Assessment of the VA is mandatory in patients with cervical spine trauma in order to prevent further cerebral stroke. Although CTA has been widely used for the evaluation of the VA, it has various disadvantages that US could compensate for. Considering this, we tried to evaluate VAs through US in the emergency room and determined the degree of reliability of US. The results of this study suggest that the agreement between US and CTA was high, particularly if VA blood flow was confirmed by US, as seen on CTA similarly in all cases.
There have been several papers on the assessment of the VA using US; however, most of them have been performed on patients with dizziness, limbs disturbance, dysphagia, hemianopia, and other clinical symptoms due to vertebrobasilar insufficiency [2,7,8] and none in the emergency room in an acute setting. The accuracy of US in the assessment of the VA has improved in previous years, and the sensitivity of CTA has been increasing [8,9]. Yin et al. [8] reported that as a non-invasive examination, neck-brain integrated US is valuable in the diagnosis of stenotic lesions in cervical VA. However, they also noted that in the diagnosis of VA stenosis, which was divided into four grades—non, mild, severe, and occlusion—there was no significant difference between severe and occlusion in sensitivity, but a significant difference between non and mild in the assessment with CTA. In this study, there was a case with cervical dislocation (Fig 4A), in which the diagnosis was different between US and CTA. In fact, it was difficult to diagnose an occlusion due to injury or hypoplasia. The left side was > 50% stenosed compared to the right side on CTA and CTA showed the blood flow in the left side (Fig 4B) although the examiner assessed it as occlusion on US (Fig 4C). This suggests that it is difficult for US to determine VAs that are narrower than usual in addition to situations in which patients’ cooperation is not possible.
There are common variations in the course and size of the VA [10]. In this study, there were two VAs that run anterior to the C6 vertebral body without passing through the C6 foramen after passing through the C5 foramen (Fig 5A and 5B). In the two cases here, there was no stenosis of VA compared to the normal side, only abnormalities in the course of the vessels. This blood flow in the VA could be confirmed on US as shown on CTA (Fig 5C).
This study has some limitations. First, US was performed at levels C4–7 only. If there is an occlusion outside of this level, its location could not be observed. Second, cases with severe stenosis might be judged to have an occlusion despite the presence of blood flow because of the lack of quantification. Third, the sample size of this study was too small for generalization of the results. It must be noted that cervical spine surgery still cannot be performed without CTA assessment at present. Nevertheless, this was the first study that evaluated the agreement between US and CTA in the assessment of TVAI in the emergency room. Moreover, the sensitivity of the tests obtained in this study was sufficient for screening. In future practice, CTA may not be mandatory for TVAI at levels C4–7 if VA flow can be confirmed.