Imaging examination of cervical instability

At present, the most commonly used X-ray film of cervical spine is lateral film of cervical spine, followed by anteroposterior film, odontoid opening film, flexion-extension dynamic film and left-right oblique film.

Conventional radiological examination of cervical spine mainly refers to lateral radiographs of cervical spine. Common signs are:

(1) The physiological curve of cervical vertebra is broken, which indicates that the motion of cervical vertebra segment corresponding to the broken curve is increased.

(2) Vertebral displacement, such as forward, backward or lateral horizontal displacement >; 3.5 mm (some scholars point out that 3 mm is the standard), and the angle difference between two adjacent intervertebral spaces >: 1 1 (Figure 14-1). In the evaluation of cervical degenerative instability, besides horizontal displacement and angular displacement, the measurement of sagittal diameter, A value and B value of spinal canal (Figure 14 -2) is also of great significance, that is, the larger sagittal diameter, A value and B value may not necessarily cause spinal cord compression even if the degenerative instability is serious; However, those with smaller sagittal diameter, A value and B value of spinal canal may develop into cervical instability or cervical spondylosis with the aggravation of instability or further degeneration of diseased segments.

(3) The spacing between laminae or spinous processes is widened, and the standard is that the spacing between laminae or spinous processes is 2 mm wider than that of adjacent segments.

(4) Abnormal widening or narrowing of intervertebral space.

(5) The articular space of articular process is widened or narrowed.

(6) The connecting line of the posterior edge of vertebral body is discontinuous.

(7) The spinal canal is widened or narrowed. The widening of spinal canal means that the distance between pedicles is more than 2 mm in front and back X-ray films.

X-ray flexion and extension dynamic lateral X-ray film is of great significance in diagnosing degenerative cervical instability, which can observe the relative displacement between cervical vertebrae, abnormal increase of angulation and abnormal spinal activity. It is generally believed that cervical instability can be diagnosed when the horizontal displacement between adjacent vertebral bodies is >: 3.5 mm or inclined to > 1 1.

(2) CT of neck

Cervical CT can provide the injury of axis vertebral body, pedicle and articular process and the change of spinal canal volume. There is no overlap in CT cross-sectional images, especially in C ↓ 1 ~ C ↓ 2 bone ring. In the unstable injury of cervical spine, facet dislocation and subluxation are more common, often accompanied by fractures, and most of them are bilateral. The width of joint space and joint locking can be clearly displayed on CT cross section, so as to judge dislocation. However, it is very difficult to diagnose the facet joint, especially the up-down joint. It is necessary to perform thin-slice scanning and three-dimensional reconstruction to show the dislocation and fracture of facet joint at multiple levels and angles. When the X-ray film is unclear or the position of X-ray film is limited during acute trauma, cervical CT can be considered.

(3) MRI of cervical spine

MRI is considered as the best imaging examination method, because it can not only show the abnormal changes in the medullary cavity, but also visually show the relationship between the spinal cord and the spinal canal, the course of the spinal cord in the spinal canal, and the position changes to adapt to the deformed spinal canal. MRI plays a unique role in evaluating the stability of cervical spine injury, that is, it has an obvious diagnostic role in spinal cord and nerve injury and tissue compression degeneration caused by cervical spine injury, and can understand the compression of vertebrae and intervertebral discs on spinal cord, hematoma, liquefaction and degeneration of nerve and spinal cord tissue, and soft tissue injury of intervertebral disc and ligament structure, thus evaluating the stability of cervical spine.

Jinkins et al. first reported the use of a specially designed MRI scanner to evaluate the performance of patients with cervical degeneration in different postures and dynamic exercises. The scanner adopts ultra-open design, which allows the examinee to complete the examination under normal upright position, load (the weight of the head itself) and dynamic conditions, so as to ensure the consistency between the examinee and the daily physiological state, and obtain more information than the routine supine examination, such as sliding hernia of intervertebral disc, abnormal increase of spinal mobility, stenosis of spinal canal and nerve root canal, etc. These are all potential pathological conditions, which are related to the bearing and movement of cervical spine. In this state, the cervical curvature obtained by examination is more accurate, reflecting the real physiological state, and it can be distinguished whether the curvature abnormality is caused by the patient's posture or muscle pain.