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Cervical spine fractures

Nanfang Xu

Description

Cervical spine fractures, commonly known as ‘broken neck’, typically happen in high-energy traumas such as motor vehicle accidents, and account for the majority of fractures of the spinal column, as the cervical spine represents the part of the spine that is the most mobile and the most vulnerable to injury. While spinal cord involvement is often associated with significant morbidity and mortality, a few lucky patients with undisplaced cervical spine fractures will have no serious neurologic complications.  

Structure and function

Cervical spine fractures are typically classified into two groups according to their distinct anatomies: upper cervical spine (including the occiput, atlas (C1), and axis (C2)) and lower cervical spine (consisting of C3-C7). The osseoligamentous structures of the ­­upper spine are commonly referred to as the craniocervical junction (CCJ) and are anatomically and functionally different from the subaxial cervical spine (C3-C7), the motion segments.

The soft tissues contents surrounded and protected by the bony structure include the brainstem, cranial nerves CN IX, X, XI, XII, the high cervical spinal cord, the vertebral artery and internal carotid artery for the high cervical spine, and the spinal cord, nerve roots, and vertebral arteries for the subaxial spine. These neurovascular components are of utmost importance in the evaluation and treatment of cervical spine injuries.   

Epidemiology

Cervical spine injuries occur in 3% to 4% of all trauma patients.  Injuries to the upper cervical spine peak in children (due to motor vehicle accidents) and those older than 60 years of age (due to fallings), while subaxial cervical injuries are more prevalent among adults between these two age groups. High-energy traumas, especially when occurring in conjunction with head injury, often lead to a high rate of neurologic injury and mortality. 

 

Clinical presentation

Cervical injuries show a wide spectrum of clinical presentation depending on the underlying neurologic lesions involved. A complete spinal cord injury secondary to a CCJ trauma would present as quadriplegia with respiratory muscle paralysis, rendering the patient ventilator-dependent. Owing to its proximity to the cardiovascular and respiratory centers in the brainstem , injuries to this region of the spine can be accompanied by large variations in vital signs and also dysfunction of the lower cranial nerves (also seen in skull base injuries). A particular form of partial paralysis called 'cruciate paralysis' has been associated with upper spine injury when there is compression on the pyramidal decussation and the crossed arm fibers and the uncrossed leg fibers of the corticospinal tracts are involved. If only the upper decussation is involved, then the clinical finding mimics that of central cord syndrome. Sensory deficit in the occipital area may be seen when C1 and C2 roots are injured. Injuries to the lower cervical spine usually present with typical dermatomal distribution of motor and sensory deficits in the upper extremities- C5 for biceps, C6 for wrist extension, C7 for triceps, C8 for finger flexion, and T1 for finger abduction. Hyperreflexia, clonus, Babinski signs, and Hoffmann signs indicate spinal cord compression, although areflexia is common initially in an emergency injury. Perineal function may be absent in the acute phase following the injury (as seen in spinal shock), but if it does not return in several days, the prognosis for the patient is grave. 

Red flags

  • The majority of trauma to the CCJ is not accompanied by neurologic deficit. But a high index of suspicion is necessary for the early diagnosis and optimal treatment of these potentially devastating complications!
  • All blunt trauma patients should be assumed to have cervical spine injury until prove otherwise! 
  • Incomplete cord injuries (those with some sensory or motor function) have a significantly better prognosis!
  • Perineum examination important as predictor of prognosis!  

Differential diagnosis

Cervical spine clearance, a systematic process for ruling out neurologic injury (so that collar immobilization can be removed), is elaborated in this article. A complete neurological examination following the American Spinal Injury Association standard, should be done multiple times to record the deterioration and recovery of the neurological functions. According to this standard, the level of spinal cord injury is defined as the level of the lowest nerve root with a motor function no less than grade 3. The overall impression of the spinal cord impairment is determined using the modified Frankel (ASIA) scale: A-motor and sensory complete; B-motor complete with sensory sparing; C-motor and sensory sparing but not functional strength; D-motor and sensory sparing with functional strength; E-normal motor and sensory.In addition to the spinal trauma, concurrent damages to other parts of the body (face, head, and non-contiguous spine regions) should be carefully assessed. Brain damage, subarachnoid haemorrhages, subdural haemorrhages, and cerebral contusions call for special attention and must be expeditiously treated when present, as they may significantly change the treatment plan of the cervical lesion as well as the clinical outcome of the patient. Vertebral artery injury also needs to be ruled out in any patient suspected of cervical spine trauma. Even though most cases are clinically silent, bilateral or dominant vertebral artery injury can lead to ischemic damage to the brainstem and cerebellum, while delayed cortical blindness and recurrent quadriparesis are possible sequelae of occult vertebral artery. Acute hemorrhage of the spinal cord itself, when present, usually does not bode well for a neurological recovery.  

