Do left handers get more migraines?

I read an article the other day about a study that claimed left handers ran several times the risk of suffering from migraines as their right-handed counterparts. This was because they found there was a higher frequency of left-handedness in patients who suffered from migraines than in their control groups.

Interesting finding, but why should that be?

I then read that another study, done by scientists in Germany, found there was no evidence at all to suggest we southpaws are more prone to migraines.

So how are we supposed to know what to believe when we read such articles? My anecdotal evidence is that the people I know who suffer from migraines are all right handed.