Observation without treatment is appropriate in some cases to confirm that the visual loss is progressive before intervening.
Among 42 patients with unilateral optic nerve sheath meningiomas treated at Massachussets Eye and Ear Infirmary from 1973 to 1999
- 16 were observed without treatment for a mean of 10.2 years from onset of symptoms
- 4 had stable visual function
- 3 showed improvement without treatment (Arch Ophthalmol 2002; 120:1505)
In a 180-patient study of the progesterone receptor inhibitor, mifepristone, there was no demonstrated efficacy over placebo. (J Neurooncol 2010; 99:365).
Tamoxifen, an oral estrogen receptor inhibitor, was found not to have efficacy in a phase II.
- This was predictable because only 10%–30% of meningiomas express estrogen receptors and their functional role is not known (J Neurooncol 1993; 15:75; Current Opinion Oncol 2012; 24:666).
Interferon seems to have short-term, limited efficacy.
Hydroxyurea has been studied and seems to be ineffective (J Neurooncol 2012; 107:315).
Temozolomide is an oral alkylating agent, a prodrug of dacarbazine, used effectively for intracranial malignancy.
- However, in 16 patients with meningioma treated with temozolomide in a phase II trial, there was no radiographic response (Neurology 2004; 62:1210).
About 90% of meningiomas harbor somatostatin receptors.
- Although its role is not known, somatostatin has been found to inhibit meningioma growth in vitro (J Neuooncol 2004; 66:155).
- Octreotide is a somatostatin analogue that is metabolized more slowly and can be radiolabeled.
- Octreotide scintigraphy is used to demonstrate overexpression of somatostatin receptors in a meningioma.
- Octreotide can be administered subcutaneously and is well tolerated, but demonstrated no efficacy in a small phase II trial (Neurooncol 2011; 13:530).
Topical mitomycin-C can be applied in conjunction with surgical resection for cystic tumors (OPRS 2008; 24;235).
Stereotactic fractionated radiotherapy is the preferred modality as adjuvant treatment after surgery for meningioma in general and is the preferred primary modality of treatment for meningiomas that are in close proximity to important neurovascular structures such as the optic nerve.
The standard fractionation scheme is 1.8–2 Gy fractions, 5 days/week (Int J Rad Onc Biol Phys 2012; 82:1268).
In a study of 113 eyes with optic nerve sheath meningioma treated with stereotactic fractionated radiotherapy, tumor regression was observed in 5 eyes, progression in 4 eyes, and 104 remained stable. Visual acuity was preserved in 95% after 1 year and 91% after 5 years (Int J Rad Onc Biol Phys 2012; 82:773).
Similar results have been reported in numerous smaller studies:
- 15 patients (BJO 2002;86:1265)
- 35 patients (AJO 2006;142:343
- 25 patients (Int J Rad Onc Biol Phys 2009;75:1166)
- 11 patients (BJO 2010;94:559
- 34 patients (BJO 2010;94:564
- 30 patients (J Neurosurg 2010; 113:S28)
Surgery is associated with a high risk of precipitating blindness secondary to optic nerve vasculature damage (Ophthalmology 2003;110:2019).
Surgery is indicated for large intraorbital tumors with no useful vision.
Tumors can be approached by pterional craniotomy, unroofing the optic canal, and decompressing the nerve (J Neurosurg 2004; 101:951).
Small feeding vessels between the carotid artery and optic nerve should be preserved.
Irrigation instead of coagulation should be used.
The dura mater around the optic canal can be resected.
The optic canal bone can be decompressed by drilling laterally until the floor of the optic canal is reached to prevent contact with the nerve.
- The optic canal is then unroofed and tumor around the optic nerve and dura mater are removed.
For tumors infiltrating the nerve, resection is limited to the exophytic part, unless the eye has no light perception, in which case the optic nerve can be transected.
As an alternative to surgical resection of the tumor, a window can be created in the dura to relieve pressure on the optic nerve (OPRS 2006; 22:278).