Trauma to the cervical spine encompasses a wide spectrum of injury, ranging from muscular strain, capsular or ligament sprain/tear, to facet subluxations or dislocations with or without fracture. Cervical dislocations have classically been associated with traumatic spinal cord injuries. These injuries can cause spinal cord compression and dramatic neurological deficits, and the severity of the injury is dependent upon multiple factors. These can include the force applied to cause the injury, the extent of damage to the stabilizing osseous and soft tissue structures of the cervical spine, patient age, syndromic issues, bone quality, and underlying patient comorbidities.
- The cervical spine consists of 7 vertebral bodies. C1 (atlas) articulates with the occiput and C2 (axis), which is considered the axial spine, and from C2-C7, which is considered the sub-axial spine. From C2-C7, the cervical spine has a resting lordotic curve. These structures function to provide physiological motion and protect neural elements. The spine can be broken up into 3 distinct columns, each contributing to cervical stability. The anterior column consists of the anterior longitudinal ligament (ALL), and the anterior two-thirds of the vertebral body and disc. The middle column consists of the posterior longitudinal ligament (PLL), posterior one-third of the vertebral body and disc, and the posterior vertebral wall. The posterior column consists of the pedicles, lamina, spinous process, and the posterior ligamentous complex (PLC). The PLC is considered to be a critical predictor in spinal stability, and this includes the ligamentum flavum, facet joint/capsule, interspinous ligament, and the supraspinous ligament. In the setting of a traumatic event, the osseous and soft tissue structures injured will determine the stability of the cervical spine and the treatment needed.
Cervical dislocations have a bimodal distribution, and the mechanism of injury varies depending on the patient's age. Younger patients are typically associated with a more high injury mechanism, such as a motor vehicle collision. While elderly patients are more commonly associated with low injury mechanisms such as a ground-level fall. Facet joint dislocations can be purely ligamentous or accompanied by fracture depending on the mechanism of injury. Facet dislocations are typically caused by a flexion-distraction event at the time of injury and located in the subaxial spine. Hyperflexion creates a distraction force that causes failure of the posterior osseous/ligamentous structures to fail in tension, and a rotation/shear force will cause fracture or dislocation.
Cervical dislocations can occur in two locations; axial, consisting of the occipitocervical (occiput/C1) and atlantoaxial articulation (C1/C2), and subaxial, which includes from C2/C3 to C7/T1. Acquired instability causing dislocations can occur in the axial spine and can be seen in the pediatric population. However, The majority of these dislocations are secondary to a traumatic event, and about 75% occur in the subaxial spine. Most subaxial dislocations are associated with males, high energy mechanisms in younger patients, such as a motor vehicle collision. However, cervical dislocations are commonly associated with low energy mechanisms in the elderly population, such as a fall from standing height. Special consideration should be given to the pediatric population in the setting of cervical trauma due to the increase in the likelihood of spinal cord injury and lethality associated with cervical trauma. Patients younger than 8 years old are more susceptible to cervical spine injury due to larger head size, weaker muscles, and increased ligamentous laxity.
Axial cervical dislocations can occur from traumatic or atraumatic etiologies. Atraumatic or acquired occipitocervical instability is typically seen in patients with Down syndrome and is rarely symptomatic. Traumatic occipitocervical dislocation is a severe injury in which patients rarely survive because of brainstem destruction. Atlantoaxial dislocation typically occurs from degenerative conditions such as rheumatoid arthritis, Down syndrome, or via trauma from odontoid fractures (C2), atlas fractures (C1), or transverse ligament injury.
In the setting of trauma, cervical dislocations may lead to compression and injury to the spinal cord. The primary injury to the cord occurs by damaging the neural tissue from direct trauma. The secondary injury to the spinal cord can be as important, or more important than the initial injury. The secondary trauma comes from injury to the adjacent tissue/structures, and this leads to an abundant inflammatory response causing decreased local perfusion, cytokine release, apoptosis, lipid peroxidation, and hematoma formation. Steroids are used to try and prevent this secondary injury by improving perfusion and decrease free radical formation leading to decreased inflammation. Two common associated conditions with acute spinal cord injury that one should always be cognizant of are spinal shock and neurogenic shock. Neurogenic shock can lead to bradycardia and hypotension due to decreased sympathetic outflow, which can further potentiate spinal cord injury due to hypoperfusion.
