Back-to-back: The co-occurrence of DISH and ankylosing spondylitis from early modern Poland.

OBJECTIVE: This case study evaluates an individual with skeletal changes consistent with DISH and ankylosing spondylitis. We present here an evaluation of the individual's pathological skeletal changes and a review of the potential diagnoses. Finally, we offer a differential diagnosis of co-morbidity infrequently found in the paleopathological record. MATERIALS: The skeletal remains of a male, aged 50 + years from the early modern Polish (17th-18th century CE) site of Drawsko 1. METHODS: Skeletal remains were examined for the presence of spondyloarthropathies. RESULTS: The individual presented with anterolateral fusion of the vertebral bodies of T6-T10 with a "dripping candle wax" appearance, fusion of the right costovertebral joint at rib 8, fusion of the left apophyseal joints of T8-T10, and the calcification of the supraspinous ligament at T3-T4. The left sacroiliac joint shows intra-articular and para-articular fusion; the right has bony changes consistent with ongoing fusion. Entheseal reactions were noted on the left clavicle, scapulae, first metacarpals, ulnae, and humerii. Diffuse idiopathic skeletal hyperostosis (DISH), ankylosing spondylitis (AS), reactive arthritis (RA), psoriatic arthritis (PA), and enteropathic arthritis (EA) are considered as differential diagnoses. CONCLUSIONS: Based on the skeletal pattern of involvement, the individual suffered from both DISH and AS, which has previously been reported once in the paleopathological literature since 1950. The clinical literature indicates that co-occurrence of these two conditions is possible, with approximately 40 individuals affected. SIGNIFICANCE: This case study is significant for demonstrating the co-occurrence of DISH and AS in the paleopathological record. Additionally, this case contributes to the understanding of heterogenous frailty and syndemics. LIMITATIONS: No radiographs were taken to confirm the differential diagnosis. No aDNA analysis was conducted. SUGGESTIONS FOR FURTHER RESEARCH: The remains have been reburied; no further analysis is possible.

A case of diffuse idiopathic hyperostosis of bone (DISH) in a patient on hemodialysis.

Diffuse idiopathic skeletal hyperostosis (DISH) is a noninflammatory progressive disease resulting in ossification of the anterior longitudinal ligament of the spine and tendons. Herein, we describe a case of DISH in a patient on long-term hemodialysis. The patient was a 79-year-old man undergoing hemodialysis for chronic kidney disease due to diabetic nephropathy. He presented to the emergency department complaining of back pain after a slip and fall. Radiographs revealed bamboo spine-like findings, extending from the cervical to the lumbar spine. Computed tomography and magnetic resonance imaging revealed a compression fracture of thoracic vertebra 12, with abnormal ossification of the anterior longitudinal ligament. Inter-vertebral vertical osseous bridges were also observed at the cervical 7 and lumbar 2 vertebrae. There was no obvious spinal cord compression. Leukocytosis and C-reactive protein levels were not elevated and the human leukocyte type antigen HLA-B27 test was negative. Based on this finding, a diagnosis of DISH was made. In the absence of neurological findings, the patient was treated conservatively. Our findings show an overlap between the clinical features of DISH and those of hemodialysis patients, including older age, male sex, and diabetes.

The role of diffuse idiopathic skeletal hyperostosis (DISH) in positive identification.

The use of skeletal pathologies in establishing positive identifications via radiographic comparison is often avoided-and thus understudied-due to the dynamic nature of the skeleton in response to pathological conditions. Using an online survey, this study tests the accuracy of diffuse idiopathic skeletal hyperostosis (DISH), a relatively common vertebral pathology, in making positive identifications through radiographic comparison. Three digital radiographic images from 51 DISH-positive individuals were obtained from the Boston Medical Center: one image taken at a baseline date (Group A), one image taken within 2 years from baseline (Group B), and one image taken greater than 4.5 years from baseline (Group C). Survey participants were tasked with comparing between simulated lateral "antemortem" and "postmortem" images from living patients and identifying which pair represented the same individual at different time intervals. A total of 40 responses were recorded and analyzed by measuring accuracies, sensitivities, and specificities. Information about survey participants' field, degree, experience working with radiographs, and familiarity with DISH was also recorded. Series 1 compared Group A to Group B images and resulted in an accuracy of 87.3%, sensitivity of 46.9%, and specificity of 94.3%. Series 2 compared Group A to Group C images and resulted in an accuracy of 83.4%, sensitivity of 34.3%, and specificity of 95.8%. The results indicate that the progressive changes associated with DISH render the condition unreliable for making positive identifications but suggest that DISH could be used to winnow potential matches.

