Cort -- thank you so much for bringing up this topic. It is something that is rarely discussed or mentioned in the usual list of ME/CFS symptoms, but I think it is much more common than people realize. Whenever I mention it to a fellow PWC (or is it PWM/C now?), it seems almost everyone can relate at least on some level. I know my fiance also has difficulty speaking, and can rarely talk on the phone, etc. It's extremely draining for him.
As for the reasons why -- it's funny, but it's difficult to put into words. I can relate to what both you and Jody mention. It seems to be a combination of things.
After the crash that left me homebound, there was a time where I could still speak, but with significant difficulty. I remember the vibrations my voice made when I spoke always left me feeling dreadfully dizzy, and seemed far too loud in my head. It was also somewhat painful and very draining in ways I couldn't understand. It's amazing the things you never realized (when healthy) require energy.
I also find that when I try to speak, I have quite a bit of difficulty breathing. It's weird, but... talking requires some coordination with your breath, and I struggle with this now. Even when I whisper, I often have to get everything out in one out-breath. I can't seem to manage breathing in and out and talking at the same time -- at least, not very easily.
And then there's the problem of sensory overload. It's like my brain can't handle the task of speaking, listening to what the other person says back, thinking of a response, and getting all the words out in reply. I have to think of exactly what I want to say before I speak (or whisper). It all feels very slow and complicated, as Jody said.
I have trouble with even just listening to someone talk, too... I often have to close my eyes. I'm not sure why, as I can listen to audio books and such w/o much problem. It seems watching someone talk and knowing I need to respond in some way (even if just in nonverbal cues) is just too much info for my brain to process.
It all sounds so crazy, but it's such a struggle for me. The sensory overload carries over to a lot of other things as well. While not as bad as Patient X (I can usually listen to music, audio books, etc) -- I can't watch TV. The images change much too fast for me. My brain seems locked on the first image, and before I know it -- 20 different images/camera angles have flashed in front of me and my brain just shuts down. Trying to also listen to what's being said as the images flash by, and then make sense of it all, is just impossible for me. It causes an instant crash. So I haven't been able to watch TV in 9 years either. Not sure if that's a good or bad thing.
I can listen to it, though -- I have a tapestry over the TV so I can't see it, but can still listen and keep up with the news, etc.
I have trouble reading as well... I have a speaker program on my computer that reads everything for me with a click or 2, or I wouldn't be able to be on these boards, write a blog or even email my friends, family or fiance. So that has been a godsend.
It's funny because before I became homebound, I didn't even really have any cognitive symptoms at all. But it became a major problem for me seemingly over night.
Okay, I went way off topic here. I have a habit of rambling sometimes... I think because I can't talk, that when I write.. I tend to carry on. And on.
Anyway, my point was that the difficulty speaking seems to have many layers to it.
Thanks again for bringing this up!
(sorry for all the edits)