Hi, Tulip.
In myasthenia gravis there is an autoimmune attack on the acetylcholine receptors, which interferes with the signalling from the nervous system to the muscle cells to contract the muscles. Treatment for myasthenia gravis includes use of cholinesterase inhibitors, which lower the rate of breakdown of acetylcholine, so that there is more acetylcholine to stimulate the remaining receptors. This works for a while, but the damage mechanism continues to decrease the number of acetylcholine receptors, so the disease is progressive.
In ME/CFS, though it has been suggested that choline is elevated, and hence that acetylcholine is not likely lower than normal, I believe that this was based on a misinterpretation of the magnetic resonance spectroscopy data, and that acetylcholine is indeed low in ME/CFS, as WillowJ has noted. There is a published paper in which pyridostigmine, a cholinesterase inhibitor, was found to be beneficial in ME/CFS. There is another study of a different cholinesterase inhibitor, which was found not to help. I don't know why.
So in a sense, these two conditions are similar in this respect: Either low acetylcholine or low acetylcholine receptors will interfere with the neuromuscular stimulation, and a cholinesterase inhibitor should counter either of them.
My impression is that the damage mechanism continues in myasthenia gravis until the muscles will no longer get the signal to contract. This starts to show up in the eyelids, which droop (called ptosis), and then it spreads to other muscles. I don't think the results of low acetylcholine in ME/CFS are progressive. I haven't heard of ptosis developing in ME/CFS.
By the way, a good friend of mine had myasthenia gravis, and I can testify that it was corrected by Rife therapy, because I saw him before the treatment as well as afterward, on a regular basis. He stopped his medication, which had included both a cholinesterase inhibitor and an immune suppressant after he had received the Rife treatment, and the ptosis resolved and did not come back. Unfortunately, the FDA shut down the people who were doing the Rife therapy. I'm not making this up.
Best regards,
Rich