I'm coming out of lurkdom to respond to this interesting thread.
My DD (17 months) is a bit of a mystery baby- suffered a full on regression of all motor skills at 6 months and has sloooowly gained, but remains severely delayed (can't sit up, crawl, fed by g-tube, etc. ) We have done an absolute poopload of diagnostic testing, the most recently being a muscle biopsy, but so far everything's coming back normal.
She's been labeled with central hypotonia and developmental delay. Its never even occured to me that hypotonia could be a diagnosis in and of itself. Very interesting!
Anyone out there with an older hypotonic kiddo who eventually learned to walk after super-delayed sitting? I keep reading that kids who don't sit by two generally don't learn to walk. I hope she's sitting by then, but that birthday's just kind of hanging out there like a dark cloud.
My youngest son is 4.5 years old. He did not sit up unassisted until he was 27 months, he walks, runs, etc. We did a lot of trunk strengthening exercises, bought him a Rifton chair and and propped him up with pillows to help him until he could sit up unassisted.