Acute traumatic cervical cord injury in patients with os odontoideum.

We retrospectively reviewed acute cervical cord injury after minor trauma in 10 patients with os odontoideum. Their clinical history, neurological symptoms, radiological investigations, follow-up period, American Spinal Injury Association impairment classification and motor score were reviewed. Before their traumatic injury, three patients were asymptomatic and seven reported myelopathic symptoms, including four patients with neck pain, two patients with unsteadiness and one patient with dizziness. Falls were the most common cause of injury (n=6), followed by minor motor vehicle accidents (n=3) and assault (n=1). MRI and dynamic cervical lateral radiographs showed that all patients had atlantoaxial instability and cord compression. Most patients had spinal cord thinning and hyperintensity on T2-weighted MRI. Spinal cord compression was posterior (n=5), or both anterior and posterior (n=5). All patients underwent posterior rigid screw fixation and fusion, including atlantoaxial fusion (n=8) and occipitocervical fusion (n=2). We conclude that patients with asymptomatic or myelopathic atlantoaxial instability secondary to os odontoideum are at risk for acute spinal cord injury after minor traumatic injury. Fixation and fusion should be undertaken as prophylactic treatment for patients at risk of developing myelopathy and to avoid the neurological deterioration associated with acute traumatic cervical cord injury.