Hi and welcome,
MS is not typically a quick diagnosis, it can occasionally be diagnosed relatively fast if you've got clinically abnormal neurological signs and your MRI shows both old and new enhancing lesions, in the right locations, no other medical explanation, other suggestive test evidence etc etc but that's not typically the norm.
The only tests i can think of that you could get done prior to your first nuero appt would be visual and blood, the visual may be a common issue or something like Nystagmus, Optic Neuritis etc and associated with neurological conditions like MS, so you could get the health of your eyes tested by an ophthalmologist. Bloods your PCP could run but if your general practitioners can order MS protocol MRI's that might also be helpful......
The LP is probably one of the more invasive tests in comparison to all the others, the LP though is only useful in diagnosing MS if it's positive, but you can still have MS and not have obands. An LP may not even be necessary after all the other test evidence comes in, but if it is your LP results will get added to all the other suggestive-consistent diagnostic evidence, otherwise i wouldn't recommend you try to push getting an LP without first having any of the other diagnostic tests done.
I actually think it would probably be better to keep in mind that you can't necessarily speed up finding out if you have MS or not, even if there was 'something' that made MS a likely explanation, there might not even be enough diagnostic evidence to clearly diagnose, so you'd have to wait, wait until there was more hard evidence, and that can unfortunately take years.
At this stage MS is just one of many medical explanations, try not to get to worried about MS because it honestly might not be MS, 1 step at a time...
Hope that helps.....JJ
Unfortunately, there is no one test indicative of ms, and an LP is rarely used any more, other than as back up, supportive evidence to a less than obvious MRI. An LP is not done in the office, and I can't imagine a neurologist ordering one up front without already having a suspicion himself/herself that a patient "might" have ms (or other conditions that can be evaluated by LP).
Have you had a brain mri? That would be the absolutely necessary test since multiple sclerosis means "multiple scars" (plus also a lot of bloodwork to rule in or out mimics such as metabolic, vascular or vitamin deficiencies).
Unfortunately, unless the mri is textbook, with lesions that scream ms by size, location, shape, AND a portion of them currently enhancing ... there will have to be a lot more testing for an ms diagnosis. Also to rule out other conditions.
I did have my first mri prior to seeing the neurologist; if you haven't had one, that is an option. I was referred by my gp for the first one. It should be done with ms protocol and gadalinium contrast.
Keep us posted, SG :).