I'm a medical malpractice defense attorney and represent doctors, hospitals and variety of other medical entities in the Chicago area. And, although I respect the opinions of those who offered them (Cathy and Odd_Duck) I have a little different view of this question and issue.
I have to admit I have not had a failure to diagnose MS case. In fact, I am unaware of any at my firm (and we're a large firm here in Chicago). This may be because the disease is rare or that there weren't therapies available before that effected the outcome of the disease as there are now. But, we get plenty of failure to dx cases involving other ailments, etc.
I think it was fairly clear but would like to overemphisize that people shouldn't be discouraged from investigating potential malpractice claims. Every case is very fact intensive and depending on the actions of a physician and patient's circumstances negligence can occur even with MS patients. Again, please note that I say this as a med mal defense lawyer. It happens with cancer patients all the time and awards are justly deserved and paid out.
So, please don't think that because you have MS and that it is a chronic disease you are not entitled to some type of compensation to make yourself whole again (whatever that means be it to compensate you for limping more, walking less, etc....). Wrong is wrong and if a misdiagnosis led to a worse, permanent injury, then its worth pursuing if you feel that strongly about it.
Take for example one case (although I have many examples) I have: a lady with multiple myeloma (a pretty bad cancer) is diagnosed 1 year too late. Had she been diagnosed properly on day 1 (not 365 days later) her condition would not have deteriorated as much, the cancer would not have spread as quickly, she would have been able to obtain better, more effective treatment earlier and her long-term survial would have been extended (possibly...not definitely) by a couple years.
It ain't much people but when you're the lady with the aggressive cancer, 2 kids, a husband and you're the bread winner with a life expectancy of 5 years at best, 2 more years is A LOT. I have kids and if you told me I could have one more day with them I'd want it and be really upset with anyone who negligently took it away from me.
Comparing that to your MS case, assuming the doctor did delay, you were a candidate for drug therapy at the time when the dx should have been made and you progressed signficantly (again you define signficantly be it walking with more of a limp, not walking, or being tipped so slightly on the scale of disability that NOW you're disabled and unable to work, etc.), you might be entitled to compensation as well. For instance, if you had all the signs and sx, lesions, two episodes of exacerbations seperated by time but had a negative LP or were labelled as suffering from anxiety, somatoform (its all in your head) illnesses, etc. and the doc failed to dx you, that could be a good case. Of course, I can think of numerous situations that would make it a good case. And, this is just a hypothetical but you get the picture. You'll have to apply the analysis to your own situation.
Now, throw in the fact that new drugs, like Tysabri (assuming it comes back) and even the regular CRABs drugs, are on the market and have been shown to help disease progression to a degree, that helps the case for patients who say, "Hey, had you made the dx earlier, I'd have gone on the drugs, had less lesions and more likely than not less symptoms and a better prognosis." Please understand that the other posters are right, its a disease that is difficult to dx, can take time and can be confusing with other disease process mimicking it or also being involved. But, its not impossible to dx. And, physicians have to show diligence in finding answers. If they don't, they're negligent and we as a society have a duty to sue them, report them and get them to better their practice or give up their license. I believe its a form of regulation (although I wish it were not necessary as such but does serve a dual purpose) which is good because the physician DO NOT regulate themselves and ALWAYS allow doctors to continue to practice when they should not. Say what you will about laywers, at least we have an ARDC that is active and sanctions us if we do not act accordingly. The AMA and docs do nothing. However, I digressed.
Without knowing the exact facts and using a very general evaluation, if I were the defense attorney defending a doc in a hypothetical MS case, I'd say that the case is generally a difficult one for plaintiff if you can show the some physician diligence given the nature of the disease and good charting by the doc. Damages may be reduced due to the chronic nature of the disease. Depending on the physician's actions and charting and plaintiff's background it could be a winner for the defense or a seven figure damages case. Either way, it is still a case that will cost a lot to defend. A tough thing would medical break throughs (Tysabri could really hurt the defense if available) that would make earlier dx and treatment (holding the patient until something better comes along) critical. I hesitate to include a settlement posturing note, case valuation, etc. here as there aren't enough facts but its intriguing.
Enough hypotheticals, the point is that this begs investigation by a trained med-mal lawyer who is willing to put the time and money into the case. As a result, I HIGHLY suggest you see an attorney regarding your specific case. You'd be surprised how knowledgeable some can be (again, some are just dogs but some are great) and you may just have a case. Good luck and, as always, I wish you good health.