High incidence of optic canal involvement in clinoidal meningiomas: rationale for aggressive skull base approach.

INTRODUCTION: Literature specifically focusing on clinoidal meningiomas is scant, particularly with regards to the postoperative visual outcome. In this study, we aimed to document the incidence of optic canal involvement (OCI) by the tumor, its management using a skull base technique, and its significance with relation to the visual outcome.

MATERIALS AND METHODS: Fifty-two patients with clinoidal meningiomas were retrospectively analyzed. In 47 patients, skull base technique consisting of extradural anterior clinoidectomy with falciform ligament and optic nerve sheath opening was performed. Pre-operative visual status and post-operative outcome were analyzed with respect to OCI.

RESULTS: The incidences of OCI was present in 19 (36%) and pre-operative visual deficit (VD) in 24 (46%) patients. With regard to pre-operative visual status, OCI was seen in 14 (58%) of 24 patients with VD, as compared to five (18%) in 28 patients without (p = 0.004). Among the 22 patients with VD and detailed postoperative neuro-ophthalmological evaluation, 17 (77%) had visual improvement, and in five patients (23%), vision was unchanged. In the presence of OCI in 11 patients, vision improved in seven (64%), and remained unchanged in four patients (36%), whereas all but one of the 11 patients (91%) without OCI improved and in the remaining one (9%), remained unchanged. Simpson Grade I and II resection was achieved in 71%.

CONCLUSION: OCI is observed in 36% of clinoidal meningiomas, and it correlates well with pre-operative visual status. With the use of the skull base technique, without which the tumor in the optic canal could not have been removed completely and safely, visual improvement of 77% and stability of 23% was achieved.