Hangman’s Fracture (Atypical Type) with Vertebral-Venous Fistula Following Blunt Trauma to the Cervical Spine

Sir, Vertebral-venous fistula (VVF) following blunt traumatic vertebral artery injury is very rarely reported in the literature, even rarer is their association with the Hangman’s fracture.[1-4] Only three such cases have been described in the literature till date, to our knowledge and none was associated with atypical Hangman’s fracture as discussed in this report [Table 1].[5-8]Table 1: Table showing the cases reported in the literature with Hangman fractures and vertebral-venous fistula (VVF)A 38-year-old male presented in the trauma casualty with severe pain in the neck, after a history of falls from height. On admission, he was hemodynamically stable, conscious, and cooperative without any neurological deficits. Computed tomography (CT) scan of the cervical spine with a Philadelphia collar in situ showed a complex C2 fracture involving pedicle, pars, foramen transversarium, and part of the posterior vertebral body on the left side along with the right side lamina fracture. There was no subluxation or cervical canal compromise [Figure 1]. As the fractured segment involved the left foramen transversarium, a CT angiography of the neck vessels was done. CT angiography showed a large, lobulated pseudoaneurysm arising from the left vertebral artery (VA) at V2-V3 junction measuring approximately 17 × 25 × 11 mm [Figure 2]. The VA was focally attenuated in this segment; however, proximal and distal arteries were of normal caliber. Diagnostic digital subtraction angiography (DSA) was done to further evaluate the extent of vascular injury. DSA revealed a high-flow VVF at the level of the C2 vertebra with retrograde filling of the fistula via the distal left VA and nonopacification of the mid and distal basilar artery and its branches, findings suggestive of arterial flow steal phenomenon [Figure 3]. As there were no neurological deficits and no canal compromise, a conservative approach with a cervical collar in situ and regular follow-up (periodical radiological scanning) was planned for the cervical spine fracture. However, for the treatment of VVF, the patient was subsequently planned for therapeutic endovascular intervention. Complete occlusion of the fistula with detachable coils was done. Postembolization DSA of the right VA showed resolution of normal antegrade flow with opacification of the basilar artery and its branches [Figure 3]. No periprocedural complications were seen. The patient was discharged home 3 days after the endovascular intervention with a cervical collar in situ. At a year’s follow-up period, the patient was doing fine, and a repeat CT scan of the cervical spine showed evidence of bony fusion along the C2 neural arch [Figure 4].Figure 1: NCCT spine (a) Sagittal, and (b) axial images showing atypical Hangman fracture (type A2 fracture pattern)Figure 2: CT angiography, MPR reconstruction (a) axial, (b) sagittal, and (c) coronal images show an extradural fistula of the left vertebral artery at the level of C2 vertebra (solid white arrows). Axial (a) image also reveals fractures involving right-sided lamina (white arrowhead) and left pedicle through the left transverse foramen at C2 vertebra (black arrowhead)Figure 3: Pre-embolization DSA images (a-d): (a) AP and (b) lateral projections of the left vertebral artery (LVA) in arterial phase DSA, showing the high-flow vertebral-venous fistula (VVF), at the level of the C2 vertebra with arterial flow steal. (c) AP projection of the right vertebral artery (RVA) shows retrograde filling of the fistula via the distal LVA with nonopacification of the mid and distal basilar artery and its branches due to arterial flow steal phenomenon. (d) Lateral projection of left internal carotid artery in the arterial phase DSA shows good cross flow across the robust left posterior communicating artery (PCOM) with opacification of the distal and mid basilar artery and its branches. Post embolization DSA images (e-g): (e) AP and (f) lateral projections of the left vertebral artery (LVA) in arterial phase DSA show complete occlusion of the fistula with coils. (g) AP projection of right vertebral artery (RVA) shows normal antegrade flow with opacification of the basilar artery and its branches after complete occlusion of the fistula with coilsFigure 4: At 1-year follow-up NCCT cervical spine (a and b) axial, (c) sagittal, and (d) coronal images showing bony fusion (white arrow)In 1993, Starr and Eismont et al.[9] in their case series of 19 patients with Hangman’s fractures, first of all, focused on fractures involving the posterior cortex of C2 and referred to them as “atypical Hangman’s fractures.”[10] In 2017, Li et al.[11,12] proposed a novel classification system for atypical Hangman’s fracture, further dividing them into type A1, type A2, type B1, and type B2. Computed tomographic angiography (CTA) along with three-dimensional (3D)-volume rendering technique (VRT) imaging remains the gold standard for diagnosing and delineating vascular injuries associated with fractures of the transverse process extending into the foramen transversarium, upper cervical spine fractures involving C1-C3, and facet dislocations/subluxations.[13] In our case, the fracture line involved the pedicle, foramen transversarium, pars interarticularis, and part of the posterior cortex of the C2 body on the left side and lamina fracture on the right side. Therefore, it can be labeled as a type A2 fracture pattern, described by Li et al.[11,12] Fall from height with hyperextension, and severe rotational injury may be responsible for the fracture pattern as seen in our case. Such fractures are usually associated with the highest incidence of neurological deficits as seen in 50% (6/12) of type A2 cases reported by Li et al.[12]; however, our patient had no neurological deficits. Unstable Hangman’s fracture can be treated by an anterior approach (anterior C2-C3 discectomy and fusion), posterior approach (posterior C2-3 fusion or pars pedicle screw alone), or by a combined approach. Unreliable opposition of the fracture fragments by anterior fixation alone, difficult-to-correct angular component, and exposure-related neurovascular injuries favor posterior approach or 360-degree fixation as a reliable method for correction of such types of fractures.[14] There is a multiplanar malalignment of this fracture and therefore it is important to study the radiological details of the fracture as well as their relationship to the critical neurovascular structures (vertebral arteries) before contemplating any surgical approach.[15] The treatment of choice for VVFs is the closure of the fistulous tract with the preservation of the parent artery. Historically, this was accomplished by open surgery via proximal and distal trapping with excision of the fistula; however, it was associated with high failure rates (ineffective proximal VA ligation because of extensive anastomotic circulation) and significant morbidity.[16-18] Because of the high success rate of obliteration of fistula, the possibility of preservation of flow in the parent artery and low-morbidity endovascular treatment is now considered the treatment of choice for treating vertebral AVFs. Endovascular treatment can be accomplished by a variety of techniques like balloon occlusion, coil embolization, and/or stent deployment with good results.[16-18] Cyanoacrylate glue and other particulate embolic agents are usually avoided in the endovascular treatment of high-flow VVF due to the risk of being swept away by the rapid flow with failure to occlude the fistula.[19] Selective occlusion of the fistula with the placement of a detachable balloon with preservation of the parent artery is preferred. However, at times, it may be technically challenging, the fistula can be masked by ectatic vessels, and the occluding balloon can deflate leading to recurrence of the fistula.[19] If selective balloon occlusion of the fistula with preservation of parent artery is not possible, trapping of the fistula can be done, after confirming adequate collateral blood supply to the posterior fossa as was done in our case with detachable coils. The initial occlusion was done distal to the fistula in the V3 segment of the left vertebral artery, to avoid an increase in blood steal from the brain collaterals. Moreover, the trapping of the fistula was done by placing detachable coils as near as possible to the fistula to avoid filling of the trapped segment from the collaterals, otherwise, recruitment of muscular and spinal collaterals may maintain the fistulous patency. Hangman fractures typical as well as atypical may be associated with VVF and a high index of suspicion is needed for its diagnosis, especially if there is an associated foramen transversarium fracture. They should be properly evaluated using a CT angiogram and DSA, before contemplating any surgical intervention. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.