Pre-foraminal vertebral artery variation in the United States: A multi-institutional cadaveric study

While vertebral artery (VA) variants are uncommon, they may be more prevalent than previously reported. To date, there are no cadaveric studies that have examined VA segment 1 variations or defined normal VA anatomy in U.S. whole-body donors. This study addresses that gap through a multi-year, multi-state cadaveric analysis.

Donors (n = 188) from Ohio, Nebraska, and Mississippi were dissected to expose the pre-foraminal VA which were then categorized as normal or variant. Collected data included artery origin, vertebral level of origin, entrance level, diameter, lengths in relaxed/taut states, distance from subclavian or carotid origin, and demographics. Data were analyzed using T tests, Chi-Square, and Fisher's exact tests.

Normal segment 1 VA anatomy was present in 86.17 % of donors; 13.83 % exhibited anomalies, including abnormal origin (4.79 %), high entrance (10.64 %), and double VA (1.06 %). Most origin anomalies involved the left VA (LVA) originating from the aortic arch. High entrance anomalies were more frequent on the right. Anomalies decreased in donors over 80, with no sex association. The LVA had a significantly larger origin diameter than the right (5.31 mm vs. 4.77 mm; p < 0.001). Tortuosity increased with age and was greater in females on the right (p = 0.025).

The U.S. anomaly prevalence for the V1 segment may be higher (13.83 %) than what is reported in the literature, particularly concerning high entrance VAs. These findings have clinical implications, as VA variants may complicate vascular procedures. Increased LVA tortuosity with age suggests remodeling, and fewer anomalies in older donors may relate to longevity. This study supports the need for region-specific anatomical data and emphasizes the importance of preoperative imaging.