SCIWORA

Definition: SCIWORA (Spinal Cord Injury Without Radiographic Abnormality) was defined by Pang and Wilberger in 1982. It refers to objective signs of myelopathy in the presence of NORMAL plain radiographs and CT scans. Note: With the advent of MRI, we now often see the "abnormality" in the soft tissues, but the term persists.

Epidemiology:

• Age: Predominantly children less than 8 years old. The elasticity decreases with age, so true SCIWORA becomes rarer in adolescents.
• Incidence: Accounts for 20-30% of pediatric spinal cord injuries. It is the most common pattern of spinal cord injury in young children.
• Region: Cervical spine is most commonly involved (Upper cervical in very young, Lower cervical in older kids). Thoracic SCIWORA is rare and often associated with high-velocity distraction (lap-belt injury).

Historical Context: Pang and Wilberger's original series (1982) was landmark because it shifted the focus from "fractures" to "neurology". Before this, many children were dismissed as malingerers or "hysterical" because X-rays were normal. They identified that 52% of these children had a delayed onset of severe paralysis, typically occurring between 30 minutes and 4 days after injury. This lead to the cardinal rule: Treat the symptoms, not the X-ray.

Spinal Shock vs Neurogenic Shock: It is vital to distinguish these two entities, which often coexist in severe SCIWORA.

• Spinal Shock: A physiological loss of all spinal cord function caudal to the level of injury (flaccid paralysis, areflexia). It is transient (24-48 hours usually). Recovery is heralded by the return of the Bulbocavernosus Reflex.
• Neurogenic Shock: A hemodynamic phenomenon resulting from loss of sympathetic tone (T6 and above).
  • Triad: Hypotension, Bradycardia, Peripheral Vasodilation (Warm peripheries).
  • Treatment: Fluids + Inotropes (Noradrenaline/Dopamine) to maintain perfusion. Atropine for severe bradycardia.

Any child with neck pain and a normal X-ray requires careful clearance. Do not dismiss transient symptoms.

Anatomical Predisposition (The Pediatric Spine): The pediatric cervical spine has unique biomechanical properties that predispose to SCIWORA:

1. Ligamentous Laxity: Generalized joint hypermobility allows for excessive intersegmental motion.
2. Horizontal Facet Joints: The facet joints in children are oriented more horizontally (flatter) compared to the vertical orientation in adults. This allows for significant AP translation (sliding) without fracture or dislocation.
3. Large Head-to-Body Ratio: The head is disproportionately large and heavy. In young children, the fulcrum of motion is at C1-C2 (Upper Cervical), whereas in adults it is C5-C6. This places the upper cervical cord at highest risk in toddlers.
4. Uncinate Processes: The uncinate processes (Joints of Luschka) are undeveloped and flat in children (they ossify and heighten by age 10). This lack of bony side-walls offers less resistance to lateral and rotational forces.
5. Anterior Wedging: The vertebral bodies are wedge-shaped anteriorly, facilitating hyper-flexion.
6. Blood Supply: The spinal cord blood supply is tenuous, particularly the anterior spinal artery. Watershed zones (T4-T8) are vulnerable, but in cervical SCIWORA, the mechanism is often traction injury to the penetrating vessels.
   • Vampire Bite Sign: Describes the tiny paired hyperintensities on axial MRI, representing disruption of the central sulcal arteries. This finding specifically predicts poor motor recovery (LMN injury).

The Mismatch Hypothesis (Leventhal): The spinal column can be distracted (stretched) up to 2 inches without structural failure (due to elastic ligaments and discs). However, the spinal cord ruptures after only 1/4 inch of distraction.

• Trauma: Hyperextension or Distraction.
• Action: The column stretches, tractioning the cord to failure.
• Recoil: The column snaps back to normal alignment.
• Result: The cord is injured, but the X-ray/CT looks perfect.

Patterns of Cord Injury:

• Concussion: Transient dysfunction, rapid recovery.
• Contusion/Edema: Structural change, variable recovery.
• Infarction: Vampire bite sign (vascular disruption).
• Transection: Complete loss.

History:

• Mechanism: MVC, Fall, Sports.
• Transient Symbols: "Stingers", "Burning hands", "Electric shocks" (Lhermitte's).
• Delay: Ask specifically about the time between injury and onset of weakness (can be delayed in 50%).

Physical Examination:

• Neurology is Key: ASIA Exam classification.
• Motor: Weakness (often bilateral).
• Sensory: Level to pin prick and light touch.
• Reflexes: Hyper-reflexia (upper motor neuron) or absent (Spinal shock).
• Tone: Flaccid initially (Shock) then Spasticity later.
• Autonomic: Priapism, bradycardia (Neurogenic shock/Hypotension).

