Arterial Fencing: A Challenge During Complex Craniovertebral Junction Surgery.

A 32-year-old woman presented with chronically progressive spastic quadriparesis. Detailed clinicoradiological evaluation led to the diagnosis of irreducible atlantoaxial dislocation and basilar invagination, with associated "kissing" carotids and an anomalous right vertebral artery (VA). Both internal carotid arteries had an abnormally tortuous course, "kissing" retropharyngeally at the level of C1-C2. The right VA became intradural at the level of C2-C3, an extremely rare anomaly-C3 segmental artery. Despite the deformed joints and the possibility of injuring the anomalous right VA during C2-C3 instrumentation, a tailored posterior-only approach was used to circumvent the arterial fence created by both vascular anomalies. The patient underwent bilateral C1-C2 joint opening and left C1-C2 joint spacer placement, followed by bilateral occipito-C3-C4 fixation. This is possibly the first reported case of a complex craniovertebral junction anomaly associated with both kissing carotids and a C3 segmental VA.