The authors report a case of an unstable C1 fracture with magnetic resonance imaging
demonstrating rupture of the transverse ligament. Posterior vertebral artery anomaly
in the form of a right persistent first intersegmental artery was identified preoperatively
in the region of the right posterior C1–C2 lateral mass interval. The surgical plan
was altered to avoid the anomalous vertebral artery and the patient was successfully
managed with an uncomplicated occiput to C3 instrumentation and fusion procedure.
The literature review includes a discussion of the work by Uchino et al who have reported
a persistent first intersegmental artery in up to 3.2% of normal subjects and an overall
prevalence of craniovertebral junction vertebral artery anomalies of 5%.[1]
This article is an important addition to the existing literature as it highlights
the relatively high prevalence of vertebral artery anomalies at the craniovertebral
junction. The case described involves an aberrant vertebral artery with an anomalous
course located posteriorly between the C1 and C2 lateral masses. This particular vertebral
artery anomaly poses great risk to the conventional placement of C1 lateral mass screws
through previously described techniques involving the exposure of the C1 lateral mass
or placement of the screw through the C1 posterior ring. The anomaly was identified
preoperatively by computed tomography angiography in this case, and intraoperative
vertebral artery injury was avoided. The utility of the use of routine of preoperative
imaging studies to demonstrate the course of the bilateral vertebral arteries before
any planned exposure of the craniocervical junction is clearly implied in this case
report.
The significance of this case report and review of the literature lies in the identification
of the increased risk of complication involving vertebral artery injury through a
routine posterior cervical spine surgical exposure. Much of the existing literature
involving vertebral artery injury in cervical spinal surgery has focused on injuries
incurred with anterior cervical spinal surgical procedures. Tortuous anterior course
of the vertebral artery in the subaxial cervical spine has been well described by
Curylo et al in approximately 5.5% of subjects.[2] Multiple reports of injury to the vertebral artery during anterior cervical decompression
surgery exist in the literature.[3] Five studies reported rates of 0.10 to 1.96%, depending on the type of anterior
cervical spine procedure.[3] There remains, however, a paucity of literature with respect to vertebral artery
injury incurred with a posterior cervical surgical exposure. Molinari et al recently
reported vertebral artery injury in two cases involving a persistent first intersegmental
artery in the region of C1–C2. Both injuries were incurred with routine posterior
exposure of the C1–C2 anatomy. A review of the existing literature demonstrates few
publications on this topic.[3]
The authors should be applauded for this work, which raises a greater sense of awareness
as to the increased potential for vertebral artery injury during posterior cervical
spine exposure in the region of the craniocervical junction. Their work underscores
the need for thorough preoperative evaluation of the course of the vertebral artery
before performing operative procedures on the cervical spine.