Case Report: Identifying Andersson-Like Lesions in Diffuse Idiopathic Skeletal Hyperostosis.

Andersson lesions (ALs) in ankylosing spondylitis (AS) pose a severe risk to the stability of ankylosed spine, which might result in significant deterioration of spinal cord function after traumatic or inflammatory causes. Herein, erosive discovertebral lesions in diffuse idiopathic skeletal hyperostosis (DISH) presented important clinical similarities to AL in AS, but failed to completely recognize unstable spinal lesions. Therefore, we pioneered to identify spinal discovertebral lesions similar to Andersson-like lesions (ALLs) in DISH, followed by the characterization and summarization of the etiology, radiology, laboratory results, clinical symptoms, and treatment strategies for AL in AS with ALL in DISH. By characterizing the ALL in DISH cases, we showed that the ALL was mainly traumatic and established at the junction of focal stress between two adjacent ossified level arms. Erosive discovertebral ALLs were formed after trivial stress of direct impact and could be subdivided into transdiscal, transvertebral, and discovertebral types radiologically. Patients who presented with ALL frequently suffered from consistent back pain clinically and experienced a decrease in motion ability that could reflect skeletal stability, which received treatment effectiveness after conservative external spinal immobilization or further surgical internal fixation, indicating the significance of recognizing ALL in the ankylosed DISH spine to further maintain spinal stability in order to prevent catastrophic neurologic sequelae. Our work highlighted the clinical relevance of ALL in DISH in comparison with AL in AS, which provided broader insight to identify ALL in DISH, thus facilitating early intervention against DISH deterioration.

Heterotopic ossification in a patient with diffuse idiopathic skeletal hyperostosis: Input from histological findings.

A high incidence of heterotopic ossification (HO) has been reported in patients with diffuse idiopathic skeletal hyperostosis (DISH), a metabolic disease characterized by calcifications of entheses at spine and peripheral sites. We performed histological and immunohistochemical analyses in five different HO sites in a patient with DISH to study a possible mutual interaction of bone morphogenetic protein 2 (BMP-2), transforming growth factor beta (TGF-ß), and decorin, crucial for bone mass increasing, matrix calcification, and endochondral bone formation. We speculated that the surgical trauma triggered HO, inducing TGF-ß release at the lesion site. TGF-ß recruits osteoblast precursor cells and determines the overexpression of BMP-2 in the surrounding skeletal muscle, inducing a further osteogenic differentiation, contributing to HO onset.

DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS WITH SECONDARY DYSPHAGIA IN A BLACK-HANDED SPIDER MONKEY (ATELES GEOFFROYI).

A 32-yr-old male black-handed spider monkey (Ateles geoffroyi) with marked kyphosis and reduced spinal range of motion developed intermittent regurgitation, which was managed with an acid reducer. Diffuse idiopathic skeletal hyperostosis (DISH) was suspected in this animal due to radiographically evident ossification of the anterior longitudinal ligament. At repeat radiographic evaluation 1.5 yr later, due to weight loss and increased frequency of regurgitation, the cervical spine was deviated ventrally and appeared to be impinging on the thoracic inlet. The spider monkey was humanely euthanized due to poor prognosis, and the presumptive diagnosis of DISH was confirmed via postmortem computed tomography and necropsy. DISH has not been reported in black-handed spider monkeys, and secondary dysphagia, an uncommon but recognized consequence in humans, has not been reported in a nonhuman primate. Earlier recognition of this possibly underreported disease process may increase treatment options and effectiveness of intervention.

Imaging of diffuse idiopathic skeletal hyperostosis (DISH).

Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterised by calcification and ossification of ligaments and entheses. The condition usually affects the axial skeleton, in particular, at the thoracic segment, though also other portions of the spine are often involved. DISH often involves also peripheral tendinous and/or entheseal sites either alone, or in association with the involvement of peripheral joints. At times, new bone formation involves the bone itself, but sometimes it involves joints not usually affected by osteoarthritis (OA) which result in bony enlargement of the epiphysis, joints space narrowing and a reduced range of motion. Because of the entheseal involvement, DISH can be mistaken for seronegative spondyloarthropathies or for a "simple" OA. Furthermore, other implications for the recognition of DISH include spinal fractures, difficult intubation and upper endoscopies, decreased response rates in DISH with concomitant spondyloarthritides, and increased likelihood to be affected by metabolic syndrome and cardiovascular diseases. This Atlas is intended to show the imaging finding in DISH in patients diagnosed with the condition by the Resnick classification criteria.

Sacroiliac joint variation associated with diffuse idiopathic skeletal hyperostosis.

BACKGROUND: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by the ossification of vertebral bodies and peripheral entheses. However, variations in sacroiliac (SI) joint change in patients with DISH have not been fully clarified. The purpose of this study was to evaluate SI joint variation in patients with DISH in comparison with a non-DISH population. METHODS: A total of 342 SI joints in 171 patients (DISH+, n = 86; DISH-, n = 85) who had undergone lumbar spine surgery were analyzed by computed tomography examination. SI joint variations were classified into four types: Type 1, normal or tiny peripheral bone irregularity; Type 2, subchondral bone sclerosis and osteophytes formation; Type 3, vacuum phenomenon; and Type 4, bridging osteophyte and bony fusion. The type of bridging osteophyte in SI joints and the prevalence of ossification in each spinal segment from C1 to SI joint were also examined. RESULTS: The most common SI joint variation in the DISH+ group was bony fusion (Type 4), with 71.6% exhibiting anterior paraarticular bridging. On the other hand, SI joint vacuum phenomenon (Type 3) was the most frequent change (57.1%) in the DISH- group. The middle to lower thoracic spine and SI joints were highly affected in DISH and caused bony ankylosis. CONCLUSIONS: Anterior paraarticular bridging was the most common type of SI joint change in patients with DISH who underwent lumbar spine surgery. The present results regarding variations of SI joint changes in DISH should help understand the etiology of DISH.

Back to the beginning: Identifying lesions of diffuse idiopathic skeletal hyperostosis prior to vertebral ankylosis.

OBJECTIVE: To better understand the pathogenesis of DISH, identifying early or pre-DISH lesions in the spine and investigating the relationship between spinal and extra-spinal manifestations of DISH. MATERIAL: 44 skeletonized individuals with DISH from the WM Bass Donated Skeletal Collection. METHODS: For each vertebra, location, extension, point of origin and appearance of vertebral outgrowths were recorded. The size of the enthesophytes at the olecranon process, patella and calcaneal tuberosity was measured with digital callipers. RESULTS: At either end of the DISH-ankylosed segment, isolated vertical outgrowths arising from the central third of the anterior aspect of the vertebral body can usually be observed. These bone outgrowths show a well-organized external cortical layer, an internal structure of trabecular bone and usually are unaccompanied by or show minimal associated endplate degeneration. Analysis of the relationship between spinal and extra-spinal manifestations (ESM) suggests great inter-individual variability. No correlation between any ESM and the stage of spinal DISH was found. CONCLUSIONS: Small isolated outgrowths represent the earliest stages of the spinal manifestations of DISH. The use of ESM as an indicator of DISH should be undertaken with great caution until the relationship between these two features is understood. SIGNIFICANCE: Improved accuracy of paleopathological diagnostic criteria of DISH. LIMITATIONS: Small sample comprised of only individuals with DISH. FUTURE RESEARCH: micro-CT analysis to investigate the internal structure of the spinal lesions. Analysis of extra-spinal enthesophytes in individuals with and without DISH to understand their pathogenesis and association with the spinal lesions in individuals with DISH.

DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS IN CAPTIVE GORILLAS (GORILLA SPP.): APPEARANCES AND DIAGNOSIS.