Objective evidence

Plain X-ray remains the first imaging modality for the cervical spine. An anteroposterior view, a lateral view, and an open mouth view constitute the standard series for high cervical spine injury. A lateral view is evaluated for the sagittal alignment of the spine. It’s also useful for assessment of prevertebral soft tissue swelling; though not specific for cervical injury, this is evident of severe ligamentous injury in the upper cervical spine. Computed tomography (CT) is the most sensitive imaging modality for complex fracture structures, even more so with the additional benefit of coronal and sagittal reconstruction. CT scan has been shown to be cost-effective for primary screening in high- and moderate-risk patients. The availability of intraoperative CT provides surgeons with more precise control over internal fixation than previously possible with fluoroscopic imaging. MRI is the imaging choice for soft tissues (the spinal cord, the nerve roots, the ligaments, the disc, etc.) in the cervical spine. Different MRI modalities can have been used for different purposes: T2-weighted images have been used to detect acute hemorrhage; diffusion studies have been used for assessment of spinal stenosis, and the latest MRI neurography even provides visualization of nerve roots as they exit the spinal cord. 

Risk factors and prevention

People older than age 60 are more susceptible to cervical injuries due to minor trauma from falls. Most of these involve injuries to the C1-C2 complex. Possible explanations for this include osteoporosis/osteopenia at the CCJ, subaxial spondylosis causing increased stresses on the upper cervical spine, decreased locomotor function and balance control in the elderly. Each of these calls for different measures for prevention. Cervical injuries among paediatric and young adult populations are most commonly caused by vehicular accidents. 

Treatment options

Emergency medical care: All victims of trauma should be suspected of a cervical spine injury until proven otherwise and if confirmed, the treatment must be initiated at the scene of the injury. When high cervical injuries are suspected, nasotracheal intubation/cricothyroidotomy may be the safest in the acute setting, as other intubation techniques would involve more neck manipulation. This is usually followed by reduction and stabilization via Gardner-Wells tong traction in a Roto-Rest bed  which may reverse the neurologic injury if performed within a few hours of the injury, except for type II occipitoatlantal dislocations and type IIA hangman's fractures and also patients with skull fractures and distraction injuries across the disc space or cranially in the spine, for which it is contraindicated. 

Evaluation: The primary goal of treatment for these patients is to restore stability. Therefore, a classification system based on the stability of the cervical spine could be important in surgical decision making. The Cervical Spine Injury Severity Score (CSISS) has been shown to have a significant correlation with different surgical approaches: high CSISS score (>11) associated with posterior or combined approaches, and the average score for anterior approach patients is 6.3. Another example is the SLIC (Overall Subaxial Cervical Spine Injury Classification Score) score , which takes into consideration fracture morphology, disco-ligamentous complex and neurologic function in assessment of treatment decisions, where a score less than four is treated nonoperatively, a score greater than four indicates surgery, and a score of four can be treated either way.

Nonoperative treatment: The treatment of choice for the majority of cervical trauma patients with stable displacement. There are primarily four classes of cervical orthoses that can be used for that purpose: 1. Soft collar; 2. Hard collar; 3. Cervicothoracic orthosis (CTO); 4. Halo vest. Soft collars should only be used for patients with trivial injury in the cervical spine. Hard collars provide better stability especially for mid-cervical spine lesions. CTOs provide even better stability especially for injury near the cervicaothoracic junction, but patient tolerance is not as good as for collars. Halo vests are the most rigid of these four. However, they do not protect against axial loading and 'snake phenomenon' has been reported with their use. Anteroposterior and lateral upright radiographs are obtained once the orthosis is applied and the patient is mobilized. A follow-up at two weeks is required to compare the translation and angulation at the fracture displacement.

Surgical treatment: For patients with neurologic injuries and unstable injuries, surgeries are often necessary to maximize their neurologic recovery and stabilize the spine before bony healing can occur. The timing of surgical procedures in this setting remains controversial until today. Early (<24 hours) decompression surgeries are held by some to be beneficial for neurologic recovery and potentially associated with fewer complications and shorter hospitalization, but again these are all inconclusive results. Two general surgical approaches are commonly used, and the decision as to which one to choose for a specific case depends on many factors with the location of the neural compression, the bony structures needed for internal fixation being the most important. Each of the two approaches has its advantages and disadvantages. The anterior approach gives direct access to the underlying pathology without disrupting the weight-bearing structure of the spine, but involves potential damage to the important neuro-vasculatures and is hard to be extended cranially and caudally. The posterior approach is basically the opposite of the previous approach, with perhaps higher infection rate and greater muscle dissection. Although quite uncommon, there are cases where there are anterior and posterior neural compression and a combined approach is warranted.  

Outcomes

As a result of better initial care at the acute setting, earlier diagnosis, improvement over life-support and surgical techniques, we have witnessed a trend toward positive outcome for spinal cord injury patients over the past forty years. However, there has been no conclusive study comparing the outcome of the anterior approach vs. the posterior approach.   

 

Miscellany

  • Always evaluate the head CT for potential fractures before halo pin placement.
  • Vascular anomalies are often seen when congenital bony malformation is present- pre-op CTA/MRA may be needed for exclusion.
  • Seemingly benign lesions may occur with occult ligamentous injuries that reduces stability and lead to neurologic dysfunction. 
  • Early surgery is recommended if there is indication.
  • The choice of surgical approaches primarily depends on the need for decompression. 

Key terms

  1. cervical spine/cord injury
  2. modified Frankel (ASIA) scale 
  3. CSISS, SLIC
  4. anterior/posterior/combined approach 

Skills

  • Evaluation of patients with cervical trauma in an acute setting.
  • Examination a patient with spinal cord injury and interpretation of the result.
  • Choice of the most suitable treatment modality for a patient with cervical spine injury

References

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