Crowned dens syndrome detected by positron emission tomography-computed tomography (PET-CT): a case description

Abstract

CDS is currently believed to arise from the deposition of calcium salt crystals in the soft tissue surrounding the odontoid process of the axis vertebra, and these depositions manifest similarly to the ossification of the posterior longitudinal ligament in the cervical spine (5,9). Calcifications surrounding the odontoid process can compress the cervical cord, leading to neurological symptoms of limb weakness. Recurrent episodes can easily be misdiagnosed as cervicogenic pain or occipital neuralgia. Another characteristic feature of CDS is restricted neck movement. It's typical clinical presentation is reminiscent of the triad seen in meningitis: acute head and neck pain, stiffness, and fever (10-13). Meningitis typically presents with neck stiffness, a high fever, headache, vomiting, and a positive Kernig's sign, which can easily be confused with CDS. In this patient, there were no signs of increased intracranial pressure, no high fever above 39 °C, the pathological signs on examination are negative, and the test results for leukocytes and PCT were normal, so a diagnosis of meningitis was not considered. If a patient presents with fever and limited neck movement in the emergency clinic, careful questioning of the patient's symptoms and detailed examination should be the first step. Besides neck stiffness and fever, meningitis also presents with special manifestations such as increased intracranial pressure and positive pathological signs. Moreover, blood counts and CT scans are also effective in differentiating CDS from meningitis, which may show signs such as hydrocephalus and parenchymal changes. In contrast, CDS usually features normal intracranial tissue, but foci of calcification are seen around the dentate process. However, clinical distinction between CDS and meningitis is not easy. Theoretically, the headache associated with meningitis and the neck pain resulting from CDS may present distinct characteristics. CDS is notably marked by a significant limitation in cervical rotation. Nonetheless, in the case of early-stage or atypical symptomatic meningitis, prematurely dismissing the possibility of meningitis as a diagnosis could result in delayed treatment, potentially leading to more severe outcomes, which requires lumbar puncture to rule out meningitis (14).