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Neuroradiology Case of the Week

Case 257

Brian Sorensen, MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A 3-year-old child presented as unresponsive with head and neck injury following a motor vehicle collision.

Imaging Findings: Sagittal and coronal reformatted CT images reveal a transverse fracture of the odontoid process involving the superior portion of C2 vertebral body. The upper fracture fragment is superiorly distracted with mild anterior displacement and angulation. The remainder of the cervical spine is normal.

Diagnosis: Type III odontoid fracture

Discussion: Odontoid fracture accounts for approximately 15% of all cervical spine fractures. Motor vehicle accidents and falls comprise the major mechanisms of injury. Patients often present with neck pain or evidence of myelopathy, such as sensory deficit or loss of fine motor control. In the elderly, spasticity may be the only presenting sign.

     Classification of odontoid fracture is based on three types:

• Type I: Dens tip avulsion.
• Type II: Transverse fracture through the base of dens.
• Type III: Odontoid fracture extending into the body of axis.

     Conventional radiography may reveal prevertebral soft tissue swelling or displacement of C2 or C1 arch. When CT is performed, coronal and sagittal reformations must be included given the risk of false negative interpretation of transverse fractures in the axial plane. The above case emphasizes the importance of the coronal view and potential misinterpretation of a severely distracted dens in the sagittal plane. Additional features to consider while examining a cervical fracture include comminution, central canal and transverse foraminal integrity, facet involvement, and ligamentous disruption.
     Management of odontoid injury is guided by fracture classification. Although C2 fractures are generally considered unstable, type I avulsions may be treated with simple immobilization. Nonunion is common in untreated type II fractures and primary fusion is often necessary to prevent myelopathy. Nonunion is less common in type III fractures which are often managed with traction and bracing.

References:

1. Boyarski I, Godorov G. C2 Fractures. Emedicine, March 15, 2005. http://www.emedicine.com/orthoped/topic597.htm.
2. Kirkpatrick JS, Sheils T, Theiss SM. Type-III dens fracture with distraction: an unstable injury: a report of three cases. J Bone Joint Surg Am. 2004 Nov;86-A(11):2514-8. [Medline]
3. Mueller JB, Davenport M, and Roy S. Fractures, cervical spine. Emedicine, May 11, 2006. http://www.emedicine.com/emerg/topic189.htm.
4. Ross JS, Brant-Zawadski M, Chen MZ, Moor KR. Diagnostic Imaging: Spine, 1st ed. Altona: Amirsys Inc; 2004.