Cincinnati children's hospital medical center offers comprehensive information, written by health professionals, on electromyograms (emgs) and nerve conduction tests:

http://www.Cincinnatichildrens.Org/health/ info/neurology/procedure/emg.Htm

I had an emg back in december and I had to take a week off work. I saw my doctor and my neurologist a couple of days after the tests as I was in chronic pain. Both said that my reaction was very unusual. I was put on a high dose of endep (amitriptyline) as it helps with nerve pain (which is possibly the burning sensation that your mother is getting). The endep hasn't gotten rid of my original problem but it did help with calming down the pain associated with the emg. Maybe your mother would benefit from this drug or something similar.