I was diagnosed at Mayo Clinic about 1970 by Tensalon Test which was Very Dramatic.....I consider Mestinon to be an Obsolete Drug ....there are several good ones available now that were not back then....I was in Crisis on a Vent for 81 days un ICU about 1975....Only drug available was still Mestinon, which was useless....have since been on Pred, CelCept, IVig, VYVGART, others....Plex works best when really needed!...I AM 89 YRS OLD and still haning in there after two other Crisis ICU stays...>DM