Case Report: A Case Series Using Natural Anatomical Gaps-Posterior Cervical Approach to Skull Base and Upper Craniocervical Meningiomas Without Bone Removal

Abstract

Background: Removal of anteriorly located tumors of the upper cervical spine and craniovertebral junction (CVJ) is a particular surgical challenge. Extensive approaches are associated with pain, restricted mobility of neck and head and, in case of foramen magnum and clivus tumors, with retraction of brainstem and cerebellum. Methods: Four symptomatic patients underwent resection of anteriorly located upper cervical and lower clivus meningiomas without laminotomy or craniotomy using a minimally invasive posterior approach. Distances of natural gaps between C0/C1, C1/C2, and C2/C3 were measured using preoperative CT scans and intraoperative lateral x-rays. Results: In all patients, safe and complete resection was conducted by the opening of the dura between C0/C1, C1/C2, and C2/C3, respectively. There were no surgical complications. Local pain was reported as very moderate by all patients and postoperative recovery was extremely fast. All tumors had a rather soft consistency, allowing mass reduction prior to removal of the tumor capsule and were well separable from lower cranial nerves and vascular structures. Conclusion: If tumor consistency is appropriate for careful mass reduction before removal of the tumor capsule and if tumor margins are not firmly attached to crucial structures, then upper cervical, foramen magnum, and lower clivus meningiomas can be safely and completely removed through natural gaps in the CVJ region. Both prerequisites usually become clear early during surgery. Thus, this tumor entity may be planned using this minimally invasive approach and may be extended if tumor consistency turns out to be less unfavorable for resection or if crucial structures cannot be easily separated from the tumor.

Keywords: cervical spine; craniovertebral junction; meningioma; minimally invasive; spinal tumor operation.

Figure 1

Lateral X-ray of case 4 after prone positioning with inclination. Colored sectors indicate the theoretical access supplied by the interspace between the occiput and the posterior arch of C1 (blue), C1 and the cranial edge of the lamina of C2 (yellow) and, at times, between the inferior edge of the lamina of C2 and the superior edge of the lamina of C3 (red).

Figure 2

Preoperative sagittal (A) and transverse (B) T1-weighted contrast enhanced MRI of case 1 depicting an anteriorly located meningioma of the upper cervical spine with cranial extension into the foramen magnum. Postoperative sagittal (C) and transverse (D) T1-weighed contrast enhanced MRI showing complete resection of the WHO °II meningioma without the need of resecting any boney structures.

Figure 3

Preoperative sagittal (A) and transverse (B) images depicting an anteriorly located craniocervical meningioma (case 2) removed through the atlantooccipital space. After dura tuck-up sutures the microsurgical view shows a nicely exposed tumor surface (C) without any removal of boney structures. The vascular tumor base was bipolar coagulated and resected in total so that finally a Simpson °II resection was achieved (D).

Figure 4

Preoperative sagittal T2-weighted (A) MRI of case 3 depicting a foramen magnum and lower clivus meningioma with a cranial extension up to the vertebral junction. Axial 3D-CISS images (B) show a sufficiently wide craniocervical cerebrospinal fluid (CSF) space and a bilaterally well distinguishable vertebral artery. After preparation of the paravertebral muscles, an Adson retractor was placed exposing all boney structures from occiput down to C2 (C) showing a wide enough space for tumor resection.

Figure 5

Preoperative sagittal (A), coronary (B) and transverse (C) contrast-enhanced T1-weighted image of case 4 depicting a lateral craniocervical meningioma growing anterior and posterior from the denticulate ligament.