There are not many emergencies that occur as a direct result of a rehabilitation diagnosis, however the emergencies that occur can be difficult to diagnose and deadly. In the spinal cord injury (SCI) population, one such medical emergency is called Autonomic dysreflexia (AD). AD is clinically characterized by elevated blood pressure and bradycardia. Patients can also experience headache, flushing, sweating above the level of injury, goose bumps below the level of injury, nasal congestion and anxiety.
AD occurs only in the SCI population and mostly with neurologic injuries at, or above the T6 spinal cord level. Patients with more complete injuries (meaning less sparing of motor or sensory) are at higher risk of developing AD during their lifetime. Upwards of 48 percent (Linden et al) of patients with SCI at, or above T6 develop AD during the first year post-injury. However, patients can also develop AD years after their initial injury.
Important to note, the definition of AD includes elevated blood pressure (BP) from the patient’s baseline. In the SCI population, baseline BP can be lower than the able-bodied population. For this reason, elevated BP is defined as systolic BP 20-40 mmHg above baseline or 20 percent elevation of systolic BP above baseline.
AD is due to an uninhibited sympathetic surge from a noxious stimuli below the level of injury. This stimuli excites the sympathetic nervous system causing severe vasoconstriction of arterial vasculature below the level of injury, and in turn, elevated blood pressure. In the able-bodied population, the nervous system responds to this sympathetic surge via the parasympathetic system, thereby preventing prolonged constriction of the vasculature. However, in the SCI population, the injury to the spinal cord prevents this inhibitory parasympathetic response from reaching the splanchnic vascular bed. Baroreceptors identify elevations in BP and respond via the vagus nerve and cause a relative slowing of the heart.
The only way to definitively treat AD is to identify and remove the noxious stimuli. Bladder distention and fecal impaction account for most causes of AD. Non-pharmacologic interventions to remove the inciting stimuli are recommended prior to pharmacologic intervention for hypertension if possible.
It is important to identify AD in the SCI population as it can be difficult to treat and can increase morbidity and mortality in this population. For a full review of treatment of AD, please refer to the Clinical Practice Guideline released by the Consortium for Spinal Cord Injury Medicine.
By Dana Clark, MD
Dana Clark attended college at Johns Hopkins University where she majored in Neuroscience and participated on the track team. She completed a year of volunteer work with the National AIDS fund through Americorps prior to starting Medical School at Rutgers New Jersey Medical School. She graduated from Physical Medicine and Rehabilitation Residency from Harvard University and went on to complete Spinal Cord Injury Medicine fellowship at Kessler Rehabilitation Institute. After fellowship she moved to Orlando with her husband and dog and has been employed at HealthSouth for the last year. She can be contacted at Dana.Clark@HealthSouth.com