Autonomic dysreflexia in tetraplegic patients: evidence for alpha-adrenoceptor hyper-responsiveness

Clin Auton Res. 1995 Oct;5(5):267-70. doi: 10.1007/BF01818891.


A controlled study of acute pharmacological intervention was designed to determine whether decreased sympathetic nerve activity in tetraplegic patients results in increased responsiveness of alpha-adrenoceptors which might contribute to vascular hyperreactivity and the clinical scenario of autonomic dysreflexia. The study took place in a university teaching hospital and included six male tetraplegic patients and six age-matched normal male controls. All tetraplegics were 5 months or longer post-traumatic spinal cord injury and all had experienced symptoms of autonomic dysreflexia on at least one occasion. The dorsal foot vein diameter was recorded with a tonometer during local infusions of noradrenaline 0.125-256 ng/min given through a short intravenous needle. In tetraplegic patients, there was a significant shift to the left of the dose-response curve indicating increased venous responsiveness to noradrenaline. The concentration of noradrenaline required to cause a 50% reduction of the resting vein diameter was decreased in tetraplegics (1.6 ng/min, geometric mean) compared to normal controls (10.9 ng/min, p < 0.02). alpha-Adrenoceptor responsiveness in dorsal foot veins is increased in patients with tetraplegia. Hypersensitivity of vascular alpha-adrenoceptors may contribute to autonomic dysreflexia in patients with high spinal cord injury.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Autonomic Nervous System Diseases / etiology*
  • Autonomic Nervous System Diseases / physiopathology
  • Blood Pressure / drug effects
  • Dose-Response Relationship, Drug
  • Heart Rate / drug effects
  • Humans
  • Male
  • Norepinephrine / administration & dosage
  • Quadriplegia / complications*
  • Quadriplegia / physiopathology
  • Receptors, Adrenergic, alpha / drug effects
  • Receptors, Adrenergic, alpha / physiology*
  • Reflex / physiology
  • Spinal Cord Injuries / physiopathology
  • Veins / anatomy & histology
  • Veins / drug effects
  • Veins / innervation


  • Receptors, Adrenergic, alpha
  • Norepinephrine