MD Notes

creation date: 2026-02-23 18:07
tags: Pathologies

Spinal Cord Injury

Background

Definitions

Spinal cord injuries (SCIs) are disorders arising from direct or indirect spinal cord damage.

The anatomy and physiology of the spinal cord is discussed separately.

SCIs disproportionately affect individuals younger than 30 and thus have a long runway of functional impairment.

Etiology

SCIs can result from traumatic or nontraumatic etiology.

Traumatic causes include:

  • Motor vehicle accidents (40%)
  • Falls (30%)
  • Violence (10%)
  • Sports-related injury (10%)
  • Medical/surgical complications (5%)

Non traumatic causes include:

  • Tumours (spinal neoplasms, metastatic lesions)
  • Infections (epidural abscesses, spinal osteomyelitis)
  • Degenerative spinal changes (eg. spinal stenosis, spondylosis)

Pathogenesis

In most cases, spinal cord injuries occur in association with injury to the vertebral column. These may include:

  • Vertebral fracture
  • Dislocation of intervertebral or facet joints
  • Tearing of spinal ligament
  • Disruption and herniation of intervertebral disc

Mechanisms of injury are categorized as primary or secondary processes.

Primary injury refers to immediate effects of trauma which include transection, compression, contusion, vascular compromise, and shear injury to the cord. It should be noted that while some injuries involve direct penetration and damage, in the setting of a trauma such as a gunshot wound, this one cord may be injured from the kinetic energy of a nearby hit.

  • Transection: penetrating or massive blunt trauma that may cut all or part of the spinal cord
  • Compression: arthritically enlarged vertebrae can compress the spinal cord in certain positions (eg. neck extension)
  • Contusion: blood produced due to bony dislocations, subluxations, or fracture fragments
  • Vascular compromise: dissection or compression of vertebral arteries can reduce blood flow and thus cause ischemia

Secondary injury refers to the physiologic response to the primary injury over the several hours following in which a combination of ischemia, hypoxia, inflammation, edema, excitotoxicity, electrolyte imbalance, and apoptosis causes neurologic deterioration.

Clinical Presentation

Signs & Symptoms

Spinal cord injury typically presents with neurologic deficits. The distribution of symptoms allows for localization to the spinal level of injury. Typically, muscle strength and sensation will be intact cephalic to the injury and impaired caudally.

Syndromes by injury location

Cervical cord injury
Approximately half of spinal cord injury involve the cervical cord. This may present with:

  • Quadriplegia
  • Sensory loss in the legs, trunk, and arms
  • Respiratory failure (if upper cervical)
  • Neurogenic shock

Thoracic cord injury
Thoracic cord injury can produce:

  • Paraplegia with numbness in the legs that extend up trunk to the spinal level of injury
  • Respiratory dysfunction due to inward movement of chest and expansion of abdomen
  • Neurogenic shock

Thoracoumbar junction cord injury
Injury near the end of the spinal cord can present with conus medullaris syndrome, characterized by:

  • Numbness of the legs that extends into the perineal region (saddle anesthesia)
  • Weakness of the legs

Specific spinal cord syndromes

Depending on the severity and location of the injury, a specific pattern of neurologic dysfunction may manifest. This is due to the organization of nerve pathways and vasculature of the spinal cord.

Complete cord injury
This results from a cord transection and are considered severe (grade A). Presents with:

  • Muscle weakness at spinal level of injury
  • Complete paralysis of all more caudal myotomes

Additionally, acute findings include:

  • Absent muscle stretch reflexes
  • No response to plantar stimulation
  • Flaccid muscle tone
  • Absent bulbocavernosus reflex and anal reflexes
  • Male may have priapism (painful, persistent erection)
  • No sensation to deep anal pressure on DRE
  • Urinary retention and bladder distension

Incomplete cord injury
Incomplete injuries range in severity from grade B-D. This presents with:

  • Some muscle weakness at spinal level immediately at or below the level of injury
  • Varying degrees of motor dysfunction with the myotomes caudal of the injury
  • Sensation is typically more preserved than motor function (sensory tracts are typically more peripherally located and thus less vulnerable)

Central cord syndrome
Acute central cord syndrome is characterized by:

  • Disproportionately greater weakness of arm than legs
  • Variable degree of sensory loss below the level of injury
  • Loss of pain and temperature sensation restricted to the spinal level of injury (preserved cranially and caudally)

This is associated with edema and occurs after mild trauma in setting of preexisting spondylosis.

Anterior cord syndrome
Anterior cord syndrome presents with:

  • Weakness or paralysis at spinal level immediately below level of injury
  • Loss of pain and temperature sensation at spinal level immediately below level of injury
  • Tactile, vibratory, and positional sense functions remain intact (posterior column functions)

This is associated with nontraumatic lesions that disrupt blood flow to the anterior spinal artery although traumatic causes can directly injure the anterior cord too.

