The pain woke the 52-year-old physician from a dead sleep. It was as if all the muscles in his right leg, from those in the buttock down his thigh to the very bottom of his calf, were on fire. He shifted slightly to see if he could find a more comfortable position. There was a jag of pain, and he almost cried out. He glanced at the clock: 4 a.m. In just three hours he would have to get up. He had a full day of patients to see. Massage didn’t help. He couldn’t get comfortable lying flat, so finally he moved to the living room, to a recliner. Only then, and only by lying completely still, did he manage to get the pain to abate. He drifted off, but never for long. The searing pain in his leg and buttock slowly eased, and by the time his alarm went off, he could stand and walk — though his muscles still ached and he had to baby his right leg, causing a limp.

Between patients, he arranged to see his own doctor. He’d had pain off and on in his buttocks, one side or the other, for more than a year. The pain was in the middle of each cheek and was worse when he was sitting and at the end of the day. Walking to and from his car on the way home was brutal. And then, as mysteriously as it came, it would disappear — only to come back a week or two later.

When he first told his doctor about his pain, the exam didn’t show much. He was a little tender at the bottom of the bones you sit on, called the ischia. His doctor thought it was ischial bursitis. Between the tips of the ischia and the largest muscles of the buttocks, there are little pads called bursae. Sometimes these pads become inflamed. The man’s doctor recommended stretching exercises for the muscles around the bursae. He did them regularly, though he wasn’t sure they helped.

The pain he had that night, though, was different, and a whole lot worse. Again, his doctor couldn’t find much. Maybe it was a kind of nerve pain, like sciatica, the patient suggested. The doctor agreed and ordered an M.R.I. to look for a pinched nerve. The result was normal.

The acute pain went away after a few days, but the old pain, the usual pain, came and went with depressing regularity. Ibuprofen or naproxen helped but irritated his stomach. His primary-care doctor put him on Celebrex, which is easier on the gut. The medications, along with a cushion that he now had to carry with him everywhere, got him through the worst of the attacks. Every now and then, he would try a new specialist to see if anyone had anything new to offer. He saw a physical-medicine doctor, a neurologist, a pain specialist and finally an integrative-medicine doctor. They ordered imaging, physical therapy, massage therapy, injections, pills. He stopped his statin. He started yoga. Nothing really seemed to help much. So he stuck with his Celebrex and his cushion and his regular trips to the gym. He wasn’t getting better, but he wasn’t any worse either. The nighttime attacks of terrible pain were thankfully rare.

The doctor suffered for nearly a decade. Finally he found an answer and a treatment. But it didn’t come through any of the experts he saw for his pain.

Credit…Illustration by Ina Jang

When the physician turned 60, he scheduled a colonoscopy, a recommended test to screen asymptomatic individuals over 50 for colon cancer. He had one at 50; it was completely normal. When it was time for his next exam, the doctor who did it the first time had retired, so he asked a friend, Dr. Erick Chan, a gastroenterologist, to perform the test.

He was still a little foggy from the anesthesia when Chan came by with what the physician assumed would be the usual report of normal results. He was wrong. “I took some biopsies, and we’ll wait to see what they show,” Chan said. “But I have to tell you, it didn’t look normal.” The test had been routine until Chan got close to the spot where the colon and the small intestine connect, a structure known as the ileocecal valve. Chan noticed that the valve looked a little asymmetric.

It was his usual practice, when possible, to extend his evaluation beyond the colon into the last section of the ileum, the tail end of the small intestine. Most gastroenterologists limit their screening examinations of healthy, asymptomatic patients to the colon. The ileum is not scoped during a routine screening because doing so takes more time and because the chance of finding something significant is small. But Chan had been trained by a doctor who specialized in inflammatory bowel diseases like Crohn’s disease and ulcerative colitis. A simple colonoscopy will reveal ulcerative colitis, when present. But only half of those with Crohn’s disease will have evidence of it in their colons. The chance of making that diagnosis goes up markedly when the terminal ileum is included.

As Chan advanced his scope, he could see that the valve was distorted by scar tissue — so much so that the connection was too narrow for his instrument to enter. Bringing his scope as close to the opening as he could, he saw that the tissue on the other side was an angry red and dotted with ulcers. They would have to wait for the biopsies to come back, but Chan suspected Crohn’s disease. That’s impossible, the man responded. He had no G.I. symptoms at all. No pain, no diarrhea, no blood in his stools. How could he possibly have Crohn’s?

Crohn’s disease is an autoimmune disorder in which antibodies, the body’s chief defense against infection, mistakenly attack the digestive tract as if it were a foreign invader. Although it can affect the G.I. tract anywhere, it is most frequently found in the terminal ileum. Most patients with Crohn’s will have pain and diarrhea — but not all. In studies of patients with known Crohn’s disease, one in six will have no symptoms at all.

The biopsy results came back consistent with Crohn’s. So did blood tests designed to help diagnose inflammatory bowel disease. But it wasn’t the diseased bowel that was giving the man the pain in his buttocks. It was an associated disorder, a type of arthritis known as sacroiliitis — an inflammation of the joint between the pelvic girdle and the sacrum, the triangular bone that forms the connection between the hips. Although the reason this happens is not well understood, it appears that some of the immune cells misdirected to attack the gut can also attack the joints. Up to 39 percent of patients with an inflammatory bowel disease develop arthritis in some form. And up to 20 percent will develop the arthritis before getting the bowel disease. In this patient’s case, it’s hard to know which came first, because the bowel disease was discovered almost by accident.

Because Crohn’s is usually painful and is associated with complications including bowel perforation, anemia and malnutrition, patients are usually treated with medications to calm down the immune system and reduce the inflammation. These are powerful drugs that suppress the immune system. They are very effective at controlling the pain and destruction but can leave a patient open to infection. Because of that, it’s less clear how to treat patients with asymptomatic disease. For those with no pain and no signs of inflammation, watchful waiting is a common strategy.

The same type of medications are used to treat the arthritis associated with inflammatory bowel disease. The physician wasn’t sure if it made sense for him to use an immune-suppressing medicine while seeing sick patients. His rheumatologist, seeing him put the pad on his seat before gently lowering himself onto the chair, was much less uncertain. She had put many people on these medications, she told him — some of them doctors. Most did fine. He agreed to start taking it. The effect was immediate and amazing. His pain — a regular visitor for nearly a decade — is gone. Even at the end of the day, his walk to and from his car is painless. He still uses the pad at times; those bones are still a little tender. But the rest of him feels great.