Prognostic factors in the surgical treatment of intracanalicular primary optic nerve sheath meningiomas

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OBJECTIVE

Although meningiomas frequently involve the optic nerve, primary optic nerve sheath meningiomas (ONSMs) are rare, accounting for only 1% of all meningiomas. Given the high risk of vision loss with these tumors, surgical intervention is seldom considered, and radiation or observation is commonly applied. Here, the authors describe the visual outcomes for a series of patients who were treated with surgery aiming at maximal tumor resection and highlight their prognostic factors.

METHODS

The authors retrospectively analyzed the data for 8 patients with intracanalicular ONSMs who had been surgically treated by the senior author (O.A.) between 1998 and 2016. Meningiomas extending into the optic canal from the intracranial cavity (i.e., clinoid, sphenoid wing, tuberculum sellae, diaphragma sellae) were excluded. Diagnosis was based on ophthalmological, radiological, and intraoperative findings, which were confirmed by the typical histological findings. Preoperative, postoperative, and follow-up visual assessments were performed by neuro-ophthalmologists in all cases.

RESULTS

The patients included 7 females and 1 male. The mean age at diagnosis was 45.1 years (range 25.0–70.0 years). Mean duration of follow-up was 38.9 months (range 3.0–88.0 months). All patients reported visual complaints, and all had objective evidence of optic nerve dysfunction. Their evaluation included visual field, visual acuity, funduscopy, and retinal fiber thickness. Total resection was obtained in 4 cases. Comparing preoperative and postoperative visual function revealed that 4 patients had improvement at the last follow-up, 1 patient had stable vision, and 3 patients had decreased function but none had total vision loss. All patients with good preoperative visual acuity maintained this status following surgical treatment. There was no surgical mortality or infection. Operative complications included binocular diplopia in 4 patients, which remitted spontaneously.

CONCLUSIONS

Surgery can play a beneficial role in the primary treatment of ONSM, especially lesions located in the posterior third of the nerve. Total removal can be achieved with vision preservation or improvement, without major surgical complications, especially at early stages of the disease. Patients with good preoperative vision and CSF flow in the optic sheath have better chances of a favorable outcome than those with poor vision.

ABBREVIATIONS GTR = gross-total resection; ONSM = optic nerve sheath meningioma.

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Article Information

Correspondence Ossama Al-Mefty: Brigham and Women’s Hospital, Harvard Medical School, Boston, MA. almeftyossama@bwh.harvard.edu.

INCLUDE WHEN CITING Published online September 21, 2018; DOI: 10.3171/2018.4.JNS173080.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

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Figures

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    Postcontrast T1-weighted MRI studies. Left: Oblique view depicting a meningioma along the posterior third of the right optic nerve. Right: Coronal view showing the radial distribution of the tumor along the optic nerve circumference.

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    Postcontrast axial T1-weighted MRI studies revealing intracanalicular lesions. A: Tumor extending into the posterior third of the optic nerve. B: Tumor extending into the middle third of the optic nerve. C: Tumor extending into the anterior third of the optic nerve. D: Bilateral involvement of the optic nerve by tumor.

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    Axial diffusion-weighted imaging studies. Left: Preoperative image showing a hyperintense signal in the anterior portion of the optic nerve (white arrow), suggesting ischemia. Right: Postoperative image disclosing the same sign along the whole length of the nerve.

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    Anatomical dissections of a left optic nerve and sheath. Upper: Opening the optic sheath reveals a dense arachnoidal trabeculae (arrowheads) serving as a barrier between the dura and the vasculature of the optic nerve. Asterisks in both images indicate the eye globe. Lower: After removing the trabeculae, one can identify, in the inferolateral aspect of the nerve, the central retinal artery (arrowhead) and its branches. Copyright Ossama Al-Mefty. Published with permission.

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    T2-weighted MRI studies. Left: Axial view revealing an intracanalicular tumor (asterisk) with dilation of the distal subarachnoid space (arrows). Right: The same phenomena can be observed in a coronal plane (arrows).

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    Artistic representation of the right orbit, superior view, where a tumor (light red) is occupying the optic canal and extending to the posterior third of the intraconal optic nerve, just before the central retinal artery (seen crossing below the nerve). The four forms of ONSMs: I, type 1; II, type 2; III, type 3; IV, type 4. Yellow indicates the optic nerve; blue, CSF at the subarachnoid space; red, tumor; gray, dura (optic nerve sheath). Copyright Anil Can. Published with permission.

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    Intraoperative photographs of an intracanalicular ONSM extending to the posterior third of the optic nerve; the anterior clinoid was removed and the optic sheath was opened. Left: Tumor (T) location in relation to the eye globe (asterisks). Right: An intact arachnoidal plane is identified (arrowheads).

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