Neurogenic Shock in Children

To celebrate the end of trauma season (is it ever really over?), we here at the Ped EM Morsels Bakery have cooked up a morsel to remind you that pediatric trauma can be even more difficult than you think. Never fear. As our fearless leader likes to say: “children are not aliens, but they are a special population with unique anatomy and physiology.” Children compensate for blood and volume loss very well… until they don’t. Physical exam findings of occult shock in children can be subtle. Fortunately, there are screening tools for occult shock. Unfortunately, there are numerous other pitfalls that can be encountered during the management of pediatric trauma patients.  Recently, while caring for a persistently hypotensive pediatric trauma patient, the great Dr. Lia Cruz reminded me that there is more to think about than just hemorrhage.  Let’s take a moment to digest a delicious morsel of knowledge on Neurogenic Shock in Children:

Neurogenic Shock in Children: Basics & Anatomy           

We would be remiss to waste another opportunity to talk about pediatric anatomy:

  • Kids have big heads.
    • Head circumference at 2 years old is 50% of adult size.
    • Making it much larger in proportion to the rest of their tiny little bodies 
  • The fulcrum is much higher (C2-C3 at birth) than that of adults and even children older than 8 (C5-C6).
  • Small children have proportionally weaker cervical muscle tone, ligamentous laxity, and differently positioned facet joints, allowing the spinal column to be much more compliant than those of adults.
    • Unfortunately, the spinal cord does not allow for the same amount of movement, resulting in cord injuries. 

A (sorta) Quick Blurb about Spinal Shock

If you, like me, have recently had to go back to review the difference between spinal and neurogenic shock, here is a quick refresher on the topic.

  • Spinal shock is a phenomenon of transient, physiologic (rather than anatomic) complete loss of spinal cord function inferior to an injury.
    • Refers to the Spinal Cord Function and Reflexes, not specifically hemodynamic issues.
    • It may, however, be seen preceding or concurrently with neurogenic shock.
  • Thought to be a “stunning” of the spinal cord.
    • May be due to a profound increase in the inhibitory neurotransmitter, Glycine, in the spinal cord.
    • Other mechanisms are also described.

Neurogenic Shock in Children

Finally, the meat and potatoes of this morsel…yum. Whereas spinal shock is a temporary change in spinal physiology after a profound spinal cord injury, neurogenic shock is a more immediate cardiovascular life threat that is important to recognize immediately in the trauma bay. 

Definition
  • A series of hemodynamic changes related to autonomic denervation and loss of sympathetic tone.
    • Main symptoms include hypotension and bradycardia.
Pathophysiology
  • Primary injury happens at the time of the traumatic event or shortly after in the high cervical to mid-thoracic spine. This leads to descending sympathetic tracts being disrupted.
    • Most commonly caused by fracture or dislocation of vertebrae.
    • Injury generally occurs above the level of T6 (otherwise some sympathetic tracts are maintained).
  • Secondary spinal cord injury occurs hours to days after the initial insult.
    • Results from vascular insufficiency, electrolyte shifts, and edema that lead to progressive central hemorrhagic necrosis of grey matter at the injury site.
  • Lack of sympathetic input leads to unopposed parasympathetic activity. 
    • Poor venous tone and inability to vasoconstrict in the extremities leads to distribution of blood volume away from the core, causing hypotension and distributive shock. Shunting of blood to the extremities results in thermal dysregulation and subsequent hypothermia.
    • Unopposed vagal tone leads to bradycardia.
Signs/Symptoms

The trouble with traumatic neurogenic shock is that some of the common signs and symptoms can be nonspecific.

