Endoscopic Endonasal and Transcranial Surgery for Microsurgical Resection of Ventral Foramen Magnum Meningiomas: A Preliminary Experience

BACKGROUND: Purely ventral foramen magnum meningiomas are challenging tumors to treat given their location, and proximity and relationship to vital neurovascular structures. OBJECTIVE: To present endoscopic endonasal surgery (EES) as a complementary approach to the far-lateral suboccipital approach (FLA) for ventral midline tumors. METHODS: From May 2008 to October 2013, 5 patients underwent EES and 5 FLA for primary ventral foramen magnum meningiomas. We retrospectively reviewed their records to evaluate outcomes. RESULTS: Nine of 10 patients presented with long-tract and lower cranial nerve deficits. All patients who presented with deficits preoperatively completely normalized after tumor resection regardless of approach. Gross total resection was achieved in 2 cases in the EES group and 4 cases in the FLA group (the rest were near total). Vascular encasement was a limitation to gross total resection with both approaches. Preoperative median Karnofsky Performance Scale score was 80 and improved to 100 in both groups. Following EES, 1 patient developed cerebrospinal fluid leak with resultant meningitis. Two patients developed hydrocephalus, one of which developed an epidural abscess following necrosis of the nasoseptal flap, requiring debridement. In the FLA group, 1 patient developed a pseudomeningocele associated with hydrocephalus. One patient developed an abdominal fat graft site hematoma. CONCLUSION: Both approaches provide excellent results for resection of ventral foramen magnum meningiomas, with reconstruction and hydrocephalus as the main sources of complication. In our practice, EES is a preferred technique in ventral, purely midline tumors with limited inferior extension and reduced lower cranial nerve manipulation, whereas FLA is preferred in tumors with lateral and caudal extension below the tip of the dens.