Diffuse idiopathic skeletal hyperostosis (DISH) is a disorder of unknown cause, in which new bone forms in soft tissues attached to the skeleton. Originally described in humans, in whom it is quite common, it is usually asymptomatic. New bone may completely bridge across joints, especially in the spine. However, it can be difficult to distinguish from diseases such as spondyloarthritis and spondylosis. With safer and increased use of radiography in diagnosis, the unfamiliar skeletal changes of asymptomatic DISH may now be coincidentally revealed during investigation of other disorders and result in misdiagnosis and unnecessary treatment. There have been case reports of its occurrence in great apes, but this is the first study to illustrate its appearances in a series of 11 skeletons of western and eastern lowland gorillas (Gorilla gorilla gorilla and Gorilla beringei graueri) from zoos in Europe and the United States. The study combines a review of available clinical and postmortem records with examination of the skeletons and radiologic investigation, such as computed tomography (CT). The results indicate that the disorder is probably common in older (>30 yr) captive gorillas, but that it is asymptomatic. It was not symptomatic during life in any of these animals. Several cases had unexpected features, such as extensive involvement of the thorax and extra-articular sacroiliac and tibiofibular joint fusions that are not typical in humans. By illustrating these skeletons, the study should aid differentiation of DISH from spondylosis (syn spondylosis deformans) and spondyloarhritis. It illustrates those features that are atypical of human DISH. CT scanning is valuable in such cases for examining diagnostically important areas such as sacroiliac joints. Increased awareness of DISH should help with understanding its cause, both in gorillas and humans.

Epidemiology of ossification of the spinal ligaments and associated factors in the Chinese population: a cross-sectional study of 2000 consecutive individuals.

BACKGROUND: The epidemiology and cause of ossification of the spinal ligaments (OSL) remains obscure. To date, there is no study that comprehensively evaluates the prevalence, distribution, and concomitance of each type of OSL by CT among general Chinese population. We therefore aimed to comprehensively investigate epidemiological characteristics of OSL using whole spine CT in the Chinese population and examine the factors that correlate with the presence of OSL. METHODS: Ossification of the posterior longitudinal ligament (OPLL), ligamentum flavum (OLF), anterior longitudinal ligament (OALL), nuchal ligament (ONL), and diffuse idiopathic skeletal hyperostosis (DISH) were evaluated from the subjects who underwent PET/CT for the purpose of cancer screening in our hospital. Prevalence, distribution, and concomitance of OSL were reviewed. Logistic regression analysis was performed to identify the risk factors of OSL. RESULTS: A total of 2000 subjects (1335 men and 665 women) were included. The prevalence rate of cervical OPLL (C-OPLL) was 4.1%, thoracic OPLL (T-OPLL) 2.25%, lumbar OPLL (L-OPLL) 0.8%, thoracic OLF (T-OLF) 37.65%, lumbar OLF (L-OLF) 1.45%, ONL 31.5%, DISH 3.85%. The most commonly involved level was C5 for C-OPLL, T1 for T-OPLL, T10 for T-OLF, and T8/9 for OALL. 21% of subjects with C-OPLL had T-OPLL, 44% of C-OPLL had T-OLF, 38% of T-OPLL had C-OPLL, 53% of T-OPLL had T-OLF, 44% of L-OPLL had T-OPLL, and 56% of L-OPLL had T-OLF. The average age of OSL-positive subjects was significantly higher than that of OSL-negative subjects. The results of the multiple regression analysis revealed that males had a strong association with DISH (odds ratio, 3.15; 95% confidence interval, 1.27-7.78; P = 0.013). CONCLUSION: The prevalence of OSL in the Chinese was revealed. Tandem ossification is not uncommon in people with OSL. There is a high incidence of multiple-regional OPLL in the whole spine. Approximately half of the subjects with OPLL coexist with T-OLF. For patients with clinical symptoms induced by OPLL, thorough evaluation of whole spine using CT is recommended.

Criteria for Early-Phase Diffuse Idiopathic Skeletal Hyperostosis: Development and Validation.

