What is neurogenic shock primarily caused by?

Neurogenic shock is primarily caused by spinal cord injury, particularly injuries that disrupt sympathetic nerve pathways. This condition results in a loss of sympathetic tone, leading to vasodilation, decreased systemic vascular resistance, and subsequently reduced blood pressure. This is often accompanied by bradycardia due to unopposed vagal tone. When the spinal cord is injured, especially at higher levels (such as cervical or thoracic), the body's ability to regulate vascular tone and blood flow is significantly impaired, resulting in the characteristic clinical presentation of neurogenic shock.

In contrast, dehydration primarily causes hypovolemic shock due to a reduction in blood volume, while severe allergic reactions can lead to anaphylactic shock, involving different mechanisms and physiological responses. Cardiac arrest results in circulatory collapse due to a failure of the heart to pump effectively, which also does not align with the mechanisms involved in neurogenic shock. Understanding these distinctions is crucial for effective diagnosis and management of shock in clinical settings.