Differential Diagnosis: It is crucial to differentiate SCIWORA from other causes of acute weakness:

• Transverse Myelitis: Often viral prodrome, slower onset (hours to days), fever. MRI shows enhancement.
• Guillain-Barre Syndrome: Ascending paralysis, areflexia, normal MRI spine. Lumbar puncture shows albuminocytologic dissociation.
• Spinal Cord Tumor: Insidious onset, night pain.
• Conversion Disorder: Inconsistent exam, "Hoover's sign" positive. Diagnosis of exclusion.
• Brachial Plexus Injury: Unilateral, lower motor neuron signs only (root level).

Red Flags for Non-Accidental Injury (NAI):

• Inconsistent history.
• Delayed presentation (parents waited days).
• Multiple fractures or bruises in different stages of healing.
• SCIWORA in a non-ambulatory infant (e.g. "fell from couch").

Protocol:

1. Plain Radiographs: AP, Lateral, Odontoid. (Often normal). Look for prevertebral soft tissue swelling (greater than 6mm at C2), ADI widening, or subtle kyphosis.

2. CT Cervical Spine: To rule out occult fracture. (Usually normal in SCIWORA). Indicated if plain films are inadequate or suspicion of bony injury is high.

3. MRI (The Gold Standard): Must be performed URGENTLY (within 24-48 hours) to detect signal changes.

   • Sequences: T2 Weighted (best for edema and ligament disruption), STIR (highlights edema in soft tissues), Gradient Echo/GRE (detects hemorrhage), DWI (early infarction).
   • Findings: Extraneural (ligament disruption, disc herniation, epidural hematoma) or Intraneural (edema, hemorrhage, transection).

Blood tests are usually normal. Consider metabolic workup if etiology weak (e.g. transverse myelitis differential).

Advanced Imaging Considerations

• DTI (Diffusion Tensor Imaging): Emerging research tool. May show tract disruption even when T2 is normal.
• fMRI: Evaluation of cortical reorganization in chronic cases.
• Electrophysiology (SSEP/MEP): Mandatory if surgery is planned. Can help prognosticate in comatose patients.

Surgical Challenges in Pediatric Spine

• Small Anatomy: Pedicles in children under 8 are miniscule (often less than 3-4mm), making screw fixation risky.
• Growth Potential: Fusing the spine arrests vertical growth. Rule of thumb: Fusing C1-C2 loses very little height, but subaxial fusion results in loss of 0.07mm per segment per year (negligible). However, it induces "Crankshaft" phenomenon if posterior fusion only is done in growing scoliosis (less relevant here).
• Fusion Rates: Massive healing potential. Non-union is rare, but overgrowth can occur.

Acute Nursing Care:

• Log Rolling: Strict spinal precautions until cleared.
• Skin Care: Regular collar care (changing liners) to prevent occipital and mandibular pressure ulcers (high risk in children with thin skin).
• Blood Pressure: Avoid hypotension. Maintain MAP greater than 85mmHg (adult targets) or age-appropriate equivalent (e.g. greater than 70-75mmHg) to ensure cord perfusion.
• Bladder: Intermittent catheterization if retention present.

Long Term Rehabilitation:

• Spasticity Management: Baclofen, Botox injections for contractures.
• Scoliosis Surveillance: 98% of children with SCI before skeletal maturity will develop neuromuscular scoliosis. Require 6-monthly spine X-rays until maturity.
• Psychological Support: PTSD is common in both the child and parents (guilt).

• Type I (Normal MRI): Nearly all recover fully, but recurrence risk exists if not immobilized.
• Type II (Edema): Variable. Short segment edema recovers well. Long segment does poorly.
• Recurrence: A "Second Hit" within 2 weeks is often more severe than the first. This is why the collar is non-negotiable.
• Mortality: High in upper cervical transections (Respiratory arrest).

• Transport: Retrieval services (RFDS/NetS) are critical for rural cases. Stabilization (Collar) before transport is mandatory.
• MRI Access: Major challenge in rural Australia. Any child with neuro deficit needs transfer to a center with MRI capabilities.
• Referral: All pediatric SCI should be managed in a specialized Paediatric Spinal Unit (e.g. Westmead, SCH, RCH).
• Rugby: High index of suspicion in junior rugby league/union "stingers". Strict "No Return" without clearance.

Prevention Strategies

• Car Seats: Proper restraint education is the primary prevention strategy (Forward vs Rear facing). Rear-facing as long as possible (up to 4 years) drastically reduces cervical distraction forces.
• Trampolines: A significant cause of severe cervical trauma in Australian children. The RCH Melbourne guidelines recommend against trampolines for children under 6 due to developing coordination and softer bones.
• Sports: Neck strengthening programs in Rugby ("Mayday" procedure) are vital.