History and Physical
The key to proper treatment in cervical spine trauma is early diagnosis and management. Unfortunately, in the setting of blunt trauma, physical exam alone is unreliable to diagnose or exclude cervical spine injury. Therefore, a thorough understanding of the mechanism of injury, neurological exam, and proper imaging is imperative. If trauma to the head and neck is expected, the cervical spine must be immobilized to prevent the risk of secondary injury to the spinal cord. This is accomplished with the use of a rigid cervical collar, with the neck placed in a neutral position.
In the setting of any trauma evaluation, before the patient can undergo clinical and radiologic assessment, the patient must undergo a primary survey as per the Advanced Traumatic Life Support protocols. The first stage is to assess the airway and protect the cervical spine, followed by support of breathing, circulation, assessment of neurological status, and exposure. Once the patient is stabilized, a secondary survey can be performed. A detailed history and physical is needed to understand the mechanism of injury, any medical comorbidities that can predispose the patient to have a higher likelihood of spinal injury, and to determine if there are any other axial injuries of the spinal column or distracting injuries in the extremities.
A thorough neurological exam is vital at the time of presentation to assess and document the patient's baseline. Periodic reexaminations should be performed and compared to the patients' baseline to determine any improvement or deterioration. Assessment using the American Spinal Injury Association (ASIA) spine exam is classically used to assess a patient's neurological status by examining key motor groups, sensory, digital rectal, and reflex examination. With cervical spine trauma, patients can present with unilateral upper extremity symptoms indicating a nerve root injury, or bilateral upper extremity and lower extremity symptoms, indicating a spinal cord injury. To obtain an accurate ASIA exam, you must first determine if the patient is in spinal shock. Spinal shock is defined as a temporary loss of spinal cord function and reflex activity below the level of spinal cord injury. This is done by first assessing if the bulbocavernosus reflex is present, this reflex is characterized by the anal sphincter contraction in response to squeezing the glans penis in a male or clitoris in a female, or by tugging on the foley catheter. The absence of this reflex indicates that the patient is in spinal shock, which could last from 24 to 72 hours. Therefore, once the patient is no longer in spinal shock, then an accurate neurological exam can be obtained.
Listed below are key exam findings associated with neurologic injury:
Occiput/C1: The occiput is in close proximity to the lower cranial nerves (CN).
CN-IX (glossopharyngeal), CN-X (vagus nerve): Test gag response, uvula deviation away from the affected side.
CN- XI (spinal accessory nerve): Test the ability to shrug shoulders (trapezius innervation), and turn head from side to side (Sternocleidomastoid).
CN-XII (hypoglossal nerve): Test the ability to stick out tongue and move from side to side, look for fasciculations
C4: Injury to this nerve root can present with deficits in scapular stabilization with scapular winging, as it primarily innervates serratus anterior.
C5: Injury to this nerve root can present with deficits in shoulder abduction and elbow flexion (palm up), as it primarily innervates the deltoid and the biceps muscles. Also, sensory deficits in the lateral arm and below the deltoid, and an abnormal biceps reflex.
C6: Injury to this nerve root can present with deficits in elbow flexion (thumbs up) and wrist extension, as it primarily innervates brachioradialis and extensor carpi radialis longus. Also, sensory deficits in the thumb and radial hand and an abnormal brachioradialis reflex.
C7: Injury to this nerve root can present with deficits in elbow extension and wrist flexion, as it primarily innervates the triceps and flexor carpi radialis. Also, sensory deficits in fingers 2, 3, 4, and an abnormal triceps reflex.
C8: Injury to this nerve root can present with deficits in finger flexion, handgrip, and thumb extension, as it primarily innervates flexor digitorum superficialis, flexor digitorum profundus, and extensor pollicis longus. Also, sensory deficits in the small finger.
T1: Injury to this nerve root can present with deficits in finger abduction, as it primarily innervates the hand interossei muscles. Also, sensory deficits in the medial elbow.