  • Hypotension 
    • Consider neurogenic shock when a patient’s blood pressure fails to respond with initial crystalloid and blood infusion.
    • Negative E-FAST and no signs of long bone injuries should raise concern for neurogenic shock in the hypotensive trauma patient with suspected spinal injury.
  • Bradycardia
    • Failure to mount tachycardia with shock is helpful in diagnosis, as we would expect a hemorrhaging trauma patient to have an appropriate tachycardic response to blood loss.
  • Warm extremities!
  • Normal capillary refill
    • Typical hemorrhagic shock will usually present with cold extremities and poor capillary refill, as the sympathetic system causes vasoconstriction in the extremities, shunting blood to vital organs.
    • Neurogenic Shock will have the opposite with lack of vasoconstriction and shunting of blood to the extremities.
  • Neurologic deficits
    • These patients will almost always have signs of neurologic injury (i.e extremity sensory deficits, paralysis, loss of all spinal function, etc.).
Treatment
  • Cautious crystalloid infusion
    • This can lead to worsening anemia and coagulopathy in polytrauma patients with hemorrhage and may increase spinal cord edema.
    • Crystalloid may help, but neurogenic shock may not respond to fluid administration.
  • Alpha 1 agonists are necessary to maintain appropriate blood pressure.
    • Both norepinephrine and epinephrine can be used. Epinephrine is key if there is significant bradycardia. 
    • While we may allow permissive hypotension in damage control resuscitation of hemorrhagic shock, in neurogenic shock you should maintain an age-appropriate blood pressure.
      • This is a relatively evidence free zone, but I personally would maintain SBP at least 50thpercentile for age (90+ 2x Age in years).
        • If you need a refresher on estimating expected pediatric SBP.                
  • These patients become hypothermic due to vasodilation, keep them warm.
  • Extremely bradycardic patients may require atropine or pacing.            

Moral of the Morsel 

  • Anatomy Matters! Young kids have higher C spine fulcrums and are more likely to have high C-spine injuries, making them more at risk for neurogenic shock.
  • Similar Words with Different Meanings! Spinal shock is a transient loss of all spinal cord function, but neurogenic shock is the hemodynamic instability caused by sympathetic denervation.
  • Response to Therapy Matters! Always consider neurogenic shock in the shocky trauma patient not responding to crystalloid or blood. 
  • Basics are the Best! Treat patients suspected of having neurogenic shock with warming and vasopressors. They may even need atropine and/or pacing for persistent bradycardia.

References

Coleman-Satterfield, TT. Shock. Tenenbein M, Macias CG, Sharieff GQ, et al, eds. In: Strange and Schafermeyer’s: Pediatric Emergency Medicine. 5th Edition. McGraw Hill Education; 2019:104-109

Dave S, DAHLSTROM JJ. Neurogenic Shock. [Updated 2022 Feb 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459361 

Ko HY. Revisit Spinal Shock: Pattern of Reflex Evolution during Spinal Shock. Korean J Neurotrauma. 2018 Oct;14(2):47-54. doi: 10.13004/kjnt.2018.14.2.47. Epub 2018 Oct 31. PMID: 30402418; PMCID: PMC6218357.

Patel JC, Tepas JJ 3rd, Mollitt DL, Pieper P. Pediatric cervical spine injuries: defining the disease. J Pediatr Surg. 2001;36(2):373.

Orenstein JB, Klein BL, Gotschall CS, Ochsenschlager DW, Klatzko MD, Eichelberger MR. Age and outcome in pediatric cervical spine injury: 11-year experience. Pediatr Emerg Care. 1994;10(3):132.

Mohseni S, Talving P, Branco BC, Chan LS, Lustenberger T, Inaba K, Bass M, Demetriades D. Effect of age on cervical spine injury in pediatric population: a National Trauma Data Bank review. J Pediatr Surg. 2011;46(9):1771.

Suessman A, Endom EE. Evaluation and management of the multiple trauma patient. Tenenbein M, Macias CG, Sharieff GQ, et al, eds. In: Strange and Schafermeyer’s: Pediatric Emergency Medicine. 5th Edition. McGraw Hill Education; 2019:125-138

Ziu E, Mesfin FB. Spinal Shock. [Updated 2022 Mar 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448163/

Author

Zach Gibson
Zach Gibson
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