Meeting Management Challenges in axSpA

Axial Juvenile Spondyloarthritis

Dr. Weiss

Pamela Weiss, MD, clinical research director of the Rheumatology Division at Children’s Hospital of Philadelphia, reviewed some of the subtleties and challenges in axial juvenile spondyloarthritis (axJSpA).

It’s helpful to think of axJSpA as having a rule of 20, she said. About 20% of SpA is juvenile onset, about 20% of juvenile idiopathic arthritis (JIA) is JSpA, about 20% of JSpA cases involve axial disease, and about 20% of JSpA cases fail to achieve remission within five years.

Dr. Weiss cautioned that, when reading pediatric MRI images of the sacroiliac joint, a bright signal often does not indicate disease; the maturing SI joint tends to appear this way. A handy way to tell the difference, she said, is that if it looks like the whiteness around the edge of the joint could have been neatly drawn in with a Sharpie pen, “it’s probably just maturational signal.”

AxJSpA classification criteria published last year include seven domains with two or three levels in each domain, scored on a scale of 100, with 55 the threshold for a diagnosis.² MRI findings are given the most weight in the scoring, and an online calculator is available, Dr. Weiss said.³

Key differences between the juvenile and the adult criteria are that back, hip or groin pain can satisfy the requirements for juveniles, but only back pain is relevant in the adult criteria because young people can often have different ways of describing their pain, she said. Also, among juveniles, both imaging and clinical criteria must be met, rather than either one for adults.

Treatment options are much more limited for the JSpA population, Dr. Weiss noted. Research has also found that juvenile onset of axSpA tends to lead to fewer functional issues with the spine as people age, compared with adult-onset disease, but more hip functional issues compared with adult-onset disease.⁴

Mimics of axSpA

Dr. Gensler

Lianne Gensler, MD, director of the University of California, San Francisco Ankylosing Spondylitis Clinic, drew attention to the many mimics that can initially appear to be possible axSpA.

Pregnancy is an important contributor to mimics of sacroiliitis, Dr. Gensler said. Women can have bone marrow edema from stress fractures during pregnancy that can persist for a year after they’ve given birth, but it might appear to be sacroiliitis. Low-dose computed tomography scans can provide additional clarity that can be highly useful. “Just interpret those [imaging] results with caution because it may be sacroiliitis, but it could also just be the pregnancy-related changes,” she noted. Osteitis condensans ilii and degenerative disease are two axSpA mimics that can be brought on by pregnancy.