Autonomic Dysreflexia Explained – When the body can’t hit the brakes
It is a boring Friday night in winter, and you’re on your way out to pick up some epic pizza from the best place in town. Noticing the cold air, as you step onto the concrete, a guy wheels up to you in his electric wheelchair, “mate… I’m busting… can you please help me”? His face is flushed, it almost looks like a rash? He’s sweaty but it’s freezing cold out, his eyes are pressed tightly together, his brow is furrowed as though his head is about to implode from pain. He’s breathless and flustered. like he’s just sprinted a marathon. And he’s just said he’s busting? What on earth do you do now?
What you might be witnessing, is a life-threatening medical emergency known as autonomic dysreflexia, or “AD”. AD is a complex but critical phenomenon occurring in the day-to-day life of someone with a spinal injury above T6 (Eldahan & Rabchevsky, 2018). For some people post spinal cord injury, their body manages to continue to send messages about things that are causing them discomfort from below the height of injury, where they cannot “feel”. Cragg and Krassioukov (2012) can attest, autonomic dysreflexia (AD) is a potentially life-threatening response caused by our nervous system going into overdrive telling the post spinally injured body, that something is up, somewhere down there.
The nervous systems are like centralised ecosystems, constantly adjusting to the information entered in. Our brain and our spinal cord transport information back and forth from our peripheral nervous system, about everything happening around us. Think back to the little toe that you hooked on the corner of the bedroom door as you rushed to work. That’s about where the autopilot of our autonomic nervous system comes online, fast.
Like a car, this system has its own accelerator (the sympathetic nervous system) pushing up the blood pressure when a painful message comes in, and brakes (parasympathetic nervous system) trying to bring it down (Garafola, 2020). However, unlike a car’s accelerator and brake, the autonomic nervous system, despite the name, doesn’t imply that you have any autonomy over it – it does its own thing (The Dysautonomia Project, 2023). It can even drive itself, depending on where it’s told to go, but things will stop and start it along the way depending on the input it receives, such as a pedestrian in its path or a stop sign. These two systems, the sympathetic and parasympathetic nervous system, are constantly working together to keep us safe and comfortable allowing for rapid control of our bodies blood pressure, heart rate, bladder, gut bowel and temperature (Gibbons, 2019). This can be a remarkably effective system, when everything is working as it should, and messages can travel up and down the spinal cord. But what happens when “go faster” and “slow down” messages are obstructed?
There are a lot of processes that need to happen for our body to interpret a pain message from the accelerator, through the spinal cord and up into the brain. Then hit the brakes and send the message back, down. The message needs to travel through cervical level – think our head and neck area, through to our thoracic level – think ribcage and abdomen, to our lumbar spine – think lower back like the lumbar support on your ergonomic office chair and finally into the sacral spine – think the “sacred” parts of your body. Is a big job.
In the experience of Autonomic Dysreflexia, Eldahan & Rabchevsky (2018) describe that for person with spinal cord injury above the height of the sixth thoracic spinal cord segment (also known as “T6”), they’re experiencing the bodies response, to a “noxious stimulus”. A break or injury to the spinal cord, stops the response signal from the brakes telling the bodies blood pressure to “slow down” or decrease in response to something painful. Think of the last time you were busting for the loo. You’re feeling stressed, your blood pressure goes up, your heart is pumping, you might even jump up and down on the spot. So, you hop to it and find a loo, and empty that bladder or bowel. But what if you can’t physically do that? Or you have a permanent catheter in your bladder, it’s blocked, and you can’t physically release the increasing pressure?
Enter the guy at the pizza shop, sweating bullets and feeling like his head is about to explode. He hasn’t run a marathon, but if you asked his heart, it might just tell you otherwise, because his parasympathetic system, isn’t able to hit the brakes and send the message back to modulate the blood pressure. He’s asking for help, because in that moment with a few litres in his bladder from a blocked catheter and an old spinal injury above T6, his blood pressure is escalating uncontrollably from the sympathetic output (think of the foot on the accelerator unable to be removed). He is possibly about to experience one of the complications of Autonomic Dysreflexia being Cerebral haemorrhage (brain bleed) leading to death (Dolinak & Balraj, 2007).
In a study by Wan and & Krassioukov (2013) 72% of instances of death due to unresolved instances of AD, were central nervous system related, and this is what can happen, when the body can not put the brakes on.
So how can we help people when they’re in the situation with uncontrolled AD? Three questions. One. How can I help you? Two. Can I call you an ambulance? Three. Have you had a medication to control this? (Queensland Health, 2012). That’s it, that’s how you can help the guy asking you for help at the pizza shop on a Friday night, experiencing uncontrolled symptoms of autonomic dysreflexia. Understanding that our bodies nervous systems are an ecosystem, all working coherently together, until the spinal cord is injured above T6 and blocks the body’s ability to send messages to slow down might one day help someone experiencing the life-threatening emergency of Autonomic Dysreflexia.
References
Cragg, J., & Krassioukov, A. (2012). Autonomic dysreflexia. Canadian Medical Association Journal, 184(1), 66. https://doi.org/10.1503/cmaj.110859
Dolinak, D., & Balraj, E. (2007). Autonomic dysreflexia and sudden death in people with traumatic spinal cord injury. The American Journal of Forensic Medicine and Pathology, 28(2), 95–98. https://doi.org/10.1097/PAF.0b013e3180600f99
Eldahan, K. C., & Rabchevsky, A. G. (2018). Autonomic dysreflexia after spinal cord injury: Systemic pathophysiology and methods of management. Autonomic Neuroscience, 209, 59–70. https://doi.org/10.1016/j.autneu.2017.05.002
Garafola, M. (2020, May 20). The science of stress: Understanding your stress response. Connecticut Science Center. https://ctsciencecenter.org/blog/the-science-of-stress-understanding-your-stress-response/
Gibbons, C. (2019). Basics of autonomic nervous system function. In K. H. Levin & P. Chauvel (Eds.), Handbook of clinical neurology (Vol. 160, pp. 407–418). Elsevier. https://doi.org/10.1016/B978-0-444-64032-1.00027-8
Harmison, L., Beckham, J., & Adelman, D. (2023). Autonomic dysreflexia in patients with spinal cord injury. Nursing, 53(1), 21–26. https://doi.org/10.1097/01.NURSE.0000902944.16062.1f
Queensland Health. (2012). Autonomic dysreflexia: Acute management in spinal cord injury (Clinical guidelines). Queensland Government. https://www.health.qld.gov.au/__data/assets/pdf_file/0034/424888/dysreflexia.pdf
The Dysautonomia Project. (2023). What is the autonomic nervous system? https://thedysautonomiaproject.org/what-is-the-autonomic-nervous-system/
Wan, D., & Krassioukov, A. V. (2013). Life-threatening outcomes associated with autonomic dysreflexia: A clinical review. The Journal of Spinal Cord Medicine, 37(1), 2–10. https://doi.org/10.1179/2045772313Y.0000000098