Patient Care, Trauma

Assessment and Treatment of Spinal Cord Injuries and Neurogenic Shock

Issue 11 and Volume 39.

You’re called to the home of an 82-year-old female patient who fell down a flight of stairs. Upon arrival, you find an elderly woman lying at the base of a staircase complaining of back and chest wall pain. Initial vital signs demonstrate a pulse of 68 and regular blood pressure (BP) of 104/60, and a respiratory rate of 18 and regular with saturations of 98% on room air.

After completing a primary survey without need for immediate intervention, you notice she doesn’t move her noticeably warm lower extremities. With care, you place the patient in a rigid C-collar and onto a spine board.

During transport to the nearest trauma center, you note a repeat BP of 100/62 and heart rate of 60. On arrival, her BP is 98/62 despite getting a 750 mL bolus of isotonic crystalloid solution via an IV that you established en route.

LEARNING Objectives

  • Learn how to identify, assess and treat spinal cord injury.
  • Understand the difference between neurogenic shock and spinal shock.
  • Recognize signs and symptoms of neurogenic shock and understand treatment modalities.

KEY Terms

  • Neuorgenic shock: A form of distributive shock that results from unopposed parasympathetic response after a disruption of the spinal cord at mid-thoracic levels (T6) and above.
  • Parasympathetic nervous system: A division of the autonomic nervous system that performs many functions, including increased intestinal activity during digestion and slowed heart rates.
  • Pressor: A substance that causes elevation of blood pressure.
  • Spinal cord: Long, round structure found in the spinal canal and reaching from the base of the skull to the lumbar spine. The cord carries sensory and motor signals to and from the brain and controls many reflexes.
  • Spinal shock: Characterized by similar cardiovascular signs of neurogenic shock (bradycardic, hypotensive and hypothermic) but more often includes a marked reduction or loss of somatic and/or reflex functions of the spinal cord beyond the level of the injury.
  • Sympathetic nervous system: A division of the autonomic nervous system that functions during strenuous muscular work and other stresses. Functions include dilating blood vessels in the skeletal muscle; increasing adrenal secretion, heart rate and pupillary size, and decreases digestive functions in preparation for fight-or-flight reactions.

 

 

Epidemiology
Although there haven’t been any significant studies on the incidence of spinal cord injuries over the last 10 years, the annual incidence is about 12,000 new cases per year (not including the patients who die at the scene).1 Nearly half of all the injuries occur in patients between the ages of 16 and 30 and the majority (80%) of them are men.

Motor vehicle crashes account for the majority of causes at ~36%, followed by falls, acts of violence and sports.1 There’s a tremendous financial cost associated with these injuries both in hospital charges and in wages and productivity lost.

Anatomy & Physiology
The vertebral column—the bony spine—is made up of different regions identified as cervical, thoracic, lumbar and sacral. These regions have 7, 12, and 5 vertebral bodies respectively, along with a fused sacrum. (See Figure 1 below.) The bony spine acts as a support for other skeletal structures, gives a partly rigid and flexible axis for the body, gives a pivot for the head, and protects the spinal cord.

Figure 1: Vertebral column and spinal cord

The spinal cord is an extension of the brain and runs in the vertebral canal the length of the spinal column from the foramen magnum until it ends at the lumbar 1 (L1) or 2 (L2) vertebra. The spinal cord is a bundle of nerves arranged in a very specific manner that allows a clinician to identify the nature and level of an injury by clinical presentation. Sympathetic nervous system outflow comes from the thoracic and lumbar regions and the parasympathetic system via cranial and sacral nerves.

Among other actions, the spinal cord mediates the effects of the autonomic nervous system through complicated pathways. With the sympathetic nervous system responsible for “fight or flight” types of responses (i.e., tachycardia and vasoconstriction) and the parasympathetic nervous system for “rest and digest” types of responses, an injury to the spinal cord at high-enough levels will result in unopposed parasympathetic activity.

Specifically, without an effective sympathetic nervous system the patient won’t be able to vasoconstrict or produce tachycardia.

Neurogenic Shock/Spinal Shock
Although frequently used interchangeably, true definitions of neurogenic and spinal shock are hard to identify. Multiple definitions have been used, but, from a practical standpoint, neurogenic shock is a form of distributive shock that results from unopposed parasympathetic response after a disruption of the spinal cord at mid-thoracic levels (T6) and above.

