Residency · Residency · Emergency Medicine

Cervical Spine Clearance and Spinal Cord Injury

Epidemiology and Anatomy

C-Spine Injury Epidemiology

Cervical spine injury occurs in 2 to 4 percent of blunt trauma patients, with the most commonly affected levels being C1-C2 and C5-C7. Motor vehicle collisions, falls, diving injuries, and sports are the leading mechanisms. Missed cervical spine injuries carry devastating consequences, making a systematic approach to evaluation and clearance essential.

Relevant Anatomy

The cervical spine consists of seven vertebrae and eight cervical nerve roots. The Denis three-column model divides the spine into the anterior column (anterior two-thirds of the vertebral body and the anterior longitudinal ligament), the middle column (posterior one-third of the body and the posterior longitudinal ligament), and the posterior column (pedicles, facets, laminae, spinous processes, and ligamentum flavum). Instability is defined by involvement of two or more columns. At C1, the spinal cord occupies approximately 50 percent of the spinal canal, as described by Steel's rule of thirds: one-third cord, one-third dens, and one-third available space. The vertebral arteries travel through the transverse foramina of C1 through C6.

Upper vs. Lower Cervical Spine

Upper cervical spine injuries (C0-C2) include atlantooccipital dislocation, atlas (C1) fractures (Jefferson fracture), and axis (C2) fractures (odontoid and hangman's fractures). Lower cervical spine injuries (C3-C7) include burst fractures, flexion-distraction injuries, facet dislocations, and compression fractures.

Clinical Clearance Decision Rules

NEXUS (National Emergency X-Radiography Utilization Study)

The NEXUS criteria allow cervical spine imaging to be omitted if all five criteria are met: no midline cervical tenderness, no focal neurologic deficit, normal alertness (GCS 15), no intoxication, and no painful distracting injury. The rule achieves a sensitivity of 99.6 percent for clinically significant cervical spine injury, but its specificity is only 12.9 percent, meaning that most patients do not meet all five criteria and therefore still require imaging. NEXUS is simple to apply and widely used in the United States.

Canadian C-Spine Rule (CCR)

The Canadian C-Spine Rule is a three-step algorithm. First, the clinician asks whether any high-risk factor mandating imaging is present: age 65 or older, dangerous mechanism, or paresthesias in the extremities. If yes, imaging is indicated. Second, the clinician checks for any low-risk factor that allows safe assessment of range of motion: simple rear-end motor vehicle collision, sitting position in the ED, ambulatory at any time, delayed onset of neck pain, or absence of midline tenderness. If no low-risk factors are present, imaging is indicated. Third, if a low-risk factor is present, the patient is asked to actively rotate the neck 45 degrees to the left and right. If the patient is unable to do so, imaging is indicated. The CCR has higher sensitivity (99.4 to 100 percent) and specificity (45 percent) than NEXUS by most comparative data. It cannot be applied to patients with GCS below 15, age under 16, non-trauma presentations, or known vertebral disease. The rule is more complex to apply but demonstrates better overall performance.

Comparison

Both rules have very high sensitivity and either can be used for clinical clearance. The CCR is preferred in Canadian practice, while NEXUS is simpler and more widely used in the United States.

Imaging

CT Cervical Spine

CT is the standard of care for imaging the cervical spine in trauma and has effectively replaced plain radiographs. Its sensitivity exceeds 99 percent for fractures. Plain radiographs (the three-view series) are no longer recommended as first-line imaging at most trauma centers, as CT is faster, more sensitive, and more readily available in the ED.

MRI Indications

MRI is indicated when there is a neurologic deficit with a normal CT, suggesting ligamentous injury, cord contusion, or epidural hematoma. It is also the definitive study for suspected SCIWORA (spinal cord injury without radiographic abnormality), for evaluation of ligamentous integrity in obtunded patients (though this application remains controversial, with some institutions using flexion-extension CT or serial clinical examination after 24 to 72 hours when the patient becomes alert), for cord compression evaluation before surgical planning, and for disc herniation assessment.

