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

Background And Objectives: Ultrasound-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.

Methods: An ultrasound-guided intermediate cervical plexus block (20 ml of ropivacaine 0.75%) was performed (n = 28). Then, depending on the individual sonoanatomy, 5 ml of prilocaine 1% was injected into the carotid sheath (group 1: no perivascular infiltration, n = 14, group 2: perivascular infiltration, n = 14). The third step was subplatysmal injection of 5 ml 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.

Results: The requirement for supplemental local anesthetic infiltration in the skin incision area was minimal at mean (M) 1.1 ml (standard deviation (SD) ±2.4 ml). Perivascular infiltration in group 2 significantly decreased the total amount of local anesthetic supplemented: group 1 M = 4.2 ml (SD = ±3.1 ml), group 2 M = 1.7 ml (SD = ±2.0 ml) (p = 0.018). The incidence of block-related side effects was not significantly different between the two groups.

Conclusion: This 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.