Surgical Treatment of Unilateral Optic Nerve Gliomas

ARIOUS manifestations of the unpredictable natural history of optic gliomas have resulted in controversy as to the best form of treatment. Some reports of successful partial removal of these tumors 1,12 may be questioned because of the limited follow-up period at the time of reporting. Taveras, et al., 1~ described remissions and arrest with improvement in exophthalmos and vision in a group of patients treated by radiotherapy alone. On the basis of this experience they concluded that tumors limited to the orbital cavity may be treated successfully by intraorbital surgical removal but that all other cases should be treated by irradiation. Later, Chutorian and his coworkers 2 at the same institution found four cases of recurrent optic nerve glioma following radiotherapy. One of these had been reported by Taveras, et al., ~ as free of recurrence after 21 years. Some ophthalmological surgeons have advocated transorbital excision of optic nerve gliomas as adequate therapy2 TM In one of the 13 cases in this report, the tumor recurred with chiasmal spread 6 years after orbital resection. These experiences lend credence to the impression that, although radiotherapy may be effective in nonresectable optic glioma, transcranial chiasmal inspection and prechiasmal resection is the treatment of choice when tumor is confined to a single optic nerve. Furthermore, excellent cosmetic results have been possible when the structures of the orbital apex have been meticulously approached by the frontal transcranial route. The operative technique to be described is based on our surgical experience with nine cases of optic glioma. Proptosis and visual impairment were the most common presenting symptoms. The diagnosis of optic nerve glioma may be made on the basis of radiographic evidence of enlargement of one optic foramen2 Pneumoencephalography has been useful in outlining the intracranial portion of the optic nerve. Preservation of the chiasmarie notch, between the optic and infundibular recesses of the anterior third ventricle, usually indicates that the chiasm is not involved. Radioactive mercury scan has been of great value as supporting evidence for the presence of optic nerve or chiasmal glioma. Technetium scanning has proved to be less reliable.