Clearance in the Obtunded Patient

Cervical spine clearance in the obtunded patient remains one of the most debated topics in trauma. Options include MRI within 48 to 72 hours to evaluate ligamentous injury (the traditional approach), CT-only clearance if an adequate-quality CT is normal (increasingly accepted, as CT alone has greater than 99 percent negative predictive value for unstable injuries), and clinical clearance when the patient regains alertness. The Eastern Association for the Surgery of Trauma (EAST) guidelines suggest that CT alone may be sufficient to clear the obtunded patient if the CT is normal, allowing collar removal.

Spinal Cord Injury (SCI)

Complete vs. Incomplete Injury

Complete spinal cord injury is defined as no motor or sensory function below the level of injury (ASIA A). Incomplete spinal cord injury involves some preserved function below the level (ASIA B-D), and the prognosis is significantly better for incomplete injuries. Sacral sparing — perianal sensation, voluntary anal sphincter contraction, and great toe flexion — differentiates incomplete from complete injury and must always be checked.

Incomplete SCI Syndromes

Central cord syndrome is the most common incomplete spinal cord injury. It produces upper extremity weakness greater than lower extremity weakness and typically results from a hyperextension injury in elderly patients with cervical spondylosis, with a "cape-like" pattern of sensory loss. Anterior cord syndrome causes loss of motor function and pain and temperature sensation below the level of injury while preserving proprioception and vibration (because the posterior columns remain intact). It carries the worst prognosis among the incomplete syndromes. Brown-Sequard syndrome results from hemisection of the cord, producing ipsilateral motor and proprioception loss with contralateral pain and temperature loss, and carries the best prognosis. Cauda equina syndrome is a lower motor neuron injury below the conus (L1-L2) that presents with saddle anesthesia, bowel and bladder dysfunction, and lower extremity weakness, and represents a surgical emergency.

SCIWORA (Spinal Cord Injury Without Radiographic Abnormality)

SCIWORA is more common in children because of their ligamentous laxity and large head-to-body ratio. CT and plain radiographs are normal, but MRI reveals cord signal abnormality. MRI is the definitive diagnostic study. SCIWORA can present with delayed neurologic deficits.

Neurogenic Shock vs. Spinal Shock

Neurogenic shock results from loss of sympathetic tone below the level of injury and presents with the triad of hypotension, bradycardia, and warm, vasodilated skin below the injury level. It typically occurs with injuries above T6. Treatment includes IV fluids and vasopressors (norepinephrine or phenylephrine). It must be differentiated from hemorrhagic shock, which produces tachycardia and cool extremities. Spinal shock is a temporary loss of all spinal cord function below the level of injury, manifesting as areflexia, flaccidity, and loss of the bulbocavernosus reflex. Resolution begins with return of the bulbocavernosus reflex, usually within 24 to 48 hours. Only after spinal shock resolves can the injury be classified as complete versus incomplete.

ED Management of SCI

Immobilization

A rigid cervical collar is applied for suspected cervical injury. A spine board is used for transport only and should be removed as soon as possible to prevent pressure ulcers. Logroll precautions are maintained for bed transfers and examination.

Hemodynamic Management

The target MAP is 85 mmHg or greater for 5 to 7 days per BTF/AANS guidelines to optimize cord perfusion. Volume resuscitation is performed first, but a hemorrhagic source must be excluded. Norepinephrine is the preferred vasopressor because of its combined alpha and beta effects. Hypotension must be avoided because cord ischemia worsens secondary injury.

Steroids in Acute SCI

The use of high-dose methylprednisolone for spinal cord injury remains controversial. The NASCIS II and III trials suggested benefit with methylprednisolone 30 mg/kg bolus followed by 5.4 mg/kg/hr for 24 to 48 hours, but these studies had significant methodologic flaws. The current consensus from most guidelines, including those from the AANS/CNS and AO Spine, is that high-dose steroids are not recommended as standard of care. Side effects include increased infection, GI bleeding, hyperglycemia, and myopathy. Some spine surgeons still use the protocol, and practice variation persists. If used, the protocol must be initiated within 8 hours of injury per the NASCIS protocol.

