Neurogenic Shock: Clinical Presentation
Neurogenic shock presents with the characteristic combination of hypotension and bradycardia (or relative bradycardia without the expected compensatory tachycardia), resulting from loss of sympathetic tone following spinal cord injury, typically at the cervical or high thoracic level. 1, 2
Cardinal Signs
The defining hemodynamic features that distinguish neurogenic shock from other shock states include:
- Hypotension (systolic blood pressure typically <90 mmHg) without compensatory tachycardia 1, 2
- Bradycardia or inappropriately normal heart rate despite hypotension—this is the key distinguishing feature from hypovolemic shock 1, 2
- Warm, dry skin rather than the cold, clammy skin seen in hypovolemic or cardiogenic shock 3, 4
Associated Neurological Findings
Patients with neurogenic shock will demonstrate:
- Motor weakness or paralysis below the level of spinal cord injury 1, 2
- Sensory deficits corresponding to the level of injury 2
- Loss of reflexes below the injury level 1
- Priapism (in males) may be present as a sign of unopposed parasympathetic activity 1
Temporal Pattern
The hemodynamic instability follows a characteristic progression:
- Immediate onset following spinal cord trauma, typically within hours 1, 2
- Characteristic decline in blood pressure may occur after the first week post-injury 2
- Duration can persist for days to weeks, requiring ongoing vasopressor support 1, 2
Critical Distinguishing Features from Other Shock States
Unlike hypovolemic shock, neurogenic shock presents with:
- Absence of tachycardia—the hallmark difference 1, 2
- Warm extremities rather than cold, clammy skin 3, 4
- Wide pulse pressure rather than narrowed pulse pressure 3
- Clear neurological deficit corresponding to spinal cord injury level 1, 2
Common Pitfalls
The most critical error is misdiagnosing neurogenic shock as pure hypovolemic shock, leading to excessive fluid resuscitation without vasopressor support. 2 Studies demonstrate that hypovolemia is often the primary confounding factor in inconsistent diagnosis, and that fluid management alone is insufficient—vasopressors are required as primary therapy alongside judicious fluid resuscitation. 1, 2
Do not rely on tachycardia as a marker of shock severity in patients with suspected spinal cord injury, as the absence of tachycardia despite hypotension is the defining feature of neurogenic shock. 1, 2
The calculated incidence of true neurogenic shock is approximately 29% in cervical spinal cord injuries when appropriate hemodynamic and laboratory criteria are applied, though reported incidence varies widely (from much lower to much higher) depending on which clinical definition is used. 2