An Anatomic Variant of the Ansa Cervicalis Precluding Its Use as a Donor Nerve

Abstract

Background: The ansa cervicalis is useful for cranial nerve repair, and may be harvested without apparent morbidity. Herein we report an unusual and surgically relevant anatomic variant of the ansa cervicalis. Methods: An adult male with left parotid adenoid cystic carcinoma underwent parotidectomy with upper-division facial nerve resection and planned interposition repair using the ansa cervicalis. The ipsilateral hypoglossal nerve was identified, together with a descending branch producing strap muscle contraction when stimulated. This presumed descendens hypoglossi was unusually large in caliber; further dissection revealed continuity with the vagus nerve. Results: Ansa cervicalis harvest was aborted when its separation from vagus nerve epineurium was not possible. The sural nerve was alternatively harvested. The patient awoke with left vocal fold palsy, which completely resolved within 3 months. Conclusion: Anatomic variants of the ansa cervicalis exist that may preclude graft harvest and place the vagus nerve at risk of inadvertent injury.

An Independent C1 Nerve Root Variant of the Ansa Cervicalis: A Case Report

“…In one case, a patient underwent a parotidectomy for adenoid cystic carcinoma with planned upper-division facial nerve resection to be repaired using the AC. Following the identification of a vagal ansa variant, surgery was aborted to preserve vagal nerve function [24]. Without careful exploration of the associated structures, unexpected anatomical variation can predispose to complications.…”

Facial nerve communication with ansa cervicalis – An unusual anatomical variation

“…Similarly, there are no documented innervations to strap muscles from any cranial nerve nucleus. [ 6 ]…”

“…[ 10 ] Ansa is used as a donor nerve for facial reanimation as well as for laryngeal reanimation in patients of recurrent laryngeal nerve palsy because of redundancy in supply to strap muscles of the neck, as well as no discernable loss of function or cosmetic concern. [ 1 6 11 12 13 ] Iatrogenic injury to ansa can occur during various surgeries including thyroplasty, cervical lymph node dissection, arytenoid adduction, carotid endarterectomy, facial reanimation, and infrahyoid myocutaneous flap reconstruction. [ 1 13 ]…”

“…Classifications of ansa according to its various neural connections with vagus and hypoglossal nerves (Jelev’s classification)[ 1 6 ] have been described.…”