Learn About Ankylosing Spondylitis Or Diffuse Idiopathic Skeletal Hyperostosis Differences

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Ankylosing Spondylitis

Ankylosing spondylitis, also known as AS, is a type of arthritis or chronic inflammation mainly affecting the spine, but it can affect other joints as well. The most common locations, according to MedicineNet, are in the spine and sacroiliac joints, which are in the low back just above the tailbone. As the disease progresses, fusion of the vertebrae can occur causing immobility of the spine. In addition, AS is a systemic disease which can affect any tissue or organ in the body.

AS is considered an inherited disease with the presence of the HLA-B27 gene. While all ages can be affected, the most common group consists of individuals in their twenties and thirties. AS occurs when the body’s immune system attacks itself. Possible symptoms of AS include fatigue, pain, stiffness and difficulty breathing, if the area where the ribs attach to the spine is affected.

What is Diffuse Idiopathic Skeletal Hyperostosis?

Diffuse idiopathic skeletal hyperostosis, or DISH, is considered a type of osteoarthritis that doesn’t show any wear and tear, and may be present with no symptoms. According to Spine University, DISH occurs most often between ages 50 and 60, with more cases reported in men than women. The most common ligament affected is the anterior longitudinal ligament on the front of the spine.

When symptoms do appear, stiffness and a reduced range of motion are the most common, particularly when bending sideways. With DISH, extra bone growth or bone spurs can develop. Possible symptoms of bone spurs include: difficulty swallowing, if the bone spur occurs near the esophagus; or numbness, if the spur puts pressure on the spinal cord.

Diagnostic Testing

Whether testing for ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis, your doctor will begin with a complete physical examination. This includes locating any painful areas, especially related to your spine and joints. Blood tests to define or rule out other disease processes may be done.

In evaluating for DISH, the Mayo Clinic recommends X-rays, computerized tomography (CT) and magnetic resonance imaging (MRI) be used as diagnostic tools. An X-ray may show the characteristic distinction of calcification along the spine, and an MRI or CT is particularly helpful in determining if a condition is AS or DISH.


There is no known cure for ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis, so treatment depends on the level of pain and involvement of the disease. Pain control for DISH includes acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, or corticosteroid injections for severe pain. Physical therapy may be an option for the stiffness related to DISH.

Medications used to treat AS include NSAIDs, disease modifying anti-rheumatic drugs and TNF Blockers. Exercise, posture management and the use of heat or cold compresses are conservative treatment measures. In severe cases of AS, surgery, such as joint replacements, may be necessary for relief of symptoms.


MedicineNet: Ankylosing Spondylitis https://www.medicinenet.com/ankylosing_spondylitis/article.htm

Spine University: Diffuse Idiopathic Skeletal Hyperostosis https://www.spineuniversity.com/diffuse_idiopathic_skeletal_hyperostosis

Mayo Clinic: Tests for Diffuse Idiopathic Skeletal Hyperostosis https://www.mayoclinic.com/health/diffuse-idiopathic-skeletal-hyperostosis/DS00740/DSECTION=tests-and-diagnosis

Spondylitis Association of America: Ankylosing Spondylitis Treatment https://www.spondylitis.org/about/treatment.aspx