Autonomic dysreflexia in tetraplegic patients: Evidence for α-adrenoceptor hyper-responsiveness
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.
Keywordsα-adrenoceptor autonomic dysreflexia noradrenaline tetraplegia
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- 1.Mathias CJ, Frankel HL. Cardiovascular system in tetraplegia and paraplegia. In: Frankel HL, ed.Handbook of Clinical Neurology, Vol. 17 (61),Spinal Cord Trauma. Amsterdam: Elsevier Science Publishers, 1992; 435–456.Google Scholar
- 4.Debarge O, Christensen NJ, Corbett JL, Eidelman BH, Frankel HL, Mathias CJ. Plasma catecholamines in tetraplegics.Paraplegia 1978;12: 44–49.Google Scholar
- 17.Kongpatanakul S, Blaschke TF, Hoffman BB. The role of postsynaptic α2-adrenoceptors in human hand veins.Clin Res 1990;38: 94.Google Scholar
- 18.Kongpatanakul S, Blaschke TF, Hoffman BB. The role of postsynaptic α2-adrenoceptors in human hand veins.Clin Pharmac Ther 1990;47: 141.Google Scholar