Complicated migraines
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Talk to your neurologist about changing your preventative medication. Topomax doesn't seem to be doing anything for you. However, although I've been on Depakote for several years now, it did take a long time adjusting the dosages until we got to an effective level, and even then it took a long time for me to notice that my migraines were less severe. I stopped passing out reasonably soon after the Depakote dosage got right, and the dizziness disappeared about a year and a half later. Although milder, my headaches can still last a week or more. I don't know how conscientious you are about taking your medications on time, but I definitely noticed that I needed to take mine at the same time every day to keep my blood levels even. Don't miss a dose.
You didn't mention any abortive treatments. Most of them only worked for a month or two at most. I went through the gamut and still haven't found anything that works totally and reliably, but Maxalt seems to be the most effective of the triptans for me (not everyone reacts the same to every medication).
In addition to increasing your magnesium, try adding Vitamins B-2 and B-12. Strangely enough, I also found that although everyone tells you to get off of caffine (and if you haven't, you should--it does make a difference), I found that one of two things would frequently help: either a large amount (1/2 gal.) of orange juice or a 2-ltr bottle of cola (I always drink diet, I don't know if this makes a difference). I don't know why, but if one doesn't help the other frequently does. I usually start with the oj, because it's the healther of the two. The cola does make sense, though, because caffine somehow speeds up the absorption rate of certain medications (ergo the otc migraine relief medications). The baby aspirin (or Feverfew if you can't take aspirin) probably isn't a bad idea, but do make sure you avoid ginko. You might also want to try yoga exercises to get your circulation moving and elongate your spine (don't try to push yourself to do anything that's uncomfortable--and don't do anything that makes the blood rush to your head). And last, but not least, if you suspect that your headaches might be related to a hormonal imbalance (you didn't mention your age), and if you don't have any family history of breast cancer, you can try supplementing your diet with natural estrogens (like soy). This might take a while for you to notice any effect).
In any event, you should definitely get a second opinion. If your unconscious episodes are anything like mine were, they are extremely dangerous (I not only had to stop driving because they would come on with very little notice, but I was afraid to go anywhere by myself--it was terrifying). Your numbness brings this all much too close to stroke symptoms.