Through statistics, it is suspected that one-half of cases are inherited, and one-half are the result of new,  de novo mutations. Cause loss of hearing
The hearing loss caused by NF2 is gradual and results from the presences of bilateral cochleovestibular schwannomas, also known as acoustic neuromas, which damage to cochlear nerve causing hearing loss. Hearing loss may also result from benign tumors that grow on the vestibular and auditory nerves, which lead to the inner ear. Pathogenesis
NF2 is caused by a defect in the gene that normally gives rise to a product called Merlin or Schwannomin, located on chromosome 22 band q11-13.1. Merlin was first discovered as a structural protein functioning as an actin cytoskeleton regulator. Later merlins tumour suppressant role was described. Merlin regulates multiple proliferative signalling cascades such as receptor tyrosine kinase signalling, p21-activated kinase signalling, Ras signalling, MEK-ERK cascade, MST-YAP cascade. In a normal cell, the concentrations of active (dephosphorylated) merlin are controlled by processes such as cell adhesion (which would indicate the need to restrain cell division). It has been shown that Merlin inhibits Rac1 which is crucial for cell motility and tumour invasion. Also, merlins interaction with cyclin D was described. It is known that Merlins deficiency can result in unmediated progression through the cell cycle due to the lack of contact-mediated tumour suppression, mainly because of the cell:cell junction disruption, sufficient to result in the tumors characteristic of Neurofibromatosis type II.
Treatment hearing loss
As hearing loss in individuals with NF2 is generally gradual, eventually profound and sensorineural, the best options for treatment for hearing loss are cochlear implants and auditory brainstem implants (ABIs), as well as supplementing hearing with lip-reading, cued speech or sign language. Cochlear Implants
A cochlear implant is an electronic device that is surgically implants to stimulate the cochlear nerve. Cochlear implants will work only when the cochleovestibular nerve (8th nerve) and the cochlea are still functioning. In a study done with open-set speech perception testing and closed-set speech perception testing by Neff et al., they discovered that the use of cochlear implants with NF2 patients allowed significant improvement of hearing abilities. In testing of recognition of sentences of everyday speech, five out of six patients scored within the 90–100% range, and in testing of hearing in noise setting, four of six of the patients scored within the 83–96%. Additionally, all testing was done without lip-reading. Auditory Brainstem Implants (ABIs)
Auditory Brainsteam Implants, or ABIs, are used when the cochlea or any portion of the cochleovestibular nerve are not functioning due to damage to those areas or anatomic abnormalities. The procedure is done by implanting a device that send an electrical signal directly to the cochlear nucleus, allowing sound to bypass the peripheral auditory system and straight into the brain stem. Prognosis
NF2 is a life limiting condition. It is a rare genetic disorder that involves noncancerous tumors of the nerves that transmit balance and sound impulses from the inner ear to the brain.