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|LETTER TO EDITOR
|Year : 2017 | Volume
| Issue : 1 | Page : 209-211
A case of traumatic C2-3 listhesis without pars fracture: Insights from this possible variant of hangman's fracture
Madhivanan Karthigeyan, Vasundhara Rangan, Pravin Salunke
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||12-Jan-2017|
Dr. Pravin Salunke
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Karthigeyan M, Rangan V, Salunke P. A case of traumatic C2-3 listhesis without pars fracture: Insights from this possible variant of hangman's fracture. Neurol India 2017;65:209-11
|How to cite this URL:|
Karthigeyan M, Rangan V, Salunke P. A case of traumatic C2-3 listhesis without pars fracture: Insights from this possible variant of hangman's fracture. Neurol India [serial online] 2017 [cited 2019 Aug 19];65:209-11. Available from: http://www.neurologyindia.com/text.asp?2017/65/1/209/198219
Traumatic spondylolisthesis of the axis is generally synonymous with hangman's fracture. It occurs due to the dysjunction of C2 body and neural arch, classically at the pars-interarticularis. Rarely, C2-C3 listhesis can be present without a pars fracture. We report one such case of angular listhesis without a typical hangman's fracture that presented with spinal cord injury. The patient had soft tissue injuries, which possibly led to the development of this type of subluxation. This case provides indirect evidence that, even in hangman's fractures, co-existing soft tissue injuries are often unaddressed, and therefore, fixation of the fractures alone does not treat the instability.
A 60-year-old man presented with a history of fall from a bogie, followed by neck pain and weakness of the right side of the body (American Spinal Injury Association grade D). Cervical spine radiograph (in neutral position of the neck) was apparently normal. The flexion/extension views showed angular subluxation of the C2-C3 vertebrae along with fracture of the C2 lamina [Figure 1]a and [Figure 1]b. Computed tomography confirmed the X-ray findings [Figure 1]c,[Figure 1]d,[Figure 1]e. Magnetic resonance imaging (MRI) showed cord contusion at C2-C4 levels [Figure 1]f. He underwent a C2-C3 posterior fusion with C2 pedicle and C3 lateral mass screws. Intraoperatively, bilateral laminar fractures were noted; the pars-interarticularis was intact. Bilateral C2-C3 facet capsules were found to be disrupted. Postoperative imaging showed satisfactory reduction and screw placement [Figure 1]g. At a 3-week follow-up, he showed a recovering neurological trend.
|Figure 1: (a and b) Dynamic plain radiographs show C2-C3 angular listhesis along with C2 laminar fracture (arrow). (c) Axial computed tomography (CT) image shows bilateral C2 laminar fracture (arrow) with an intact pars interarticularis (PI). (d and e) Right and left parasagittal CT images show a normal PI on both the sides. (f) Sagittal T2 magnetic resonance image shows cord contusion at the C2-C4 levels. (g) Postoperative plain radiograph shows the normal alignment after C2-C3 posterior fixation|
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Of the C2 injuries, 20% are constituted by hangman's fractures. Atypical hangman's fractures are those that involve the posterior aspect of the vertebral body and present more often with neurological deficits than the classical ones. Majority of hangman's fractures can be managed conservatively. Surgical stabilization is reserved for unstable cases (Effendi-Levin type IIA and III), and the options include either anterior or posterior C2-C3 fusion., More recently, placement of C2 pars screws alone have been described.
The present report is unique because C2-C3 listhesis occurred in the absence of an obvious pars-interarticularis fracture or a facetal fracture-dislocation. A laminar fracture alone cannot explain the instability leading to C2-C3 listhesis. The stability of C2, as of any other vertebra, is contributed by the integrity of three spinal columns, as described by Denis. Other elements that are important in maintaining stability include the muscles attached to C2 posterior elements and the C2-C3 joint capsule as well as ligaments.
In the absence of pars-interarticularis fracture, the C2-C3 subluxation may be attributed to disruption of bilateral facet capsules and/or ligamentous injury, which may not be apparent on MRI. The other factor that needs emphasis is the muscular attachment of C2 posterior elements. Possibly, the muscles attached to the C2 spinous process in the presence of intact posterior bony elements would resist forward translation of C2. In the presence of laminar fractures, the vertebral body may slip anteriorly, free from the restraining pull of the posterior muscular attachments. However, laminar fractures alone cannot explain C2 translation in the presence of intact facets. Thus, in our case, a combination of capsulo-ligamentous injury, as well as the loss of muscular forces holding the C2 in position due to disrupted posterior elements, could have caused the C2-C3 listhesis. It is also possible that the laminar fractures were the result of anterior C2 translation being resisted by the backward muscular pull at the posterior arch. Therefore, whether or not the laminar fractures were the causative factors or occurred as a consequence of this injury complex, can only be speculated.
The present injury pattern may be considered to be an atypical variant of traumatic C2-C3 listhesis in which there was no pars fracture and/or facetal fracture-dislocation but C2-3 listhesis occurred owing to capsular and musculo-ligamentous injury. In the context of the classical description of hangman's fracture as traumatic spondylolisthesis, whether the present case should be considered as an atypical hangman's fracture or as a distinct entity remains unclear. The reported injury may add to the spectrum of atypical hangman's fracture.
Experimental studies in the subaxial spine have shown the importance of faceto-ligamentous complex in maintaining its stability., However, the C2-C3 junction is a gray area, the dynamics of which are relatively less studied. An in-vitro study comparing the biomechanics of various stabilization techniques for hangman's fracture has suggested that posterior C2-C3 fusion is superior to anterior C2-C3 fusion and pars-pedicle screws alone. The present case, thus, focuses on the different kinematics/mechanisms of injury that occurs at this level.
Through this case, we would like to highlight the role of capsulo-ligamentous complex and paraspinal muscles, apart from the bony continuity at pars, in maintaining C2 stability. This provides evidence, although indirect, that pars screws for fracture fixation alone may not be sufficient. Addressing the C2-C3 instability in the management of hangman's fractures, whether typical or atypical, is vital.
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