Treatment of meningiomas involving the optic nerve sheath

Abstract

Optic nerve sheath meningiomas (ONSM) represent one-third of all optic nerve tumours, but they account for only 1-2 % of all intracranial meningiomas. Although these tumours are rare, they represent an important clinical entity because slow but progressive tumour growth with increasing visual loss will lead to unilateral or even bilateral blindness if not treated [ 43, 48 ]. The fi rst case of ONSM in a young woman with decreased vision in one eye was probably described by Spry in 1755. In 1816, Scarpa characterized tumours of the optic nerve including cases of optic nerve sheath meningiomas, which he treated with surgical excision, but he noted a high rate of orbital recurrence [ 39 ]. Optic nerve tumours were not further differentiated until Hudson‘s classifi cation in 1912, clearly separating optic nerve sheath meningiomas from optic gliomas [ 19 ]. Later on, other authors collected series of patient harbouring orbital meningiomas, but no distinction was made between primary optic nerve tumours and secondary meningiomas with intraorbital extension from intracranial sites [ 29 ] until Coston and Friedenwald unequivocally described the primary origin of meningiomas at the optic nerve sheath [ 12 ]. Since then, the diagnosis and treatment of primary optic nerve sheath meningiomas have been reported in small heterogeneous series.