Functional outcome after removal of intracochlear acoustic neuromas and simultaneous cochlear implantation

Abstract

Introduction: Schwannomas of the vestibular nerve are the most common neoplasm of the temporal bone whose cardinal symptoms are sensory neural hearing loss and vertigo. These schwannomas are rarely located in the cochlea. There is limited data available about simultaneous implantation of a cochlear implant (CI) and excision of the intracochlear tumor. Methods: This retrospective study presents preoperative symptoms, surgical features and CI performance in patients who underwent the aforementioned procedure between 2012 and 2017. Results: 5 patients with single-sided deafness and a patient with Neurofibromatosis type 2 (NF2) with bilateral deafness (unilateral implantation) were identified in our CI databank. The most common symptom was tinnitus. In MRI pathological contrast enhancement in the cochlea with missing fluid signal was detected, compatible with a schwannoma. In the patient with NF2 no hearing nerve was detectable. In all cases the intracochlear removal of the tumor was performed. Regarding the implantation insertion of a practice electrode before implantation was necessary in 2 cases. 3 insertions were performed with stylet. The patient with NF2 had no speech understanding at the first fitting. Other patients reached an understanding rate of 85 - 100% in Freiburger numbers test as well as 15 - 75% in Freiburger monosyllabic test. The results improved further in next follow-ups. Conclusion: Simultaneous cochlear implantation in the context of excision of intracochlear schwannomas is a good option for speech rehabilitation. The advantages of immediate implantation (quicker hearing, no risk of ossification of the cochlea before implantation) should be weighed against the disadvantages (poorer tumor postoperative follow-up with imaging methods) in each individual case.