Other features

Transient paralysis and spinal shock
Immediately following injury, there may be loss of all spinal cord function caudal to the level of injury with:

  • Flaccid paralysis
  • Anesthesia
  • Bowel and bladder incontinence
  • Areflexia
  • Priapism

This is referred to as spinal shock and lasts 1-4 weeks. As spinal shock wears off, clinical manifestations may normalize but typically are replaced by spastic paresis with hyperreflexia.

Nonspinal features
Injuries may also cause brain and systemic injuries.

History & Physical Exam

In cases of trauma, standard trauma assessment protocol should be followed. Note that spinal immobilization including cervical collar should be maintained until spinal injury has been ruled out or stabilized.

Physical exams include neurological (cranial and peripheral) examination including mental status.

Assessment of disability using the Glasgow coma scale and the American Spinal Injury Association (ASIA) spinal cord impairment scale for severity and prognostication.

Risk Factors

Risk factors for traumatic spinal cord injury involves diseases that increase the likelihood of injury (eg. alcohol consumption) and underlying conditions that increase the susceptibility of an injury becoming serious:

  • Cervical spondylosis
  • Atlantoaxial instability
  • Congenital spinal cord conditions
  • Osteoporosis and vertebral compression fractures
  • Spinal arthropathies (eg. ankylosing spondylitis, rheumatoid arthritis)

Diagnosis

Criteria

Diagnosis is made with spinal imaging. The site and extent of lesion should be identified.

Work-up

Initial imaging
Noncontrast CT is typically the initial imaging study due to its availability and rapidity. A head CT may be included if head trauma is involved.

The body site for imaging is determined by neurological features (most cephalic spinal level with neurologic symptoms). This may not always be helpful, especially in cases of incomplete cord injury and imaging site should be adjusted accordingly.

In patients with features suggestive of multifocal injury, imaging of the entire neuraxis may be warranted.

Further imaging
In patients with confirmed injury, spinal MRI is performed for:

  • Further confirmation of injury
  • Soft tissue abnormalities (eg. disc herniation, ligamentous disruption, hematomas)

An MRI may also be used for diagnosis if CT was nondiagnostic but there is still clinical suspicion for spinal cord injury.

Differential

While spinal cord injuries can typically be diagnosed through presentation and associated with a traumatic event, a differential must be maintained for sensorimotor weakness, especially when preceding events are unclear.

CNS conditions:

  • Cerebrovascular accident
  • Postictal paralysis
  • Hemiplegic migraine
  • Multiple sclerosis

PNS conditions:

  • Guillain-Barre syndrome
  • Transverse myelitis
  • Tick paralysis

Neuromuscular junction pathologies:

  • Myasthenia gravis
  • Organophosphate toxicity
  • Botulism

Others:

  • Hypoglycemia
  • Hypokalemic periodic paralysis
  • Hypocalcemia
  • Diabetic neuropathy
  • Functional neurological disorder

Red Flags / Complications

A number of chronic complications are associated with SCI.

Cardiovascular

  • Autonomic dysreflexia - SCI above T6 causes exaggerated sympathetic responses to noxious stimuli below injury (eg. bladder distention)
  • Coronary artery disease
  • Disrupted cardiovascular homeostasis
    Pulmonary
    Cervical and high thoracic SCIs can affect respiratory muscles.
  • Ventilatory failure
  • Increased risk of pneumonia (due to difficulty mobilizing secretions)
  • DVT and pulmonary embolism
    Urinary
    Neurogenic bladder resulting in:
  • Bladder dysfunction (storage and voiding)
  • Urinary tract infections
  • Vesicoureteral reflux (results in high bladder pressures and recurrent UTI)
  • Kidney failure
  • Kidney calculi
    Sexual Dysfunction
  • Decreased libido
  • Impotence
  • Infertility
    Gastrointestinal
  • Constipation and fecal retention - injuries above conus medullaris
  • Constipation with frequent incontinence - injuries at or below the conus medullaris
    Musculoskeletal and Bone Metabolism
    After SCI, muscle contractures result in changes to tissue matrix around the muscle.
  • Immobility
  • Spasticity

Bone changes can occur:

  • Osteoporosis
  • Heterotopic ossification

Neurologic, pain, and other dysfunction

  • Spasticity (velocity-dependent increase in muscle tone)
  • Chronic pain syndrome that may be neuropathic in character
  • Psychiatric complications including depression, suicide, drug addiction, divorce

Management

Following immobilization and initial trauma assessment and treatments, managing is then directed at the injury and prevention of complications. This is done in a critical care unit.

Treatment of Acute SCI

Measures are given to counter further neurologic deterioration, primarily from spinal hypoperfusion and cord compression.

Maintain MAP of 85-90 mmHg using IV fluids or blood transfusion and vasopressors as needed

In cases of cord compression with neurologic deficits, embedded foreign body, or unstable vertebral fractures/dislocations, surgery is indicated.

Management of Complications and Rehabilitation

Complications should be treated respectively. This may include use of vasopressors, ventilators, and condition specific therapy.

Once the spinal column instability and underlying cause has been treated, occupational and physiotherapy may be started for stable patients.

References

Tools / Guidelines

ASIA Spinal Cord Impairment Scale

Additional Reading