Acute Cervical Spine Injuries

                         Acute Cervical Spine Injuries

                                               DR KS Dhillon

Introduction

In patients with blunt trauma, cervical spine injuries are not uncommon. The most commonly involved vertebra is C2 followed by the C6 and C7 vertebra. The mortality rates from cervical spine injuries can be high because of high rates of spinal cord injury. Motor vehicles accident is the most common cause followed by falls from a height. Broadly, cervical spine injuries are classified into upper cervical and lower cervical spine injuries. The mainstay of diagnosis of cervical spine injuries are x rays and CT scan of the cervical spine. Treatment of injuries to the cervical remains a challenge. There is a dearth of literature on the long term outcome of management of cervical spine injuries.

Epidemiology and mechanism of injury

Cervical spine injuries are not uncommon in patients with blunt trauma. Goldberg et al [1] reported a 2.4% incidence of cervical spine injury in patients with blunt trauma and Hasler et al [2] reported a 2.3% incidence of cervical fractures/dislocations in patients with major blunt trauma.

The Goldberg et al [1] study showed that the C2 vertebra was injured in 24% of the patients with cervical injuries (most common). The second most commonly fractured vertebrae were the C6 and C7 vertebrae with a combined incidence of 39.3% of all cervical injuries. The vertebral body was the most common site of fracture. About one third of the injuries were considered clinically insignificant.
Cervical spine injuries constitute between 19% and 51% of all spinal injuries [3,4]. The incidence of cervical spine injuries peak between the ages of 20 to 45 years and 70 to 80 years [5]. The incidence of cervical spine injuries increase with age and male gender and age older than 64 years are risk factors [5]. The mortality rates for cervical spine injuries is the highest as compared to injuries in other parts of the spine because cervical spine injuries have a higher rate of cord injury [6].

The most common cause for the cervical spine injury is motor vehicle accidents which accounts for about half of the injuries. Falls from a height of less than 2 meters account for 20% of all injuries and sports injuries also play an important role in these injuries [2].

Classification of upper cervical spine injuries

The anatomical difference allows classification of cervical spine injuries into two i.e the upper cervical spine (occiput to C2) and the lower cervical spine (C3 to C7).

Classification of upper cervical spine injuries

Fractures of the upper cervical spine include fractures of the occipital condyle and fracture dislocations of C1 and C2 including the odontoid process.
Fractures of the occipital condyles are rare and are often classified according to a classification by Anderson and Montesano [7].They differentiated occipital condyle fractures into three types:

Type 1: Impression fractures of the occipital condyle (usually stable);

Type 2: Skull base fracture extending into the occipital condyle (usually stable);

Type 3: Avulsion fracture of the occipital attachment of the Alar ligament (potentially unstable).

Several classification systems are available for classification of C1 (Atlas ) fractures. The commonly used ones include the Jefferson classification [8], and the Gehweiler classification [9].

According to the Jefferson classification there are 4 types of fractures of the Atlas:
Type 1 = Fracture of the posterior arch alone
Type 2 = Fracture of the anterior arch alone
Type 3 = Fracture of both the posterior and anterior arches (also known as a burst or Jefferson's fracture)
Type 4 = Fracture of the lateral mass or masses of C1

The Gehweiler classification has five sub-groups of atlas fractures :
Type 1: Isolated fracture of the anterior arch
Type 2: Isolated (usually bilateral) fracture of the posterior arch
Type 3: Fracture of the anterior and posterior arch of the atlas (Jefferson fracture’).
Type 3A: Stable injuries with intact transverse atlantal ligament
Type 4: Fractures of the lateral mass
Type 5: Isolated fractures of the C1 transverse process.

The Odontoid fractures are usually classified according to a classification by Anderson/D’Alonzo [10]. There are 3 types of odontoid fractures:
Type 1: Fracture of the tip of the odontoid peg (rare)
Type 2: Fracture through the base of the odontoid peg (usually unstable) Type 3: Fracture through the base of the odontoid peg which runs in a u- or v-shape through the body of the axis (usually stable).

The commonly used classification for fractures of axis is the one by Effendi et al.[11] which was later modified by Lewine and Edwards [12]. The modified classification has five types.