Background Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterized by the formation of new bone along the anterolateral spinal column at four adjacent vertebral bodies. Purpose To propose and validate criteria for the early phase of DISH by using CT data from two large-scale retrospective cohorts, each with 5-year follow-up. Materials and Methods For this retrospective study, CT data at baseline and follow-up in 1367 patients (cohort I) from 2004 to 2011 were evaluated by two observers to define no DISH, early-stage DISH, and definite DISH on the basis of interval development of consecutive complete or incomplete bone bridges. An independent group of 2267 participants from the COPDGene cohort from 2008 to 2016 was used to validate the early DISH criteria (cohort II). The sensitivity and specificity of early DISH criteria were based on findings in the last CT study as the reference standard by using a nested case-control design. κ Values were calculated between seven readers and with a 3-month interval for one reader. Results Cohort I consisted of 100% men, with a mean age of 60.0 years ± 5.6 (standard deviation) and a mean time between baseline and follow-up CT of 5.0 years ± 1.1. Cohort II consisted of 51% men, with a mean age of 59.9 years ± 8.6 and a mean time between baseline and follow-up CT of 5.4 years ± 0.5. In the derivation cohort, 55 patients comprised the early DISH group. Early DISH was defined as the presence of a spinal segment with a complete bone bridge with an adjacent segment of at least a near-complete bone bridge and another adjacent segment with at least the presence of newly formed bone or when three or more adjacent segments were recorded as showing a near-complete bone bridge. In the validation cohort, sensitivity for early DISH (vs no DISH) was 96% (99 of 103 participants; 95% confidence interval [CI]: 90%, 99%). The corresponding specificity was 83% (1695 of 2034 participants; 95% CI: 82%, 85%). The Fleiss κ for interrater reliability was 0.78 (95% CI: 0.77, 0.78), and the κ for intrarater reliability was 0.89 (95% CI: 0.82, 0.96). Conclusion Early diffuse idiopathic skeletal hyperostosis (DISH) criteria had high sensitivity and specificity for predicting the development of DISH. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Block in this issue.

The controlled study of diffuse idiopathic skeletal hyperostosis for the assessment of physical function in elderly populations.

BACKGROUND: Diffuse idiopathic skeletal hyperostosis (DISH) is associated with increasing age, obesity, and diabetes mellitus. However, little is known about the clinical impacts of DISH on physical function and spinal deformity in elderly populations. The purpose of this study was to elucidate the influence of DISH on physical function, spinal deformity, and health-related quality of life (HRQOL) in elderly populations. METHODS: We enrolled 504 volunteers (203 men and 301 women, mean age 74.0 years). Height, weight, body mass index (BMI), blood pressure, grip strength, one-leg standing time, sit-and-reach, functional reach, and bone mineral density (BMD) were measured. Using whole spine standing X-rays, the prevalence, location, and numbers of fused vertebra of DISH and spinopelvic parameters were measured. HRQOL measures, including the Oswestry Disability Index and the EuroQuol-5D were also obtained. We compared DISH subjects with control subjects of age and sex matching. We compared DISH subjects in the thoracic spine (T-DISH) to those in the thoraco-lumbar spine (TL-DISH). RESULTS: DISH occurred more frequently in men (14.3%) than in women (4.3%). The mean age was significantly higher of subjects with DISH than of those without DISH. The mean number of fused vertebra by DISH was 5.5 ± 1.5, and T-DISH was observed in 57% cases. DISH group showed greater body weights, BMIs, blood pressures, and BMD in the lumbar spine compared to the control group. No inter-group differences were observed in physical function, HRQOL and spinopelvic parameters. Subjects with TL-DISH had significantly lower values of sit-and-reach and functional reach than those with T-DISH. CONCLUSIONS: Subjects with DISH showed greater body weights, BMIs, blood pressures, and BMD compared to age- and sex-matched controls, while physical function, spinal alignment, and HRQOL were comparable between groups.

Abdominal fat distribution in diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis patients compared to controls.

AIM: To evaluate abdominal fat distribution (subcutaneous adipose tissue [SAT] and visceral adipose tissue [VAT]) in two enthesopathy-related diseases with known correlation to metabolic syndrome (MS): diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) compared with controls. MATERIALS AND METHODS: Abdominal computed tomography (CT) examinations of 43 DISH (Resnick radiographic criteria) patients, 31 AS (Modified New York Criteria) patients and 42 age- and gender-matched (to DISH) controls (males: 29; 29; 27 and mean age: 71.7±7; 56.1±16; 72.7±8 years, respectively) were evaluated and compared for VAT and SAT surface areas on mid L3, L4, L5 levels. RESULTS: AS patients were significantly younger compared to DISH patients and controls. No significant differences were observed between VAT and SAT of DISH and AS patients or between SAT values in all groups even after correction for age. VAT was higher in DISH and AS patients compared to controls on all three levels, but reached significance (p<0.05) only for DISH patients (L3: 24.34/23.6/18.43; L4: 23.85/22.21/18.05; L5: 19.09/18.94/14.24 mm2, respectively). This did not change after correction for age. The VAT/SAT ratio was significantly larger in DISH and AS patients on all levels compared to controls. CONCLUSION: The higher VAT surface area, a known marker for MS, which by itself is associated with bone proliferation, in DISH and AS patients compared to controls substantiates its role as a potential surrogate marker for MS as well as suggests a potential shared pathogenic pathway for enthesopathic excessive bone production in DISH and AS.

