Which type of shock is caused by increased stimulation of the vagus nerve causing vasodilation and hypotension?

• A. Neurogenic shock
• B. Psychogenic shock
• C. Anaphylactic shock
• D. Septic shock

Answer: (B)

When the vagus nerve is stimulated, the parasympathetic system slows the heart and can cause the vessels to dilate. This combination reduces blood returning to the heart and lowers blood pressure, leading to transient cerebral hypoperfusion and fainting. This reflex, often linked to emotional stress or pain, is classically called vasovagal syncope, a psychogenic form of shock driven by excess vagal activity.

Neurogenic shock, by contrast, stems from loss of sympathetic tone after spinal injury, causing vasodilation and hypotension but not primarily through vagal stimulation. Anaphylactic shock involves widespread vasodilation and increased vascular permeability due to an allergic reaction. Septic shock arises from a severe infection triggering systemic inflammation and vasodilation. Thus, the described mechanism fits psychogenic (vasovagal) shock.