Why did mainstream medicine largely reject Dr. John Sarno’s theories despite many patient success stories?

If you have lived with chronic back pain, you may already know the name Dr. John Sarno.

Perhaps you have read his books. Perhaps you have heard dozens of stories from people who say they recovered after accepting his diagnosis of Tension Myositis Syndrome (TMS).

Despite these success stories, mainstream medicine largely rejected his theories during his lifetime. Why?