DISH, or Diffuse Idiopathic Skeletal Hyperostosis, is characterized by the abnormal formation of new bone tissue (ossification) in the body’s ligaments and tendons, primarily affecting the spine. This process stiffens the soft tissues where they attach to the skeleton. DISH is also referred to as Forestier’s disease. Although considered a type of arthritis, it is distinctly non-inflammatory, separating it from autoimmune diseases like rheumatoid arthritis. While ossification can occur throughout the skeleton, it most commonly begins along the front of the vertebral column in the thoracic spine.
Recognizing the Symptoms
The earliest and most common manifestations of DISH typically involve stiffness and a general reduction in the range of motion, particularly in the middle and upper back. This spinal stiffness is often most noticeable in the morning or following periods of prolonged inactivity. Patients may experience a dull, persistent pain, which is usually localized to the affected areas of the spine.
Many individuals with Diffuse Idiopathic Skeletal Hyperostosis, however, remain entirely without symptoms, and the condition is only discovered incidentally during imaging for an unrelated issue. When symptoms do occur, they are a direct result of the progressive bony overgrowth. Ossification extending outside the spine can also cause pain and stiffness in peripheral joints like the shoulders, hips, and knees where tendons and ligaments attach to the bone.
A more serious complication arises when ossification occurs in the cervical spine. Large bony growths (osteophytes) that extend forward from the vertebrae can press against the esophagus. This compression can lead to dysphagia (difficulty swallowing) or a change in voice. In rare, severe cases, the bony mass can impinge on the airway, potentially causing breathing difficulties or obstructive sleep apnea.
Understanding the Causes and Risk Factors
The term “idiopathic” in the condition’s name indicates that the exact underlying cause of DISH remains unknown. Current research suggests the disease is not caused by typical wear-and-tear or inflammation, but instead involves an abnormal tendency for the body to form bone in soft tissues. This bone formation is thought to be driven by an excessive amount of growth factors, such as insulin and insulin-like growth factor-1.
A strong connection exists between DISH and metabolic disorders, making this a significant area of focus for research. The condition is tightly associated with Metabolic Syndrome, a cluster of conditions that includes obesity, high blood pressure (hypertension), and elevated cholesterol or insulin levels. Specifically, individuals with Type 2 Diabetes Mellitus are at a statistically higher risk of developing Diffuse Idiopathic Skeletal Hyperostosis.
Demographic factors also play a substantial role in susceptibility to the condition. DISH is most prevalent in older populations, with rates increasing significantly after the age of 50. Men are diagnosed with the condition approximately twice as often as women. The combination of advanced age, male gender, and the presence of metabolic conditions are the most consistent predictors of developing the characteristic bony overgrowth of DISH.
Diagnosis and Differential Considerations
The definitive diagnosis of Diffuse Idiopathic Skeletal Hyperostosis relies on specific evidence gathered through medical imaging, primarily X-rays. Physicians use a set of established criteria, most commonly the modified Resnick and Niwayama criteria, to confirm the condition. The hallmark radiographic finding is the presence of “flowing ossification” along the anterolateral side of the spine, which resembles melted candle wax dripping down the front of the vertebral column.
For a formal diagnosis based on these criteria, the flowing calcification must span and bridge the gap between at least four contiguous vertebral bodies. Crucially, the intervertebral disc spaces in the affected regions must be relatively preserved, meaning they do not show significant degenerative collapse. This preservation helps distinguish DISH from typical degenerative disc disease.
The diagnosis also requires the absence of bony fusion in the small joints of the spine, specifically the facet and sacroiliac joints. This absence is key to ruling out Ankylosing Spondylitis (AS), an inflammatory form of arthritis that fuses these particular joints. Ruling out other conditions that cause spinal stiffness, such as severe osteoarthritis, is necessary for an accurate diagnosis. The thoracic spine is the most common location for ossification, often sparing the left side due to the protective pulsation of the nearby aorta.
Treatment and Management Strategies
Since the bony overgrowth associated with DISH cannot typically be reversed, treatment focuses on managing symptoms, maintaining mobility, and preventing complications. Non-surgical management is the primary approach for most patients. This includes the use of nonsteroidal anti-inflammatory drugs (NSAIDs) or other analgesics to control pain and discomfort.
Physical therapy is a fundamental component of the management plan, aiming to preserve the spine’s flexibility and range of motion. A tailored exercise program helps strengthen surrounding muscles and mitigate the stiffness caused by the ossification. Given the strong link between DISH and metabolic dysfunction, controlling blood sugar levels and addressing obesity are important strategies to potentially slow the disease’s progression.
Surgical intervention is reserved for cases where the bony formation leads to severe complications that do not respond to conservative measures. For example, surgery may be necessary to shave down large osteophytes in the cervical spine causing severe, progressive difficulty swallowing or breathing. Surgery is also sometimes required to stabilize the spine following a fracture, which can occur even after minor trauma due to the spine’s increased rigidity.