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    Autonomic Dysreflexia Diagnosis and Treatment


    Last Updated Jul 03, 2021
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    By Julian Marsden, Neil Thurley


    Autonomic dysreflexia (AD) is a state of sympathetic hyperactivity resulting in acutely elevated systolic and diastolic blood pressure (BP).1,2,3,5

    It occurs in individuals with spinal cord injury (SCI) at the T6 level or higher; however, levels as low as T8-T12 have been reported.1,2,3,5

    • Caused by noxious stimulation below the level of spinal injury1,2,3,5 most commonly urinary bladder distension, followed by bowel distension.
    • Other causes include:
      • GU: kidney stones, catheterization, blocked catheter, urinary tract infection.1
      • GI: bowel impaction, hemorrhoids, fissures.
      • Other: constrictive clothing, ingrown toenails, pressure ulcers.1
      • Reproductive: sexual stimulation, male ejaculation, menstruation, pregnancy.1
      • Trauma: fracture, abrasion, laceration.1
      • Risk for hypertensive encephalopathy, intracranial hemorrhage, cardiac arrest, cardiac arrhythmias, and seizures.1,2,3,5

    Diagnostic Process

    The presentation is variable, and the severity of symptoms does not correlate with the degree of BP increase. Patients with recurrent AD should be asked about their prior experiences of AD.3 Potential symptoms include:1,2,3,5

    • Bradycardia or tachycardia.
    • Pounding headache.
    • Sweating and flushing of the skin above the level of spinal injury.
    • Piloerection and pallor of the skin below the level of spinal injury.
    • Blurred vision.
    • Nasal congestion.
    • Anxiety.

    AD is generally clinically defined by the following elevations in systolic blood pressure (SBP):

    • Adults: 20-40 mmHg above baseline SBP.1,2
    • Adolescents and Children: 15-20 mmHg above baseline SBP.1,2

    Note: Individuals with SCI at T6 or above will typically have a resting SBP of 90-110 mmHg.1,3

    Recommended Treatment

    Immediately sit patient up and loosen constrictive clothing; BP should be monitored every 2-5 minutes (or continuously) for the duration of the episode.1

    Treatment focuses on identifying and removing the causative factor of the AD episode.1,2,3,4,5

    Assess urinary system for the causative factor:

    • Catheterize the patient if an indwelling catheter is not in place using 2% lidocaine jelly 2 minutes prior to catherization.1
    • If an indwelling catheter is in place, perform point of care ultrasound to check for obstructions. A blocked catheter may be corrected via normal saline irrigation (10-15mL for adults, 5-10mL for children), or simply replace the catheter.1

    If the elevated BP does not resolve with urinary management, assess the bowel next:

    • Manually evacuate the rectum, applying 2% lidocaine jelly to the rectum 2 minutes prior to digital evacuation.1
    • If the elevated BP does not resolve following urinary and bowel management, assess for other causative factors.1
    • Following the resolution of an AD episode patients should be monitored for at least 2 hours.
    • Consider hospital admission for those with poor response to treatment or no causative factor has been identified.1


    Pharmacological Management

    Consider pharmacologic management if BP remains elevated following urinary management (prior to proceeding with the bowel survey) for patients with SBP ≥150mmHg.1 Pharmacologic management should also be considered in patients where elevated BP persists despite removal of the causative factor, or if no causative factor is identified.4


    (for the management of mild-moderate AD):

    1. Nitroglycerin.
    • Nitroglycerin spray (1-2 sprays); repeat dose after 20-30 minutes if necessary.3
      • Note: Nitroglycerin is contraindicated for patients who have used a Phosphodiesterase inhibitor (e.g. sildenafil) within the last 24 hours.1
    1. Nifedipine
    • 10mg PO (not sublingual – can cause precipitous drop in BP); repeat dose after 20-30 minutes if necessary.1,3,4
    1. Captopril
    • 12.5-25mg PO.1


    (for the management of severe or resistant AD):

    1. Hydralazine: 20mg IV as a single dose.4,5
    2. Labetalol: 10 – 20mg IV as a single dose.4

    Quality Of Evidence?


    Clinical practice guideline recommendations are primarily supported by expert consensus alone, or low quality scientific evidence (nonrandomized trials and case series). See guidelines for grading of individuals recommendations.


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