My understanding of AD is that it is caused by damage to the nerve. Most often it is due to surgeries or procedures or sudden injury. However, if the damage occurs over time, then I would assume that it can come on gradually. Perhaps if you were injured, had a bony protuberance from an injury, then the nerve could be injured over a period of time by the protuberance. Normally, though, when I think of gradually coming on, I think TN. Also, you asked if it covers the whole face. It does not have to cover the whole face but the numbness will cover the whole area of pain. Does that make sense? If that is the right side of your face, then it would be the right side. But I am going by what I picked up about AD when I read about TN, and I noticed that even on the well respected medical sites, there seemed to be some vagueness in the two conditions and how they are different....at least to me. Were you diagnosed with AD?