| Objectives: Vertebral arteries injuries (VAI) may be a complication of both penetrating and closed cervical spine trauma. Although it was previously believed infrequent, the lately reports showed that this complication is not rare. Several prospective researches have pointed out that vertebral arteries injuries are prone to occur in the situation of cervical facet dislocation. The purpose of our experiment is to determine the incidence of VAI after cervical facet dislocation and study the mechanism of VAI by establish the animal model of unilateral cervical facet dislocation, to compare two-dimensional time-of-flight(2D TOF) magnetic resonance angiography(MRA) with transfemoral four-vessel angiography in diagnosis of VAI and to find the relationship between the radiodiagnosis and pathology. Methods: Twenty-six dogs were selected to establish the model of cervical facet dislocation between C5-6. These dogs were divided into three groups according to the different surgical management previously. Group A includes six dogs, whereas the group B and group C include ten dogs respectively. In group A, the supraspinous and interspinous ligaments between the C5-6 were destroyed by surgery previously. In group B, not only the supraspinous and interspinous ligaments but also the the ipsilateral articular capsule, ligamentum flavum were destroyed preciously. In group C, anterior longitudinal ligaments between C5-6 were destroyed on the basement of management done in group B. All the three group then experienced a stuck by the type of the BIM-II biomechanical machine. X-ray screening was performed to determine whether the dog has cervical facet dislocation. MRA and transfemoral four-vessel angiography were performed to diagnose the VAI. All the dogs of three groups received the study of pathology.Results: 1. No cervical facet dislocation were found in group A.There are five cases of cervical facet dislocations in group B.Nine cases of cervical facet dislocations were found in group C.2. The results of MRA of twelve dogs which have no cervical facet dislocations were nomorl.However,in the fourteen dogs wiich have cervical facet dislocations,the results of MRA showed eight cases of nomoral and a case which was hard to decide.3. The follow-up MRA examination showed:when flow-related enhancement of the MRA images in the expected location of the vertebral artery was obviously narrow than that of the normal,the final result of the vertebral artery may be normal or abnormal in the follow-up screening. 4. The pathology form of VAI following the cervical facet dilocation disruption of intima,with or without the dissection of the media. Mural thrombus was prone to develop in this condition.Conclusion: 1. VAI were prone to occur in the situation of cervical facet dislocation.The mechanism of VAI following cervical facet dislocation was: the immediate reverse tension caused the disruption of intima and then developed the mural thrombus.2. 2D TOF MRA was a effective method which has high sensitivity and specificify in diagnosising VAI.3. Because of the flaw that MRA can't show the difference between the spasm of the vertebral artery and the delayed vertebral artery thrombosis thrombosis, false-positive result may come out in this situatioin. 4. The results of pathology of vertebral artery injuries showed that the level of VAI were more ommon according to the level of facet dislocation.However,the level of VAI may also below the level of that of facet dislocation.The main injuries of pathology include: laceration of the intima and tunica media, mural thrombus. 5. The ligamenta flava, ipsilateral articular capsule and anterior longitudinal lig may play an important role in maintain the stability of the cervical facet zygapophysial joints. |
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