There is a line from Romeo and Juliet that probably fits here:
"For in an hour, there are many days." I'm sending lots of pixie dust for your hours to be full of minutes, not days, the test to run smoothly and give the answers that will help your son.
I don't have a lot to add to the good advice you got, since my DD has never had one. I've seen video/nursing education of people having one done, a friend had one done about 20 years ago and another friend's son had one done about 5 years ago.
I do know that if they find out what they are looking for, they will shorten the test like BCV23 mentioned. I've been told the hardest part can often be waiting for a seizure (it seems like when you want one for them to be able to observe, you don't get one). That's where the "few days" part comes in. For some people, a small amount of sleep deprivation (or whatever stimuli they are looking for) will bring a seizure; for some, it may take a few days. When they see a seizure with that stimuli, they can usually cross that one off the list and go on to the next type of stimuli.
Your hardest task will be to keep him in view of the camera at all times, but that may not mean being confined to the bed. He may have a range of locations in the room where he can be. I'm sure that they will have done the test on children like your son (or children who are 18-24 months by age and by development). They should know some "tricks" to help you/him out and ways to keep him from pulling the electrodes off - one way is to cover them with gauze. I know some people who won't leave IVs alone don't even give them a second look if they are covered. So, they will do everything they know to make the test less traumatic. The best way for you to help is to be exactly what you are - an expert on your son.
I second the advice about having friends, etc maybe lined up to do some respite for you.
As was already mentioned, the nurses will have ways to keep him clean. They can do bedbaths. The hospital where I work has many people with spinal cord injuries or comas who can't get out of bed for bathing. We have ones in our hospital that come prepackaged with nice soft disposable washcloths and are microwaved to warm them. They also do something called "Bag baths" where they put a small amount of hot water and a diluted skin wash product in a zip lock bag with 6-8 washcloths. The washcloths stay in the bag (and warm) until they are used and patients
really like them. (A lot of people ask where they can get the prepackaged ones for use at home).
Another thing to think about is clothing - you want to bring things that will open down the front (you won't be able to slip things over his head. Also anything that is static-y can cause "interference/noise" on the video. I've heard also to avoid thing with stripes or lots of pattern (apparently the video cameras autofocus try to keep stripes in focus or something). If the fact sheet they gave you doesn't mention those things, maybe my information is old.
Here are some good websites with information:
Video EEG fact sheet from the UK
University of Iowa Fact Sheet
I found a lot of other references, but they were either too clinical or repeated what these said.
I KNOW you and your son will get thru it and hopefully it will give the doctors the information they need to control his seizures.
