Optic nerve sheath meningiomas: current diagnosis and management

Chicago-A number of advances have been made in the ability to diagnose and manage optic nerve sheath meningiomas. Neil Miller, MD, described how best to handle these patients Monday at the American Academy of Ophthalmology annual meeting.

“There have been some major shifts in the paradigms for diagnosing and managing of these lesions, particularly during the last few years,” Dr. Miller pointed out.

Primary optic nerve sheath meningiomas, usually a unilateral disease in patients who are 95% middle-aged women, have two main clinical presentations, i.e., anterior and retrobulbar optic neuropathy, Dr. Miller explained during the William F. Hoyt Lecture.

The anterior type is characterized by variable loss of visual acuity, color vision, and visual fields, and almost always the presence of a relative afferent defect, which may not be obvious. Most cases have no proptosis, but when present, it is mild, he said. Dr. Miller is professor of ophthalmology, neurology, and neurosurgery, Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore.

Virtually all of the cases have benign disc swelling without hemorrhages or exudates, and the presence of choroidal collaterals. The retrobulbar type is characterized by lesions in the apex of the orbit, the optic canal, or the cranial end of the canal with evidence of progressive retrobulbar optic neuropathy, relative afferent defect, color vision loss, and a normal or pale disc.

Observation of these patients is an accepted form of management; however, he cautioned, these patients require a careful clinical assessment at regular intervals. Patients should be advised to contact a neurologist if there is even a slight change in visual function.

No medical therapy has been shown to be beneficial. Surgery is not an option because of the extremely tight adherence of the tumor to the optic nerve; however, there may be specific cases in which surgery is possible, specifically in rare primary exophytic tumors and in cases with acute visual loss that can be addressed by sheath fenestration and radiation therapy. The efficacy of stereotactic radiosurgery as a treatment is unclear because of the small numbers of cases treated in this manner and the absence of long-term follow-up. Stereotactic or three-dimensional conformal fractionated radiation therapy is now the standard of care and the treatment of choice for patients who require treatment, Dr. Miller pointed out.

“There have been a tremendous number of advances in both the diagnosis and treatment of optic nerve sheath meningiomas. Hopefully, there will be more in the future,” he said.