Neurogenic Shock: Definition and Management
Definition
Neurogenic shock is a distributive form of circulatory shock resulting from spinal cord injury, characterized by the combination of hypotension and bradycardia due to loss of sympathetic tone below the level of injury. 1, 2
- The condition occurs most commonly with cervical spinal cord injuries, with an incidence of approximately 29% in cervical SCI when appropriate hemodynamic and laboratory criteria are applied 2
- The pathophysiology involves disruption of descending sympathetic pathways, leading to unopposed parasympathetic activity, peripheral vasodilation, and decreased cardiac output 1
- Hypotension (systolic blood pressure <90 mmHg) combined with bradycardia distinguishes neurogenic shock from other shock states 1, 2
Initial Assessment and Stabilization
Immediate spinal immobilization is critical to prevent worsening of the spinal cord injury and progression of neurogenic shock. 1, 3
- Establish invasive arterial line monitoring immediately to guide vasopressor titration and continuously assess hemodynamic response 4
- Monitor mean arterial pressure, heart rate patterns, lactate levels (target <2 mmol/L), and urine output serially to guide treatment intensity 4, 5
- Differentiate neurogenic shock from hypovolemic shock, as hypovolemia is frequently the primary confounding factor in misdiagnosis 2
Pharmacological Management
Administer fluid challenge with normal saline or Ringer's lactate (>200 mL over 15-30 minutes) as first-line treatment if there are no signs of overt fluid overload. 4, 6
Norepinephrine is the preferred first-line vasopressor when mean arterial pressure requires pharmacologic support after initial fluid resuscitation. 4, 5, 6
- The combination of vasopressor (dopamine or norepinephrine) with normal saline is most effective for reversing hypotension in neurogenic shock 7
- Titrate vasopressors to maintain adequate mean arterial pressure while using the minimal efficacious dose to prevent complications from excessive support 4, 6
- Avoid blood transfusion in the absence of true hypovolemia, as packed cells or whole blood can cause further deterioration of blood pressure in neurogenic shock. 7
Critical Pitfall to Avoid
The most common error is misidentifying hypovolemic shock as neurogenic shock or vice versa, leading to inappropriate fluid management—many patients are currently managed at net fluid intake ≤ zero, which may be inadequate 2
Surgical and Specialized Care
Arrange rapid transfer to a tertiary trauma center with 24/7 neurosurgical capabilities, advanced hemodynamic monitoring, and intensive care unit support. 4
- Early surgical decompression is recommended for incomplete neurological deficits identified within the first 6 hours post-injury 1
- Facilities must have multidisciplinary shock team protocols and mechanical circulatory support availability if needed 4
Monitoring During Recovery
Blood pressure characteristically declines further after the first week post-injury, requiring ongoing vigilance and adjustment of vasopressor therapy. 2
- Continue serial hemodynamic assessment and titrate vasopressors downward as sympathetic tone recovers 4, 6
- Monitor for complications of prolonged vasopressor use and adjust therapy to the minimal dose that maintains adequate perfusion 4
Contraindicated Therapies
Corticosteroids are not recommended for the treatment of neurogenic shock or acute spinal cord injury. 1