Background: Regardless of optimal treatment, hearing disability in neurofibromatosis type 2 (NF2)-related vestibular schwannoma is irreversible. Therefore, aggressive surgical intervention for hearing preservation still has been controversial. To the moment, there is a limited number of studies about prediction of hearing outcome in NF2 related vestibular schwannoma.
Objectives: Aiming to improve their care and establish individual hearing prognosis the earliest possible, we performed a retrospective analysis of hearing outcomes in NF2 related vestibular schwannoma and propose early prediction of hearing outcome.
Methods: We conducted a retrospective analysis of 48 patients reviewing their full clinical and imaging data follow-up of 15.0 ± 6.6 years. Mutation analysis of germline DNA was performed with Sanger sequence and multiple ligation-dependent probe amplification (MLPA). We analyze their hearing outcome with respect to “Asymptomatic,” “Useful hearing” (Gardner-Robertson Hearing Scale Grade I, II),” and “Disabled hearing (Gardner-Robertson Hearing Scale Grades III, IV, V) or Deafness.” Kaplan–Meier survival and Cox regression analyses were used to evaluate predictors of “Disabled hearing or Deafness.”
Results: An NF2 gene alteration was identified in 28 patients (58.3%) including truncating mutation (13:27.1%), large deletion (4:8.3%), splice site mutation (8:16.6%), missense mutation (3:6.2%), and somatic mosaic and undetected cases (20:41.6%). Hearing preservation period and outcome in relation to each clinical/genetic factor, estimated by Kaplan–Meier method/log-rank tests, differed statistically significantly depending on mutation type and onset age. Among factors, “truncating mutation,” “Somatic mosaic and Undetected case,” and “Onset age?25” had the most significant effects on hearing disability. Consequently, it was established that the patients with “Mosaicism or Undetected” and “Onset age?25” had clearly different hearing prognosis compared with other NF2 patients.
Conclusion: Hearing outcomes in NF2-related vestibular schwannoma are predictable by considering age at diagnosis NF2, and germline mutation of NF2 gene.
