Ultrasound-guided intermediate cervical plexus and additional peripheral facial nerve block for carotid endarterectomy: Aprospective pilot study

Background and objectivesUltrasound-guided intermediate cervical plexus block with perivascular local anesthetic infiltration is an established anesthetic procedure for carotid endarterectomy. In this prospective pilot study an additional subplatysmal block of the superficial ansa cervicalis is presented for the first time. The target structures are the anastomoses between the facial nerve (cervical and marginal mandibular branches) and cervical plexus.MethodsAn ultrasound-guided intermediate cervical plexus block (20ml of ropivacaine 0.75%) was performed (n=28). Then, depending on the individual sonoanatomy, 5ml of prilocaine 1% was injected into the carotid sheath (group1: no perivascular infiltration, n=14, group2: perivascular infiltration, n=14). The third step was subplatysmal injection of 5ml of prilocaine 1% between the medial edge of the sternocleidomastoid muscle and the submandibular gland (n=28). The investigated parameters included the need for supplementation and block-related side effects.ResultsThe requirement for supplemental local anesthetic infiltration in the skin incision area was minimal at mean (M) 1.1ml (standard deviation (SD) 2.4ml). Perivascular infiltration in group2 significantly decreased the total amount of local anesthetic supplemented: group1 M=4.2ml (SD=3.1ml), group2 M=1.7ml (SD=2.0ml) (p=0.018). The incidence of block-related side effects was not significantly different between the two groups.ConclusionThis study presents an ultrasound-guided subplatysmal block of the superficial ansa cervicalis for the first time, with the aim of optimizing anesthesia quality during surgical interventions in the carotid triangle.