Our DD 4 has infrequent meltdowns during our homeschooling time, but nonetheless, they are total meltdowns that just shock us, since it is out of her character.
We thought things through and recognized that it seems to build over the months and then just explode. During these meltdowns, we attempt to talk to/reason with her, however it is as if she doesn't want to be the intelligent gifted girl at that moment, and she just wants to/needs to have a totally unreasonable fit. Almost as if saying, "I know I shouldn't be reacting this way, and it frustrates me that my emotions are controlling my logic...but let me do it".
We find that just sitting quietly in the room with her (at her level, if she is on the floor - I sit on the floor, if she is on her bed - I sit at the foot of her bed) without talking to her or even touching her...just being there for her. She seems to get it all out and then still grunting/or sobbing/or even still grumbling she will start to nudge or bump up against me getting closer (I still say nothing, but open my posture up, allowing her to settle into my arms or lap if she chooses). This then turns into me holding her (still silent) as her breath returns to normal. I then ask if she is okay, and we get up and go back to whatever we were doing.
We do not speak about the incident, since she knows I was there witnessing it, and still stayed and allowed her to be her. (Trust me, there are many moments in my life when I react irrationally, and can get defensive when called on it...mostly out of embarrassment...nobody wants to talk about their embarrassing moments)
We only figured this out after one day when we were working on a LA assignment writing a poem about feelings, and she chose to write this:
My Mood
When I am mad
& I don�t know why
I shout �I don�t want to be glad�
Just let me cry!
I think that is when we started to just sit with her and let her deal with it the way she needed to.
I always try to reason with her at a level beyond her years, since that is how she herself likes to be dealt with, however, I do see the glimpses of a 4 year old every now and then just wanting to be 4. And I need to let her be her. :-)