First Bite Syndrome after Carotid Endarterectomy for High Carotid Bifurcation and Extensive Lesions: Two Case Reports and Literature Review.

First bite syndrome (FBS) is an extremely rare complication of carotid endarterectomy (CEA). FBS presents with unique characteristics, development of brief and intense pain in the ipsilateral parotid region at the first bite of each meal, and improvement with subsequent mastication. Here, we report two cases of FBS following CEA. Both cases had anatomical difficulty of a high carotid bifurcation and a high cervical lesion. The lingual and facial arteries (or their common arterial trunk) branched off the external carotid artery (ECA) close to a high carotid bifurcation. The operations required exposure of the ECA distal to these two branches and the distal internal carotid artery (ICA) with a wider range of dissection for clamping the vessels. Several days or weeks after CEA, the patients developed FBS, and their meal-related pain completely resolved in the ensuing weeks. Especially in patients with a high carotid bifurcation, several branches of the ECA tend to originate from the proximal portion of the ECA, similar to octopus arms. During CEA, in these patients, dissection around the ECA and its branches in a wider range is required for exposure of each vessel and placement of the cross-clamp. These procedures can lead to injury to the external carotid nerve and plexus, possibly causing FBS. Additionally, because of the close location of the superior cervical ganglion, external carotid nerves, and distal ICA, manipulation for exposure of the distal end of a high plaque can increase the risk of injury to the cervical sympathetic nerves.