Articles

Stimulating the human midbrain to reveal the link between pain and blood pressure

Green, Alexander L.^a,b,*; Wang, Shouyan^b; Owen, Sarah L.F.^b; Xie, Kangning^b; Bittar, Richard G.^a; Stein, John F.^b; Paterson, David J.^b; Aziz, Tipu Z.^a,b

Author Information

^aDepartment of Neurosurgery, Radcliffe Infirmary, Woodstock Road, Oxford, OX2 6HE, United Kingdom

^bUniversity Laboratory of Physiology, University of Oxford, Parks Road, Oxford, OX1 3PT, United Kingdom

^*Corresponding author. Tel.: +44 1865 311188/+44 1865 224221; fax: +44 1865 224786.

E-mail: [email protected]

Submitted November 9, 2005; revised April 20, 2006; accepted May 2, 2006.

Pain 124(3):p 349-359, October 2006. | DOI: 10.1016/j.pain.2006.05.005

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Abstract

The periaqueductal grey area (PAG) in the midbrain is an important area for both cardiovascular control and modulation of pain. However, the precise relationship between pain and blood pressure is unknown. We prospectively studied 16 patients undergoing deep brain stimulation of the rostral PAG for chronic pain. Pre-operatively, post-operatively, and at 1 year, pain scores were assessed using both visual analogue scores and the McGill Pain Questionnaire. Patients were tested post-operatively to determine whether electrical stimulation of the PAG would modulate blood pressure. We found that the degree of analgesia induced by deep brain stimulation of the rostral PAG in man is related to the magnitude of reduction in arterial blood pressure. We found that this relationship is linear and is related to reduced activity of the sympathetic nervous system. Thus stimulation of the PAG may partly control pain by reducing sympathetic activity as predicted by William James over a century ago.