Facial nerve anatomy, dissection and preservation in lymphatic malformation management

SummaryObjectiveTo describe facial nerve anatomy and surgical techniques used for safe lymphatic malformation resection of malformation involving the facial nerve.MethodsDesign: retrospective case series. Setting: tertiary pediatric hospital. Subjects: record review of lymphatic malformation patients after facial nerve dissection, from 1996 to 2005. Data collected included: facial nerve function, relationship of lymphatic malformation to facial nerve, facial nerve anatomy, dissection extent and clinical outcome.ResultsSixteen patients who met inclusion criteria underwent a total of 21 facial nerve dissections. Mean age at dissection was 48 months (range 1–72 months). Mean follow-up was 38 months (range 8–144 months). Pre-operative lymphatic malformation stage by patient: II = 7/16, III = 4/16, IV = 2/16 and V = 3/16. Higher stage lymphatic malformations required more extensive dissections (p = 0.026). Pre-operative facial nerve function was House-Brackmann grade (HBG)-1 in 20, and HBG-6 in 1. Eight months postoperatively, facial nerve function was HBG-1 in 18, HBG-2 in 1, and HBG-6 in 2. The facial nerve was surrounded by lymphatic malformation in 10/21, deep to the lymphatic malformation in 5/21, superficial to the lymphatic malformation in 4/21, and not identified in 2/21. Imaging studies predicted facial nerve position in 15/21 procedures. Antegrade nerve dissection was performed in 10/21, retrograde in 7/21 and not done in 2/21. Abnormally elongated facial nerve was identified in 11/21 cases and required more extensive dissection (p = 0.040). Facial nerve monitoring was used in 15/21 dissections. Clinical outcomes were felt to be good in 19/21 dissections.ConclusionsIn lymphatic malformation surgery, the facial nerve is often abnormally elongated and encompassed by malformation. Pre-operative imaging, facial nerve identification and dissection allow excellent postoperative facial nerve function.