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Autonomic Dysreflexia

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What is "Autonomic Dysreflexia?"

Autonomic dysreflexia is a syndrome
characterized by abrupt onset of excessively high blood pressure
caused by uncontrolled sympathetic nervous system discharge in
persons with spinal cord injury. Persons at risk for this problem
generally have injury levels above T-6. True autonomic
dysreflexia is potentially life-threatening and is considered a
medical emergency.

What are signs and symptoms of Autonomic

  • Hypertension (blood pressure greater than
  • Pounding headache (secondary to hypertension/vasodilatation)
  • Flushed (reddened) face (secondary to vasodilatation)
  • Red blotches on the skin above
    level of spinal injury (secondary to vasodilatation)
  • Sweating above level of spinal
    injury (secondary to vasodilatation)
  • Nasal stuffiness (secondary to vasodilatation)
  • Nausea (secondary to vagal
    parasympathetic stimulation)
  • Bradycardia – slow pulse <60 beats per
    minute – (secondary to vagal parasympathetic stimulation)
  • Piloerection ("goose bumps") below
    level of spinal injury
  • Cold, clammy skin below level of
    spinal injury

What sort of things can precipitate this syndrome?

In general, noxious stimuli (irritants, things
which would ordinarily cause pain) to areas of body below the
level of spinal injury. Things to consider include:

  • Bladder (most common)
    from overstretch or irritation of bladder wall
    • Urinary tract infection
    • Urinary retention
    • Blocked catheter
    • Overfilled collection bag
    • Non-compliance with intermittent
      catheterization program
  • Bowel – over distention or irritation
    • Constipation / impaction
    • Distention during bowel program (digital stimulation)
    • Hemorrhoids or anal fissures
    • Infection or irritation (eg.
  • Skin-related Disorders
    • Any direct irritant below the
      level of injury (eg. – prolonged pressure by
      object in shoe or chair, cut, bruise, abrasion)
    • Pressure sores (decubitus ulcer)
    • Ingrown toenails
    • Burns (eg. – sunburn, burns from
      using hot water)
    • Tight or restrictive clothing or
      pressure to skin from sitting on wrinkled
  • Sexual Activity
    • Over stimulation
      during sexual
      activity [stimuli to the pelvic region which
      would ordinarily be painful if sensation were
    • Menstrual cramps
  • Labor and delivery
  • Other
    • Heterotopic ossification
      ("Myositis ossificans",
      "Heterotopic bone")
    • Acute abdominal conditions
      (gastric ulcer, colitis, peritonitis)
    • Skeletal fractures

What can be done to manage an episode of autonomic

Principle #1 is to identify and
remove the offending stimulus
whenever possible.
Often, this alone is successful in allowing the syndrome to
subside without need for pharmacological intervention. It is also
good for the person with the symptoms to be sitting up with
frequent blood pressure checks until the episode has resolved.
[In hospital-based settings or in high-risk individuals / persons
who have recurrent episodes, consideration should be given having
atropine at the bedside]

Suspected cause = bladder?
Check catheter – remove kinks if found, empty urinary collection
bag, irrigate catheter. If catheter is not draining, replace it
immediately. If an intermittent catheterization program is in
place, a straight catheterization should be performed immediately
with (slow drainage to prevent bladder spasms).

Suspected cause = bowel? If
episode happens during digital stimulation,
stop stimulation until symptoms and signs subside. Consider use
of a prescribed anesthetic ointment to suppress the noxious
stimulus. If the issue is impacted stool, disimpact. If it occurs
while doing a bowel program in bed, try commode-based bowel
evacuation. Consider use of abdominal massage instead of digital

Suspected cause = skin?
Loosen clothing. Check for source of potential offending stimulus
– check for pressure sores, toenail problems, soles of the feet.

If symptoms persist despite
interventions such as the foregoing, notify a physician.

What medical interventions are possible when removal of
noxious stimuli doesn’t end an episode of autonomic dysreflexia?

Medications are generally used only if the
offending trigger/stimulus cannot be identified and removed – or
when an episode persists even after removal of the suspected
cause. Potentially useful agents include:

  • Immediate/emergent
    • Procardia – 10 mg. p.o./sublingual
    • Nitroglycerine – 1/150 sublingual
      or 1/2 inch Nitropaste topically
    • Clonidine – 0.1 to 0.2 mg. p.o.
    • Hydralazine – 10 to 20 mg. IM/IV
  • Chronic (recurrent episode prevention)
    • Prazosin ("Minipress")
      – 0.5 to 1.0 mg. daily
    • Clonidine ("Catapres")
      – 0.2 mg. p.o. b.i.d.

How can autonomic dysreflexia be prevented?

  • Frequent pressure relief in bed/chair
  • Avoidance of sun burn/scalds (avoid
    overexposure, use of #15 or greater sunscreen, watch
    water temperatures)
  • Faithful adherence to bowel program (no
    longer than 3 days between bowel evacuations)
  • Keep catheters clean and remain faithful
    to intermittent catheterization schedule
  • Well balanced diet and adequate fluid
  • Compliance with medications
  • Persons at risk and those close to them
    should be educated in the causes, signs and symptoms,
    first aid, and prevention of autonomic dysreflexia.