Orbital meningiomas: surgery, radiotherapy, or hormones?

Orbital meningiomas generally arise from the sphenoid and cause ophthalmic problems by virtue of an expanding mass near the orbital apex. These benign tumours often have a soft tissue component within the orbit, cranium, or temporalis fossa (Fig 1) and may induce hyperostosis of the postero-lateral wall of the orbit. Symptoms are generally caused by displacement of the globe-with diplopia or progressive proptosis-or compression ofnerves and vessels at the orbital apex. Embarrassment of flow through orbital veins can lead to enlargement of the episcleral vessels and chemosis, while compression of the third to the sixth cranial nerves at the superior orbital fissure may cause neurological deficit. Narrowing of the optic canal by tumour or hyperostosis causes the serious complication of visual loss; such loss is frequently slow and steadily progressive , but may show periods of faster progression ('stuttering' visual loss). Treatment of sphenoidal meningiomas may not be required in the elderly or where the symptoms are minor and only slowly progressive. However, the currently available treatments are often unsatisfactory for younger patients with significant visual impairment and for patients with grossly disfiguring proptosis. Surgery Surgical resection of intracranial meningiomas is generally recognised to be the treatment of choice, although such surgery may be impossible or may carry high morbidity.'2 Sphenoidal meningiomas are intimately related to the anterior visual pathways, superior orbital fissure, and to the frontal and temporal lobes; resection ofthese extensive, deep seated lesions is generally incomplete and the morbidity is greater than that for many other intracranial meningiomas.3 Where sphenoidal wing meningiomas are slow growing, especially in the elderly, surgical efforts may usefully be directed towards the 'camouflage' of proptosis and prevention of corneal exposure: adequate recession of the retractors in the upper and the lower eyelids, together with closure of the lateral (and occasionally medial) canthus, are oculoplastic procedures of particular value in such cases. Figure I Right sphenoidal wing meningioma within the orbit, middle cranialfossa, and temporalisfossa. Radiotherapy As with many slowly dividing tumours, high doses of radiotherapy (between 50 and 100 Gy) appear necessary to affect the growth of meningiomas."245 Such doses carry two small, but significant, risks-namely, the induction of malignant transformation within the parent meningioma and the formation of new tumours, either meningiomas or sarcomas. Adequate radiotherapy for sphenoidal meningiomas is further complicated by the intimate relationship between the tumour and the optic nerve. Visual failure from neoplastic compressive optic neuropathy becomes …