Selective midfacial neurectomy for postparalytic facial nerve syndrome

Chemodenervation with botulinum A toxin and neuromuscular retraining therapy are commonly performed as first-line treatments for postparalytic facial nerve syndrome (PFS). However, their effects are temporary, and side effects typically develop. Currently available selective neurectomy approaches are limited by variations in the anatomy of the peripheral branches of the facial nerve and the ability to reduce perioral synkinesis, but not periocular synkinesis. We devised a novel selective midfacial neurectomy for PFS that considers anatomical characteristics and is effective for both periocular and perioral synkinesis. In our approach, the facial flap was elevated subcutaneously, and facial nerve branches were identified at the anterior margin of the parotid gland. Using intraoperative nerve stimulation, the thin cranial zygomatic branches that innervate the lateral portion of the orbicularis oculi muscle and the buccal branches that innervate the orbicularis oris muscle independently were preserved. The thick caudal zygomatic branch and its communicating branch with the cranial buccal branches, which simultaneously and strongly contract both the periocular and perioral mimetic muscles, especially around the medial upper and lower eyelids, were selectively excised. From March 2021 to September 2022, selective midfacial neurectomy was performed in five patients with House-Brackman (HB) grade III-IV unilateral facial paralysis. With respect to the synkinesis score and palpebral fissure width ratio, statistically significant improvements were observed between the preoperative and 18-month postoperative values. Selective midfacial neurectomy is effective in treating patients with postparalytic facial nerve syndrome.