Disposal of Occipital Condyle in Far Lateral Approach for Ventrolateral Foramen Magnum Meningiomas.

Objective: To investigate the necessity of drilling the occipital condyle in a tailored far lateral approach for resection of ventrolateral foramen magnum meningiomas (FMMs).

Methods: Clinical data of 15 patients with ventrolateral FMMs who underwent surgery during a 6-year period were reviewed retrospectively.

Results: A retrocondylar approach was performed in 8 cases (6 above the vertebral artery [VA] and 2 below the VA) in which the dural attachment was surgically accessible with no restriction of the initial part of the V4 segment of the VA, and a partial transcondylar approach was performed in 7 cases on both sides of the VA where the dural attachment associated with the VA auxiliary space was reached by superolateral displacement of the VA by drilling of the condyle. Exposure of the V3 segment of the VA was performed in all patients, but no circumcision of the dural ring along with transposition of the VA was needed. Simpson grade II resection was achieved in all patients. Postoperative complications were encountered in 20% of patients, predominantly associated with cranial nerve impairment. No tumor recurrence was demonstrated during follow-up lasting 7-68 months (mean 29.2 months).

Conclusions: The surgical approach for ventrolateral FMMs varies depending on the location of dural attachment with reference to VA dural entry. Bone removal is warranted in FMMs arising from both sides of the VA to allow superolateral displacement of the VA to some extent, improving surgical accessibility to the hidden VA auxiliary space and achieving a more radical tumor resection. It should be a reasonable alternative to the conventional aggressive VA transposition in cases of ventrolateral FMMs.