Surgical management of meningiomas involving the optic nerve sheath.

Object: The management of optic nerve sheath meningiomas (ONSMs) remains controversial but includes surgery, radiotherapy, and plain observation. Surgery is often thought to result in postoperative blindness. The authors report on a large series of patients surgically treated for ONSM, with an emphasis on the visual outcome.

Methods: Seventy-three patients with ONSMs who had undergone surgery between 1991 and 2002 were retrospectively analyzed. The standard surgical approach consisted of pterional craniotomy, intradural (54 patients) or extradural (10 patients) unroofing of the optic canal, or a combined procedure (seven patients). Thirty-two tumors demonstrated extension through the optic canal. Twenty-nine tumors reached the chiasm or contralateral side. Patients with intraorbital flat tumors should undergo radiotherapy instead of surgery. Those with a large intraorbital mass and no useful vision should undergo surgery. Tumors extending intracranially through the optic canal are amenable to decompression of the optic canal and resection of the intracranial portion. The follow-up period was a mean 45.4 months (range 6-144 months). Ten patients underwent postoperative radiotherapy. Visual acuity was not significantly influenced by surgery but did become worse with a longer duration of preoperative symptoms and a longer follow-up period. A tumor location in the optic canal was another negative factor. Radiotherapy preserved vision in five of 10 cases.

Conclusions: The loss of vision in patients with ONSM is only a matter of time. In patients with good vision the role of radiotherapy becomes more important. Surgery is recommended for intracranial tumors to prevent contralateral extension.