I had an EMG over the summer. I just had a 2 level ACDF. If you use a doctor that is certified and well versed in the EMG it is mildly uncomfortable. You feel twinges and maybe a radiating pain down the arm. Definitely less painful than a muscle spasm or the pain involved in disk herniation. If you are concerned about permanent nerve damage it is worth doing the test. If you plan on surgery regardless, than it may not matter. My feelings after putting off the ACDF until I could not handle the pain is . . . don't wait. The rewards are worth it. I have been off narcotic pain killers since a week out of surgery where I was taking narcotics 3 times a day for 6 months.