Prevention of Complications Due to Autonomic Dysreflexia in SCI Individuals

Overview

Autonomic dysreflexia (AD) is a syndrome of unbalanced response of the sympathetic system to noxious stimuli below the level of spinal cord injury (SCI), characterized by paroxysmal hypertension. Mostly, it is combined with symptoms such as pounding headache, slowed heart rate, and upper body flushing, but it can also be asymptomatic. When resulting in hypertensive crisis, it can be life-threatening and result in seizures, cardiac arrest, retinal or subarachnoid hemorrhages, stroke, and even death. The aim of this study is to determine the risk level of vascular complications in SCI people by correlating the clinical symptoms with their individual perception during AD triggered below the level of injury.

After spinal cord injury, the disruption of descending vasomotor pathways to sympathetic neurons causes their hyperexcitability. When irritated by noxious stimuli below the level of injury, a massive sympathetic reflex is triggered, causing widespread vasoconstriction. If the neurological level of injury is at or above T6, this vasoconstriction can lead to progressive hypertension possibly involving the splanchnic vessels. In response to hypertension, the baroreflex system lowers blood pressure by reducing heart rate and decreasing the activity of sympathetic neurons. However, a decrease in peripheral vascular resistance below the injury level does not occur because of the disruption of descending vasomotor pathways to sympathetic neurons. Thus, hypertension persists until the triggering stimulus is removed. Hypertensive crises can result in vascular complications like cardiac arrest, retinal or subarachnoid hemorrhages, stroke, and even death. Vasodilatation above the lesion level is accompanied by characteristic signs and symptoms such as upper body flushing and sweating, and a pounding headache. Sometimes bradyarrhythmia, seizures, nausea, or anxiety can occur. Unfortunately, AD can take place asymptomatically in almost 40 %. These asymptomatic individuals are at high risk of life-threatening complications mentioned above. The most frequent AD triggers are overfilled bladder or bowel. Nevertheless, it can be any irritating stimuli below the level of injury, i.e., skin lacerations, ingrown toenails, or pressure sores. Higher intensity of perception of clinical symptoms accompanying AD decreases the risk of vascular complications. People who perceive subjective signs of AD even in slightly elevated blood pressure can eliminate irritating stimuli or use an antihypertensive medication and thus avoid life-threatening complications. On contrary, people who cannot perceive the signs intensely enough are at a significantly higher risk of vascular complications. The aim of this study is to determine the risk level of vascular complications in SCI people. The AD will be triggered below the injury level so that the clinical symptoms can be correlated with their subjective individual perception. Moreover, the development of a method allowing capturing AD episodes in individuals without subjective signs is intended.