Autonomic dysreflexia

Following SPINAL CORD LESION at T6 or above a noxious stimulus below the lesion leads to unopposed sympathetic response and dangerous HYPERtension.

This may lead to convulsions, intracranial haemorrhage or arrhythmias.


Occurs in 50-90% of all cord lesions (above T6)

Noxious stimulus below lesion - splanchnic sympathetic plexus - excessive release of norepinephrine - vasoconstriction skin of abdomen and legs - marked hypertension.

Compensation (aortic arch baroreceptors via IX and X) with ↓HR and vasodilation. Cord damage prevents vasodilation so: flushing above lesion and bradycardia


Any noxious stimulus below lesion e.g. bladder distension, bowel distension, UTI, DVT, PE, pressure ulcers, fractures, cellulitis etc. etc.

Signs and symptoms

  • Flushing and sweating above the lesion
  • Nasal stuffiness
  • Paleness and piloerection below the lesion
  • Pounding headache
  • HYPERtension
  • Bradycardia
  • Blurred vision
  • Anxiety/apprehension


  • Recognise the condition!
  • Monitor BP
  • Sit patient up, legs down
  • Look for cause (bladder obstruction [change catheter], bowel obstruction [faecal loading disimpaction])
  • Consider analgesia (IV opiates)
  • Consider GTN spray if SBP > 150mmHg (normal for those with cord lesion is SBP 90-110 mmHg)

Content by Dr Íomhar O' Sullivan 12/12/2011. Last review Dr ÍOS 15/06/21.