ST. LOUIS – All Tina Allen wants is a doctor like TV’s Dr. House. He’d figure out what’s wrong with her.

She has plenty of symptoms and diagnoses. Her medical records cram a tote bag six inches thick. She’s boiled down the highlights for new doctors into a four-page summary. It starts with a list of 29 symptoms and 26 diagnoses and ends with a plea for a House-like commitment to get to the bottom of what’s wrong.

Allen has a suite of conditions that includes irritable bowel syndrome, fibromyalgia, headaches and pain and tingling in her hands and arms.

Millions of people across the country share at least one of Allen’s conditions, and many battle more than one.

Doctors have been stumped as to why those people are so susceptible.

But researchers now think the ailments may have a common cause. Studies have shown that the brains of people with these conditions may interpret pain signals differently than those of other people.

Doctors have labeled the problems “functional syndromes” because they haven’t found a physical cause for the complaints.

In fact, most patients with combinations of these conditions have been told at least once that the problem is all in their heads. Most of the time patients are referred to specialists and subspecialists to deal with individual sets of symptoms. Patients tend to talk about digestive problems only with their gastroenterologists, saving joint pain, headaches and other problems for other specialists, Mayer said. But patients will report those other problems if asked.

“The way that society and the health care system responds to these disturbances is part of the problem,” said Dr. Emeran Mayer, director of neurovisceral sciences and women’s health at the University of California at Los Angeles.

About eight years ago, Dr. Ray Clouse, a gastroenterologist at Washington University, and his colleagues started asking patients to fill out a form listing about 30 symptoms, only a subset of which included stomach and bowel problems. Patients who had conditions such as Crohn’s disease or ulcers usually would mark only stomach pain and bleeding. But patients with irritable bowel syndrome and related conditions often would tick off nearly all the digestive tract symptoms plus a host of others including trouble sleeping, joint and muscle pain, lower back pain and headaches, Clouse said.

As many as one in five people have irritable bowel syndrome. Between 3 million and 6 million people, most of them women, suffer from fibromyalgia. People with fibromyalgia experience joint and muscle pain, fatigue and multiple tender spots. The tingling and pain in Allen’s hands, a condition known as peripheral neuropathy, affects about 20 million people. About half of patients with one of the ailments also have others, such as chronic fatigue syndrome, tension headaches, restless leg syndrome or multiple chemical sensitivity.

The doctors weren’t the first to note that patients with functional syndromes often have a history of psychiatric conditions such as depression or anxiety.

“That was a big distraction,” Clouse said.

The correlation pushed doctors into two camps: those who believed the syndromes were psychiatric conditions and those who thought they had physical causes. The fact that low doses of antidepressants or talk therapy are often effective in treating irritable bowel syndrome and other functional disorders further complicates the matter, Clouse said.

Brain imaging studies show that the nerves of people with functional syndromes send normal pain signals to the brain. Once those signals reach the brain, though, they are processed in areas involved in emotion, stress and thinking. That processing center appears to be more active in people with functional disorders, suggesting that the interpretation of pain signals, rather than the sensation itself, goes awry in people with the syndromes, Clouse said.

What’s more, the geared-up processing center may rile up the autonomic nervous system, the part of the nervous system that controls automatic responses such as sweating, heartbeat and blood pressure, so it makes the person sweat, causes cramps and triggers pain. Those sensations are sent back to the brain where the whole process repeats, each time rachetting up the patient’s pain and distress, Clouse said.

Clouse and his colleague Dr. Gregory Sayuk, a Washington University gastroenterologist who specializes in irritable bowel syndrome and other functional digestive syndromes, are trying to understand how pain is processed in people with multiple functional syndromes. They have already shown that the pain processing center is more active in people with irritable bowel syndrome than in people without it.

Now they will look at how people such as Tina Allen, who have many functional syndromes, process pain compared with people who have only irritable bowel syndrome and with people who have no syndromes.

Allen, who is 50, made the trip from her home in Kansas City to participate in the study.

“I have believed my whole life that there’s some sort of interference between my GI tract and my brain,” she said. Her test results tell her she’s not crazy. “I have quantifiable evidence of physical processes, so it’s not just psychosomatic.”

Sayuk expects to collect data on 24 volunteers by the end of the summer. It will take months to analyze the results.

More than 100 genes may be involved in making people with functional syndromes more sensitive to pain and stress, said UCLA’s Mayer. As much as 20 percent of the population may carry genes that make them more susceptible to pain, Mayer said. But genes are not the whole story.

People who develop functional syndromes probably have some defect in their central nervous systems, Mayer said. Different events may trigger symptoms in different parts of the body, he said. Some studies have shown that people who get food poisoning are more likely to develop irritable bowel syndrome. Other things may trigger restless leg syndrome or pelvic pain or jaw pain.

Mayer predicts that within five years scientists will finally understand what drives functional syndromes. Finding treatments will probably take longer, but at least Allen and others may finally know what is wrong with them.

Overlapping syndromes

Dr. Muhammad B. Yunus, a rheumatologist at the University of Illinois College of Medicine at Peoria, is a leading proponent of the theory that functional syndromes are caused by a pain processing defect in the brain. The disorders are more common in women than in men. The overlapping syndromes include:

• Fibromyalgia syndrome – chronic pain in the muscles, tendons and ligaments coupled with fatigue and multiple tender points on the body

• Chronic fatigue syndrome

• Post-traumatic stress disorder

• Female urethral syndrome and interstitial cystitis (painful bladder syndrome)

• Multiple chemical sensitivity

• Primary dysmenorrhea (painful menstrual cramps)

• Periodic limb movements in sleep

• Restless legs syndrome

• Myofacial pain syndrome

• Temporomandibular joint disorders

• Tension-type headaches

• Migraine

• Irritable bowel syndrome, including functional dyspepsia

• Gulf War syndrome appears to be a combination of several of these syndromes.

• Others group low back pain with these syndromes.