Craniovertebral Junction Instability after Oncological Resection: A Narrative Review

Abstract

The craniovertebral junction (CVJ) is a complex transition area between the skull and cervical spine. Pathologies such as chordoma, chondrosarcoma and aneurysmal bone cysts may be encountered in this anatomical area and may predispose individuals to joint instability. An adequate clinical and radiological assessment is mandatory to predict any postoperative instability and the need for fixation. There is no common consensus on the need for, timing and setting of craniovertebral fixation techniques after a craniovertebral oncological surgery. The aim of the present review is to summarize the anatomy, biomechanics and pathology of the craniovertebral junction and to describe the available surgical approaches to and considerations of joint instability after craniovertebral tumor resections. Although a one-size-fits-all approach cannot encompass the extremely challenging pathologies encountered in the CVJ area, including the possible mechanical instability that is a consequence of oncological resections, the optimal surgical strategy (anterior vs posterior vs posterolateral) tailored to the patient's needs can be assessed preoperatively in many instances. Preserving the intrinsic and extrinsic ligaments, principally the transverse ligament, and the bony structures, namely the C1 anterior arch and occipital condyle, ensures spinal stability in most of the cases. Conversely, in situations that require the removal of those structures, or in cases where they are disrupted by the tumor, a thorough clinical and radiological assessment is needed to timely detect any instability and to plan a surgical stabilization procedure. We hope that this review will help shed light on the current evidence and pave the way for future studies on this topic.

Keywords: atlanto-occipital joint; atlantoaxial fusion; chordoma; endoscopic surgical procedure; joint instability; skull base; spinal fusion.

Figure 1

Craniovertebral junction chordoma. Sagittal (A) T1-weighted image after contrast and (B) T2-weighted image depicting a large chordoma invading the rhinopharynx and extending into the premedullary cistern.

Figure 2

Lower clivus solitary plasmacytoma. (A) Axial CT scan showing a lytic expansile lesion at the left lower clivus (circle). (B) Axial T1-weighted after contrast injection image showing a heterogenous and hyperintense lesion (circle). A minimally invasive endoscopic endonasal biopsy disclosed the plasmacytoma.

Figure 3

Commonly used radiological parameters to predict CVJ instability. (A) Clivoaxial Angle (CXA). (B) Grabb–Oakes line. (C) Basion–Dens Interval (BDI). (D) Basion–Axial Interval (BAI). (E) Atlantodental Interval (ADI). (F) Powers ratio: ab/cd.

Figure 4

Endoscopic endonasal approach (EEA) to a CVJ chordoma. Sagittal (A) and axial (B) T1-weighted images after contrast injection showing a craniovertebral junction chordoma invading the C1 anterior arch, transverse ligament and tip of the odontoid. The patient underwent a gross total removal through an EEA. Postoperative sagittal (C) and axial (D) T1-weighted images after contrast injection confirmed the entity of resection and the integrity of C1-C2 joint. (E) Axial CT scan showing the occipital condyle integrity >90%. Dynamic cervical spine CT scans in maximal extension (F) and flexion (G) showing no abnormal movements and excluding any postoperative CVJ instability.

Figure 5

Endoscopic endonasal approach to CVJ chordoma and occipitocervical fixation. Sagittal preoperative (A) and postoperative (B) T1-weighted MR images after contrast injection showing the chordoma infiltration of C0-C1-C2 complex joint and a gross total resection. In the same surgical setting, an occipitocervical fixation was performed. A 3D reconstruction of the postoperative CT (C).

Figure 6

Combined endoscopic endonasal approach and far-lateral transcondylar and petro-occipital trans-sigmoid approach to recurrent CVJ chordoma and subsequent occipitocervical fixation. Axial T2-weighted MR image (A) and angio CT scan (B) showing a recurrent predominantly right craniovertebral junction chordoma. The chordoma infiltrates the rhinopharynx, C0-C1-C2 joint complex and the entire right occipital condyle. A combined endoscopic endonasal approach associated with far-lateral transcondylar and petro-occipital trans-sigmoid approach has been performed. (C) Axial postoperative T1-weighted after contrast injection image and (D) noncontrast CT scan disclosed a gross total resection with the destruction of the right clival–atlo–axial joint. An occipital-cervical fixation was therefore postoperatively planned and performed (E,F).