There’s some indication that a transient hypertension exists immediately after injury, but, most commonly, because of the loss of sympathetic activity, these patients can present bradycardic, hypotensive and hypothermic. Because of the profound vasodilation that occurs, the patient’s extremities will be warm as opposed to the cool, clamped down feeling one normally finds in hemorrhagic shock.

Spinal shock is an entity that can encompass the earlier noted cardiovascular findings but is more often characterized by a marked reduction or loss of somatic and/or reflex functions of the spinal cord beyond the level of the injury. This has the potential to last for days or weeks post injury.

It should be noted that the patient with spinal cord injury and neurogenic shock as a result of trauma often has other injuries that could result in hemorrhagic shock. This could cloud the presentation and make diagnosis difficult. It’s therefore imperative to exclude other causes of hypotension before attributing the cause to neurogenic shock, as their treatments may be different.

Patient Assessment
Although obvious in those clinical scenarios where the patient presents paralyzed or with motor/sensory dysfunction, a heightened level of suspicion for a spinal column or cord injury should also be maintained when the provider finds altered mental status, suspected extremity fracture or distracting injury, or spine pain/tenderness.

As always, the prehospital provider should follow the basic airway, breathing, circulation approach to the trauma patient while protecting the spine from any extra movement.

While maintaining in-line cervical spine immobilization, the airway should be assessed for patency with a jaw thrust maneuver. If there’s a cord injury above C5, the patient will present in respiratory failure. Breathing and circulation should be assessed in the usual manner. Neurologic deficits and a general level at which abnormalities began should be identified.

Spinal column integrity should be ensured by log rolling the patient onto the immobilization device.

 

Treatment
As the initial traumatic insult can’t be reversed, the goals of treatment for a patient with a spinal cord injury and shock should be to prevent or limit worsening of the initial injury.

There’s old (but often quoted) data to suggest that upward of 25% of injury to the spinal cord occurs after the initial insult.2 To that end, the provider needs to be cautious about manipulating the spine while performing any treatment.

Although little good data exists as to the efficacy of spinal immobilization, the cervical spine should be immobilized in a rigid collar and ultimately the patient should be placed on a backboard for transport with supportive blocks on either side of the head.

Maintain spinal column integrity by log rolling the patient onto the backboard or other firm device. In general, this combination will provide the best immobilization for the patient. Bony prominences can be padded for comfort without compromising spine neutrality.

If the airway is a concern, securing it becomes paramount. Care must be taken to maintain cervical spine neutrality.

Because a C-collar may impede your ability to effectively open the mouth, the front part of the C-collar can be removed, but someone should then be assigned to hold the neck to prevent motion during the procedure (manual in-line stabilization).

There’s some evidence to suggest video laryngoscopy is superior to standard laryngoscopy when it comes to visualization and minimizing cervical motion during intubation.3,4 Additionally, the practitioner should be ready for a difficult airway. Rapid sequence is the method of choice for the intubation. If endotracheal intubation isn’t warranted, supplemental oxygen can be provided to the patient.

Circulatory collapse and shock needs to be promptly recognized and treated. As standard in these scenarios, a large bore (14- or 16-gauge) IV should be established. For those presenting in shock, regardless of the cause, a fluid bolus with crystalloid should be administered per local protocols. In the case of isolated neurogenic shock, the resultant vasodilation results in pooling of blood and decreased venous return to the heart.

Initial treatment for this is IV fluid, but if there’s no response, pressors can be considered. Large amounts of fluid without response should be avoided as it could result in a worsening respiratory failure.

Several pressor options exist and include dopamine, norepinephrine and phenylephrine. If the patient presents with both hypotension and bradycardia, one should avoid phenylephrine due to its potential for reflex bradycardia.

For isolated bradycardia, atropine can be used. From a practical standpoint, pressors are rarely used in the prehospital environment for neurogenic shock due to relatively short transport times and the inability to always identify the true nature of the shock.

Because of the vasodilation that occurs in neurogenic shock, the patient is also at risk for hypothermia. It’s therefore imperative that temperature be monitored and maintained in a normal range. In the prehospital environment, the patient should initially be exposed to identify all injuries but then promptly covered and kept warm.

