Good question! I don't think anyone has a comprehensive theory.

You get schwannomas of other CN eg V and VII but they are either rarer or at least subclinical/incidental findings. I was thinking about this before and bookmarked this webpage - one hypothesis on why most clinically significant schwannomas are vestibular in paragraph 2; there is some genetics further down the page.

http://www.medmerits.com/index.php/article/vestibular_schwannoma/P5

Thank you so much, the article is really interesting! It seems that although there is indeed plenty of knowledge about the carcinogenic mechanisms of this Schwannoma, there is still quite a lack of literature coverage about its predisposition to the vestibular nerve. The issue looks very intriguing and fascinating, though!

Neuromas in the body are generally an overexuberant reaction to some sort of nerve trauma, an out-of-control process of nerve repair.  So I do not think vestibular schwannomas are any exception to this rule.  The fact that they are only bilateral if there is a generalised genetic disorder like neurofibromatosis supports this idea.  So we need to consider that there is some sort of local trauma, albeit slight and long forgotten, that has damaged the vestibular organs and/or nerve.  Looking for general pathophysiological mechanisms is likely to be misleading.

That indeed makes sense. I have looked up some epidemiology, and remarkably, it seems that vestibular schwannoma incidence increased throughout the '90s, peaked in 2004 and afterwards went through a small reduction (Propp et al. 2006, Stangerup et al. 2010). This can support the trauma hypothesis as well, but still it looks quite odd that traumas concerned specifically the vestibular location. In fact, nonvestibular schwannomas seem to have diminished through the '90s. The vestibular n. must have something special.

I suppose it could not be its course, as it runs much close to other CNs associated to less frequent neoplastic transformation. And it could not be radio wave exposure either, as it should have increased the tumorigenesis of neighbour nerves too. In fact most studies on cell phone exposures seem to deny a correlation. A few papers suggest a possible correlation to loud noise exposure, but the evidence seems quite weak and again, why the vestibular and not the cochlear n.?

The distal location in the vestibular n. of central glia to Schwann cell transition (as indicated in Dr. Lau's article) sounds really interesting. Do you think it could possibly enhance its predisposition to chronic inflammation, and consequently to traumas?

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1871924/

http://www.ncbi.nlm.nih.gov/pubmed/20871439

"A few papers suggest a possible correlation to loud noise exposure, but the evidence seems quite weak and again, why the vestibular and not the cochlear n.?"

I think at least some VS are secondary to perilymph fistulae, from a sudden loud noise for example.   I don't think focussing on the nerve itself will be productive, since any possible causal neural factors will likely damage other neighbouring nerves, or the opposite vestibular nerve.  It is the vestibular and auditory membranous end organs that have different anatomy and susceptibility to trauma.