Neurogenic vs Spinal Shock: Circulation and Reflexes
What is the difference between neurogenic and spinal shock?
Neurogenic shock is circulatory dysfunction from loss of sympathetic control after spinal cord injury. Spinal shock describes depressed reflexes and muscle tone below an acute injury. One patient can have both. A slow pulse or a documented cord injury does not exclude hemorrhage or another cause of impaired perfusion.
Key takeaways
- Neurogenic shock describes circulation; spinal shock describes neurological findings.
- Loss of sympathetic vascular tone can reduce venous return as well as arterial resistance.
- Bradycardia does not rule out simultaneous bleeding.
In this video
- Neurogenic and spinal shock: two questions
- Two names, two questions
- How the pressure drops
- Why the heart slows
- Which injuries raise the concern
- What spinal shock looks like
- What spinal shock is and isn't
- Two exams, two answers
- A patient, step by step
- First reveal
- Second reveal
- Other causes of shock
- Pressure, flow and perfusion
- When one side improves
- No treatment recipe
- Interview
- Quick check
- Recap
How does loss of sympathetic control affect circulation?
Descending sympathetic pathways help maintain arteriolar and venous tone. Disruption can lower vascular resistance and reduce the return of blood to the heart. Cardiac sympathetic interruption can also contribute to a slower heart rate.
The vagus does not run through the spinal cord. The balance of autonomic activity changes when sympathetic pathways are interrupted, but the actual response depends on the injury and the patient. A vertebral imaging level does not by itself describe every functional deficit.
What does spinal shock describe?
Spinal shock refers to transient depression of reflex activity and tone below an acute cord injury. Flaccidity or absent reflexes early in the course does not, by itself, establish a peripheral nerve injury or a final neurological prognosis.
This is a separate assessment from circulatory shock. Follow the neurological examination over time while also reassessing pressure, flow and perfusion. Return of a reflex is not proof that cardiovascular function or motor function has fully recovered.
Why must hemorrhage remain in the assessment?
A patient with traumatic cord injury may also be bleeding. A slow pulse does not make those mechanisms mutually exclusive, and one named shock category does not prevent another from contributing.
The 2024 spinal cord injury guideline describes uncertainty in hemodynamic management. This educational comparison does not prescribe a universal pressure target, support duration or vasopressor.
