Diffuse idiopathic skeletal hyperostosis (DISH) is a tendency for ossification of ligaments, tendons and joint capsule insertions, most often affecting the spine. Calcification of the longitudinal ligaments (particularly anterior) can often produce the radiological appearance of ‘wax dripping from a candle’, distinct from the vertebral bodies.
The thoracic spine is mainly affected but it can also affect the lumbar and cervical spine, and other areas of the skeleton.
The tendon/osseous junctions are occasionally affected around the elbow, patella, calcaneus, hip and knee joints. The cause is unknown.
Pathological features of spinal DISH include 5:
- focal and diffuse calcification and ossification of the anterior longitudinal ligament
- paraspinal connective tissue and annulus fibrosis
- degeneration in the peripheral annulus fibrosis fibers
- anterolateral extensions of fibrous tissue
- chronic inflammatory cellular infiltration
- periosteal new bone formation on the anterior surface of the vertebral bodies
The cervical and thoracic (particularly T7-11 5) spine in particular are affected.
The prevalence may be as high as 28%. Elderly men are most commonly affected.
it is uncommon in patients younger than 50 years and rare in patients younger than 40 years.
Most often, it affects the thoracic spine, especially on the right side.
- florid, flowing ossification is noted along the anterior or right 7 anterolateral aspects of at least four contiguous
- vertebrae, so-called flowing ossifications
- disc spaces are usually well preserved
- ankylosis is more commonly seen in the thoracic than in the cervical or lumbar spine.
- frequently incomplete
- can have interdigitating areas of protruding disk material in the flowing ossifications
- no sacroiliitis or facet joint ankylosis
Enthesopathy of the iliac crest, ischial tuberosities, and greater trochanters and spur formation in the appendicular skeleton (olecranon, calcaneum) are frequently present
- acute spinal fractures
- rarely dysphagia 8
- Clinical features vary from monoarticular synovitis to dysphagia and even airway obstruction.
- Is often asymptomatic and discovered by chance on X-rays or CT/MRI scans.
- Symptoms may include pain, stiffness and restricted movements of the affected areas.
- Osteophytes may rarely cause symptoms by mechanical compression or by causing an inflammatory reaction.
When an upper segment of the cervical spine is involved, particular at the C3-C4 level, the larynx may be affected. This could be result of hoarseness, stridor, laryngeal stenosis and obstruction.
Sometimes vocal fold paralysis may result from injury to the recurrent laryngeal nerve.