Spinal Cord Injuries

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SCI Basics & Anatomy - Cord Under Siege

  • Etiology:
    • Trauma (common): RTA, falls, violence.
    • Non-traumatic: Vascular, tumors, infections, degenerative.
  • Cord Structure:
    • Meninges: Dura, Arachnoid, Pia.
    • Grey matter (central H-shape): Neuronal bodies.
    • White matter (peripheral): Tracts.
      • Ascending: Dorsal columns (proprioception, vibration, fine touch), Spinothalamic (pain, temp).
      • Descending: Corticospinal (motor).
  • Vascular Supply:
    • Anterior Spinal Artery (ASA): Anterior 2/3.
    • Posterior Spinal Arteries (PSAs): Posterior 1/3.
  • Key Concepts:
    • Spinal Shock: Transient reflex loss below injury.
    • Neurogenic Shock: Hypotension, bradycardia (injury ≥T6).

⭐ Vertebral level often doesn't correspond to spinal cord segment level, especially in lower spine (e.g., L1 vertebra injury can affect S1-S5 cord segments).

Spinal cord cross-section with tracts and injury patterns

SCI Classification & Syndromes - Code Red Cord

  • ASIA Impairment Scale (AIS):

    • A: Complete. No S4-S5 motor/sensory.
    • B: Sensory Incomplete. Sensory preserved below neurological level (NL) & S4-S5; no motor.
    • C: Motor Incomplete. Motor preserved below NL; >half key muscles <3.
    • D: Motor Incomplete. Motor preserved below NL; ≥half key muscles ≥3.
    • E: Normal.
  • Key SCI Syndromes:

SyndromeMotor DeficitSensory Deficit📌 Key / Prognosis
Brown-SéquardIpsilateral UMN, proprioception, vibrationContralateral pain/tempHemi-section. Good. 📌 "One Sided Story"
Central CordUE > LE weakness"Cape-like" pain/temp lossHyperextension. Fair. Central Cord Syndrome Somatotopy Models
Anterior CordComplete motor paralysisPain/temp loss; proprioception intactFlexion; ASA occlusion. Poor.
Posterior CordMinimal weaknessProprioception/vibration lossRare; PSA occlusion. Good.
Conus MedullarisSymmetric LMN LE; Early bowel/bladderSaddle anesthesiaL1-L2; UMN+LMN. Variable.
Cauda EquinaAsymmetric LMN LE; Late bowel/bladderSaddle anesthesia; radicular painBelow L2; LMN. Variable.

Clinical Picture & Diagnosis - Spotting the Damage

  • Initial: ABCDEs. Neuro exam (motor, sensory, reflexes). ASIA Scale.
  • Spinal Shock: Temp. reflex/sensorimotor loss below injury. Flaccid paralysis, areflexia, absent BCR. BCR return ends shock.
  • Neurogenic Shock (SCI ≥T6): Sympathetic loss → vagal. Hypotension (SBP <90 mmHg), bradycardia, poikilothermia. ⚠️ Vs. hypovolemic.
  • Table: Shock Types
    FeatureSpinalNeurogenic (≥T6)
    CauseReflex lossSympathetic loss
    BPNorm/Var↓ Hypotension
    HRNorm/Var↓ Bradycardia
    ReflexesAbsentUnaffected
  • Autonomic Dysreflexia (SCI ≥T6, post-shock): Trigger: noxious stimuli (full bladder). Sudden HTN (↑SBP 20-40 mmHg), headache, bradycardia, sweating above.
    • ⭐ > Autonomic dysreflexia is a medical emergency in patients with SCI at or above T6, characterized by paroxysmal hypertension, bradycardia, and headache, often triggered by bladder or bowel distension.
  • Diagnosis: Clinical (ASIA). Imaging: X-ray, CT; MRI (cord std).

Spinal Cord Injury Pathophysiology Diagram

SCI Management & Complications - Road to Recovery

Acute Management:

  • Medical:

    ⭐ While controversial and not universally recommended, the NASCIS II protocol for methylprednisolone (bolus 30 mg/kg IV over 15 min, then 5.4 mg/kg/hr for 23 hrs if started within 3-8 hrs of injury) is a frequently tested topic.

    • Hemodynamic support (MAP >85-90 mmHg).
    • DVT/Stress ulcer prophylaxis.
  • Surgical: Decompression, stabilization if indicated.
  • Complications:
    • Neurogenic Shock (↓BP, ↓HR).
    • Spinal Shock (transient flaccid paralysis).
    • Autonomic Dysreflexia (≥T6): noxious stimuli → HTN, headache. Rx: sit up, remove trigger.
    • Pressure Sores. Pressure ulcer sites in supine and side-lying positions
    • Respiratory, DVT/PE.
  • Rehab: Multidisciplinary team approach for functional recovery and quality of life improvement.

High‑Yield Points - ⚡ Biggest Takeaways

  • ASIA Scale is vital for SCI classification and predicting prognosis.
  • Distinguish spinal shock (transient areflexia) from neurogenic shock (hypotension, bradycardia).
  • Central cord syndrome: Most common incomplete SCI; upper limbs affected more than lower.
  • Anterior cord syndrome: Worst prognosis; motor, pain, temperature loss below lesion.
  • Brown-Séquard syndrome: Ipsilateral motor/proprioception loss, contralateral pain/temperature loss.
  • Autonomic dysreflexia (lesions above T6): Medical emergency; triggered by noxious stimuli below injury.
  • Sacral sparing indicates an incomplete lesion and a better chance of recovery.

Practice Questions: Spinal Cord Injuries

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