Editor's note: This popular story from the Daily Briefing's archives was republished on Jul. 26, 2023.

When a 56-year-old woman started experiencing "excruciating leg pain," her doctors could not determine the cause of her symptoms—until a rheumatologist discovered a link between her leg pain and severe asthma, ultimately leading to a diagnosis, Lisa Sanders writes for the New York Times Magazine.

'Struggling mightily' with 'excruciating leg pain'

When a 56-year-old woman started experiencing severe leg pain, she sought advice from her friends and loved ones on Facebook. "I've been struggling mightily for the past few weeks with sciatica, which is excruciating leg pain caused by a pinched or irritated nerve," she wrote. "Any suggestions out there from people who have gone through this?"

"It hurt to stand; it hurt even more to sit — the weight of her body was torture on her thighs," Sanders writes. "The only times she was mostly pain free were when she was lying down and when she was walking."

Until she was 50 years old, the woman had always been healthy. Then, she was diagnosed with colon cancer. Four years after she recovered, she suddenly developed severe asthma. While her pulmonologist helped her manage the condition, she had not felt well since.

"It was as if she had crossed some threshold," Sanders writes. "She got these strange bouts of aches and pains, occasional numbness and weakness that lasted for days. Lymph nodes blew up to a painful size, then disappeared. Now this terrible leg pain. Strangely, her back didn't hurt at all, but her legs, especially the left, were killing her."

She saw her doctor, who prescribed a muscle relaxer, and her chiropractor, who adjusted her back—but nothing had provided any relief.

Within a few hours of posting on Facebook, the woman received more than 60 replies. One of her Facebook friends told her to visit her husband, who was a physical therapist. She told the woman that her husband would be able to tell right away whether she needed an MRI or if physical therapy (PT) would be sufficient.

After following a PT regimen, the patient saw no improvement in her pain—and they determined that she needed an MRI—but the MRI did not reveal a diagnosis.

"The sciatic nerve is the largest nerve in the body, and the irritation of that nerve that causes the pain better known as sciatica is usually a result of pressure from the bony spinal column," Sanders writes. "Those points can often be seen on an M.R.I. But not, as it turned out, on her M.R.I."

'Do any of these symptoms seem familiar?'

Three days later, the woman went to see Dustin Nowacek, a neurologist at Bronson Methodist Hospital. When Nowacek tested the patient's reflexes and sensation in her legs and feet, everything seemed normal—"until he pricked the top of her left foot," Sanders writes. "There she felt nothing."

Nowacek soon determined that the woman's nerve injury was likely the result of an infection. He ordered blood tests to rule out Lyme disease, HIV, hepatitis, thyroid conditions, and autoimmune diseases, most of which came back normal.

The only abnormality detected in her blood tests suggested that the woman could have an autoimmune disease—but Nowacek was not sure which one.

Then, Nowacek referred the patient to Lakshmi Kocharla, a rheumatologist in his practice.

To narrow the possible diagnoses, Kocharla asked the patient to describe her symptoms. As the patient explained her medical history, Kocharla took note of the woman's sudden asthma diagnosis.

"Hang on a second," Kocharla said, after hearing about her asthma. She passed her computer to the patient and asked her to review a list of symptoms. "Do any of these symptoms seem familiar?" she asked.

The patient noted that she had experienced fatigue, weight loss, swollen lymph nodes, and muscle pain. In addition, she had asthma and numbness and weakness in her left foot and right toe.

"I think you have something called eosinophilic granulomatosis with polyangiitis [EGPA]," Kocharla said.

According to Sanders, this condition "is linked to an elevated level of white blood cells called eosinophils — the cells that respond in allergic reactions."

"Somehow these cells become involved in the destruction of small blood vessels all over the body," Sanders writes. "That's what causes the numbness and the loss of strength and reflexes. These cells can lead an attack on blood vessels anywhere in the body." While it is unclear what triggers EGPA, the condition is a destructive—and sometimes deadly—disease.

To help confirm the patient's diagnosis, Korcharla tested her blood and found that the woman's eosinophil count was eight times higher than it should have been.

A biopsy is required to officially confirm an EGPA diagnosis, but that could have permanently damaged the woman's already-injured nerve, Sanders notes.

While the woman fit the diagnostic criteria, Kocharla sent the woman's results to the Mayo Clinic to confirm her diagnosis. In the meantime, she started the patient on a high dose of prednisone to treat her symptoms.

The rheumatologist at the Mayo Clinic had extensive experience with EGPA and agreed with Kocharla's diagnosis. They prescribed a second immune-suppressing medication to further treat the condition.

'She has never felt healthier'

After the patient started taking the medication, her pain disappeared. "She could sit and stand. The level of eosinophils dropped to normal. She could go back to work," Sanders writes.

When the patient started researching EGPA, one article suggested that walking can help control it. Now, she walks six to seven miles a day, on average. "It has allowed her doctors to lower her medication doses, and she says that even though she is sick — in a very real way sicker than she has ever been — she has never felt healthier," Sanders writes. (Sanders, New York Times Magazine, 1/12)