The big problem with accupuncture is that it has not been systematically studied in different ethnic populations. In the case of pain relief, accupuncture works because the body, under certain circumstances, cannot transmit more than one pain signal at once. And the body prioritizes pain signals. Thus an injury to the head is prioritized over an injury to the thigh. The tiny needle that goes in does not cause significant damage, but depending on where it goes in the body may perceive there is damage. Orientals have used accupuncture for a thousand years, but the accupuncture points taught by Chinese or Koreans are not necessarily the same as for a European or Mexican. Cutting to the chase this means an accupuncture point that will neutralize pain from Sciatica in a person of Chinese origin may not help at all for a caucasian. This is one reason why the procedure helps some people and others feel no effect. If you look at a book of genetic variations you can see that the veins on the top of the hand form many different patterns depending on the genetic make-up. But these are finite patterns. The accupuncture points vary in the same manner.
I have seen a video of neurosurgeon, Dr. Casey from Michigan who states that acupuncture appears to help some TN patients. I have also read blogs on other sites from people gaining some success with specialized forms of chiropractic.
There is no cure for TN, only pain relief from drugs, surgery, or the alternative methods listed above. Luckily some people get long term pain relief that can last years.