is challenging. The study’s objective was to evaluate the efficacy of a combined endoscopic transethmoid and transconjunctival approach in patients without functional vision.

Design

A retrospective, noncomparative case series.

Methods

Retrospective data were collected from all patients who had undergone tumor resection using this approach at the authors’ institution between 2015 and 2021. Preoperative assessments included magnetic resonance imaging and ophthalmological examinations, and re-assessments were conducted three months after surgery and regularly during the follow-up period.

Results

Seventeen patients, mean age 35 ± 19.0 years, were enrolled. Of these, 64.7% presented with visual acuity (VA) of light perception or no light perception. Gross total resection was realized in all patients. The average decline in exophthalmos was 3.63 ± 1.93 mm. Tumor histopathological analysis identified 12 optic nerve sheath meningiomas and 5 optic gliomas. The mean follow-up time was 30 months during which there was no local recurrence in any of the patients.

Conclusions

The combined endoscopic transethmoid and transconjunctival approach offers an additional choice for accessing optic nerve tumors. The procedure is both safe and effective and provides an alternative transcranial route to the orbit.

Long-Term Visual Function After Fractionated Stereotactic Radiotherapy for Primary Optic Nerve Sheath Meningioma: A Retrospective Analysis of 34 Subjects

Objective

To evaluate long-term visual function after fractionated stereotactic radiotherapy (FSRT) for primary optic nerve sheath meningioma (PONSM).

Methods

This 22-year retrospective study included 34 subjects (34 affected eyes) with PONSM who were treated with FSRT exclusively. Subjects with a history of biopsy/resection were excluded. Visual function, including visual acuity (VA) and visual field mean deviation (VF MD), was evaluated at presentation (pre-radiotherapy; pre-RT) and at the final follow-up (post-radiotherapy; post-RT); treatment complications were also evaluated. Treatment success was defined as either stabilization or improvement of visual function.

Results

The median pre-RT VA and pre-RT VF MD were 0.70 logarithm of the minimum angle of resolution (logMAR; range: 0.0–2.9 logMAR) and −15.4 decibels (dB) (range: −31.4 to −3.2 dB), respectively. The median total dose of FSRT was 50 Gy (range: 45–54 Gy) and the median number of fractions was 25 (range: 25–30). The median follow-up interval was 89 months (range: 6–251 months). The median post-RT VA and post-RT VF MD were 0.48 logMAR (range: 0.0–2.9 logMAR) (p = 0.010) and −6.8 dB (range: −20.6 to −1.6 dB) (p = 0.005), respectively. Among the 34 included eyes, VA was successfully treated in 29 eyes (85.3%) and worsened in 5 eyes (14.7%). Of the 14 eyes with both VA and reliable VF MD at pre-RT and post-RT time points, VF MD was successfully treated in 13 eyes (92.8%) and worsened in one (7.2%); overall visual function was successfully treated in 13 eyes (92.8%) and worsened in 1 eye (7.2%). Complications occurred in one subject (2.9%; radiation retinopathy).

Conclusion

Approximately 90% of PONSM subjects exhibited long-term treatment success in terms of VA, VF MD, and overall visual function after FSRT. Additionally, the incidence of complications was low. Therefore, FSRT is effective and safe treatment for PONSM.

Radiotherapy and Radiosurgery in the Management of Optic Nerve Sheath Meningiomas: An International Systematic Review and Meta-Analysis of Twenty Studies

BACKGROUND

Optic nerve sheath meningiomas (ONMs) are often managed with radiotherapy (RT) with the goal of achieving radiographic local control (LC) and preventing deterioration of visual acuity (VA). We aimed to perform a systematic review and meta-analysis of outcomes for patients with ONM treated with RT.

METHODS

The PICOS/PRISMA/MOOSE selection criteria were used to identify studies. Primary outcomes were stable or improved VA and radiographic LC at last follow-up. The secondary outcomes were incidences of radiation-induced retinopathy and xerophthalmia and stable or improved visual fields (VFs). Weighted random-effects meta-analyses using the DerSimonian and Laird methods were conducted to characterize effect sizes. Mixed-effects regression models were used to examine potential correlations between gross tumor volume (GTV) and outcomes.

RESULTS

In total, 444 patients with ONM across 20 published studies were included. The estimated LC rate was 99.8% (95% confidence interval [CI], 98.3%-100%), and the estimated proportion of patients with stable or improved VA or VF was 89.7% (95% CI, 86.2%-92.4%) and 93.3% (95% CI, 89.5%-95.8%), respectively. Estimated incidences of radiation-induced retinopathy and xerophthalmia were 7.2% and 10.1%, respectively. GTV was significantly associated with VA (P = 0.014) with estimated VA rates of 96.4%, 91.4%, and 80.5% for GTVs of 2.0, 3.0, and 4.0 cm³, respectively.

CONCLUSIONS

RT was well tolerated, with excellent LC achieved. Nearly 90% of patients noted either stability or improvement in VA and VF. Larger ONMs were associated with poorer VA.