Type I: Fracture of the pedicles, intervertebral disc C2/3 is intact, dislocation ≤3mm without angulation
Type IA: Fracture lines on each side are not parallel and the fracture line may involve foramen transversarium on one side
Type II: Fracture of the pedicles with more than 3mm dislocation and/or angulation with involvement of the C2/3 disc
Type IIA: Oblique fracture - anterior-inferior to posterior-superior with more angulation and some subluxation
Type III: Type II with C2/3 vertebral joints luxation. The posterior arch is free floating.
A locked C2-C3 facet joint constitutes a type III lesion.

Atlanto-Occipital dislocations or dissociations (AOD) are severe injuries with high fatality rates. The commonly used classification for these injuries is the one by Traynelis. The Traynelis classification [13] divides AOD into 3 types:
Type I: Anterior displacement of the occiput relative to the atlas
Type II: Distraction of the occiput from the atlas
Type III: Posterior displacement of the occiput relative to the atlas.

Powers’ ratio [14] is often used to diagnose anterior dislocation injuries. It compares measurements between the skull base and C1. The distance from the basion to the midpoint of the anterior cortex of the posterior arch of C1 is measured (X). The distance from the opisthion to the midpoint of the posterior cortex of the anterior arch of C1 is measured (Y). If X/Y exceeds 1, then AOD is suspected. Normal values are usually less than  0.9.

Classification of Lower cervical spine fractures

The widely used classification for lower cervical spine injuries is the one by the AO group. It divides lower cervical spine injuries into 3 types i.e type A, B, C based on the trauma mechanism.

A: compression
B: distraction
C: rotation

Type A compression injuries are further subdivided into type A.1  =  impaction; A.2  =  split; A.3  =  burst.
Type B distraction injuries are further subdivided into  B.1  =  posterior distraction with vertebral body intact; B.2  =  posterior distraction + fracture of the vertebral body; B.3  =  anterior distraction + hyperextension.
Type C rotation injuries are subdivided into C.1  =  unilateral facet fracture-dislocation; C.2  =  unilateral facet dislocation; C.3  =  rotational shear injury of the joint mass.
To remedy a lack of consensus on classification of lower cervical spine injuries the Subaxial Injury Classification (SLIC) Scale was created (15).This classification takes into account  morphology; status of the disco-ligamentous complex and neurological assessment.

Table 1. Subaxial Injury Classification (SLIC) scale.

                                                                                                                        Points
Morphology
No abnormality                                                                                              0
Compression + burst                                                                                1 + 1  =  2
Distraction (e.g., facet perch or hyperextension)                                               3
Rotation or translation (e.g., facet dislocation, unstable teardrop,
or advanced-stage flexion-compression injury)                                               4

Disc-ligamentous complex
Intact                                                                                                                0
Indeterminate (e.g., isolated interspinous widening or
MRI signal change only)                                                                                       1                                                                                                     
Disrupted (e.g., widening of the anterior disk space or facet perch
 or dislocation)                                                                                                       2                                                                                              

Neurological status
Intact                                                                                                               0
Root injury                                                                                                        1
Complete cord injury                                                                                        2
Incomplete cord injury                                                                                        3
Continuous cord compression (neuro-modifier in the setting
of a neurological deficit)                                                                              + 1

Based on the above parameters, scores are assigned to each injury. Patients with a score lower than 4 will need nonsurgical treatment and patients with higher then 4 will require surgical treatment. Patients with a score of 4 can be treated surgically or nonsurgically depending on the experience of the surgeon.

Radiographic Assessment

AANS/CNS Joint Guidelines recommend the following in the guidelines for radiographic assessment of patients with cervical spine injuries [15].

Awake, Asymptomatic Patient
Level 1 evidence
     • In an asymptomatic patient who is awake and has no neck pain and
       tenderness and in whom the neurological examination is normal and
       the range of cervical movement is normal, radiological assessment is
       not recommended   
    • Discontinuance of cervical immobilization is recommended in these
      patients without cervical spine imaging.

   2.  Awake, Symptomatic Patient
       Level I evidence
     • In a symptomatic awake patient, high-quality computed tomography
      (CT) imaging of the cervical spine is recommended.
     • When high-quality CT imaging is available, routine cervical spine
       radiographs are not recommended.
     • In situations where high-quality CT imaging is not available, 3-view
       cervical spine radiographs are obtained (anteroposterior, lateral, and
       odontoid views). The radiographs can be supplemented with CT (when
       it becomes available) if necessary for better visualization of suspicious
      Areas.

