Extensor injuries of III-VII cervical vertebrae: causes, symptoms, diagnosis, treatment

When treating victims with cervical spine injuries, we often encounter patients who have severe spinal disorders, up to and including complete physiological disruption of the spinal cord at the level of injury, which occur with minor, minimal dislocations of the vertebrae, often limited to a slight anterior displacement of the body of the overlying vertebra.

The unusualness of the observed clinical picture is further aggravated by the fact that many victims with cervical spine injuries, in whom radiologically much more severe anterior displacements of up to 1/2 or 3/4 of the anteroposterior diameter of the body are detected, have minimal or no neurological disorders. For a long time, these severe spinal cord injuries with seemingly harmless injuries with minimal radiological changes remained a mystery and found no explanation. The symptoms from the spinal cord in these victims were explained by isolated injuries, hematomyelia, etc. The curtain of mystery about the origin of these severe cervical spinal cord injuries was lifted by Taylor and Blackwood (1948), who described the mechanism of posterior displacement of the cervical vertebrae, and Forsyth (1964), who described in detail the changes that occur with extension injuries of the cervical spine.

It is generally accepted that extension injuries of the spine, including the middle and lower cervical spine, are rare.

In 1964, Forsyth reported that in a retrospective analysis of 159 patients with cervical spine injuries observed over a 12-year period, the extension mechanism of violence occurred in half of the cases. Therefore, extension injuries of the cervical spine are common and are often accompanied by severe spinal cord injuries.

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Causes of extension injuries of the III-VII cervical vertebrae

Extension injuries of the cervical vertebrae occur when force applied to the chin, face or forehead of the victim suddenly and sharply extends the unsupported cervical spine. The extension mechanism of cervical vertebrae injuries has recently been increasingly observed in motorists during sudden sharp braking at high speed, when the head is thrown back sharply. The breaking force acts on the spine in the backward and downward direction. The head and neck simultaneously and sharply extend, which leads to a forced convergence of the articular and spinous processes. The head and the overlying section of the neck continue to rotate backwards around the frontal axis passing through these articular processes, which leads to a rupture of the anterior longitudinal ligament. Then either the intervertebral disc ruptures, or a fracture of the body of the overlying vertebra occurs above its caudal endplate. The overlying section of the spine, located above the site of this rupture, is displaced posteriorly, tearing the intact posterior longitudinal ligament from the posterior surface of the body of the vertebra below. At the level of injury, the spinal cord is trapped between the arches and the posterior angle of the caudal endplate of the posteriorly displaced body of the overlying vertebra in the case of a ruptured disc, or the posteroinferior angle of the body in the case of a rupture of spongy bone near and parallel to the caudal endplate. The separated posterior longitudinal ligament also contributes to compression and even crushing of the spinal cord.

This is how an extension “dislocation” or fracture-dislocation of the cervical vertebrae occurs.

How can we explain the anterior displacement of the vertebra located above the site of injury in extension violence? After all, such a displacement is usually characteristic of flexion violence. Forsyth (1964) explains this by the direction and nature of the breaking force. Extension violence on the spine does not act strictly backwards, but backwards and downwards. Its immediate effect causes the injuries described above. Continuing its action, the violence leads to the head and upper section of the neck continuing to move along an elliptical curve, which returns the head and upper section of the spine.

This explains the situation where severe spinal cord injury is combined with minimal radiographic findings, since spondylography is performed after the violence has ended, and the spinal cord injury occurred at the moment of its maximum impact.

At the moment of maximum impact of extension force with a sufficiently strong anterior longitudinal ligament, a fracture may occur in the area of the roots of the arches, articular processes, in the area of the arches and spinous processes. With continued action of force, overcoming the strength of the anterior longitudinal ligament, along with damage to the posterior elements of the vertebrae, the previously described damage and displacement occurs. In these cases, both in the anterior and in the posterior elements of the vertebrae, the most severe damage occurs in the form of a complex fracture-dislocation, the severity of which is aggravated by complete instability in the area of damage, while extension injuries without a fracture of the posterior elements of the vertebrae are stable in the flexion position.

Finally, if the extension force is unable to overcome the strength of the anterior longitudinal ligament, then the damage is limited to a fracture in the above-mentioned posterior elements of the vertebrae.

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Symptoms of extension injuries of the III-VII cervical vertebrae

Symptoms of extension injuries of the cervical spine are characterized by the manifestation of varying degrees of intensity of neurological disorders. Symptoms of spinal cord injury may be minimal, but, more often, they can be extremely severe, up to the immediate development of tetraplegia. Extension injuries without neurological disorders also occur.

