Mine was triggered by stress of building a house and an extremely hot summer.
How is your son doing?

I don't know what triggered my MG, but if I had to guess I would say it was probably extreme stress.

Looking back before I was dx with mg , I was suffering from cluster headaches that were devastating . Clusters are bought on by various triggers , food allergies , vision difficulties and yes stress .

I've always speculated that stress is the trigger for me as well as after my clusters were bought under control it wasn't long after that mg symptoms we're beginning to show . Of course at the time I had no clue that the symptoms were mg as that's a story for another day lol.

Cj

I was abducted by aliens and was injected with the MG virus. They knew I was a prime candidate because the virus alone wouldn't give me all the symptoms. It has to bond with another existing, non-removable virus in our bodies to create the full myasthenic effect. The virus and/or number of viruses that it bonds that we carry all the time in our bodies is what determined the severity.

Well, maybe that is how it works. Could be that stress thing too! That sounds good.

So when an earthquake or tornado hits your neighborhood, do you say what was I doing that triggered it? Sometimes I think that is the way we should think about MG--it just happened.

Most of us have had MG long before the symptoms show up strongly enough to be recognized. So when my eye closed, and my breathing went bad, undoubtedly I had the problem for months or maybe years before with only when enough receptors were killed off was it noticeable (the general statement is we only notice the symptoms when 80% of our voluntary muscle receptors are damaged, gone or blocked--under 80% there is enough redundancy to function almost normally).

So, speculating on what was happening immediately before the noticeable onset is probably not going back far enough. After I was diagnosed and treatment began to work, I felt better than I had for many years--indicating I probably had it at a low level for a long time and only when my eye slammed shut did we figure out what was wrong.

Good Luck

Suspect the radical diet measures I took to control my diabetes, along with BP meds, have created havoc in my gut. Many ongoing gut complaints. Not debilitating, but clearly present. To the point, I think gut issues, notably gut permeability, played a significant role in the development of my case. Sickness was unknown to me before my gut began acting up...I estimate I had MG 3-4 yrs. before dx. After several days on Mestinon, I began walking better than I had in yrs. The 100 meter walk to my car no longer required 2 rest stops. Fingers crossed that Mestinon magic will endure.

Here is an overview of how MG may develop.

http://myastheniagravis.org/mgfi_what_causes_mg.aspx

Some may have a genetic pre-disposition for developing this type of illness. It takes time to become full blown and none of us have traveled the exact same path. I know that certain things can aggravate it like heat and repetitive motion...so it would seem like it would manifest faster if you were in heat and using up a lot of acetylcholine in activity.

I liked CGreens answer a lot.....Abduction by aliens and direct injection....:) Someday the light will shine on MG more and we will have more answers....Marie

Extremely stressful incident, underlying cancer, and/or thyroid disease. I think it's likely I've always had it, but some combination of these things triggered the outbreak of symptoms.