Complete transposition of carotid bifurcation: can it be an additional risk factor of injury to the cranial nerves during carotid endarterectomy?

The internal carotid artery (ICA) usually, lies posterolaterally to the external carotid artery (ECA). Sometimes a complete carotid transposition can occur, with the ECA in a lateral position and the ICA on the medial side can occur. Our study evaluated the significance and impact that this anomaly may have on cranial nerve injuries. From January 2008 to November 2010, 296 patients underwent 360 consecutive primary carotid endarterectomy (CEA) procedures. During carotid isolation, we detected an unexpected lateral position of the ECA in 11 cases (3.6%). χ(2) analysis and the Student's t-test were used to compare the incidence of cranial nerve injuries between the 11 patients with the lateral ECA who underwent CEA (group A) and 11 randomized patients with a normal bifurcation (group B). Statistical significance was inferred at χ(2)>3.84 and P<0.05. A statistical difference in the incidence of superior laryngeal nerve paralysis was detected between groups A and B (18.1%, 2/11 in group A vs. 0%, 0/11 in group B; χ(2)>3.84; P<0.05). No differences in incidence of injury were detected for the other cranial nerves. A very meticulous mobilization of the ECA and ICA is needed to perform CEA, but superior laryngeal nerve injury can occur despite the use of a safe and meticulous surgical technique.