Hello John,
 You'd better believe it's caused by the AN! I started losing hearing in my left ear six to seven years ago. In 2002 I began seeing double all day, every day. This double vision was accompanied by lightheadedness and a hypoglycemic type of malaise that would come and go throughout the day and night. I lived in that condition for about two years. Then, my equilibrium went, big time. I was never dizzy, never nauseous and never had any bad headaches - as huge as my tumor was - I was just staggering around like a drunk. My condition was compounded by hydrocephalus  - csf build-up in the cranium - because the tumor was so big. So before my diagnosis, I went from thinking that I was diabetic to believing that I had M.S. or Lou Gehrig's disease. It was a very scary time in my life. Through my own research on the net and a few blood tests that bore out that I had a normal blood count or "CBC", I came to the conclusion that I had a noncancerous growth effecting my hearing and vestibular system otherwise known as an Acoustic Neuroma or Vestibular Schwanoma. I was right. Toward the end of my "guessing game" I was going around complaining about my condition to people, saying that I either had MS or a brain tumor. I remember when I first began having the double vision, I asked a friend what he thought might be causing it. Without hesitation he replied: "Brain Tumor". I knew he was right.
         Keep in touch and take care,   Paul