Neurogenic shock occurs when
injury to the brain or spinal cord or the administration of certain drugs results in the loss of sympathetic stimulation.
It can also occur when pain, stress, drugs, or toxins cause overstimulation of the parasympathetic nerves.
Arterioles lose their stimulus to maintain a constant amount of vasoconstriction (loss of vascular tone) and, therefore, peripheral vascular resistance falls.
This causes the blood volume to be redistributed to nonvital organs, with a loss of blood pressure and underperfusion of tissues.