Clinical Autonomic Research

, Volume 5, Issue 5, pp 267–270

Autonomic dysreflexia in tetraplegic patients: Evidence for α-adrenoceptor hyper-responsiveness

  • J. M. O. Arnold
  • Q. -P. Feng
  • G. A. Delaney
  • R. W. Teasell
Research Paper

Abstract

A controlled study of acute pharmacological intervention was designed to determine whether decreased sympathetic nerve activity in tetraplegic patients results in increased responsiveness of α-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). α-Adrenoceptor responsiveness in dorsal foot veins is increased in patients with tetraplegia. Hypersensitivity of vascular α-adrenoceptors may contribute to autonomic dysreflexia in patients with high spinal cord injury.

Keywords

α-adrenoceptor autonomic dysreflexia noradrenaline tetraplegia 

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Copyright information

© Rapid Science Publishers 1995

Authors and Affiliations

  • J. M. O. Arnold
    • 1
  • Q. -P. Feng
    • 1
  • G. A. Delaney
    • 2
  • R. W. Teasell
    • 3
  1. 1.Victoria HospitalUniversity of Western OntarioLondonCanada
  2. 2.Parkwood HospitalUniversity of Western OntarioLondonCanada
  3. 3.University HospitalUniversity of Western OntarioLondonCanada

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