What are the implications in individuals with unilateral vestibular schwannoma and other neurogenic tumors?

Object. Individuals who develop a unilateral vestibular schwannoma (VS) and other neurogenic tumors are at high risk of having the inherited condition neurofibromatosis Type 2 (NF2). The risk of bilateral disease and transmission risk to offspring are important in surgical planning and counseling. The authors have attempted to resolve these risks. Methods. A large NF2 dataset was interrogated for individuals who had initially presented with a unilateral VS and other tumors before developing bilateral disease, to assess the contralateral and offspring risks. Results. Ninety-six patients with a unilateral VS and additional neurogenic tumors had a bilaterality rate of 48% at 20 years in those initially diagnosed when > 18 years of age and 82% if presenting earlier. Constitutional NF2 mutations were found in blood in 25 (27%) of 92, but 13 (76%) of 17 patients presenting with unilateral VS at : IS years of age. Tumor analysis suggests that the vast majority of the remainder are mosaic for an NF2 mutation. Conclusions. Patients with unilateral VS and other NF2-related tumors who fulfill Manchester criteria have a high risk of developing a contralateral tumor, especially if presenting in childhood. Transmission risks are reduced for offspring, particularly in the older patients who are likely to be mosaic.