Because my seizures are directly tied to my monthly hormonal swings... estrogen is a seizure exciter, progesterone is an inhibitor. I can chart my cycle, and pretty darn near predict when seizures will happen based on when estrogen will be on an upswing or on a high point.
I have borderline PCOS, and as such, I produce way too much estrogen, we figure this is probably the cause of the seizures to begin with - I have a tendency towards them, and the overdose of estrogen pushes my neurological pathways over the edge. So, just taking a low dose progesterone-only birth-control pill isn't enough to control the estrogen swings... we have tried that. And since I have hypertension, my MD isn't willing to try a birth control pill with any more kick than that; it might help the seizures, but be too dangerous when combined with the hypertension.
And yes, I could try a complete hysterectomy. It probably would be a great help indeed. But, you see, I have no health insurance. And since I have several pre-existing conditions, it would bankrupt me to try to get insurance. So right now, I just muddle along, paying for my care out of pocket. And a hysterectomy out of pocket just isn't in the cards.