Fascicular-Sparing Technique for Resection of Cerebellopontine Angle Facial Nerve Schwannoma

Surgery of cerebellopontine angle (CPA) facial nerve schwannoma (FNS) in patients with good facial nerve function is a challenge.^1-10Video 1 highlights the fascicular-sparing technique for resection of a CPA FNS. A 41-year-old male patient symptomatic with persistent headaches and tinnitus underwent a retrosigmoid approach for a right cystic CPA tumor, presumed vestibular schwannoma. Intraoperatively, the facial nerve was identified as fine multiple strands splayed around the perimetry of the tumor, which elicited a motor response at a low threshold stimulation. This finding led to the intraoperative diagnosis of FNS according to the reported criteria.⁵ Neuromonitoring-assisted fascicular-sparing resection technique was performed. It involved the gradual separation of the uninvolved nerve fibers using a fine-stimulating dissector at a threshold of 0.2 mA. Entry into the tumor was at a stimulation silent cyst. The tumor was debulked with preservation of the endoneurium and pulse irrigation hemostasis. A near-total resection was performed. The patient was discharged on the second postoperative day with a House-Brackman III facial nerve deficit. The deficit remained stable during the following annual follow-up visits. Resection of CPA FNS is indicated at the earliest sign of deficit. However, it might be encountered as masquerading at the surgery of an acoustic tumor. The fascicular-sparing technique is critical in avoiding injuries to the endoneurium during the resection and with the ability to preserve function. The sparing of endoneurium avoids collagenization, fibrosis, and ischemia of the nerve, which are known to be the pathologic substrate of worse functional outcomes.