cat balance problem

Question
Hello; I have a situation with my cat that is somewhat complicated, so I will start at the beginning.

About three weeks ago, my cat (he is male, 18-years-old, in otherwise good health) suddenly started exhibiting fairly severe balance problems--'drunken' walking, head tilting.  The only previous indications that something was wrong was that for a few days prior, he had been shaking his head a bit, and sneezing/runny eyes.

We took him to an emergency clinic.  They took a swab from his outer ear and said it looked fine.  So they sent us home with a week's supply of clavamox, in case it was a middle or inner ear infection, and told us to make an appointment with a vet.

We gave him the clavamox, and he improved immediately.  Within a day or so, he wasn't walking 'drunkenly' anymore.  He steadily improved over the course of the next week.  The clavamox (a week's supply) then ran out.  He continued to be okay; the severe balance problems have not returned.  However, he does still have a bit of a head tilt, and we can tell that sometimes he is not feeling 100%.  However, this kind of comes and goes; some days he seems to feel fine, other days, he's just perhaps a bit lethargic.

We took him to the University of Illinois Teaching Hospital today.  They want to do two things: a 'videoscopy'--I'm not sure I'm spelling that right, but basically stick a camera into his ear and look around--and an MRI.  

We are somewhat hesitant about this for two reasons: first of all, the expense--it will be $1500 just for them to try to find out what's wrong--and second, the overall stress for our cat, who would have to be put under.

Given that his symptoms are very mild, and that he responded well to the antibiotics, we think it is a distinct possibility that he simply has a middle or inner ear infection.  However, the vets we have seen don't seem to think this is very likely, but we've never gotten a clear answer on WHY they don't think it's likely.  The only reasons I have discerned are: (1) such infections are uncommon in older cats and (2) such infections are usually accompanied by infection in the outer ear, which he does not have.

Our tendency is to want to give him another round of antibiotics (though not clavamox, which made him sick to his stomach), but as I said the doctors want to look around for something else.  

I have a couple of questions: first, if they do the MRI, and he actually does have a tumor or growth, how likely is it to be treatable?  I guess what I'm getting at is: are we going to go through the whole process just to find out he has a brain tumor, but then be told there's nothing we can do about it?

Second, which of the following options would you recommend:

1. Go ahead with the MRI and videoscopy and go from there

2. Give him another round of antibiotics and see if he improves

3. Do nothing and see if he improves


The procedures invovled with #1 are expensive, but we are more than willing to pay for them if they are indeed necessary.  We just want to do whatever is best for our cat.

Thank you for your time, and I apologize for going on at such length.

Jason

Answer
This was most likey a case of vestibular disease due to his age--nerve inflammation/irritation or yes, possibly a brain tumor--or maybe from an inner ear infection.  Given his age and the fact that he has almost recovered 100%, I would not have the MRI done or the videoscopy...it is more stress to him as he will have to go under heavy sedation or general anesthesia to have it done.  Sometimes pets will have a permanent head tilt after an episode of vestibular disease and as long as they can get around, we often just let them be.  You can certainly ask for a refil of the antibiotics to be on the safe side.