Why Autonomic Dysreflexia Is More Complicated Than It Looks 

Anytime someone suffers a serious spinal cord injury (SCI), the threat of autonomic dysreflexia (AD) lingers. The Cleveland Clinic notes that of the estimated 17,000 cases of spinal cord injuries in the US every year, nearly 48% to 70% of those above the T6 level are at risk of AD. 

In some cases, there are apparently no warning signs before the situation worsens. In a 2026 case report, a patient with a complete C3 spinal cord injury developed AD after defecation. Their blood pressure levels reached 178/101 mmHg. This episode was accompanied by severe headache, with imaging revealing intracerebral hemorrhage. 

Only a month later, a second hemorrhage was detected in the opposite cerebral hemisphere. Now, this was extreme, but the truth is that the body’s response can escalate even when the initial problem seems minor. 

So, this article will explore what makes autonomic dysreflexia more complicated than it looks. That will help you understand why effective management extends beyond treating the immediate crisis at hand. 

Not Just a Sudden Surge in Blood Pressure 

Many people, including those starting in the field of medicine, acquaint themselves with AD as a sudden rise in blood pressure. It’s only later that one realizes what a massive autonomic disturbance high blood pressure is hiding. The episode begins when a stimulus below the level of SCI triggers sympathetic activity that the brain cannot regulate through the injured spine. 

After a SCI, blood pressure cannot be classified as the black and white of high or low. Let’s understand this through a 2025 systematic review that examined 38 studies involving 7,167 people with acute SCI. In the 14 studies included in the quantitative analysis, blood pressure below the study-defined thresholds was associated with 3.28 times higher odds of an adverse functional outcome in the unadjusted analysis. 

That observation was heterogeneous. While considering AD, its context matters because the concern is a different form of instability in blood pressure. Instead of inadequate pressure, the patient can experience a rapid and potentially dangerous hypertensive response. 

If we go by the WHO’s 2025 emergency-care standards, people with lesions at T6 and above are especially vulnerable to AD. The same guidance identified bladder distension, pressure injuries, and bowel impaction among the possible responsible factors. 

Once blood pressure rises, the brain can still detect the change and attempt to compensate. This may produce the following:

• Severe or pounding headache 
• Sweating or flushing above the injury 
• Bradycardia 
• Nasal congestion 
• Goosebumps or chills 
• Blurred vision, anxiety, or a general feeling of unease 

What makes AD particularly concerning is that the physiological response may appear out of proportion to the initial problem. This is precisely why managing AD is not a matter of lowering the blood pressure. Perhaps the most challenging complication has to do with the stimulus occurring below the injury level, where normal sensation is impaired or absent. 

As a result, the autonomic system may be responding strongly to a problem that the patient cannot even experience in the usual way. The growing disconnect between the stimulus, what the patient can perceive, and what the autonomic system is truly doing is central to understanding AD. 

Finding the Source of an AD Episode 

When autonomic dysreflexia develops, clinicians know something is wrong the minute blood pressure rises abnormally. However, it’s still difficult to tell what’s driving the episode. This won’t happen through a single obvious diagnosis because the underlying stimulus generally occurs below the level of injury (as stated earlier). 

For someone living with a life-changing spinal cord injury, this altered sensory picture can make the clinical situation much more difficult to understand. The main issue may be huge without producing the familiar pain or discomfort that normally become clues for clinicians. 

For a systematic search, the urinary system is an important place to start. Urinary tract infections, bladder distension, and stones are among the common causes of AD. Even urological procedures can provoke an episode. For instance, urodynamic studies (UDS) that assess lower urinary tract function by filling the bladder can precipitate AD in susceptible patients. 

This is why Andrei Krassioukov, MD, a professor of physical medicine and rehabilitation at the University of British Columbia, emphasized the need to consider AD risk before any such tests. Having spent decades studying autonomic conditions after SCI, his advice to urologists was direct: “Be aware of the possibility of the development of AD in individuals with SCI undergoing urological evaluations, including UDS.”

