Pain is an ever-present complaint voiced to health-care providers. Pain may be either acute or, if it lasts more than six months, chronic. Acute pain is usually associated with a readily diagnosable condition. Chronic pain may be more difficult to localize and treat.
The Institute of Medicinei has estimated that 30 percent of Americans have complaints of chronic pain. If this estimate is correct, there are 116 million Americans living with chronic pain. These estimates correlate with those of other developed countries.
Chronic pain may be divided into nociceptive, which is caused by the activation of nociceptors, and neuropathic, which is caused by damage to or malfunction of the nervous system. Nociceptive pain may be divided into superficial or deep while neuropathic pain may be peripheral or central. Brain activity measured by EEG in persons suffering from chronic pain shows alteration of normal function. The relative beta activity compared to the rest of the brain is increased; the relative alpha activity is decreased; and the theta activity both absolutely and relatively is diminished.ii
Chronic pain is associated with higher rates of depression and anxiety. Sleep disturbances and insomnia due to medication and illness symptoms are often experienced by those with chronic pain, and those with such pain may limit their physical activity due to fear of exacerbating the pain and thus decrease their release of endorphins, which could bring pleasure and some pain relief.
I trust this issue will enable you to better understand the causes of pain and some of the potential therapeutic interventions. We all dread to see patients whose pain we cannot relieve, but their needs are great and we must make every effort to facilitate their diagnosis and treatment.
i Institute of Medicine of the National Academies Report (2011) Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research. Washington DC: The National Academies Press.
ii Jensen MP, Sherlin LH, Hakiman S, Fregni F. Neuromodulatory approaches for chronic pain management research findings and clinical implications. J Neurotherapy 2009, 13:196-213.