Management of DISH on Lumbar Spine X-ray in Adults Over 50
When DISH is identified on lumbar spine x-ray in an older adult, the primary management priority is to obtain DXA scanning of both the lumbar spine and bilateral hips to accurately assess bone mineral density, because DISH causes spuriously elevated BMD readings on lumbar spine DXA that can mask underlying osteoporosis. 1
Why DXA is Critical Despite the DISH Finding
DISH is a recognized artifact that falsely elevates lumbar spine BMD measurements on DXA, making it one of the most common causes (>81%) of spuriously elevated readings in older adults. 1
The projectional nature of DXA means that ossification of the anterior longitudinal ligament and extraspinal ligaments in DISH will artificially increase bone density measurements, potentially masking true osteoporosis that requires treatment. 1
Quantitative CT (QCT) of the lumbar spine and hip is rated as "usually appropriate" (rating 8/9) for initial osteoporosis assessment in patients with advanced degenerative changes like DISH, while standard DXA lumbar spine and hip receives a rating of 7/9 in this specific population. 1
Optimal Imaging Strategy
Order QCT of the lumbar spine and hips as the preferred modality when DISH is present, as it measures true volumetric trabecular bone density without interference from anterior ligamentous ossification. 1
If QCT is unavailable, obtain DXA of bilateral hips and distal forearm (both rated 7/9), deliberately excluding the lumbar spine from diagnostic interpretation due to the DISH artifact. 1
The ISCD specifically recommends close inspection of DXA images and exclusion of vertebral levels affected by DISH, as these cannot provide accurate BMD assessment. 1
Additional Vertebral Fracture Assessment
**Add vertebral fracture assessment (VFA) during the same DXA session if the patient has a T-score <-1.0 at any measurable site** and meets any of these criteria: age ≥70 years (women) or ≥80 years (men), historical height loss >4 cm, self-reported prior vertebral fracture, or glucocorticoid use ≥5 mg prednisone daily for ≥3 months. 1, 2
VFA is particularly important in DISH patients because they have increased risk of grossly unstable spine fractures after minor trauma, and vertebral fractures may be masked by the extensive ossification on standard radiographs. 3, 4
Symptomatic Management of DISH Itself
Treat pain and stiffness symptomatically with NSAIDs, physical therapy, and lifestyle modifications, as no specific disease-modifying therapy exists for DISH. 5, 6
Address associated metabolic conditions aggressively: DISH patients have significantly higher body mass index, higher rates of diabetes mellitus, hyperinsulinemia, hyperlipidemia, hyperuricemia, and hypertension compared to controls. 7, 5, 6
Screen for and manage dysphagia if the patient reports swallowing difficulties, as cervical DISH can cause anterior esophageal compression; this occurs more commonly than generally recognized. 3, 7
Critical Pitfalls to Avoid
Never rely solely on lumbar spine DXA T-scores in patients with DISH – the readings will be falsely reassuring and may delay diagnosis and treatment of true osteoporosis. 1
Do not exclude vertebrae from DXA analysis based solely on a T-score difference ≥1.0 between adjacent vertebrae without visual inspection, as this may represent DISH affecting one level more than another. 1
Recognize that DISH patients may have both spuriously elevated lumbar BMD AND true osteoporosis at other skeletal sites, requiring hip and/or forearm assessment for accurate diagnosis. 1
Do not assume DISH is asymptomatic – 40.4% of individuals with DISH in one study had significant musculoskeletal disability comparable to patients with lumbar spondylosis. 7
Monitoring Strategy
If osteoporosis is diagnosed at hip or forearm sites, repeat DXA (or QCT) in 1-2 years to monitor treatment response, using the same modality and, ideally, the same machine. 8, 2
Routine radiographic surveillance of DISH progression is not recommended, as there is no evidence supporting this practice and it exposes patients to unnecessary radiation. 1
Target plain radiographs only for evaluation of new, atypical musculoskeletal pain that might indicate complications such as vertebral fracture or spinal cord compression. 1, 3