Safety Ranges in V3 Segment of the Vertebral Artery for Surgical Procedures at the Craniocervical Junction

Abstract

The aim of this study was to establish safety ranges for the third vertebral artery segment (V3) for craneocervical procedures. Injury to V3 represents a potentially catastrophic complication. Its tortuous path and complex relationship with neighboring structures, increasing the risk. Ten male adult cadavers (20 vertebral arteries) with arterial infiltration of red latex were studied. The length, angles and anatomical measurements were obtained between the selected surgical landmarks and the portions of V3 segment. The horizontal portion has a length of 32.7 ± 3.6 mm with an angulation of 115.1 ± 8.3 degrees. The mean distances of the horizontal portion were: from the midline to the V3 groove of C1 posterior arch (24.7 ± 6.3 mm); from C1 pars interarticularis to the V3 distal loop of V3 (8.9 ± 1.4 mm). The vertical portion has a length 32.5 ± 5.6 mm with an angulation of the proximal loop of 113.6 ± 5.8 degrees. The mean distances between the C2 spinous process to the medial surface of the distal loop (43.8 ± 4.2 mm); from the C1-C2 joint to the V3 vertical portion (9.5 ± 1.5 mm); from C2 pars interarticularis to V3 in the C2 transverse foramen (6.5 ± 3.4 mm); from C2 pars interarticularis to V3 in the C1 transverse foramen (17.5 ± 4.5 mm). We reported four potential sites where V3 can be injured during four different surgical procedures: exposure of the posterior arch of C1, and pars interarticularis of C1 in the horizontal portion and exposure of the C1-C2 joint, and placement of C1-C2 transarticular screws one in the vertical portion. We provide measurements of redundancy and safety ranges to reduce the risk of injury to the V3 segment during craniocervical surgical procedures.

Surgical Anatomy of Vertebral Artery in Relation to Atlantoaxial Instrumentation: A Cadaveric Study

“…Cacciola et al reported that the distance of the tip or the most medial part of the VA osseous segment from the midline of the C2 body ranged from 6.1 to 16.2 mm (11.7mm average) from an anterior transoral surgical view. Cruz-Elizondo et al recorded the distance between C2 spinous process towards the medial edge of the most prominent point of the proximal loop as 43.8±4.2 mm [ 5 ]. Güvençer M et al carried out an angiographic study in 12 human cadavers and reported that the distance between the VA's medial side of the V2 segment related to the axis and the midline was 17.6±6.1 on the right side and 14.7±2.1 on the left.…”

“…It then runs in a groove present on the superior surface of the posterior arch of the atlas. The fourth segment of the artery crosses the atlantooccipital membrane and enters the cranial cavity [ 4 , 5 ]. As the VA ascends cranially, the transverse foramen moves from an anterolateral to a posteromedial position [ 5 ].…”

“…The fourth segment of the artery crosses the atlantooccipital membrane and enters the cranial cavity [4,5]. As the VA ascends cranially, the transverse foramen moves from an anterolateral to a posteromedial position [5]. The first (atlas) and second (axis) cervical vertebrae are considered atypical cervical vertebrae.…”

“…their study, Cruz-Elizondo et al measured the angle of the proximal loop of the VA segment related to the axis V3 as 112.60 degrees ±5.66 on the right side and 114.60±6.02 on the left. Cacciola et al measured the angle of the loop formed by VA within bony foramen on the inferior surface of the SAF to be 2-110 degrees (86 degrees average)[5]. Alfaouri and Hadidi measured the mean angle (a-1) between the ascending and descending bends of the loop formed by the VA segment related to the axis (V3) to be 72.13 degrees ±1.48 on the right and 75.66±1.57 on the left[1].Güvençer et al measured the angle between the V2 segment of the VA and the midline as 4.0±1.9° on the right and 2.2±1.4° on the left side[9].…”