Hiya. Ok firstly what we have is benign so thats unlikely. Often there is no known cause for an acoustic neuroma. There is a theory that xrays of head and neck as a child can cause an AN (in my case that is a possibility I had dental xrays as a child), plus maybe a genetic susceptibility: 'The cause of acoustic neuromas can sometimes be linked to a problem with a gene on chromosome 22. Typically, this gene produces a tumor suppressor protein that helps control the growth of Schwann cells covering the nerves. However, experts don't know what causes this problem with the gene that leads to an overproduction Schwann cells.
The only confirmed risk factor for acoustic neuromas is having a parent with the rare genetic disorder neurofibromatosis type 2. However, neurofibromatosis type 2 only accounts for about 5% of acoustic neuroma cases (and is usually bilateral).