Resection of Ventrally Located Meningiomas of the Craniovertebral Junction Using an Adaptable Minimal Invasive Approach via the Posterior Atlantooccipital Membrane

Objective: The surgical management of meningiomas ventrally to the neuroaxis at the level of the craniovertebral junction (CVJ) is challenging. Here, we describe a minimal invasive and adaptive dorsal approach for small ventrally located lesions at the CVJ as an alternative for the more extensive classic transoral or variants of suboccipital approaches.

Methods: Between 2012 and 2016, eight symptomatic patients with meningiomas of the ventral aspect at the level of the CVJ were treated in our institution using a minimal invasive posterior atlantooccipital membrane approach (PAM). The radio-anatomical distance of the posterior atlantooccipital membrane was assessed in our treated patients and in 100 non-treated persons based on computerized tomography.

Results: We treated eight patients with a clinical presentation of mild neurological symptoms, which disappeared after surgical resection. Minimal invasive dorsal surgical access was performed using tubular systems and utilizing the natural space between C0/C1 by dorso-lateral incision of PAM without the necessity of removal of bony structures (videos). In one case the PAM approach needed a lateral suboccipital extension due to tumor size (>3 cm) and extensive encasement of lower cranial nerve fibers. The postoperative course in all eight patients was uneventful. The neuropathological findings confirmed meningioma of WHO grade I in all cases. Simpson grade II resection was achieved in all patients and confirmed by MR imaging. The atlantooccipital distance ranged from 3 mm to 17 mm (mean 8.98 mm) in supine neutral position without a significant difference between females and males (p = 0.14).

Conclusion: Our study demonstrates that the minimal invasive PAM approach using the space between C0/C1 provides a direct and sufficient exposure for the safe surgical resection of small ventrally located meningiomas at the level of CVJ while reducing the necessity of musculoskeletal preparation to the minimum. Furthermore, this approach allows a simple extension in caudal or cranial direction when deemed intraoperatively necessary.