Additional ED Management

Additional ED management includes gastric decompression (as ileus is common with SCI), urinary catheter placement (for neurogenic bladder), venous thromboembolism prophylaxis (given the high VTE risk in SCI), and temperature regulation (since poikilothermia occurs in high cervical injuries). Emergent surgical consultation should be obtained for cord compression, incomplete and deteriorating deficits, or unstable fractures.

<image>A diagram showing the cross-sectional anatomy of the spinal cord with labeled tracts, paired with four panels illustrating the incomplete spinal cord injury syndromes. Panel 1: Central cord syndrome — shaded central area showing damage to central gray matter and medial corticospinal tracts, with a description of upper greater than lower extremity weakness. Panel 2: Anterior cord syndrome — shaded anterior two-thirds showing damage to anterior horn, spinothalamic, and corticospinal tracts, with preserved posterior columns. Panel 3: Brown-Sequard syndrome — shaded right hemicord showing ipsilateral motor and proprioception loss with contralateral pain and temperature loss. Panel 4: Cauda equina syndrome — showing nerve root compression below the conus with saddle anesthesia distribution highlighted on a dermatome map.</image>

<image>A flowchart showing the Canadian C-Spine Rule algorithm for clinical cervical spine clearance. The chart begins with the question "Any high-risk factor that mandates imaging?" listing age 65 or older, dangerous mechanism (fall greater than 1 meter, axial load, high-speed MVC, bicycle collision, motorized recreational vehicle), and paresthesias. If yes, CT imaging is indicated. If no, "Any low-risk factor that allows safe ROM assessment?" listing simple rear-end MVC, sitting in ED, ambulatory, delayed onset neck pain, no midline tenderness. If no low-risk factors, CT imaging is indicated. If low-risk factor present, "Can patient actively rotate neck 45 degrees bilaterally?" If yes, no imaging needed. If no, CT imaging is indicated.</image>

Clinical Pearls

The Canadian C-Spine Rule outperforms NEXUS in comparative studies, so CCR should be considered when feasible. CT has replaced plain radiographs for cervical spine imaging in trauma, and time should not be wasted obtaining a three-view series. Sacral sparing must always be checked in spinal cord injury because it differentiates complete from incomplete injury and carries major prognostic implications. Neurogenic shock (hypotension, bradycardia, and warm skin) must be differentiated from hemorrhagic shock (hypotension, tachycardia, and cool skin), as the treatments differ substantially. High-dose methylprednisolone for SCI is not standard of care, and most guidelines recommend against routine use, though practice variation persists. SCIWORA occurs primarily in children, and a normal CT does not exclude cord injury when neurologic deficits are present. Central cord syndrome is the most common incomplete SCI and has a favorable prognosis — upper extremities are weaker than lower due to the somatotopic organization of the corticospinal tracts. In obtunded patients, CT-only clearance of the cervical spine is increasingly accepted if the CT is normal and of high quality.

References

• Stiell IG, et al. The Canadian C-Spine Rule versus the NEXUS Low-Risk Criteria in patients with trauma. NEJM. 2003;349:2510-2518.
• Hoffman JR, et al. NEXUS: Validity of a set of clinical criteria to rule out injury to the cervical spine. NEJM. 2000;343:94-99.
• Bracken MB, et al. NASCIS: Methylprednisolone or naloxone in acute spinal cord injury. NEJM. 1990;322:1405-1411.
• Fehlings MG, et al. AO Spine Guidelines: Clinical practice guideline for the management of acute spinal cord injury. Global Spine J. 2017;7(3 Suppl):209S-226S.
• Patel MB, et al. EAST guidelines: Cervical spine collar clearance in the obtunded adult blunt trauma patient. J Trauma. 2015;78:430-441.

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