Clinical evaluation and investigation of vestibular schwannoma in NF2-related schwannomatosis.

The management of vestibular schwannoma (VS) in NF2-related schwannomatosis (NF2-SWN) is more complicated than that for sporadic VS because of the almost invariable presence of bilateral VS, as well as the presence of other types of schwannomas in the cerebellopontine angle, elsewhere intracranially, and within the spine. This requires a much more holistic approach to management. The key goal of treatment is to preserve function and quality of life. This can be very challenging given the bilateral nature of the disease in most patients and means that there is likely to be greater accumulated morbidity with treatment over time than for sporadic VS. It is, therefore, critical to assess all aspects related to bilateral cranial nerve function, particularly focusing on audiovestibular function. Hearing assessment using pure-tone audiometry, speech testing, and occasionally electrophysiologic assessment is critical to quantify the degree of hearing loss and to help make decisions around optimal hearing rehabilitation. Vestibular assessment is often helpful in determining the source of any balance disturbance and aids in tailoring vestibular rehabilitation where required. Prospective psychologic and quality of life assessment are very important in order to direct decision-making and ensure that the patient's quality of life is optimized. VS and other tumors are monitored using serial magnetic resonance imaging (MRI), usually on an annual basis. MRI may present particular challenges in NF2-SWN, given that a significant proportion of patients will have auditory implants, which cause significant signal distortion and have issues around magnet displacement. However, there are a number of strategies to limit the implications of scanning in the presence of auditory implants.