A recording form for differential diagnosis of arthropathies.

The present study is focused on a group of arthropathies that may have very similar bone manifestations (rheumatoid arthritis, ankylosing spondylitis, reactive arthritis, psoriatic arthritis, osteoarthritis and diffuse idiopathic skeletal hyperostosis), which makes it more difficult to diagnose them in human remains from archaeological contexts. A stepwise recording form was designed in order to improve the identification and differential diagnosis of these pathological conditions in bone remains, particularly in joint manifestations of the spine, pelvis, hands, feet and other limb joints. This recording form was applied in the analysis of two medieval individuals from the Basque Country (Spain) who presented very severe arthropathic manifestations. The use of this recording form allowed the researchers the diagnosis of ankylosing spondylitis in one of them and diffuse idiopathic skeletal hyperostosis in the other.

Degenerative changes of the thoracic spine do exist in patients with diffuse idiopathic skeletal hyperostosis: a detailed thoracic spine CT analysis.

Background Degenerative intervertebral disease (DID) is an exclusion criterion in the Resnick and Niwayama radiographic classification for diffuse idiopathic skeletal hyperostosis (DISH). However, although DID was previously described in DISH, no systematic computed tomography (CT) analysis has been reported so far. Purpose To assess for the presence and prevalence of such changes on CT examinations of the thoracic spine of individuals with DISH. Material and Methods Intervertebral space (D1-L1) on chest CT examinations of DISH patients was retrospectively evaluated for the presence of DID. Parameters evaluated were disc space height, disc protrusion, subchondral cysts/sclerosis, Schmorl nodes, vacuum phenomenon, and posterior elements including costovertebral and facet joints. Parameters were compared with two age- and gender-matched control groups of individuals whose entire spine CT lacked evidence of DISH (Control 1 individuals < 2 flowing osteophytes, Control 2 individuals < 4 and ≥ 2 flowing osteophytes). Results A total of 158 participants (DISH/Control 1/Control 2 = 54/54/50; 106 men, 52 women; average age = 70.6 years) were evaluated. Average intervertebral disc height was significantly lower in the DISH group compared with both control groups (DISH/Control 1/Control 2 = 4.55/5.13/5.01 mm, P < 0.001). Costovertebral degenerative changes were more prevalent in DISH patients ( P < 0.05) and, except for vacuum phenomenon (more prevalent in controls), other DID changes were as prevalent in DISH as in controls. Conclusion The presence of degenerative intervertebral changes on thoracic CT should not deter from diagnosing DISH. Thus, the radiographic Resnick and Niwayama DISH criteria cannot be directly adapted to CT.

Morphological characteristics of diffuse idiopathic skeletal hyperostosis in the cervical spine.

OBJECTIVES: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by anterior ossification of the spine and can lead to dysphagia and airway obstruction. The morphology of the newly formed bone in the cervical spine is different compared to the thoracic spine, possibly due to dissimilarities in local vascular anatomy. In this study the spatial relationship of the new bone with the arterial system, trachea and esophagus was analyzed and compared between subjects with and without DISH. METHODS: Cervical computed tomography (CT) scans were obtained from five patients with dysphagia and DISH and ten control subjects. The location of the vertebral and carotid arteries, surface area of the hyperostosis and distance between the vertebral body and the trachea and esophagus was assessed in the axial view. RESULTS: The surface area of the newly formed bone was located symmetrically anterior to the vertebral body. The ossifications were non-flowing in the sagittal view and no segmental vessels were observed. Substantial displacement of the trachea/esophagus was present in the group with DISH compared to the controls. CONCLUSIONS: The hyperostosis at the cervical level was symmetrically distributed anterior to the vertebral bodies without a flowing pattern, in contrast to the asymmetrical flowing pattern typically found in the thoracic spine. The hypothesis that the vascular system acts as a natural barrier against new bone formation in DISH could be further supported with these findings. The significant ventral displacement of the trachea and esophagus may explain the mechanism of dysphagia and airway obstruction in DISH.