Evaluation and Surgical Planning for Craniovertebral Junction Deformity

Abstract

Craniovertebral junction (CVJ) deformity is a challenging pathology that can result in progressive deformity, myelopathy, severe neck pain, and functional disability, such as difficulty swallowing. Surgical management of CVJ deformity is complex for anatomical reasons; given the discreet relationships involved in the surrounding neurovascular structures and intricate biochemical issues, access to this region is relatively difficult. Evaluation of the reducibility, CVJ alignment, and direction of the mechanical compression may determine surgical strategy. If CVJ deformity is reducible, posterior in situ fixation may be a viable solution. If the deformity is rigid and the C1-2 facet is fixed, osteotomy may be necessary to make the C1-2 facet joint reducible. C1-2 facet release with vertical reduction technique could be useful, especially when the C1-2 facet joint is the primary pathology of CVJ kyphotic deformity or basilar invagination. The indications for transoral surgery are becoming as narrow as a treatment for CVJ deformity. In this article, we will discuss CVJ alignment and various strategies for the management of CVJ deformity and possible ways to prevent complications and improve surgical outcomes.

Keywords: Alignment; Basilar invagination; Craniovertebral junction; Deformity; Kyphosis; Treatment.

Fig. 1.

Lateral x-ray shows a normal alignment of the cervical spine. On most occasions, cervical lordosis occurs at the C1–2 segment. (A) C0–1 segment is kyphotic, and the C1 slope is posteriorly slanted. (B) C0–2 segment is a hyperlordotic, and the C1 slope is reversely slanted to maintain the patient’s horizontal gaze with sagittal malalignment and subaxial cervical kyphotic deformity patient. (C) Craniovertebral junction kyphotic deformity patient shows a hyperlordotic compensation in the subaxial cervical spine and negative sagittal imbalance to maintain gaze.

Fig. 2.

The algorithm shows decision-making pathways for the treatment of the craniovertebral junction (CVJ) deformity. OC, occipitocervical.

Fig. 3.

Illustrative case. Fixed C12 subluxation. (A) Coronal reconstructed computed tomography (CT) scan showing narrow C1–2 facet joint space and joint mutilation on the right side. (B) Three-dimensional reconstructed CT scan showing lateral tilt and C1–2 joint rotation. (C) Intraoperative photograph demonstrates small osteotomes inside the C1–2 joint space (arrow) on the right side for joint release. C2 root resection provides panoramic view of C1–2 facet joint. (D) Coronal reconstructed CT scan showing remodeling and reduction of the C1–2 facet tilt on the right side.

Fig. 4.

(A, B) Sagittal T2 magnetic resonance imaging (MRI) and sagittal reconstruction computed tomography (CT) image showing odontoid compression over the brain stem and upper cervical cord. Odontoid tip (white arrow) is located above the foramen magnum. (C) Parasagittal reconstruction CT scan showing C1–2 facet subluxation and severe joint mutilation of the C0–1 facet joint (arrow). (D) Postoperative x-ray showing the final construct of C0–2 instrumentation. (E, F) Postoperative sagittal T2 MRI and sagittal reconstruction CT image showing early reduction of retroodontoid rheumatoid pannus (white arrow) and odontoid tip (black arrow) is pulled down below the foramen magnum. (G) Parasagittal reconstruction CT scan shows vertical distraction and intra-articular fusion (white arrow) inside the C1–2 facet joints.

Fig. 5.

Illustrative case. Congenital craniovertebral junction kyphosis. (A) Preoperative x-ray shows the increased atlanto-dental interval. (B) Sagittal reconstructed computed tomography (CT) scan reveals the abnormal inclination of C1–2 facet joint (arrow). (C) Sagittal T2-weighed image magnetic resonance imaging (MRI) showing os odontoideum and cord compression by the C2 dens over the upper cervical cord. (D) Postoperative x-ray shows the kyphosis reduction and facet grafts inside of C1–2 joint (arrow). (E) Sagittal reconstructed CT scan showing remodeling of the C1–2 facet joint and facet graft inside (arrow). (F) Postoperative MRI showing the decompression of the spinal cord and C2 realignment.

Fig. 6.

Illustrative case. Congenital basilar invagination and craniovertebral junction (CVJ) kyphosis. (A) Preoperative x-ray shows the atlantoaxial dislocation and severe kyphotic CVJ deformity caused by the os odontoideum. (B) Sagittal reconstructed computed tomography (CT) scan reveals the abnormal inclination and radiographical stiffness of C1–2 facet joint (arrow). (C) Postoperative x-ray shows a reduction of C1–2 dislocation. CVJ kyphosis is also reduced and clivus-canal angle is increased. (D) Sagittal reconstructed CT scan reveals postoperative remodeling and flattening of the C1–2 facet joint and PEEK cage inside the joint (arrow).