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Woman complains of transient decreased vision in left eye
Swelling of the left optic nerve with horizontal retinal folds was observed, and Humphrey visual field showed a relative inferior arcuate scotoma.
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 Jeffrey Chang |  Vivek Chaturvedi | ||
A 36-year-old woman was referred to the New England Eye Center for evaluation of blurred vision in her left eye over the past several months. The patient said that the vision in her left eye would transiently “go away” for 15 seconds and then would return. She most often noted the visual changes when looking to the left. Nothing improved or worsened the vision, and the patient did not have any pain. She denied headache, metamorphopsia, photopsias or neurologic symptoms
Review of systems and ocular history were unremarkable. The patient said that she was healthy and was not currently taking any prescription medications or eye drops. She was a music conductor and a professor at a local university. She denied smoking and drinking.
Examination
On examination, best corrected visual acuity was 20/15 in the right eye and 20/20 in the left eye. IOP and ocular motility were normal in both eyes. There was a 2+ relative afferent pupillary defect in the left eye. Manifest refraction demonstrated essentially plano refractive errors in both eyes.
The ocular adnexa and anterior segment in the left eye were unremarkable. Exophthalmometry showed 1-mm relative proptosis of the left eye when compared with the right eye. In primary gaze, confrontation visual fields were grossly normal. However, when the patient looked to the left, she lost the majority of her visual field in the left eye. The field defects recovered once the patient looked in primary gaze. Humphrey visual fields were full for the right eye. The left eye Humphrey visual field showed a relative inferior arcuate scotoma. Dilated fundus examination was notable for swelling of the left optic nerve with horizontal retinal folds (Figure 1). There were no hemorrhages, cotton wool spots, vascular changes or contralateral optic disc abnormalities.
An MRI revealed an intraorbital homogeneous mass surrounding the left optic nerve (Figure 2).
 Left optic nerve edema. |  Coronal MRI scan revealing homogenous optic nerve sheath mass. Images: Chaturvedi V, Hedges TR |
What is your diagnosis?
Transient vision loss
The differential diagnosis for a young female patient with disc edema is quite wide. The most common entities would include papilledema, idiopathic intracranial hypertension, papillitis (from demyelinating disease), white dot syndromes and orbital compressive lesions.
These optic nerve findings, combined with radiologic studies showing a homogeneous mass on the left optic nerve, are consistent with optic nerve sheath meningioma. Other optic nerve tumors, including optic nerve glioma, should be considered. However, those patients typically have a different demographic background.
Interestingly, one of the patient’s prominent presenting symptoms was gaze-evoked amaurosis. Only about 3% of patients with optic nerve sheath meningiomas present with gaze-evoked amaurosis. Gaze-evoked amaurosis represents transient reversible vision loss induced in eccentric gaze. It is thought to represent position-dependent occlusion of retinal and/or optic nerve circulation. The most common causes of gaze-evoked amaurosis are orbital hemangiomas and optic nerve sheath meningiomas.
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| Left eye visual fields at the time of presentation and 4 months after radiation therapy. | |
Discussion
Optic nerve sheath meningiomas are slow-growing benign tumors. Although the classic triad for presentation includes painless vision loss, optic nerve pallor and optociliary shunt vessels, patients can have either optic nerve pallor or edema. They represent roughly 1% to 2% of all central nervous system meningiomas and about one-third of all optic nerve tumors. Women are typically affected more commonly then men. The age of presentation is usually around 40 years. Tumor growth can be accelerated during pregnancy. Two percent of patients with optic nerve sheath meningiomas have type 1 neurofibromatosis.
More than 90% of these tumors are intraorbital, while the remaining are intracanalicular. The diagnosis is usually made based on clinical correlation with radiologic findings. Computed tomography typically reveals sheathing and enhancement of the nerve sheath with sparing of the optic nerve itself. This usually gives the classic “tram-track” sign. Occasionally, calcification can also be seen. Adjacent bony hyperostosis can also be appreciated at times. Magnetic resonance imaging will allow the clinician to identify if there is canalicular involvement.
Treatment
Therapy for optic nerve sheath meningiomas is typically divided into three options: observation, surgery or radiation. Observation is usually done for patients with good vision, few ocular complaints and few medical comorbidities. Surgical manipulation and removal of optic nerve sheath meningiomas can lead to severe functional visual deterioration in more than 95% of cases. Fractionated stereotactic radiation allows for a better focused radiation beam so that most, if not all, of the radiation goes only to the site of interest. This limits the amount of collateral damage induced by radiation. This therapy has been shown to improve visual fields and/or visual acuity.
Although our patient’s visual acuity was relatively well-preserved, her visual field changes improved dramatically after radiation treatment for her meningioma (Figure 3).
For more information:
- Vivek Chaturvedi, MD, and Thomas R. Hedges III, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com.
- Edited by Jeffrey Chang, MD, and Vivek Chaturvedi, MD. Drs. Chang and Chaturvedi can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; Web site: www.neec.com. Drs. Chang and Chaturvedi have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned.
References:
- Dutton JJ. Optic nerve sheath meningiomas. Surv Ophthalmol. 1992;37(3):167-183.
- Liu JK, Forman S, et al. Optic nerve sheath meningiomas: visual improvement after stereotactic radiotherapy. Neurosurgery. 2002;50(5):950-955.
- Otto CS, Coppit GL, et al. Gaze-evoked amaurosis: a report of five cases. Ophthalmology. 2003;110(2):322-326.
- Pitz S, Becker G, et al. Stereotactic fractionated irradiation of optic nerve sheath meningioma: a new treatment alternative. Br J Ophthalmol. 2002;86(11):1265-1268.
- Turbin RE, Thompson CR, et al. A long-term visual outcome comparison in patients with optic nerve sheath meningioma managed with observation, surgery, radiotherapy, or surgery and radiotherapy. Ophthalmology. 2002;109(5):890-900.