Correct recognition of extension injuries is assisted by determining the circumstances of the injury, the presence of bruises, abrasions, contusions on the chin, face, in the forehead area. The nature of the injury is finally clarified by a profile spondylogram.

An extension injury to the cervical spine can be recognized based on: the presence of bruises, abrasions and other signs of contusion in the area of the face, chin and forehead, which were the result of the victim falling on his head or a heavy object falling on the victim's head; the presence of pain in the back of the neck, local pain and swelling in the posterolateral parts of the neck; limited mobility of the neck and head, increased pain with movement and varying degrees of instability of the cervical spine.

In cervical spine injuries, Kienbock distinguishes three degrees of instability: severe, moderate and mild.

The severe degree is characterized by the presence of the "guillotine" symptom, which is expressed in the inability to hold the head and its fall, similar to the fall of the head of a guillotined person. This symptom occurs with severe injuries to the cervical spine with an extreme degree of instability and severe damage to the spinal cord.

The average degree of instability is expressed in the fact that the victim can hold his head only with additional external support - he holds his head in a vertical position with his hands.

Mild instability is manifested by the fact that the victim holds his head without additional external support only in a certain, strictly specified position. When trying to change the position of the head, stability is disrupted. If it is necessary to change the position of the head, even a slight turn to look to the side, he does not turn his head in the desired direction, as healthy people usually do, but turns his entire body. Wagner and Stolper figuratively called this condition of the victim "the head of a statue."

The presence of radicular and especially spinal symptoms, often severe, in combination with the above-described radiographic changes, the main ones of which are a slight anterior, sometimes barely perceptible displacement and rupture of a small area of bone tissue at the site of rupture of the anterior longitudinal ligament, make the diagnosis of extension injury of the cervical spine reliable.

Diagnostics of extension injuries of the III-VII cervical vertebrae

The above-described changes that occur with extension injuries of the cervical vertebrae explain the minimal findings that can be detected with spondylography. A lateral spondylogram usually shows a slight anterior displacement of the vertebral body located above the area of injury. Sometimes this anterior displacement can be more significant. Quite typical is the rupture of a small piece of bone tissue from the anterior-inferior angle of the vertebra that has shifted forward, which corresponds to the level of the rupture of the anterior longitudinal ligament. In the posterior elements of the vertebrae, a fracture of the roots of the arches or arch, the arch itself, or the spinous process can be noted. The most typical injury to the posterior elements of the vertebrae is a dislocation or fracture-dislocation of the posteroinferior articular process of the overlying vertebra, in contrast to flexion injuries, in which fractures of the anterior-superior articular process of the underlying vertebra are more common.

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Treatment of extension injuries of the III-VII cervical vertebrae

The choice of treatment for extension injuries of the cervical spine depends on the degree of clinical manifestations, reflecting the anatomical and physiological changes caused by the injury. It should be emphasized that extension injuries, except for cases with severe damage to the posterior supporting structures, which is not so common, are usually stable when the cervical spine is placed in a flexed position. This largely determines the choice of treatment method.

In case of minor anterior displacement of the overlying vertebral body, minor minimal manifestation of neurological symptoms or their complete absence, treatment is limited to immobilization with a craniothoracic bandage or a plaster collar of the Shantz type for 3-6 months. The prognosis in these cases is usually favorable. Usually after 4-6 months, a spontaneous anterior bone block is detected radiographically due to calcification of the anterior longitudinal ligament.

In the presence of a more pronounced anterior displacement, reduction is performed either simultaneously by manual means by imparting the necessary extension, or by traction using a Glisson loop, or by skeletal traction by the bones of the cranial vault. The traction is directed along the long axis of the spine and somewhat posteriorly. Upon achieving reduction, immobilization is performed using one of the above-mentioned methods.

In the presence of severe instability, traction is contraindicated. In these cases, external or internal immobilization should be performed.

In cases of severe instability of the spine with neurological disorders, revision of the contents of the spinal canal and internal immobilization are indicated. This is achieved by surgical intervention. The need for reliable internal immobilization in unstable injuries is obvious and understandable. In cases of relatively stable extension injuries of the cervical vertebrae, which require revision of the contents of the spinal canal, and therefore laminectomy, the need for primary early internal immobilization is dictated by the fact that during laminectomy, the posterior supporting structures of the vertebrae that provide stability to the spine are removed, and the injury becomes unstable. We consider attempts at closed reduction of displaced vertebrae in these cases to be risky. Closed reduction may be complicated by the presence of free bone fragments in the area of the roots of the arches or articular processes, and most importantly, it does not provide the ability to revise the contents of the spinal canal. During closed reduction, the possibility of additional secondary damage to the spinal cord cannot be ruled out.