   3. Obtunded or Unevaluable Patient
      Level I evidence
    • In a obtunded or unevaluable patient, high-quality computed
      tomography (CT) imaging of the cervical spine is recommended.
     • When high-quality CT imaging is available, routine cervical spine
       radiographs are not recommended.
     • In situations where high-quality CT imaging is not available, 3-view
       cervical spine radiographs are obtained (anteroposterior, lateral, and
       odontoid views). The radiographs can be supplemented with CT (when
       it becomes available) if necessary for better visualization of suspicious
       areas

Important radiographic measures

1.Cranio-cervical interval (CCI)

Although there are several radiographic parameters available for occipital-cervical instability, the one with the best sensitivity and specificity is the revised CCI (rCCI), developed by Pang et al [17]. The distance between the occipital condyle and the facet joint surface of the atlas lateral mass is measured in the sagittal plane and if the value exceeds 2.5 mm, an unstable lesion is most likely present.

2.The anterior atlanto-dental-interval (aADI)
The aADI detects translatory instability due to lesions of the transverse atlantoaxial ligament. The distance between the anterior cortex of the odontoid peg and the posterior cortex of the anterior ring of the atlas is measured. In adults, any value greater than 3 mm is regarded as abnormal.

3.Facet joint overlap
Overlap of facet joint surfaces of two neighbouring articular processes in the lower cervical spine, can indicate the presences of instability in the facet joints. An overlap of less than 50% of the length of the articular process indicates instability.

4.Prevertebral soft tissue

Prevertebral soft-tissue swelling is an indirect sign of cervical spine injury. The mnemonic ‘six at two, twenty-two at six’ has been widely used to remember normal values for prevertebral soft-tissue thickness at the second and sixth cervical vertebra. The normal thickness of the prevertebral soft tissue in front of C2 is 6mm and in front of C6 is 22mm. The prevertebral soft-tissue thickness has good specificity but very low sensitivity [18].

Management of cervical spine injuries

Steroid protocol

Methylprednisolone sodium succinate is often administered if a patient with cervical spine injury presents within 8 hours of injury. A bolus dose of 30mg per kg is administered over 15 minutes and an infusion of 5.4mg per kg per hour is maintained over the next 23 hours. This regime has been shown to  improve neurologic outcome up to one year post-injury.

In patients whom the steroid cannot be administered within 8 hours  methylprednisolone therapy can be given for an additional 24 hours (a total of 48 hours). This therapy has been shown to provide additional improvement in motor neurologic function and functional status [19].

A Cochrane database systematic review by Bracken [19] showed that high-dose methylprednisolone steroid therapy is the only pharmacologic therapy which has been shown to have efficacy in a phase three randomized trial when administered within eight hours of injury. Another trial found additional benefit of extending the maintenance dose from 24 to 48 hours, if there has been a delay in start of treatment beyond 8 hours.

Literature review did not show evidence of a significant increase in complications or mortality from the 23 or 48 hour therapy.

Cervical spine injury treatment and management principles 

The main principles of treatment include decompression of compressed neurological structures, restoration of vertebral column integrity, prevention and management of complications, and facilitation of rehabilitation [20].

Many patients with cervical spine injuries can be treated nonoperatively. Options for conservative treatment include use of a cervical orthosis or  rigid stabilisation with a halo jacket.

In patients with displaced cervical spine injury a closed reduction is carried out except in patients Hangman’s type, IIA fracture. In the Hangman’s type, IIA fractures, traction can further displace the fracture and increase the risk of spinal cord injury.

It is safe to treat, displaced Jefferson fracture, Hangman’s fracture, type II/type III odontoid peg fracture, displaced subaxial fracture and subaxial subluxations and dislocations, by traction [20].

Lee et al [21] carried out a study involving 210 patients with unilateral and bilateral facet dislocations. They found that rapid traction under sedation using weights upto 150 pounds was safer than carrying out manipulation under anesthesia. They also found that early reduction of the dislocation in patients with neurological deficit gave them the best chance of neurological recovery.