The same also applies to the investigation of an episode outside a clinical procedure. Possible sources may include:

• Bowel: This involves constipation or impaction 
• Skin and soft tissue: Look for pressure injuries, wounds, and burns 
• Musculoskeletal system: There may be fractures or other injuries that block out pain signals 
• Positioning and equipment: Even something as simple as pressure from seating or cushions can trigger AD 
• Other recent procedures: Think of catheterization, cystoscopy, or bowel care 

Identifying the source is just a piece in the puzzle. As Lesser, Landy, Smith & Siegel, PLLC, notes, the focus in spinal cord cases is not just on what has already happened. It is on what the future will require, which may include surgeries, rehabilitation, or assistive technology. 

Plus, the range of complications helps explain why it’s not so easy to detect the root cause of the problem. Larry Singer, who has lived with a C5-6 SCI for decades, described his experience in a 2025 New Mobility article. “If there’s one thing you write about in your article, it should be just how flipping hard it is to explain to people, even healthcare professionals, what is going on with autonomic dysreflexia.” 

His episodes have been associated with problems that ranged from urinary infections and bowel accidents to wounds and pressure from his wheelchair cushion. Now, an individual patient’s experience may not stand for all, but it does help to know that there is no all-black-or-white with AD. 

From Managing an AD Episode to Preventing Another 

Even after the blood pressure has stabilized, the process of AD management does not end. The important focus is to understand what the episode revealed about the patient’s ongoing risk. If a particular bladder, bowel, skin, or procedural issue was responsible, addressing that problem must be a part of the long-term prevention strategy. 

A 2025 observational study of 1,473 people with SCI gives a valuable perspective on the ongoing risk aspect. Researchers discovered that the level of injury, bowel dysfunction, and bladder-management type were independently associated with AD severity. For every 10-point increase in Neurogenic Bowel Dysfunction score, the AD score increased by about 1 point. 

What the findings clearly emphasize is the value of individualized prevention. Healthcare providers cannot assume that every patient has the same risk profile. It’s important to consider the person’s injury level, bladder and bowel function, previous episodes, as well as current management strategies. Prevention can involve several parts of routine management, including:

• Addressing problems that could lead to bladder distension 
• Maintaining a proper bowel routine and addressing constipation or impaction early 
• Checking for pressure injuries, wounds, burns, or other sources of irritation 
• Checking whether seating, cushions, and other equipment are designed for sustained pressure
• Identifying AD risk before interventions that may stimulate areas below the injury 
• Documenting what preceded previous episodes so patterns can be recognized 

Having mentioned these, it’s important to remember that a previous episode is a clue, not a full-fledged diagnosis. Prevention must simply involve applying what you’ve learnt from a previous episode so the next one is easier to manage. 

FAQs 

What should clinicians prioritize while investigating an episode of autonomic dysreflexia?

Clinicians should assess potential noxious stimuli below the neurological level of injury, particularly urinary, bowel, skin, and recent procedural causes. Since impaired sensation can mask the underlying problem, a normal pain report should not be used to exclude a stimulus. 

Why can blood pressure alone be misleading in AD?

The significance of an elevated reading depends on the patient’s baseline blood pressure and neurological context. AD can produce hypertension alongside variable autonomic manifestations, while some patients may have minimal symptoms. Hence, blood pressure should be considered only as part of a broader autonomic response. 

What should guide prevention after an AD episode?

Prevention should be individualized according to the precipitating stimulus, neurological level, previous episodes, and current management strategies. When recurring bowel and urinary problems and procedural risks are addressed, the chances of future episodes decrease. Plus, it will provide a clearer framework for rapid assessment. 

Essential Data for Context 

So, we have seen how autonomic dysreflexia is a part of a much larger process. At least research has shown promise of eventually having those underlying processes addressed. In a 2025 study, researchers found that naturally occurring AD episodes became more frequent over time in rats with complete T3 spinal cord injuries. 

However, those treated with the NF-κB inhibitor experienced considerably fewer AD episodes at 7, 8, and 12 weeks after injury. The treatment also reduced the peak mean arterial pressure during several weeks of follow-up. 

Now, that doesn’t mean NF-κB inhibition can be considered a foolproof treatment for those with AD. What the research does suggest is that the future of AD will move beyond responding to the obvious stimulus. The focus, as of now, should be proper investigation, not just destabilization. That way, at least some episodes can be prevented successfully.