Preoperative preparation, anesthesia, and the position of the patient on the operating table are similar to those described for occipitospondylodesis. Preliminary application of skeletal traction on the cranial vault bones is absolutely necessary.

Using the posterior median approach along the line connecting the tops of the spinous processes, the soft tissues are dissected layer by layer strictly along the midline to the required extent. The area of damage is exposed. The spinous processes and arches are skeletonized so that at least two arches are exposed above and below the site of damage. Lampectomy is performed to the required extent.

The technique of laminectomy is well known, we will only pay attention to the following points. The length of the skin incision is dictated by the level of laminectomy and the degree of expression of the subcutaneous fat and underlying muscles. Since the tops of the articular processes in the cervical region are located quite deep and covered by powerful cervical muscles, the incision should be made strictly along the midline through the nuchal ligament, poor in vessels. Skeletonization of the spinous processes of the cervical vertebrae presents some difficulties due to the bifurcation of their tops. No less difficult is skeletonization of the arches of the cervical vertebrae due to their mobility and relatively low strength. Skeletonization should be carried out subperiosteally with minimal use of a scalpel. After dissection of the periosteum, detachment of soft tissues from the lateral surfaces of the spinous processes and arches is performed using a sufficiently wide raspatory or, better, a chisel. I. S. Babchin recommends performing blunt detachment through a gauze ball. The small tendons and muscles attached to the spinous processes and arches that are not detached are cut with scissors. Soft tissue is detached on both sides. To stop bleeding, the space between the spinous processes and arches on one side and the detached soft tissue on the other is tightly tamponed with gauze swabs soaked in hot saline. Bleeding from larger, usually venous vessels is stopped by electrocoagulation.

The spinous processes are bitten off at their bases using curved or bayonet-shaped nippers and, after cutting off the ligaments that hold them, they are removed. Using bone nippers with large rounded jaws, additional bone tissue is removed in the area of the base of the spinous processes. In one place, using nippers, the bone tissue is thinned and removed so much that a defect in the bone is formed. Through this defect, using a laminectomy, the arches are gradually bitten off - laminectomy. Care should be taken when removing the lateral sections of the arches near their roots, where there are non-collapsible venous trunks. All these manipulations require special care in conditions of a damaged spine. The exposed epidural tissue is most often imbibed with blood and does not have the yellowish color inherent to it normally. The tissue is separated with a narrow medullary scapula and peeled apart. The dura mater is exposed. When cutting it, one should avoid damaging the underlying arachnoid membrane. The dural sac is opened when there is a need to examine the spinal cord.

After opening the spinal canal, a thorough examination of the damaged area is performed. Free small bone fragments and areas of torn ligaments are removed. Particular attention is required to the revision of the anterior wall of the spinal canal and the elimination of the causes causing compression of the anterior sections of the spinal cord. If this cannot be done through the posterior approach, anterior decompression should be used after reliable internal immobilization of the damaged section of the spine.

The lateral surfaces of the spinous processes and the arches of the vertebrae to which the grafts will be fixed are carefully and thoroughly skeletonized in advance. As mentioned above, two arches above and below the site of injury or defect after laminectomy should be exposed. Compact bone is carefully removed from the exposed arches along their posterior surface, and the underlying spongy bone is exposed. Sufficiently strong cortical bone grafts taken from the tibial crest are placed on the sides of the arches and fixed with a wire suture to the arches, from which, as mentioned above, the yellow ligaments have been previously separated. To do this, using a thin elevator inserted between the anterior surface of each arch and the posterior surface of the dural sac, the dural sac is pushed forward enough to allow the wire to be passed. A thin wire wrap suture, covering the anterior surface of each arch and the posterior surface of the graft at the appropriate level, to the right and left of the line of the spinous processes, firmly and reliably holds and fixes the cervical vertebrae, which gives the spine the lost stability. The wound is sutured layer by layer. Depending on the condition of the victim, the presence or absence of concomitant injuries, skeletal traction is continued for the next few days by the bones of the cranial vault, and then a well-modeled craniothoracic plaster cast is applied or applied immediately. In the absence of contraindications from the general condition of the victim, as the neurological symptoms regress, he can be put on his feet.

In the postoperative period, symptomatic drug treatment is carried out and antibiotics are administered. According to indications, if necessary, dehydration therapy is prescribed.

The duration of external immobilization depends on the characteristics of the previous extension injury, the extent and prevalence of laminectomy, and the degree of reliability and strength of internal fixation.

The duration of disability and the prognosis of the injury are largely determined by the nature of the spinal cord injury and the degree of residual neurological symptoms. More often, with these injuries complicated by spinal cord involvement, the prognosis is less favorable.