Musculoskeletal Resear​ch

Nervous 9-year-old Nathan Byrd sits on the exam table, listening intently as his parents exchange information with Lauren Pachman, MD . Then, with an ice-melting smile, Pachman looks at young Nathan, who had traveled to our hos​pital from Comanche, Texas, for treatment of juvenile dermatomyositis (JDM). "You're not alone," she says sympathetically. "I take care of 185 children like you and there are more than 300 across the country."

Dr. Pachman, an internationally recognized pioneer i​n immunology/rheumatology, has a special place in her heart for children with JDM, a rare, often rapidly progressive, disease characterized by acute muscle weakness. It's accompanied by a purple-red rash — typically on the face and hands — swelling and vasculitis, which is an inflammation of the blood vessels.

The vasculitis can cause devastating lesions in the skin, eyes, gastrointestinal tract and myocardium (a layer of heart muscle), which in rare cases can lead to heart block — a rhythm disorder that can cause dizziness, fainting or stroke. A later sign of disease is calcinosis, an abnormal amount of calcium salts in the tissues.

JDM once was fatal in about 33% of cases. Today, thanks to the research and devotion of Dr. Pachman and others, that number has dwindled to 2%. The primary treatment is prednisone, a steroid.

Facilitating National Rese​arch

Dr. Pachman established a diagnosis-based national registry of JDM patients in 1994. Maintained at Lurie Children's and funded by the National Institute of Arthritis and Musculoskeletal Diseases, the registry is facilitating JDM research across the nation. Based on interviews with parents of the 323 patients enrolled, Pachman and her fellow researchers have learned several important factors.

First, the incidence of JDM in the United States is 3.1 cases per million children each year. That rate is about the same whether the child is Caucasian, African-American or Hispanic. Research also revealed that more than 50% of the children had an upper respiratory illness in the months prior to diagnosis.

Interestingly enough, while the rate of JDM doesn't vary with demographics, some symptoms do. For example, African-American children might lose more weight. Children younger than seven have more upper respiratory complaints, which older kids are more likely to complain about muscle pain and weakness.

Dr. Pachman is taking advantage of the newly mapped human genome, looking for genetic markers that indicate a predisposition to JDM. "We already have identified several genetic markers that appear to be associated not only with disease susceptibility, but also the course of the disease and whether the child is at risk for calcifications," Dr. Pachman explains.

While steroids like prednisone are helpful, they have drawbacks. One of them is an adverse effect on bones, including a reduction in bone density.

One way to combat this, says Dr. Pachman's colleague Craig Langman, MD , head of Kidney Diseases at Lurie Children's, is with Vitamin D and calcium. Dr. Langman's clinical practice is closely aligned with his research into bone mineral metabolism in children. On the surface, the link between the kidney and bone is not immediately apparent. However, the kidney is where Vitamin D is activated before the body puts it to use.

Vitamin D helps calcium absorb into the bones and regulates hormones that work on calcium. Without Vitamin D, the calcium is very hard to absorb. One of his team's discoveries is the use of the compound alendronate to treat children with insufficient bone mass development.

"Bone is living tissue that's constantly being built up and broken down," Dr. Langman explains. "Most bone disease in children is a disturbance between the breakdown and the buildup, with the breakdown becoming greater. Alendronate halts the breakdown and accelerates the buildup." Alendronate also has helped in the battle against Jansen's disease, which results in disfigurement and dwarfing.

Children with cancer who must undergo chemotherapy also face the possibility of diminishing bone mass. "Some of the disease and most of the therapies accelerate bone breakdown," Dr. Langman says. "Some cancers produce more of the cells that slows buildup of the bones. Survivors of childhood cancer often develop bone disease within a decade. A lot of chemotherapy agents act as poisons hindering how the kidneys develop Vitamin D."

As with Dr. Pachman, Dr. Langman gets great joy out of seeing his patients improve. "I had a patient with brittle-bone disease come to us all the way from England," he says. "He suffered about 18 fractures a year and was in a wheel chair. Now he has less than a fracture a year is out of the chair. That kind of progress is very gratifying."