Variations of the vertebrobasilar arterial complex are important with regard to
their potential clinical impact. We present an unusual case of the vertebral
artery, in which the left vertebral artery in its ascent in the neck through the
transverse foramina passed posteriorly between the transverse processes of
C3 and C4 and supplied the posterior muscles of the neck without continuing
intracranially. Albeit speculatively, we hypothesise that the variation of the vertebral
artery reported here was caused by degeneration of the proximal portion
of the left postcostal longitudinal anastomosis (i.e. C1 and C2 intersegmental
arteries) in the context of a persistent third cervical intersegmental artery. Our case
is unique in that the left vertebral artery terminated extracranially. Knowledge of
the variations of the vertebrobasilar arterial complex is important for surgeons
operating at the skull base, craniocervical junction, and cervical region, and for
clinicians interpreting the imaging of this region
