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Neurogenic Shock
Aka: Neurogenic Shock, Vasogenic Shock
- See Also
- Spinal Shock
- Hemorrhagic Shock
- Severe Head Trauma
- Spinal Cord Syndrome
- Cervical Spine Injury
- Thoracolumbar Trauma
- Definitions
- Neurogenic Shock
- Distributive Shock from neurogenic vasodilation mediated by loss of sympathetic tone
- Follows cerebral or spinal cord injury (above T6) affecting sympathtic nervous system
- Spinal Shock
- In contrast to Neurogenic Shock, Spinal Shock is not a true shock syndrome
- Results in Flaccid Paralysis and Deep Tendon Reflex loss below level of spinal cord injury
- Pathophysiology
- Results from Severe Head Injury or upper spine injury (above T6)
- Peripheral Sympathetic Nerve denervation results in ungoverned Parasympathetic Nerve activity
- Loss of vasomotor tone (vasodilation) leading to Distributive Shock
- Loss of cardiac Sympathetic Nerve activity, leads to paradoxical Bradycardia
- Causes
- Severe Head Trauma
- Cervical Spine Injury
- Thoracic Spine Injury (above T6)
- Signs
- Mnemonic: 70/70 = SBP 70, HR 70
- Lack of normal sympathetic tone
- Hypotension
- Secondary to Bradycardia and vasodilation
- Narrow Pulse Pressure is absent
- Lack of typical sympathetic response (increased SVR and diastolic BP)
- Paradoxical Bradycardia
- Expected response is a reflex Tachycardia (a sympathetic response)
- Decreased vascular tone (vasodilation)
- Warm extremities
- Absent diaphoresis
- Associated Conditions
- See Severe Head Trauma
- See Spinal Cord Syndrome
- See Cervical Spine Injury
- See Thoracolumbar Trauma
- Spinal Shock
- Flaccid Paralysis and Deep Tendon Reflex loss below level of spinal cord injury
- Diaphragm Paralysis
- C3-5 Cervical Spine Injury resulting in phrenic nerve denervation
- Differential Diagnosis
- Hemorrhagic Shock (first priority to manage)
- Presents with Tachycardia, Vasoconstriction and cold extremities
- In actuality, distinguishing from Neurogenic Shock can be difficult
- Hemorrhagic Shock is more common, more immediately deadly and more treatable
- Address possible Hemorrhagic Shock first
- Pitfalls
- Fluid Overload (from aggressive fluid Resuscitation)
- Management
- Careful Fluid Replacement
- Vasopressors (Norepinephrine is preferred)
- Target mean arterial pressure of 85 mmHg or higher (maximizes spinal cord perfusion)
- Prognosis
- Neurogenic Shock if due to critical Head Injury may indicate terminal event
- Prognosis is often poor
- References
- (2012) ATLS, ACOS, p. 179-80