Chances of Improvement in Cases of Vestibular Schwannoma Presenting with Facial Nerve Weakness: Presentation of Two Cases and Literature Review.

Facial nerve (FN) weakness as a presenting feature in vestibular schwannoma (VS) is extremely rare. We are presenting two different cases of VS with significant facial weakness and reviewed the literature for similar cases.  We are presenting two cases of VS with significant facial weakness. The first case was a 63-year-old male patient presented with 3 weeks' history of severe left-sided facial weakness (House-Brackmann [HB] grade V) and hearing loss. Magnetic resonance imaging (MRI) of the brain showed a tumor in the left internal auditory canal. Gross total removal with anatomical and physiological FN preservation was performed through a retrosigmoid approach under neurophysiological monitoring. FN function improved postoperatively to HB grade II after 16 months. The other case was 83-year-old male patient presented with sudden left-sided hearing loss and severe facial weakness (HB grade V). MRI of the brain 2.5 years before showed a left-sided (Class-T3A) cystic VS. The tumor was asymptomatic; wait-and-scan strategy was advised by the treating neurologist. Recent MRI of the brain showed approximately three times enlargement of the tumor with brain stem compression, extensive cystic changes, and suspected intratumoral hemorrhage. Surgery was performed; the tumor was subtotally removed through a retrosigmoid approach with intraoperative FN monitoring. The FN was anatomically preserved; however, physiological preservation was not possible. Severe facial weakness with incomplete lid closure persisted postoperatively.  Surgical treatment could be offered to cases of suspected VS presenting with facial weakness, as these cases may still have a chance for improvement especially in laterally located tumors.