Standard imaging protocol consists of plain radiographs, computed tomography (CT) scan, and magnetic resonance imaging (MRI) scan. Three views, AP, lateral, and open mouth odontoid plain films, are used during a standard trauma evaluation. The plain films must contain the entire cervical spine, including the C7-T1 junction. Up to 17% of injuries in the cervical spine occur at C7/T1 junction, and this makes it imperative to see T1 when assessing cervical trauma. Therefore, if not visualized on the standard 3 view series, a swimmer's view can be obtained. These can be used to assess the cervical alignment on the lateral radiograph. Signs of cervical facet dislocation can include vertebral body subluxation compared to the vertebral body below. This can be seen with reversal or loss of the normal cervical lordosis using the 4 parallel lines of the cervical spine. Unilateral facet dislocation can lead to about 25% subluxation, and bilateral facet dislocation can lead to about 50% subluxation. Loss of disc height might indicate a retropulsed disc in the canal. CT scan is rapidly becoming the standard of care for imaging in the initial trauma evaluation due to its superior sensitivity and ability to better assess osseous anatomy compared to X-rays, especially at the cervical-thoracic junction (C7/T1).
Listed below are specific radiographic features seen on CT that could indicate cervical instability and dislocations:
- Occipitocervical dislocation: Power ratio is frequently used to determine instability. This is calculated by measuring the distance from;
basion to posterior arch / anterior arch to opisthion
- A ratio of approximately 1 is considered normal, greater than 1 consider anterior dislocation, less than 1 consider posterior dislocation
- Another commonly used measurement is Harris's rule of 12. This is the distance from the basion to the tip of the dens, greater than 12 mm suggests occipitocervical dissociation.
Sub Axial Spine
- Facet dislocations are best appreciated in the sagittal plane. It is key to examine the sagittal CT scan to examine the mid-sagittal and parasagittal cascade of the anterior vertebral column, posterior vertebral column, spinolaminar line, and the interspinous line. These lines should be smooth and continuous. In the axial plane, the facet joints resemble hamburger buns, with the flat portions articulating.
- Signs of dislocation can include; facet joint diastasis/dislocation, and translation of the vertebral body compared to vertebrae below on the sagittal plane. 'Reverse hamburger bun' sign seen on the axial plane.
MRI scans are extremely sensitive in detecting disc herniations and injuries to the spinal cord, nerve roots, and the posterior ligamentous complex (PLC). However, they are not as accurate in assessing osseous anatomy when compared to CT scan. Therefore, an MRI scan is only recommended in patients with an abnormal neurological exam, or in the unconscious or intoxicated patient where a spinal cord injury is suspected.
Treatment / Management
A cervical orthosis is only indicated for cervical facet fractures without significant subluxation, dislocation or kyphosis, or poor operative candidates. Typically these injuries occur due to a traumatic event and require some form of operative stabilization.
The use of high dose methylprednisolone (30 mg/kg bolus, followed by 5.4 mg/kg infusion) within 8 hours of presentation has classically been the standard of care for acute spinal cord injury after the National Acute Spinal Cord Injury Studies (NASCIS). However, in recent years the use of high dose steroids has shown to increase respiratory infection rate and gastrointestinal hemorrhage. Steroids are still used today in the setting of cervical trauma mainly for medicolegal issues, and at significantly lower doses.
Unilateral or bilateral facet dislocations are almost always treated with surgical management. For the facets to dislocate, the PLC must be injured, and instrumentation is required to stabilize the spine. Typically, stabilization is obtained by instrumentation of at least 1 level above and below the levels of injury. However, a longer fusion construct could be recommended when multiple levels are involved.
Immediate Closed Reduction, then MRI and Surgical Stabilization
- This procedure is done in the awake and cooperative patient with a unilateral or bilateral facet dislocation that has neurological deficits. This is performed by inserting cranial tongs with axial traction by adding weights. The weight of traction depends on patient size and level of dislocation. Generally, the weight applied is 10 lbs (for the weight of the head) followed by an additional 5 lbs per level, with a component of cervical flexion and rotation to aid in reduction. For example, a C6 dislocation would require about 40 lbs of weight (10 lbs for the head + 30 lbs for the C6 level). More weight is added as needed, and the weight can not exceed 100 lbs. Serial neurological exams and plain lateral radiographs after the addition of each weight. If the neurological exam worsens, remove all weight, and emergent MRI must be performed. Always obtain MRI after reduction to determine the best approach for surgical stabilization.
Immediate MRI, Followed by Open Reduction and Surgical Stabilization
- In a patient with facet dislocations with mental status change or is uncooperative, and patients who fail closed reduction.
Anterior Open Reduction and Anterior Cervical Decompression and Fusion (ACDF)
- Indicated when MRI demonstrates cervical disc herniation with significant anterior spinal cord compression.
- Open reduction performed using Caspar pins to distract vertebral bodies and adding rotation.