Surgical management

Surgery is usually indicated in patients when a close reduction has failed, in patients with unstable injuries, when there is bilateral facet dislocation of more than 25% or 11°. Progressive neurological deterioration would be another indication for surgery. Kyphosis of 30° or more or loss of vertebral height of more than 50% is often associated with a high incidence of late complications, and this situation may warrant surgical intervention. Late instability and severe post traumatic kyphosis may warrant surgical intervention [20].

In patients with partial neurological injury early surgical intervention is usually recommended. There is some evidence that early surgical intervention (less than 24 hours) is safe and effective, and even in patients where delayed decompression was carried out there can be some neurological recovery [22,23].

Some have claimed that 70% of patients with partial spinal cord injury improve one grade or more (American Spinal Injuries Association, International Medical Society of Paraplegia grades) if the surgery is carried in less than 6 hours after the injury [24]. When surgery is carried out after 6 hours only 12% of the patients show improvement. In patients with a complete spinal cord injury the chances of neurological recovery is poor.

Decompression and/or stabilised of the cervical spine can be carried out via the anterior, posterior or a combination of both approaches, depending on the type of injury.The clinical success rates are higher with the anterior approach though the anterior approach is biomechanically inferior to the posterior approach [20].

Long term outcome of cervical spine injury treatment

There is a dearth of literature on the long term outcome of management of cervical spine injuries. The largest study with a long term follow up is the one by Fredø et al [25]. They followed up 256 patients with subaxial cervical spine injuries who were treated surgically. The mean follow-up period was 3.1 years with range of 0.5–9.0 years. None of their patients had neurological deterioration after the surgery.

In patients who were operated within 24 hours, 48.8% showed improvement of their neurological grades whereas in patients operated after 24 hours 53.1% showed improvement in their neurological grades. The improvement in AIS (American Spinal Injury Association impairment scale) grades between the two groups were not significantly different (p = 0.442). Of the patients with preoperative radiculopathy 11 % of the patients continued to have radicular symptoms. There were four patients who developed radiculopathy after surgery, three of these patients were asymptomatic at the follow-up.

Neck pain was assessed using the Visual Analog Scale (VAS). They found that the median VAS score for neck pain was 1 (range 0–10). Eighty percent of the patients had VAS scores ≤3, 15 % had VAS scores 4–6, and 5 % had VAS scores ≥7. There was no significant association between the surgical approach and neck pain [25].

They found that 26% of the patients had no neck stiffness, 63% had mild neck stiffness and 11% had severe neck stiffness. Neck stiffness was more common in patients who had fusion with posterior screw fixation.

Six percent of patients sustained hoarseness and 9% developed dysphagia after surgery.
Of the 256 patients who were followed up with cervical CT scans, 98.4 % had a stable fusion, 0.4 % had a secondary loss of alignment, and in 1.2 % of the patients there was loosening or fracture of their fixation device [25].
In this study the surgical mortality (death within 30 days after surgery) was 2.3 %.

Conclusion

Cervical spine injuries are not uncommon in patients with blunt trauma.
Cervical spine injuries constitute between 19% and 51% of all spinal injuries. Mortality rates for cervical spine injuries is the highest as compared to injuries in other parts of the spine because cervical spine injuries have a higher cord injury rates. Broadly, cervical spine injuries can be divided into two, namely, the upper cervical spine (occiput to C2) injuries and the lower cervical spine (C3 to C7) injuries.

There are several classifications available for both the upper and lower cervical spine injuries which help in the management of these patients. Radiological examination, including X rays and CT scans, is the main diagnostic tool used in patients with cervical spine injury.

Patients who present within 8 hours are given 23 hours of steroid therapy and those who present later can be given 48 hours therapy. Steroid therapy has been shown to improve the neurological outcome.
The main principles of treatment include decompression of compressed neurological structures, restoration of vertebral column integrity, prevention and management of complications, and facilitation of rehabilitation. Many patients with cervical spine injuries can be treated nonoperatively.
Surgery would be indicated in patients when a close reduction has failed, in patients with unstable injuries and when there is bilateral facet dislocation of more than 25% or 11°. Progressive neurological deterioration and kyphosis of 30° or more or loss of vertebral height of more than 50% may be other indications for surgical intervention.

Despite the presences of a lot of literature on cervical spine injuries, there is a dearth of literature on the long term outcome of management of cervical spine injuries.

References

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