Extra-Arachnoidal Dissection and Limited Meatal Drilling for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation.

Abstract

Surgical excision of giant (>4 cm size) vestibular schwannomas (VS) with preservation of facial nerve (FN) function remains a challenge. Our surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described with the goal of improving FN preservation. Surgical results with respect to FN preservation were analyzed for two groups of giant VS patients: Group A-operated between 2002 and 2009 using "standard" surgical technique, group B-operated between 2009 and 2016 using extra-arachnoidal dissection and limited meatal drilling. All patients had a minimum follow-up of 1 year. Of the 115 patients, total excision was possible in 103 (89.5%), near-total in 7 (6%), and subtotal in 5 (4.3%) patients. At a >6-month follow-up, 68 (59.1%) patients had good FN function (House-Brackmann [H&B] grades 1-2), while 21 (18.3%) patients had poor function (H&B grade 3-5). Grade 6 involvement was seen in 26 (22.6%). Five patients had lower cranial nerve impairment necessitating tracheostomy. Of the 98 patients, total excision was achieved in 70 (71.4%) patients, near-total in 9 (9.2%), and subtotal in 19 (19.4%). Four patients had repeat surgery; 14 underwent gamma-knife radiosurgery. At >6-month follow-up, 78 (79.5%) patients had good FN function (H&B grades 1-2), while 20 (20.4%) had poor function (H&B grade 3-5). With our 'modified' surgical technique of extra-arachnoidal dissection of VS throughout surgery and limited meatal drilling, an improved rate of functional FN preservation was observed.