Classification of internal carotid artery aberrations based on CTA imaging: evaluating the risk of ICA injury in the transoral approach to upper cervical surgery.

OBJECTIVE

Cervical internal carotid artery (ICA) aberrations increase transoral atlantoaxial surgery risk. Existing classifications ignore the ICA's relationship with the atlanto-axial complex. This study aimed to define this relationship using CTA and assess associated injury risk.

METHODS

The study included 846 patients underwent CTA from January 2019 to February 2024 in our medical center. These classifications were based on the position of aberrant ICAs relative to the odontoid processes and the lateral masses of the atlas.

RESULTS

In a cohort of 846 patients with a total of 1,692 ICAs, 65 patients (7.68%) exhibited aberrations, including 27 males (41.54%) and 38 females (58.46%). The incidence of ICA aberrations was comparable between patients under 60 years (6.67%) and those aged 60 years or older (8.02%) (P > 0.05). Bilateral aberrations were significantly more common than unilateral ones (64.62% vs. 35.38%, P < 0.05). We identified a total of 108 abnormal ICAs (6.38%), with 55 on the left side and 53 on the right (50.93% vs. 49.07%, P > 0.05), showing no significant difference. According to our proposed classification, there were 65 cases of Type I, 32 cases of Type II, 9 cases of Type III, and 2 cases of Type IV. The prevalence of Subtype A aberrations (82 cases, 75.93%) was significantly higher than that of Subtype B (26 cases, 24.07%) (P < 0.01).

CONCLUSIONS

Aberrations in the course of the ICA at the upper cervical level are relatively common, presenting a potential risk of ICA injury during the transoral approach for upper cervical surgery. Therefore, our classification of ICA aberrations based on CTA should be considered a standard component of preoperative evaluation.