Optic Nerve Sheath Meningioma Clinical Presentation

Updated: May 18, 2016
  • Author: Mitchell V Gossman, MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Presentation

History

The characteristic profile of a compressive optic neuropathy, such as that caused by ONSM, is usually painless, chronic progressive visual loss that may be accompanied by proptosis.

Transient visual obscurations also have been reported; however, this phenomenon is not a specific feature, as it has been observed in patients with optic disc swelling resulting from other causes.

Age of presentation varies widely, ranging from 3-76 years across all series. In several series, the incidence of visual loss as the presenting feature was more common than proptosis, even though in some series with more ophthalmologic detail, the presentation of proptosis was greater than visual loss. Presentation with either symptom complex is about equal.

Cases may be bilateral (approximately 6%).

An important macroscopic variant of ONSM is the en plaque meningioma (EPM), which is not greatly raised above the level of dura mater. This type of meningioma grows within the meningeal sheath and expands the meninges without forming large exophytic masses. It is prone to invade adjacent bone with accompanying hyperostosis. This group of meningiomas essentially infiltrates the brain and the orbit, mainly via natural apertures (eg, foramina, fissures) and through the passageway of perforating blood vessels, which are increased in number.

Hyperostosis is present in 44% of cases, but it is not a specific finding. EPM typically occurs at the base of the skull, especially within the sphenoid ridge. Clinical presentation depends on the site or extent of the tumor. Patients with juxtaorbital EPM often present with visual complaints. In a series in 1982, Pompili et al reported 33 of 49 cases of EPMs in a series of hyperostosis meningiomas of the sphenoid ridge. [6] Clinical symptoms were not different between the various histopathological types (ie, no difference was seen clinically between EPM and the globular type of hyperostosis meningiomas of the sphenoid).

Common symptoms include the following:

Common neurologic complaints include the following:

  • Unilateral optic atrophy or subatrophy (29%)

  • Decreased visual acuity (24%)

  • Oculomotor disturbance (21%)

Hyperostosis and/or endostosis are common with meningiomas. Hyperostotic meningiomas are viewed as disease of the bone. Globular meningiomas, which are associated with bony reaction and invasion, are referred to as en masse (global) meningiomas.

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Physical

The presentation of optic nerve sheath meningioma (ONSMs) largely depends on whether they arise from the orbit, within the optic canal, or intracranially. Notwithstanding, the classic triad of ONSM is visual loss, optic atrophy, and optociliary shunt vessels.

The characteristic symptom and sign of ONSM is very slow visual loss with preservation of the central visual field for years.

The presence of an optociliary venous shunt on the disc, [7] if associated with disc pallor or visual loss, is suggestive but not pathognomonic of ONSM. These vessels are more appropriately termed retinochoroid venous collaterals and arise from chronic compression of the central retinal vein. These blood vessels shunt blood into choroidal venous circulation. Optociliary shunts result from meningiomas arising from the optic nerve sheath or from spheno-orbital meningiomas. They can occur with other types of tumors (eg, optic nerve gliomas) and chronic papilledema, but they occur most frequently from old central retinal vein occlusion.

Optic disc pallor and swelling have been reported equally in different series. If there is disc edema, the tumor is at least partially intraorbital.

Disturbance of ocular motility was mainly reported by Sibony et al in one series of 47 patients. [8]

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Causes

A common etiology for meningiomas is radiation exposure in the range of 132-315 roentgens, which is equivalent to the rad dose of 1-3 Gy. Characteristics of radiation-induced meningiomas include an average latent period of 36-38 years for patients who were exposed to low-dose radiation to the head, whereas patients who develop meningiomas after exposure to high-dose radiation may show signs as early as 5 years postradiation. [9]

In general, radiation-induced meningiomas occur more frequently over the convexities (ie, in about 80% of cases). They have a more frequent recurrence rate, and they exhibit malignant behavior that is also indicated histologically by hypercellularity and pleomorphism.

Head trauma used to be considered a possible risk factor, but recent large studies do not support this association.

Hereditary predisposition

Another factor that has been studied is hereditary predisposition.

Loss of DNA on chromosome 22 has been shown in 40% of meningiomas.

In cytogenetic studies, genetic abnormalities at the level of chromosome 22 are seen frequently in meningiomas with the loss of a copy of chromosome 22 as the most commonly reported abnormality.

Monosomy of chromosome 22 has been reported to occur in 70-80% of meningiomas.

Abnormalities of chromosome 22 have been associated with type II neurofibromatosis.

Hormonal factors

Hormonal factors, such as estrogen and progesterone, have been studied extensively as risk factors for meningiomas because of the striking predominance of meningiomas in women. Other evidence to substantiate the implication of gender-specific hormones comes from data showing increased growth of meningiomas during pregnancy and size changes with menses. Initially, interest was focused on estrogen because it had been reported in one comprehensive review by McCutcheon that 30% of meningiomas have estrogen receptors; however, no further studies were conducted, and interest became focused on other hormones (ie, progesterone). [10]

The progesterone receptor is the most likely candidate as an etiology for meningiomas. Progesterone receptors have been shown to be expressed in 81% of women and in 40% of men with meningiomas. Other studies indicate that progesterone binds to meningiomas in 50-100% of tested specimens; however, most reports show binding in the higher end of this range. No relation has been found between progesterone receptor status and age, sex, tumor location, or menopausal state. These findings have prompted researchers to develop antiprogesterone medications, such as mifepristone (RU-486), which appear to inhibit tumor growth in vitro and in vivo.

Androgen receptors have been found in 40-100% of meningiomas studied in several studies, but their receptor expression is variable, making them less likely candidates in the pathophysiology of meningiomas. Meningiomas vary in expression of receptors for other hormones (eg, epidermal growth factor [EGF], platelet derived growth factor [PDGF], fibroblast growth factor), which makes them less likely candidates for oncogenesis of meningiomas. It has been suggested that the direct stimulatory effect of EGF on PDGF or PDGF itself may be partially responsible for angiogenesis and even oncogenesis in meningiomas. PDGF is a particularly attractive candidate because it has structural homology with the product of c-sis oncogene on chromosome 22. Infectious agents that have been associated with meningiomas include simian vacuolating virus 40 (SV-40) and adenovirus.

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