Managing menacing meningioma.

The role of irradiation therapy in the management of meningiomas involving the anterior visual system is under active clinical investigation. This report documents the value of radiotherapy in a patient with a histologically verified psammomatous tuberculum sellar meningioma and presents a 15-year postsurgical follow-up. The patient experienced a return of vision from 11/200 to 20/60 in his only seeing eye following 5,000 rads to the intracanicular and intracranial portions of right optic nerve. He is able to practice his profession 3 years following irradiation therapy. The classification of optic nerve involvement by meningioma is discussed.

Radiation therapy for primary optic nerve meningiomas.

Optic nerve sheath meningiomas, formerly thought to be rare, have been encountered with surprising frequency since the widespread use of computed tomography. Early diagnosis led to an enthusiastic surgical approach to these lesions, but this has been tempered by the realization that even in the best of hands, blindness followed such surgery with distressing frequency. Optic nerve sheath meningiomas may be divided into primary, secondary, and multiple meningioma groups. Five patients with primary optic nerve sheath meningiomas treated with irradiation therapy are presented in this report. Improvement in visual acuity, stabilization to increase in the visual field, and decrease in size to total regression of optociliary veins, have been documented following irradiation therapy of the posterior orbital and intracanalicular portions of the optic nerve in some of these cases. Although each patient must be carefully individualized, there is no question that visual palliation can be achieved in some cases of optic nerve sheath meningioma. Further investigation of this therapeutic modality in selected cases in advised.

Chiasmal optic glioma after radiation therapy. Neuro-ophthalmologic/pathologic correlation.

A 16-year-old white girl with neurofibromatosis was documented as having progressive visual loss in both eyes over 3 years before diagnosis of a chiasmal glioma. She was then treated with supervoltage irradiation to the sella and parasellar area. Bitemporal fields measuring 5 x 5 cm each were initially used, and source skin distance of 80 cm with coplanar opposing technique was used whereby each field was treated daily to a midplane dose of 186 rads. The patient received a cumulative tumor dose over the 5-week course of 4680 rads. She tolerated this well, and her visual function was stabilized thereafter for over a year. Two years following therapy, she expired suddenly and unexpectedly at home. At autopsy, there was no radionecrosis in the brain or optic nerves, but minimal radiation changes were seen in the tumor. Extensive local invasion was seen in the entire chiasm, adjacent optic tracts and hypothalamus. In addition, other disparate small fibrillary astrocytic gliomas were found in the optic radiations, midbrain, and left anterior midfrontal lobe. This patient therefore documents clinically progressive visual deterioration before irradiation therapy, and palliative visual function stability for well over a year after irradiation therapy. The patient also demonstrates the difficulty in treating a locally aggressive optic chiasmal glioma, its infiltrative nature, and the multifocality of other unsuspected neural tumors in neurofibromatosis.