A Man With Stooped Posture and Mysterious Back and Neck Pain

Nirupam Prakash, MD, MBBS

Disclosures

November 19, 2020

The disease usually manifests in patients older than 50 years, and the prevalence increases with advancing age. A prevalence of 25% in men and 15% in women older than 50 years of age as well as 35% and 26%, respectively, in those older than 70 years has been reported.[6,7] In comparison, the incidence of osteoarthritis is 2-7 times higher for each age group.[6] Radiographic evaluation reveals the classic flowing ossification on the anterolateral aspects of the spine. Thoracic vertebrae are involved in 100% of cases, lumbar vertebrae in 68%-90%, and cervical vertebrae in 65%-78%.[8] Occasionally, isolated involvement of the lumbar and cervical spinal segments occurs.

Disease onset is thought to be a decade or so before clinical manifestations, and peripheral enthesopathy may often predate the development of spinal enthesopathy; as a result, the presence of isolated bony spurs in the calcaneus, patella, and olecranon may lead to an early diagnosis of DISH.[9] Diagnostic criteria that are based solely on spinal enthesopathy with the development of characteristic large ossifications may therefore delay the diagnosis. Consequently, many authorities suggest considering the diagnosis of DISH in individuals with peripheral enthesopathies, especially if it is symmetrical, or when hypertrophic osteoarthritic changes are observed at sites atypical for osteoarthritis (eg, shoulder and elbow joints) and recommend developing new diagnostic criteria.[9]

DISH may be infrequently considered and underreported. Additionally, affected individuals may be asymptomatic or present with nonspecific complaints that do not trigger an appropriate workup. However, large osteophytes may present with morbidity. The most common presentation is dorsolumbar back stiffness and pain.

The pathogenesis of DISH is not clearly understood, although causative factors may include hyperinsulinemia (with or without diabetes), hypertension, obesity, dyslipidemia, and hyperuricemia.[10,11,12] Chronic hyperinsulinemia and insulin-like growth factors have been postulated to produce invasion of blood vessels into articular cartilage and differentiation of pluripotent progenitor cells into osteoblasts, thereby promoting calcification and ossification of ligaments and entheseal regions.[10,13] In a small study, investigators found that patients with DISH have a lower pain threshold than those without this disease.[14] Relative to the control group, patients with DISH demonstrated a significant correlation between soft-tissue tenderness scores and the parameters of functional status, BMI, waist circumference, and high-grade T-spine bony bridges.

DISH may be confused with ankylosing spondylitis because of the radiologic and clinical similarities. However, patients with DISH are usually older than 50 years, have metabolic disorders, and exhibit a normal ESR. In contrast, ankylosing spondylitis generally begins in adolescence or young adulthood and is associated with elevated ESR and C-reactive protein (CRP) levels. Classically, patients with DISH do not have sacroiliac or facet joint involvement or intra-articular ankylosis.

Ossification of the anterior longitudinal ligament with a radiolucent line between the new bone and the adjacent vertebral body, in the absence of vertebral squaring, is characteristic of DISH. In contrast, axial involvement in ankylosing spondylitis is characterized by vertebral body squaring, Romanus lesions (focal destructive areas along the anterior margin of the discovertebral junction at the superior and inferior portions of a vertebral body), syndesmophytes, spondylodiscitis, apophyseal joint sclerosis, and ankylosis and sacroiliitis. However, in some cases with exuberant entheseal involvement, sacroiliac capsular bridging described in patients with DISH may give the false impression of obliteration of the sacroiliac joint space, resembling ankylosing spondylitis.[15]

Compared with those with degenerative disc disease, individuals with DISH have well-maintained disc spaces and an absence of vacuum defects, which is suggestive of lumbar spondylosis. In certain individuals, DISH may involve ligamentous insertions of the peripheral joints as well, presenting as pain and stiffness of the involved joint. This clinical picture may mimic primary osteoarthritis. However, its tendency to affect atypical non-weight-bearing joints (eg, shoulder, metacarpophalangeal, and elbow joints); hypertrophic ossification with normal joint space; entheseal calcification (calcaneal spurs, peripatellar and cruciate ligament calcification); and iliolumbar, sacrotuberous, and acetabular ligament calcification may help establish the diagnosis.[9]

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