- It can be used for unilateral facet dislocations, not as effective in reducing bilateral facet dislocations.
Posterior Reduction and Instrumented Stabilization
- Indicated when unable to reduce by closed or anterior approach and no anterior spinal cord compression from a herniated cervical disc.
- Classically performed with lateral mass screws
Combined Anterior Decompression and Posterior Reduction or Stabilization
- Indicated when cervical disc herniation is present that requires decompression in a patient that can not be reduced through closed or open anterior technique.
- The anterior approach first to perform discectomy and decompression. Then posterior approach to perform reduction and instrumentation.
Deep Venous Thrombosis Prophylaxis
- Patients have a high-risk factor for deep venous thrombosis (DVT)
- Immediate use of compression devices and starting chemical prophylaxis as soon as possible and deemed safe by operating surgeon
- Hypotension should be avoided to prevent hypoperfusion to the spinal cord.
- Blunt neck trauma
- Cervical fracture
- Spinous process
- Transverse process
- Cervical strain
- Penetrating neck trauma
- Spinal cord injury
- Spinal shock
Complete spinal cord injuries can be expected to improve one ASIA grade in about 80% of patients, two grades in about 20% of patients, and complete recovery in about 1% of patients at the time of hospital diagnosis. Prognosis primarily depends on neurologic status at first presentation, and time to surgical decompression and stabilization.
Below are examples of the level of injury and corresponding functional status:
C1-C4: Ventilator dependent, will need an electric wheelchair with head and chin control
C5: Ventilator independent, has biceps and deltoid function, can flex elbow but lacks wrist supination and extension (unable to feed oneself). Use an electric wheelchair with hand control. They can perform independent activities of daily living (ADLs).
C6/C7: Ability to bring the hand to mouth because of intact wrist extension and supination (able to feed oneself). Independent living, use a manual wheelchair, and can drive with manual controls.
C8/T1: Improved hand and finger strength/dexterity, independent transfers.
Complications from surgical intervention include:
- Vertebral artery and carotid injury
- Recurrent laryngeal, superior laryngeal, and hypoglossal nerve injuries
- Horner syndrome
- Adjacent segment disease
- Skin problems: These typically occur in tetraplegic or quadriplegic patients, treatment is prevention, skincare, frequent turning.
- Major depressive disorder: common in patients after spinal cord injury can be associated with suicidal ideations. Must educate and preemptively treat patients in the acute and chronic setting.
- Venous thromboembolism: Occurs from venous stasis, can reduce risk with immediate anticoagulation, sequential compressive devices, early ambulation if able.
- Urosepsis: Common in patients with loss of bladder control, can reduce with strict aseptic technique when placing catheters, do not let bladder become overdistended as this increases the risk of urinary tract infections.
Enhancing Healthcare Team Outcomes
The management of cervical dislocations is challenging and complex. Proper diagnosis and treatment require an interprofessional team of healthcare professionals that includes emergency room physicians, nurses, radiologists, and an orthopedic spine surgeon or neurosurgeon. Without proper management, the morbidity and mortality of cervical dislocations can be very high. The moment the patient with suspected cervical trauma hits the door, the emergency room physician is responsible for coordinating care, which includes:
- Immobilization of C-spine in a rigid collar in a neutral position
- Performing ATLS protocols in the unstable patient
- Monitoring the patient for signs of symptoms of mental status change, respiratory depression, rapidly declining neurological exam
- Monitoring for hypotension and bradycardia associated with neurogenic shock
- Obtaining proper initial imaging of the cervical spine
- Consulting with the orthopedic spine surgeon or neurosurgeon
If the patient presents with spinal cord injury and neurologic deficits, early time to reduction, decompression, and/or stabilization, leads to improved outcomes. In the postoperative period, the role of the nurse, physical therapy/occupational therapy, and social work team are critical. The nurse will assist the team in monitoring the patient's neurological status, pain, wound drainage, and frequent offloading to prevent pressure ulcers. The physical therapy/occupational team will aid in early ambulation, range of motion of the extremities, isolated strength training, gait training, and teaching how to perform activities of daily living. The social worker will help to properly arrange and coordinate the patient's needs relating to equipment and physical therapy at home or a rehab facility. Additionally, a consultation with a psychiatrist and psychologist to aid in the diagnosis and prevention of mental health disorders associated with these patients. Therefore, only by working as an interprofessional team can we better diagnose, improve prognosis, and overall survival from neurologic injury.