Neuroradiology Case of the Week

Case 31

Yevgeniy Ostrinsky, Manoj Ketkar, MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: Patient is a 27-year-old woman with sudden onset neck pain, after a motor vehicle accident.

Radiological Findings: Lateral images of cervical spine film show minimally displaced fractures of pedicles of C2, as well as some subluxation of C2 on C3. There is also an increased distance between posterior arch of C1 and spinous process of C2 (Fig. 1A & B).

Figure 1A	Figure 1B

   CT was subsequently obtained and the lateral images showed fracture of the left (Fig. 2A) and right (Fig. 2B) pedicles with mild subluxation of C2 over C3.

Figure 2A	Figure 2B

    The axial images through the cervical spine reveal fracture of the bilateral pedicles of C2 (Fig. 3A). There is an extension of the fracture line to the posterior margin of the left foramen transversarium (Fig. 3B).

Figure 3A	Figure 3B

Diagnosis: Hangman’s Fracture (Traumatic Spondylolisthesis of C2).

Discussion:
   Traumatic spondylolisthesis of C2 represents 4-7% of all cervical fractures and dislocations. This type of fracture originally received the name of “Hangman’s fracture” because it has similar radiographic findings as the injuries sustained in judicial hangings. The injury pattern is a bilateral pedicle fracture of C2 along with distraction of C2 from C3. Today the most common cause of this type of injury now is motor vehicle accident with hyperextension of the head and neck, or forced hyperflexion with compression in falls. The mechanism of action includes the occiput being forced down against the posterior arch of the atlas, which in turn is forced against the pedicles of C2.
   The differential diagnosis of Hangman’s fracture includes pseudosubluxation, which has to be considered in young children. However, this entity involves multiple upper cervical levels without any associated soft tissue swelling.
   Typical clinical presentation of a patient with Hangman’s fracture is upper cervical pain after a motor vehicle accident. Neurological symptoms are very uncommon on initial presentation. This is partly due to the fact that the cervical canal is wide at this point and is further decompressed by the fracture. In about 25% of the cases patients eventually develop neurological deficits mainly because of the vertebral artery injury. It is also very important to study the whole cervical spine as well as upper thoracic because there is a 33% chance of a concomitant fracture at another site, especially C1.
   Levine and Edwards classified Hangman’s fracture into four types. Type I fractures are minimally displaced (less than 3 mm displacement) and no angulation. Because ligamentous injury is minimal these fractures are considered to be stable and usually heal within 12 weeks after the patient’s neck is immobilized with a rigid cervical collar.
   Type II fractures have more than 3 mm of displacement and significant angulation. Treatment consists of a halo ring with slight extension of the neck, which might be necessary for 3 to 6 weeks to maintain anatomic reduction. The patient should be placed in a halo vest for the rest of the 3 month period. Type IIA fracture is a variant of Type II that shows severe angulation between C2 and C3 with minimal translation. Treatment recommendation is placement of a halo vest with slight compression to achieve anatomical reduction. Once reduction is obtained the vest can be continued for the rest of the 12 week period.
   Type III fracture combines bilateral pedicle fracture with posterior facet injury. It is the only type that requires surgical stabilization. Open reduction and internal fixation are usually required to obtain the reduction of the facet dislocation. After posterior cervical fusion at the C2-C3 level, halo vest is required for 3 months for maintenance of reduction.

References:

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