What are the different types of spinal cord injuries in a patient with a cervical spine injury and spinal cord injury at or above the T6 level?

Types of Spinal Cord Injury

Spinal cord injuries are classified by anatomical location (cervical, thoracic, thoracolumbar, lumbosacral), neurological severity (complete vs incomplete), and injury pattern (fracture-dislocation, subluxation without fracture, or isolated cord injury without skeletal damage). 1

Classification by Anatomical Location

Cervical Spine Injuries

• Cervical injuries comprise approximately 55% of all spinal cord injuries and represent the most common anatomical location 1
• High cervical injuries (C1-C3) carry the highest immediate mortality risk due to proximity to the respiratory center and involvement of the phrenic nerve originating from C3-C5 2
• Atlanto-occipital and atlanto-axial instability (C0-C2) are the most dangerous cervical injuries because they involve critical ligamentous structures with minimal bony protection 2
• Subaxial cervical injuries (C3-C7) range from stable minor soft-tissue injuries to unstable complex fracture-dislocations with neurologic compromise 1

Thoracic Injuries

• Thoracic ASIA Grade A injuries comprise only 10-15% of current spinal cord injury cases but are important for clinical trial design due to minimal functional deficit risk from treatment complications 1
• Injuries above T6 can cause neurogenic shock due to loss of sympathetic tone, requiring aggressive hemodynamic support to prevent secondary cord injury 2

Thoracolumbar and Lumbosacral Injuries

• Thoracolumbar injuries (T11-T12 to L1-L2) involve admixture of lower motor neuron cell bodies in the conus medullaris, which may have different pathophysiology and recovery potential 1
• Lumbosacral injuries (L1-L2 to S5) involve lower motor neuron axons of the cauda equina and are typically excluded from standard spinal cord injury trials due to distinct recovery mechanisms 1

Classification by Skeletal Involvement

Fracture-Associated Injuries

• 85.6% of cervical spine injuries involve vertebral fractures that are typically visible on CT imaging 3
• Fracture patterns include: cervical spine subluxation/dislocation, fractures at C1-3, fractures involving the transverse foramen at any level, and complex fracture-dislocations requiring surgical decompression and stabilization 1

Nonskeletal Injuries

• 10.6% of cervical spine injuries are subluxations without fractures, representing unstable ligamentous injuries that can appear normal on X-rays and CT but progress to catastrophic cord injury if mobilized 3
• Up to 25% of cervical spine injuries involve NO fracture but represent unstable ligamentous injuries that are invisible on plain radiographs and CT scans 2
• 3.8% are isolated spinal cord injuries without fracture or subluxation, often missed on initial evaluation, particularly in patients requiring early intubation or with altered mental status 3

Classification by Neurological Severity

Complete vs Incomplete Injuries

• ASIA Grade A patients (complete injuries) comprise approximately 45% of spinal cord injuries in developed countries, though this percentage has diminished due to improved prevention strategies 1
• The Subaxial Injury Classification (SLIC) System provides Level I evidence with excellent reliability for classifying injuries based on fracture morphology, disco-ligamentous complex integrity, and neurological status 1

Specific Injury Syndromes

• Central cord syndrome presents with disproportionate upper extremity weakness and can occur without fracture, requiring urgent MRI and potential decompression within 24 hours 2
• Brown-Séquard syndrome demonstrates ipsilateral motor weakness and proprioception loss with contralateral pain/temperature loss due to crossed versus uncrossed spinal tract anatomy 2
• Selective fasciculus gracilis injury can occur in cervical cord trauma, causing persistent hypesthesia and abnormal vibratory sensation below the injury level despite normal thoracic imaging 4

Critical Diagnostic Considerations

Imaging Requirements

• Plain X-rays miss up to 77% of cervical spine abnormalities in patients with suspected injury, making them inadequate for clearance in symptomatic patients 2
• Normal CT does NOT exclude significant injury in patients with neurological symptoms, as purely ligamentous injuries and cord contusions are invisible on CT 2
• MRI is the ONLY modality that directly visualizes cord injury, ligamentous disruption, and epidural hematoma, with over 13% of post-traumatic epidural hematomas having normal CT scans 2

Noncontiguous Injuries

• 20% of spine trauma patients have noncontiguous injuries at multiple levels, requiring full spine imaging when any level is injured 2

Temporal Classification

• Acute stage (up to 72 hours): optimal window for neuroprotection strategies but challenging for reliable neurological examination 1
• Subacute stage (72 hours to 14 days): more reliable neurological baseline, ideal for regeneration studies but too late for most neuroprotection 1
• Chronic stage (beyond 12 months): too late for neuroprotection, uncertain efficacy for regeneration strategies 1