Early transport of the patient to a center capable of dealing with injuries of this nature should ensue. This most likely involves transport to a verified trauma or spine center. If there’s concomitant trauma, the patient should be transported to a trauma center.

Once in the hospital, the trauma team will work to remove the patient from the backboard as soon as possible while maintaining spinal precautions. They’ll also complete the workup to identify the extent of injuries.

If shock is present, it remains important to rule out the most common causes of shock in the trauma patient. Once hemorrhagic shock has been ruled out and neurogenic shock identified, pressors can be initiated.

Unlike blunt trauma that requires spinal immobilization, there have been multiple studies that show you don’t have to approach the patient with penetrating trauma the same way.5,6

The potential downsides to having a C-collar in place, such as missing an injury, outweigh the benefits in this population. PHTLS no longer recommends routine placement of a C-collar in those with penetrating trauma; however, local protocols/guidelines should be followed.

Common Spinal Cord Injuries
Motor and sensory function loss from an injury can be classified as complete or incomplete. A complete cord injury will present with motor paralysis and sensory loss below the level of the cord that’s involved. These are the injuries that most often result in spinal or neurogenic shock. An incomplete injury will present in multiple different ways depending on what part of the cord is injured.

  • Central cord syndrome: This is a type of incomplete lesion to the cord that results in dysfunction in the upper extremities as opposed to the lower extremities. The patient will present with upper extremity weakness or paralysis and minimal if any dysfunction of the lower extremities.
  • Anterior cord syndrome: This is found when the mechanism results in an injury to the anterior portion of the spinal cord. Because of the specific nerve fibers that run through this region, the patient will present with absence of motor function, pain and sensation below the level of the injury. The patient will retain the ability to feel light touch, proprioception and vibration.
  • Brown-Sequard syndrome: These lesions result from injury to half the cord, which results in paralysis on the side of the injury and loss of pain and temperature sensation on the opposite side.

Conclusion
Looking back at the case presentation, we can now see that this patient presented with evidence of paralysis and neurogenic shock. The patient was appropriately immobilized and given IV fluids. Without a response from the fluid bolus, the crew should consider the initiation of pressors.

Spinal cord injury can result in a multitude of different presentations depending on the level and location of injury in the cord itself; however, the primary approach to every one of these patients should be the same.

With any suspicion for spinal column or cord injury, the blunt trauma patient should be treated with spinal stabilization that includes C-collar, backboard and head blocks. Further evaluation of these trauma patients should be done utilizing the ABC approach recognizing that any intervention should be made with the goal of not worsening the initial injury.

Care should be taken to move the patient as a unit. The airway should be secured while maintaining neutral cervical spine positions. If shock is present, the patient should be evaluated for hemorrhagic shock as well as neurogenic causes as there can be overlap.

Initial fluid boluses should be attempted but if isolated neurogenic shock is identified it may need to be treated with pressors. Finally, the patient should be transported to an appropriate center where spinal injuries can be promptly addressed.

References

1. Spinal Cord Injury (SCI) Fact Sheet. (Nov. 10, 2010.) Centers for Disease Control and Prevention. Retrieved Sept. 10, 2014, from www.cdc.gov/traumaticbraininjury/scifacts.html.
2. Bernhard M, Gries A, Kremer P, et al. Spinal cord injury (SCI)—prehospital management. Resuscitation. 2005;66(2):127–139.
3. Turkstra TP, Pelz DM, Jones PM. Cervical spine motion: A fluoroscopic comparison of the AirTraq laryngoscope versus the Macintosh laryngoscope. Anesthesiology. 2009;111(1):97–101.
4. Robitaille A, Williams SR, Tremblay MH, et al. Cervical spine motion during tracheal intubation with manual in-line stabilization: direct laryngoscopy versus GlideScope videolaryngoscopy. Anesth Analg. 2008;106(3):935–941.
5. Barkana Y, Stein M, Scope A, et al. Prehospital stabilization of the cervical spine for penetrating injuries of the neck—is it necessary? Injury. 2000;31(5):305–309.
6. Haut ER, Kalish BT, Efron DT, et al. Spine immobilization in penetrating trauma: More harm than good? J Trauma. 2010;68(1):115–120.