Chronic Pain and Blood Pressure
The relationship between chronic pain and blood pressure is much less well understood. It has been reported in a number of studies that there may be a deficiency of endogenous opioids in chronic pain patients. The blood pressure-pain relationship was studied by Bruehl et al. in 118 patients with chronic lower back pain. The main finding was that in patients in whom the duration of the pain was relatively short (less than a year) there was a weak inverse correlation between the symptoms of pain and blood pressure, but in those who had been suffering from pain for more than 2 years the correlation was positive -- those who reported more frequent or intense pain had higher blood pressures. Maixner et al. found no relationship between blood pressure and sensitivity to acute pain in patients with temporomandibular joint disorders. Thus, the normal pain-blood pressure relationship is absent or reversed in these patients, which raises questions about which comes first: Are people who do not show the usual pain-blood pressure relationship more likely to develop chronic pain, or does chronic pain impair the relationship? The effects of the duration of exposure to pain reported by Bruehl et al. favor the latter explanation, leading those authors to propose the following sequence of events: persistent pain leads to generalized arousal and elevation of blood pressure. This in turn leads to baroreceptor stimulation, which acutely lowers pain sensitivity, partly through release of endogenous opioids. However, over the long term progressive opioid dysfunction occurs, resulting in a decrease of endogenous opioids and their painkilling effects, and hence a vicious cycle whereby further pain leads to further arousal and decreased pain tolerance. Additional support for this view comes from a study showing that in women with acute pelvic pain of 2-3 days' duration, endorphin levels are increased.
© 2003 Le Jacq Communications, Inc.
Cite this: Pain and Blood Pressure - Medscape - Sep 01, 2003.