DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS: AN INCIDENTAL FINDING ON CBCT RADIOGRAPHIC ASSESSMENT

Abstract

Background Diffuse idiopathic skeletal hyperostosis (DISH) is a form of degenerative arthritis that affects individuals age greater than 60 years, with males affected more compared with females. Because it is usually painless and latent, with some incidences of intermittent pain and stiffness in the spine area, this condition is often diagnosed incidentally during radiographic examination for a nonrelated reason.1 Spinal DISH is characterized by calcification and bony growth along the anterior longitudinal ligament. The most frequently used criteria of Resnick and Niwayama for diagnosing DISH are 3 radiographic characteristics: flowing ossification along the anterolateral aspect of at least 4 contiguous vertebral bodies, preservation of intervertebral disk height in the involved segment, and absence of apophyseal joint bony ankyloses and sacroiliac joint erosion.2 These criteria, however, are considered limited in that they do not allow early stage classifications, lack standardized descriptions/measurements, and describe spinal manifestations only, and because of the mutual exclusivity of DISH and ankylosing spondylitis.3 DISH is characterized by the calcification and ossification of soft tissues, mainly ligaments, tendons, and joint capsule (enthesial) insertions. Many patients with DISH are asymptomatic and do not show any alterations in the condition of their spine, as indicated by history or physical examination findings. Objective The aim of this study was to discuss the incidental discovery of DISH upon cone beam computed tomography (CBCT) radiographic assessment that may help prevent fractures of the spine and narrowing of the airway. Materials and Methods Two cases—a 72-year-old male and an 80-year-old female—from our university-based oral and maxillofacial radiology practice are presented, both with incidental findings. The 72-year-old patient showed ossification of the anterior longitudinal ligament at the C2-C3 level, causing severe narrowing of the oropharyngeal airway. The 80-year-old patient exhibited large osseous outgrowths from the anterior aspect of the vertebral bodies/anterior arch of C1, appearing to connect the vertebrae with each other superiorly and inferiorly. At C4-C5, there was ossification posterior to the vertebral bodies; and at C2-C5, the apophyseal joints were sclerotic with loss of joint space and osteophyte formation. The anterior displacement of the posterior wall of the oropharynx caused by the osseous structures in cervical spine had significantly decreased the anteroposterior dimension of the airway in case #2. The main differential diagnoses in DISH consist of spondylosis deformans, ankylosing spondylitis, reactive arthritis, and psoriatic arthritis.4 Conclusions Spinal diffuse idiopathic skeletal hyperostosis is a common bone-forming disorder in the middle-aged and older population. Its recognition is important because this condition can render the spine susceptible to fractures even with minor trauma, such as ground-level fall, resulting in delayed diagnosis and neurologic deterioration.