A rare case of crowned dens syndrome mimicking aseptic meningitis

Abstract

Background: Crowned dens syndrome (CDS), related to microcrystalline deposition in the periodontoid process, is the main cause of acute or chronic cervical pain. Microcrystal-line deposition most often consists of calcium pyrophosphate dehydrate crystals and/or hydroxyapatite crystals.

Case presentation: This report describes the case of an 89-year-old woman who presented with sudden onset, high fever, severe occipital headache, and neck stiffness. A laboratory examination revealed a markedly elevated white blood cell count (11,100/µl) and C-reactive protein level (23.8 mg/dl). These clinical findings suggested severe infection such as meningitis with sepsis. However, the results of blood culture, serum endotoxin, and procalcitonin were all negative, and cerebrospinal fluid studies revealed only a slight abnormality. The patient was first diagnosed with meningitis and treated with antiviral and antibiotic agents as well as non-steroidal anti-inflammatory drugs, but they only had limited effects. A cervical plain computed tomography (CT) scan and its three-dimensional (3D) reconstruction detected a remarkable crown-like calcification surrounding the odontoid process. On the basis of the CT findings, the patient was diagnosed as a severe case of CDS and was immediately treated with corticosteroids. The patient's condition drastically improved within a week after one course of corticosteroid therapy.

Conclusion: Some atypical symptoms of CDS are misleading and may be misdiagnosed as meningitis, as happened in our case. A CT scan, especially a 3D-CT scan, is necessary and useful for a definitive diagnosis of CDS. CDS should be considered as a differential diagnosis of a possible etiology for fever, headache, and cervical pain of unknown origin.

Keywords: Calcium pyrophosphate dehydrate crystals; Cervical computed tomography scan; Corticosteroids; Crowned dens syndrome; Meningitis; Odontoid process.

Fig. 1

Cervical CT scans around the odontoid process (dens). a The axial image demonstrates the right, dominant, half-ringed form of calcification at the posterolateral side of the dens. b The coronal image demonstrates the remarkable crown-like calcifications around the dens. c The sagittal image demonstrates the linear calcification at the posterior side of the dens. d A 3D reconstruction obtained from data of a plain cervical CT demonstrates the marked crown-like calcification at the posterior side of the dens. The diagnosis of CDS was confirmed by these cervical CT findings.