A sleep study is not the same as the EEG you have scheduled. Sleep study would be where they video you sleeping, you'd have EEG like setup (but often with fewer leads). Lots of people with apnea have seizures so it is something to know about. Just read an article on medscape today touching on this (originally from a cleveland clinic blog)
http://www.medscape.com/viewarticle/852735 ps - sure that the ambulatory EEG would catch seizures if they are setup for different times but sleep study is more, not sure it would be recommended to all but it is something I've considered for my child in the past.

Sue does tell everyone to get SPECT, not something that is going to happen but it would be cool if the option were more available, as well as DTI or MEG. She also mentions a DNA test - she really means a liver enzyme test as lots of older AEDs are broken down in the liver so knowing that could matter for some people and some AEDs, but isn't true for a lot of the recent AEDs. My sister can't shout the benefits of probiotics enough either, lots of people like to promote what really helped them and some are more objective /scientific when they do it and others sound farther out there.

Regarding MRI - it doesn't see everything - damage/scarring can be missed or if there, can be misinterpreted. But there are also different powered machines so it can be different if you were in a 3T or 1.5T machine - the 7T machines are super rare but see more. For big problems, low powered machines are going to see it, for the equivalent of the pea that bothers the princess' back, need a better powered machine or some other technique. The epilepsy protocol MRIs at our hospital are only done with the 3T machine, but they use the 1.5T machine for other stuff.

Lots of epilepsy doctors do suggest certain supplements - taking keppra? They'll often recommend B6. There is a note fixed to all screens in the neurology dept we visit to make sure all epilepsy patients have enough vitamin D. Gluten free diets may be enough to stop one type of patient's seizures - seriously. And some catch alls - like magnesium, super popular for a variety of ailments that are hard to pinpoint. For many patients, it probably doesn't apply. I noted my child has fewer seizures in the summer - and now I know seasonal seizures is actually something reported in research, go figure. Long term use of AEDs can mess with absorption of certain things so that is something else to pay attention to.