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Risk of Vertebral Artery Injury in Cervical Spine Surgery

Rheumatoid arthritis often targets the cervical spine. Changes in the structure of the vertebrae can cause significant and dangerous myelopathy (damage to the spinal cord). Surgery may be needed to stabilize the spine and protect the nerve structures. Cervical fusion is a common procedure to accomplish these goals.

One of the problems surgeons run into in this group of patients is a thin column of bone called the pedicle. Fusion with screws through the pedicles can cause problems. If the screw goes all the way through the bone, it can cut into the vertebral artery (VA). And in up to 80 per cent of patients, the VA takes a right-hand turn at the C2 level.

In this study, researchers studied the risk of VA injury with C2 pedicle screw fixation. They used computer assisted three-dimensional (3D) views of the spine to map out the anatomy of this area. Two groups of patients were compared. One group had diagnosed rheumatoid arthritis (RA). The second group (same age and sex) did not have RA.

They found that 60 per cent of the RA group had narrow pedicles. Only 13 per cent of the non-RA group had similar findings. Normally pedicle size depends on body size. But in the RA group, the C2 pedicle was small in men compared to their body size. These results suggest that men with RA who need cervical fusion with pedicle screws are at even greater risk of VA injury than women with the same diagnosis.

And the location of the vertebral artery loop is a major consideration. Care must be taken when the artery travels through the area where the pedicle screw will be placed. Conventional CT scan images may not be enough to guide the surgeon. These authors suggest a 3D approach is needed when planning surgery for RA patients involving pedicle screw fixation of the upper cervical spine.

References: Masahiko Miyata, MD, et al. Rheumatoid Arthritis As a Risk Factor for a Narrow C-2 Pedicle: 3D Analysis of the C-2 Pedicle Screw Trajectory. In Journal of Neurosurgery: Spine. July 2008. Vol. 9. No. 1. Pp. 17-21.

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