rate (major adverse cardiovascular event rate, MACE) of < 3% (evidence level 1b; recommendation grade A)
Asymptomatic internal carotid artery stenosis > 60% and contralateral stenosis > 75% or occlusion, with a MACE of < 5% (evidence level 4; recommendation grade C)
Symptomatic internal carotid artery stenoses > 50%, with a complication rate of < 6% (evidence level 1a; recommendation grade A)
The following groups of patients are particularly able to benefit from the operation:
Those with hemispheric TIAs
Those with crescendo TIAs—i.e., with the number and/or length of transitory ischemic attacks continually increasing
Those with progressive stroke—i.e., patients with low-grade symptoms initially who show marked clinical deterioration within 6 h
Those with stroke during the previous few weeks, as the risk of recurrent cerebral ischemia is particularly high in these cases
Those with a subtotally occluded internal carotid artery but persistent residual flow (pseudo-occlusion)
Despite the lack of level 1a evidence, differential treatment consideration for carotid artery stenting (CAS) appears to be justified, above all in the presence of a “high carotid bifurcation” (bifurcation of the carotid artery higher than C2); for repeat operations in the neck; when there is paralysis of the contralateral recurrent laryngeal nerve; and after cervical radiotherapy, as it avoids local complications (e.g., nerve injuries).
Contraindications
Patients in poor general condition (American Society of Anesthesiologists IV, V) or with limited life expectancy (< 6 months)
Fresh large cerebral infarction (major stroke), with no tendency to show clinical improvement (< 4 weeks)
Following earlier disabling stroke (Rankin scale 5)
Patient preparation
Specialist neurological examination to determine prior neurological symptoms or establish the patient’s neurologic status
B-imaging and duplex ultrasonography to determine the level of the carotid bifurcation, show whether the internal carotid artery is patent, and assess the grade of stenosis
Cranial CT or MRI to identify older or more recent cerebral hemorrhage, infarct areas, and tumors
Angio-CT, angio-MRI, or intra-arterial digital subtraction angiography only if there is a suspicion of supra-aortic multiple-vessel disease, poor definition of the stenosis on duplex ultrasound, contradictory duplex-ultrasound findings regarding the grade of stenosis, suspected intracranial tandem stenoses, or extreme kinking or coiling of the vessel with ambiguous duplex findings
Prophylaxis against thrombosis with low-molecular-weight heparin s.c. on the evening before the operation
Fasting for at least 6 h before the operation; long-term medication may be taken with a little water on the morning of the operation. Caution: antidiabetic agents, clopidogrel, Coumadin
Preparations for the operation
The operation can be carried out either with regional anesthesia or general anesthesia, although a recent prospective randomized multicenter study (the GALA study) showed some advantages for regional anesthesia (Lewis et al. 2009).
Positioning: modified beach-chair position—trunk raised, legs slightly lowered, head reclining/hyperextended and turned to the contralateral side, head positioned on a rubber ring, both arms juxtaposed (in regional anesthesia, the contralateral arm is laid free and a squeezing toy is placed in the patient’s hand, which has to be rhythmically squeezed by the patient when requested and produces a loud sound)
Sterile cleaning of the side of the neck that is being operated on to beyond the midline, laterally including the shoulder (acromion), caudally as far as the nipples, and cranially to include the mandible, chin, earlobe, and mastoid
Surgical access
The incision is made at the anterior margin of the sternocleidomastoid; preoperative assessment of the level of the carotid bifurcation can provide good guidance. The level of the palpable cricoid can also be used for guidance. The skin incision is usually approximately 7 cm long, and it is carried cranially toward the inferior margin of the earlobe. As far as possible, the incision should be made as little cranially or ventrally from the earlobe as possible, as injury to the oral branch of the facial nerve could occur, either directly or due to a subsequent retractor movement, leading to pareses in the ipsilateral corner of the mouth postoperatively.
After division of the skin, subcutaneous tissue, and platysma, the common carotid artery, which is usually easily palpated, is dissected and looped with a vascular sling. Following exposure of the common carotid artery, the internal carotid artery is exposed above the carotid bifurcation. Unnecessary manipulations of the vessel are avoided to avoid triggering embolizations (“no-touch” technique). During further dissection of the bulb in the direction of the internal carotid, the ansa cervicalis of the hypoglossal nerve is spared as much as possible. However, it may also be transected if necessary, usually without sequelae. Following it cranially leads to the hypoglossal nerve as it crosses the internal carotid artery. Particularly when there is a high carotid bifurcation, the hypoglossal nerve has to be mobilized, and the sternocleidomastoid branches of the occipital artery and vein attached to it have to be ligated. Circular exposure of the carotid bifurcation is only carried out after clamping of the internal carotid artery, in order to prevent embolization (Fig. 1.1-19a, b).
Surgical procedure
There are basically two procedures that can be used for plaque removal and reconstruction of the internal carotid artery or carotid bifurcation:
