I was asked to assist one of my otolaryngology colleagues in extirpating a neck tumor that encroached on the carotid artery at the base of the skull early in my career. While the operation was complex and interesting, the most impressive part of it was the complete exposure of the neck from base of skull to the base of neck that was possible with an oblique skin line incision. This challenged bias I had about “exposure,” because up to that time, I had done the mastoid process to manubrium incision along the anterior border of the sternocleidomastoid muscle. What was doubly remarkable was that the incision was invisible in followup despite curling from ear to epiglottis because it was hidden in the fold under the submandibular fat.
This patient above had his carotid endarterectomy performed with a skin line incision. He didn’t even need his beard shaved for the operation.
The key is developing subplatysmal flaps like the kind you make with thyroidectomy. This allows cephalad and caudad exposure. More exposure means just extending the incision medially and laterally. These flaps heal well. This with retraction allows for excellent exposure of the neck.
The other advantage is that the fat is never cut across but completely avoided if you go under it and lift it up. The incision is far less disfiguring and heals well because the forces co-apt the skin without relying on tension from the closing sutures. Preop planning with CTA and 3D virtual reconstruction confirm where the incision should be placed. But most of all, the patients appreciate not having a scar on the neck that they have to constantly explain.
Planning starts with visualizing the proximal and distal extend of plaque needed to be removed.
The 3D reconstruction view can be “Window Level”-ed to bring in soft tissues and skin to anticipate the operative exposure.
Experience has shown me that it is possible to avoid cutting through the fat on the neck, and what is visually the lower part of the face as much as it is the neck, but performing this oblique incision in the skin fold.
While I was a site investigator for the CVRx Rheos Trial, a device that induced hypotension and bradycardia by stimulating the carotid baroreceptor with electrical energy to control resistant hypertension, I noticed that Hering’s nerve can be readily identified by accompanying arteries which show up as paired red lines. The baroreceptor complex is a pressure transducer and the maximum dP/dt can be transduced in areas of maximum curvature change. If you recall those tension maps of aneurysm rupture points, they occur in areas of maximum curvature and inflection points -wouldn’t a baroreceptor be constructed to sense pressure and change in pressure here? Hering’s nerve comes out over these areas. It struck me that most of the patients with carotid disease are hypertensive and it may be a disease cycle that occurs with stiffening of the baroreceptor, decreased parasympathetic tone, and hypertension as the output signal with subsequent vessel injury and plaque formation and worsening stiffness -a non virtuous cycle.
The nerve probably wraps around the origin of the internal carotid artery or wherever the curvature is best suited for pressure transduction. If you visualize the bulbous origin of the ICA as the belly of the guppy, the arteriotomy is made traditionally on the side facing you which is on the side and across at least half of Hering’s nerve -on the lateral surface of the guppy. If you make instead an arteriotomy on the belly of the guppy, and preserve as much of these nerves as possible, it would be theoretically possible to reconstitute a baroreceptor, maybe the dominant one (there is a sidedness to the baroreceptor strength).
There is an intriguing consequence to cutting the nerves -for example in skeletonizing the ICA for an eversion. Eversion endarterectomy done this way is associated with greater incidence of postop hypertension than standard endarterectomy (ref 1,2). The question is if the converse -if reconstituting the baroreceptor can bring decreased need for anti hypertensive medications or even hypotension and bradycardia -is true and if there is potential for applying this as therapy for hypertension as well as stroke risk reduction.
1. J Vasc Surg. 2012 Aug;56(2):324-33.
2. J Vasc Surg. 2001 Nov;34(5):839-45.