Cat acting psycho

[Isabelle1963]

My mother cat had a litter of 9 kittens and i gave 7 of them away to one home that wanted outdoor cats.  We have since then raised a brother and sister cat and had them both spayed and neutered.  All that went well and both cats are very loving and playful.  One day when they were about a year and a half old, I came home and found my female cat racing after her brother in full attack mode and he was running for his life.  She was so focused on attacking him that she didn't even listen to a voice command and i had to put my foot in front of her to physically stop her.  [she ran into it]
When i attempted to pick her up, she hissed and growled at me to the point that i was leery of picking her up without being bitten.  I seperated my poor male cat by putting him in  a different room and then finally caught my female and put her in a locked room with a pan and food/water.  I checked on her daily and tried to reassure her and calm her down. I even attempted to try to bring them back in the same room together daily and finally managed it after a week of seperation.  This has happened over a span of 3 years about 5 times.  The seperation time is lessening but you can never tell what sets her off.  Alot of times it may be the sound of something a bit loud like a door or something falling on the floor.  She invariably attacks her brother.  Can anyone recommend anything?

[Savas]

...if the behavior is really violent, you may want to get her checked. There are some underlying physical illnesses that can cause dramatic behavior changes. Unfortunately, environmental can cause them as well. (We had nearby road work going on that we finally realized was causing one of our cats to become quite crazed. The behavior stopped when they finished. Go figure).

Hopefully it is just a dominance issue as mentioned above.

[bedtimestory]

I think your female cats is not only telling the male she is the alpha but also she is bullying him, which is very common when you have two cats as they are territorial and jealous creatures. I have heard cases like these in other forums and some specialists, including vet techs have advised separation but you have obviously have done so. There is always going to be the strongest and the weakest. You already know which one is which. Have you taken her to a vet for this? She may also be stressed or anxious. Why don't you get her assessed?