That's a good question. The question is, what % are diagnosed with TMS, not what % actually have it.
Since the TMS docs don't all talk to each other, and Dr. Sarno was so protective of his patients, it's impossible to know. But I'll take a guess and say that 80% of the back pain sufferers get diagnosed with TMS, but that 99.9% of them actually have TMS. In my experience 2 people were diagnosed with TMS by 2 different TMS docs as having a real structural spinal problem, but they had TMS and healed nicely.
So the rule of thumb is to error on the side of caution, which makes professional sense. The TMS docs are brave men and "woman." They stick their necks out every day to go against the status quo to say, "no...this is not physical...this is emotional." That takes great courage. If they're wrong they face hellfire all around.
But of course the bigger source of confusion will always be generated in the person's beliefs. This is most evident in the placebo trials, whether in the shoulder, knee, or even the vertebroplasty fiasco. Those people who have had "successful" back surgery could simply be responding to their deeper belief that it actually worked, and may have never needed it. We may never know, but for certain, all the new evidence is pointing toward the fact that surgery isn't doing anything. But, of course there will be rare times when the structure many need repaired, odd things do happen. But I would hazard a guess to say that there are still many folks being operated on that have TMS.
Dr. Hoffman has an interesting response when the person wants the TMS diagnosis. He's replied, "what difference does it make if I give it to you?...you're still the one that has to decide if you have TMS or not." Good point, only the person can ultimately decide if they have TMS, the physician can only clear you of existing potential dangers. YOU are the one and only one that can decide if you have TMS.
You certainly can't have both TMS and a structural problem, Dr. Sarno would go ballistic if he heard that.