The evolving management of optic nerve sheath meningiomas
Consider using stereotactic fractionated irradiation
The management of optic nerve sheath meningiomas (ONSMs) has been a controversial and sometimes contentious issue for a number of reasons. In the first place, these tumours are not associated with any mortality or significant neurological morbidity. In the second place, although they theoretically can spread across the planum sphenoidale to affect the opposite optic nerve, they rarely do so and, thus, almost never cause loss of vision in the opposite eye. The major manifestation of ONSMs, therefore, is monocular visual loss, and their management should reflect these issues.
Because primary ONSMs arise from the arachnoid cap cells surrounding the intracanalicular or intraorbital portions of the nerve, they almost always are intimately associated with the nerve and tend to surround the nerve by the time they become clinically apparent. Similarly, secondary ONSMs extend from the planum sphenoidale into the subdural or subarachnoid spaces (or both) surrounding the nerve within the optic canal and, ultimately, within the orbit. As if that were not enough, many ONSMs involve the portion of the optic nerve at the apex of the orbit within the annulus of Zinn, an area not amenable to safe and …
