Overview
This lecture covers the fundamentals of spinal cord injury, including epidemiology, mechanisms, pathophysiology, clinical syndromes, neurological assessment, management strategies, and potential complications.
Epidemiology & Mechanisms
- Spinal cord injuries are most common in the mid-cervical spine and thoracolumbar junction.
- Incidence is about 10,000 cases per year in the U.S., with a trend toward fewer cases due to prevention.
- Leading causes include motor vehicle accidents, falls (especially in the elderly), and violence.
- Pre-existing spinal stenosis increases injury risk in minor trauma.
Pathophysiology
- Primary injury: direct trauma, compression, or penetration at the time of injury.
- Secondary injury: subsequent biochemical events like edema, vascular changes, free radicals causing further damage.
- Most injuries result in central cystic necrosis from central hemorrhage but the cord often remains partially continuous.
Clinical Presentation & Neurological Assessment
- Asia Impairment Scale (INSKI): grades A (complete) to E (normal) based on motor/sensory loss.
- Assessment relies on key motor groups to define the neurological level of injury.
- Spinal shock: temporary loss of reflexes and motor/sensory function after injury.
- Neurogenic shock: cardiovascular instability (bradycardia, hypotension) due to loss of sympathetic tone above T6.
Spinal Cord Syndromes
- Anterior cord syndrome: loss of motor/sensory, preserved dorsal column; rare in trauma.
- Central cord syndrome: more severe upper limb than lower limb weakness; common in elderly with cervical hyperextension and stenosis.
- Brown-Séquard syndrome: hemisection with ipsilateral motor loss and contralateral pain/temperature loss.
- Conus medullaris syndrome: bowel/bladder dysfunction, mixed upper/lower motor neuron signs.
- Cauda equina syndrome: lower motor neuron symptoms, asymmetric, better recovery potential.
Management Strategies
- ABCs (airway, breathing, circulation) prioritized to prevent secondary injury.
- Methylprednisolone: previously used; current guidelines do not recommend routine use due to unclear benefit and potential harm.
- Therapeutic hypothermia (cooling): under investigation, shows some promise in early studies.
- Early surgical decompression (<24 hours) improves neurological outcomes compared to late surgery.
- DVT prophylaxis is essential due to high risk.
- Management includes respiratory care, bladder/bowel programs, pressure sore prevention, and psychological support.
Systemic Complications
- Cardiovascular: risk of neurogenic shock requiring fluids, pressors, or pacing.
- Respiratory: risk of failure, especially with high cervical injury; may require respiratory support or tracheostomy.
- Genitourinary: urinary retention managed with catheters, risk for infections, autonomic dysreflexia.
- GI: stress ulcers, need for early feeding and bowel management.
- Musculoskeletal: risk of contractures, heterotopic ossification, and pressure sores.
Post-Traumatic Syringomyelia
- Occurs in 2–3% of cases as delayed cyst formation causing neurological decline.
- Diagnosis by MRI, sometimes using CSF flow studies.
- Treatment may involve shunting (high failure rate) or untethering with duraplasty.
Key Terms & Definitions
- Asia Impairment Scale (INSKI) — classification system for spinal cord injury severity.
- Spinal Shock — temporary loss of reflex and function after injury.
- Neurogenic Shock — cardiovascular collapse from loss of sympathetic outflow.
- Central Cord Syndrome — greater upper limb than lower weakness.
- Brown-Séquard Syndrome — cord hemisection producing ipsilateral loss of function and contralateral sensory loss.
- Conus Medullaris Syndrome — mixed upper/lower motor neuron symptoms and autonomic dysfunction.
- Cauda Equina Syndrome — lower motor neuron injury below L1/L2 with relatively good recovery.
Action Items / Next Steps
- Review the Asia Impairment Scale and neurological level assessment.
- Familiarize with management protocols for acute spinal cord injury.
- Read up on key spinal cord injury syndromes and their presentations.
- Stay updated on guidelines regarding methylprednisolone and hypothermia use.