Feasibility of total and partial uncinectomy during anterior cervical approach: MRI-based analysis of 176 patients regarding vertebral artery location.

Abstract

To determine the technical feasibility of uncinate process (UP) resection (uncinectomy) during anterior cervical approach with risk-avoidance of vertebral artery (VA) injury. One hundred and seventy-six magnetic resonance imaging images with cervical spondylosis were evaluated. The diameter between UP and VA (UP-VA distance), the presence of a fat plane, and the VA's anterior-posterior position relative to UP (anterior[A], middle[M], posterior[P]) at C3-4 to C6-7 segments were investigated. Subsequently, easy-to-use classifications were developed according to the feasibility of total and partial uncinectomy. Total uncinectomy: easy (distance: > 2mm); moderate (distance: ≤ 2 and fat plane: +); advanced (no fat plane). Partial uncinectomy: easy (distance: > 2mm and P, A, or M position); moderate (distance: ≤ 2; fat plane: + and P position), and advanced (no fat plane and P position). UP-VA distance of C5-6 on the right side (left/right: 0.41/0.31mm) was the smallest. The ratio of no fat plane of C5-6 (46.6%/49.4%) was the highest. C5-6 had a high rate of P position (7.4%/8.5%) while C6-7 had a high rate of A position (19.3%/18.2%). More than 90% individuals were classified as easy for partial uncinectomy at any vertebral segment (C3-7), while more than 30% were classified as advanced at C4-7 with the highest rate at C5-6 for total uncinectomy. When performing uncinectomy during the anterior cervical approach, the C5-6 segment may be at the greatest risk of VA injury. Hence, preoperative MR images should be thoroughly evaluated to avoid VA injury.