Neurogenic shock

Neurogenic shock is distributive shock caused by loss of sympathetic nervous system tone, often after spinal cord injury. It produces vasodilation and hypotension and may cause bradycardia.

Sympathetic nervous system: The autonomic nervous system division that mobilizes the body through signals that commonly increase vascular tone and heart rate. Its loss of influence removes the vascular constriction and cardiac acceleration that normally support blood pressure.
Shock: A life-threatening state in which circulatory failure prevents tissues from receiving adequate oxygen and nutrients. Neurogenic shock is one mechanism within this broader syndrome of inadequate tissue perfusion.
Trauma assessment: A structured evaluation of injuries and immediate threats to life after trauma. It helps identify spinal injury and detect bleeding that may coexist with neurogenic shock.
Septic shock: A form of distributive shock caused by infection-associated circulatory and cellular dysfunction. Both can cause vasodilation, but infection and its systemic effects define septic shock.
Vasodilation: Widening of blood vessels caused by relaxation of vascular smooth muscle. Reduced sympathetic vasoconstriction widens vessels and lowers systemic vascular resistance.
Distributive shock: Shock in which abnormal vascular dilation and blood-flow distribution impair effective tissue perfusion. Neurogenic shock is a subtype in which loss of sympathetic tone drives the abnormal distribution.
Spinal cord injury levels: The anatomical locations of spinal cord damage, described by spinal region and neurological level. Higher lesions are more likely to interrupt descending sympathetic pathways and cause hemodynamic instability.
Anaphylactic shock: A severe systemic allergic reaction that causes circulatory failure, often with airway or skin symptoms. It also causes distributive hypotension, but follows an allergic mechanism rather than sympathetic loss.
Bradycardia: A heart rate slower than the normal range for a person’s age and circumstances. Unopposed vagal influence and disrupted sympathetic input can slow the heart, unlike many shock states.
Spinal shock: Temporary loss of reflexes and motor, sensory, and autonomic function below a spinal cord injury. Despite the similar name, spinal shock is a neurologic state, not circulatory shock.

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