autonomic dysreflexia

Last edited 09/2018

Autonomic dysreflexia is a condition that emerges after a spinal cord injury, usually when the injury has occurred above the T6 level

  • the higher the level of the spinal cord injury, the greater the risk with up to 90% of patients with cervical spinal or high-thoracic spinal cord injury being susceptible (1,2)
    • autonomic dysreflexia most frequently develops during the first 2-4 months after the injury and affects 10 % during the first year (3)
      • lifetime frequency among persons with spinal cord injury is 19-70 %
      • condition occurs more frequently in patients with cervical lesions and complete injuries

  • dysregulation of the autonomic nervous system leads to an uncoordinated autonomic response that may result in a potentially life-threatening hypertensive episode when there is a noxious stimulus below the level of the spinal cord injury
    • injury to the spinal cord results in unbalanced autonomic control that typically presents as diminished sympathetic activity - however, following spinal cord injury some conditions can precipitate overactive sympathetic episodes that may cause life-threatening events among these individuals (2)
    • autonomic dysreflexia:
      • characterised by paroxysmal episodes of inappropriate sympathetic activity associated with hypertensive crises
      • excessive sympathetic discharge in the absence of descending inhibition (due to spinal cord injury) leads to vasoconstriction below the level of spinal cord injury and critically elevated BP
      • condition is commonly triggered by both noxious and non-noxious stimuli experienced below the level of spinal cord injury, followed by massive sympathetic output to the peripheral targets including blood vessels and the heart (2)
      • autonomic dysreflexia results in episodes of paroxysmal hypertension, frequently accompanied by baroreflex-mediated bradycardia
        • systolic blood pressure of 250-300 mm Hg and diastolic blood pressure of 200-220 mm Hg have been recorded with autonomic dysreflexia (3)

    • in about 85% of cases, this stimulus is from a urological source such as a UTI, a distended bladder, or a clogged Foley catheter
    • is a significantly increased risk of stroke by 300% to 400% (1)
    • autonomic dysreflexia can occur in susceptible individuals up to 40 times per day (1)

The initial presenting complaint is usually a headache which can be severe

  • susceptible individuals with spinal cord lesions above T6 who complain of a headache should immediately have their blood pressure checked
    • if elevated, a presumptive diagnosis of autonomic dysreflexia can be made (1)

Prompt recognition and correction of the disorder, usually just by irrigating or changing the Foley catheter, can be life-saving (1)

Reference:

Related pages:

spinal cord injury