Welcome! You have come to the right place to learn more - we have great health pages, written by our members that can help you understand more of this disease.
you can get to them at
http://www.medhelp.org/health_pages/list?cid=36
As for the spinal tap (also known as a lumbar puncture - LP) I would skip it. The doctor is right that it doesn't prove or disprove you have MS. for many of us, the LP was used as extra evidence that MS was possible. I hope that makes sense.
is your doctor an MS Specialist? It sounds to me like he isn't because he would know that with you starting Avonex (or any of the other drugs) you are doing the best thing possible to avoid being in a wheelchair. A large percentage of people with MS will never need a wheelchair in their entire life. There's no way that you doctor can tell whether you will or won't be one of those people.
As for the lesions and how many you have - that really doesn't matter. What does count is WHERE those lesions are located. We have lots of empty real estate in our brains - we only use about 10% of what's there. The rest of our brain is sitting ready if we need the reserve but it isn't doing critical work. Lesions in our brains go by that real estate adage ... location, location, location. You can have a ton of lesions but if they aren't in the right location, they won't do a thing to us.
IV steroids, like prednisone, can have some strange side effects, so keep that in mind. You may feel very hungry, extremely aggitating, unable to sleep, and gain weight. Its all normal but be sure and ask your doctor (or even post a question here) if something doesn't seem quite right. hopefully this will help and decrease the inflammation ofyour lesions.
There is so much to learn about MS - do yourself a huge favor and only take in a little bit at a time so you aren't overwhelmed. this is a slow moving disease so you don't have to be in a hurry to learn everything overnight.
Welcome again - I hope you will come through here often to learn more and ask your questions. This really is a great community of caring and knowledgeable people who just happen to also have MS (or might have!).
I'm sorry that you have joined us in the ranks of having MS , but remember it could always be worse.
be well, Lulu