Vertebral Artery Terminating Posterior Inferior Cerebellar Artery (PICA-VA) as a Potential Risk Factor in Cervical Spine Surgery

OBJECTIVE: Unilateral vertebral artery (VA) injury is thought to not result in serious complications. The dominant-side VA should be preserved, although the importance of the nondominant-side VA has not been discussed. The injury of VA terminating posterior inferior cerebellar artery (PICA-VA) may result in cerebellar infarction. The characteristics of PICA-VA were evaluated. METHODS: In study 1, results of head and neck magnetic resonance angiography were reviewed for 358 consecutive cases. VA diameter was measured at the V2 segment. Relationships between frequency of PICA-VA and asymmetry and diameter of the VA were analyzed. In study 2, results of magnetic resonance angiography were measured for 62 consecutive cases aged <= 39 years. Frequency of PICA-VA was compared between this young age group and 324 of the 358 cases aged >= 50 years. RESULTS: Mean age for the total cohort was 67.8 +/- 13.8 years (range, 10-94 years). PICA-VA was identified in 44 cases (12.3%). Mean diameter of all VAs was 3.2 +/- 0.76 mm. Mean diameter of PICA-VA was 2.0 +/- 0.55 mm, significantly smaller than the nondominant side in Confluence (+) (2.8 +/- 0.59 mm; P < 0.001). Among the 56 VAs <2.0 mm, 26 (46.4%) were PICA-VA. PICA-VA was seen in 1 of the 62 cases aged <= 39 years (1.6%), and in 43 of the 324 cases aged >= 50 years (13.3%), showing a significantly lower frequency in the younger population (P < 0.001). CONCLUSIONS: Whether PICA-VA injury causes complications is not obvious. However, PICA-VA should also be preserved considering that potential risks exist. If the VA is small or shows a large difference in diameter between sides, special care should be taken during cervical spine surgery.