Iam 36, and have been having unexplained vasovagal syncopes for almost a year now. I have had every test available, and I'm having a reveal device implanted this week to monitor my syncopes for 18 months. I have also requested blood test to be done to check hormeone levels, on the day of each syncope. You may want to try a blood test on the day as well. Several women my doctor says have syncopes between ovulation and their menstrual cycle, but they have never done blood tests to see whats happening???? And menopausal women have very wacky hormone levels. Good luck, don't give up searching!! Also dehydration,blood sugar levels, stress and fatigue, are all said to aggrivate this problem??
I would have suggested an epilepsy work-up, but that has been done. I would have also suggested a tilt test and a 24 hour Holter monitor, but hotse have also been done. The one additional test I would suggest is a 30 day event monitor (sort of like the Holter, but for a longer period of time). A cardiologist would be able to set this test up.