Facial nerve anatomy, dissection and preservation in lymphatic malformation management

To describe facial nerve anatomy and surgical techniques used for safe lymphatic malformation resection of malformation involving the facial nerve.

retrospective case series.

tertiary pediatric hospital.

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.

Sixteen 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.

In 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.