em87, that is great news. After surgery in July 2017, I finally got referred for an EEG a couple of months ago, and it turned out that seizures were most probably causing my memory issues, even after the successful surgical resolution of my cyst about 18 months ago. In December, I got a tentative diagnosis of Transient Epileptic Amnesia ~ epilepsy limited to within the brain. I have been on drugs for this for a few weeks now, and I feel much sharper. It's not clear where this sprang from, but somehow it seems to be connected to the large cyst that I had. Doctors cannot tell me how long I had the cyst. But it is possible that it had been interfering with blood circulation ("vascular insufficiency"), which my reading tells me can be connected to (epileptic) seizures.
As time goes by, I notice more and more that my memory blanks go back several years. For example, I took my mother on a trip to Japan in 2013, but I couldn't recall it. My wife reminded me of it last week. When I cast my mind back before 2013, everything seems to be in place. I am 49, and I am confident that this is not early dementia. Moreover, the academic article I read on this said there that there is no evidence of a link between Transient Epileptic Amnesia and future onset of dementia. I guess it's kind of a mechanical issue that can be sorted out. The epilepsy medication I'm on now (Vimpat) has a very high rate of completely preventing the seizures. It's just I have to stay on it forever. Now I feel more comfortable with that.
To my surprise, it turns out that all forms of epilepsy occur in about 1% of the population. I just had no idea. Another interesting thing I read is that seizures can occur right after waking up, and that definitely happened to me. Has that happened with you too?
Good luck with this all. It has felt bewildering, but I am back in a good place now.