I have had this disease for 11 years now. Only age 40 when I got it. I have researched it for many years and I've read that there have been cases in newborns. It is where the blood vessels wrap around or touch the Trigeminal Nerve causing it to send a pain signal. It's a horrible disease. Tho I've heard of the most promising treatment as Stereotactic Radiosurgery done with the help of a Neurosurgeon and an Oncologist... If it is classic TN; this one time treatment works. But if there are a-typical facial pain involved it will not. And, an MVD can lead to a far worse disease with no cure, Anesthesia Dolorosa. This is what I have after having the MVD. Sadly I was suckered into having this surgery by one doc; after six or more said, NO. Just keep doctor hunting and eventually one will do it. He never even mentioned this as a possible side effect. I just signed papers saying that I could have continued pain, etc...
I don't know about being born with TN. But I am aware of children as young as 3 years old being diagnosed with it.