A case with rheumatod arthritis and atraumatic odontoid fracture: disappearence of bony landmarks.

We aim to draw attention to occult, atraumatic fractures of the odontoid process in patients with rheumatoid arthritis (RA) and to underline difficulties encountered during clinical and radiological diagnosis. A forty-seven years old man with RA for 4 years had occipital pain for 1 year without any history of trauma. Later, he developed weakness in the upper extremities, but he did not realize weakness in the lower extremities due to deformities. Contrast magnetic resonance imaging revealed a linear fracture of odontiod process and myelopathy. Cervical computed tomography scan revealed an old fracture border with separated and almost disappeared remnant of the tip of the odontoid without free particles in the cord. It was impossible to evaluate atlantoaxial and vertical subluxations with craniometric measurements due to destruction of the tip of odontoid. Following occipitocervical fusion and decompression and a rehabilitation program, his muscle strength improved; however, functional myelopathy stage did not change. Atraumatic fractures of the odontoid process may be more common than reported and may cause compression of the spinal cord or brain stem. Surgery is the treatment of choice but functional recovery is limited once neuronal damage has occurred. Erosion of the critical landmarks makes it difficult to diagnose and follow up atlantoaxial subluxation and/or vertical subluxation, therefore clinicians should consider radiographical follow-ups during the course of the disease.