Autonomic Dysreflexia (AD) is a medical emergency occurring in individuals with a spinal cord injury, typically at or above the sixth thoracic vertebra (T6). It is defined by a sudden, exaggerated spike in blood pressure resulting from an overreaction of the autonomic nervous system to an irritating stimulus below the injury level. Since the body’s normal blood pressure regulation is disrupted, this rapid rise can lead to dangerously high levels. This poses a serious risk for complications like stroke, seizure, or heart attack. Prompt recognition and immediate intervention are necessary to resolve the episode and prevent life-threatening outcomes.
Recognizing the Key Warning Signs
The most prominent and often the first sign of an AD episode is a severe, pounding headache caused by the sudden increase in pressure. For individuals with a high-level spinal cord injury, baseline systolic blood pressure is often lower (typically 90 to 110 mm Hg). A rise of just 20 to 40 mm Hg above their normal range signals a hypertensive episode. The presence of a throbbing headache in a susceptible individual should immediately prompt a blood pressure check.
Symptoms manifest differently depending on their location relative to the spinal cord injury. Above the injury level, the body attempts to compensate for high blood pressure through the parasympathetic nervous system. This compensatory effort results in profuse sweating and flushing, particularly on the face, neck, and shoulders. Nasal congestion and blurred vision are also commonly reported due to the vasodilation that occurs above the injury site.
Below the level of the spinal cord injury, the uninhibited sympathetic response causes intense blood vessel constriction. This results in skin that is pale, cool, and clammy to the touch in the lower region. Goosebumps (piloerection) are frequently observed due to the sympathetic nervous system’s heightened activity.
An episode of AD also affects heart rate and emotional state. Although the body attempts to slow the heart rate (bradycardia) to counteract hypertension, a rapid or irregular heartbeat can also occur. Many individuals experience apprehension, anxiety, or a sense of impending doom during an episode.
Identifying Common Triggers
Autonomic Dysreflexia is initiated by a noxious or irritating stimulus that the body perceives as harmful but cannot process normally due to the spinal cord injury. The majority of AD episodes are caused by issues related to the bladder, bowel, or skin. Identifying the source of this irritation is the most important step in resolving the hypertensive crisis.
Bladder issues are the most frequent trigger, accounting for 75% to 85% of all cases. The most common cause is bladder over-distention, resulting from a blocked or kinked catheter, an overly full catheter bag, or failure to follow a timely intermittent catheterization schedule. Other urological irritants include urinary tract infections, bladder or kidney stones, and bladder muscle spasms.
The second most common category of triggers involves the bowel. Fecal impaction or severe constipation can cause enough visceral distention to initiate the reflexive reaction. Other gastrointestinal causes include hemorrhoids, anal fissures, gas, bloating, and manual bowel evacuation procedures if performed improperly.
A wide range of other stimuli can also trigger an AD episode, mostly related to skin and body integrity.
Skin and Mechanical Irritants
Skin issues include pressure ulcers (bedsores), ingrown toenails, burns, and insect bites. Mechanical irritations, such as tight clothing, restrictive braces, or a hard object pressing against the skin, can also cause a reaction.
Internal Factors
Additional internal factors like sexual activity, menstruation, labor, or fractures below the level of injury are known causes.
Immediate Emergency Steps
Managing an AD episode requires a rapid, sequential response focused on identifying and removing the inciting stimulus. The first step is to immediately change the person’s position by sitting them upright or elevating the head of the bed to a 90-degree angle. This posture uses gravity to help lower the blood pressure and should be maintained until pressure returns to normal. Concurrently, any constrictive clothing or devices, such as tight belts, abdominal binders, or shoes, should be loosened or removed.
After positioning and loosening clothing, blood pressure must be monitored every two to five minutes to track the severity and effectiveness of interventions. The next immediate priority is to check for the most common triggers, beginning with the urinary system. If a catheter is present, check it for kinks, blockages, or fullness, and correct any problem immediately.
If addressing the urinary system does not resolve the symptoms, the focus shifts to the bowel. Check for signs of fecal impaction, though this requires careful manual evacuation only after applying a numbing lubricant to prevent further stimulation. If high blood pressure persists after checking both the bladder and bowel, thoroughly check the skin and body for other irritants, such as pressure sores or an ingrown toenail. If the systolic blood pressure remains elevated above 150 mm Hg, or if symptoms do not resolve quickly after removing the trigger, emergency medical services should be called immediately.