Analysis of the carotid bifurcation levels for carotid endarterectomy.

Background: We have already introduced the visualization of the posterior belly of the digastric muscle, which is a major component of the styloid diaphragm (SD). This helped the carotid endarterectomy (CEA) simulation considering the carotid bifurcation or carotid plaque height and their accessibility. In CEA cases, we examined the relationship between the SD and carotid bifurcation to determine whether the high bifurcation cases have the specific clinical profiles.

Methods: Eighty-seven consecutive CEA-treated Japanese patients were evaluated, and the location of the carotid bifurcation, thyroid cartilage (TC), hyoid bone (HB), and gonion was measured on the computed tomography angiography, referred to the heights of cervical vertebra bodies.

Results: Mean vertebral levels of the carotid bifurcation, TC, HB, and gonion were 3.9 ± 0.6, 5.5 ± 0.6, 4.2 ± 0.5, 3.9 ± 0.6, and 2.9 ± 0.6, respectively. Seven carotid bifurcations located higher than the SD. There were no statistical differences in the distribution of sex, age, and coexisting diseases except for coronary artery disease (P = 0.02) between normal (4.0 ± 0.6) and high bifurcation (3.4 ± 0.4) cases. The multivariate analyses revealed that the coronary artery disease (P = 0.04), twisted internal carotid artery (ICA) (P = 0.031), and TC levels (P = 0.007) were correlated with the high bifurcation.

Conclusion: The high bifurcation correlates with the twisted ICA, high TC, and alternatively low gonion levels. The visualized SD could be the landmark for the CEA indication and preparation and enables meticulous surgical manipulation of the distal end of the carotid plaque.