Of all physical symptoms, the most subjective and the most notoriously difficult to asses is pain. Dr. Ina Cabaluna, anesthesiologist and head of the Pain Management and Wellness Center of the Manila Doctor’s Hospital, quotes a definition of pain formulated by a nurse, Margot McCaffery: “Pain is whatever the experiencing person says it is, existing whenever he says it does.” Pain is not always in the mind.
Dr. Ina Cabaluna, head of Manila Doctor’s Hospital’s Pain Management Center, defines the fine line between acute and chronic pain
“It starts with injury,” Dr. Cabaluna says. “It creates stimulus in peripheral pathways going to the brain. When the brain detects it, it goes through another pathway descending again, where all the neural transmitters are activated to tell you that you are in pain.” Specifically, from the peripheral receptors, through the neural pathways, the spinal-cord mechanisms and through the brainstem, the thalamus, the cortex and other areas, and through descending pathways.
First pain, second pain
There are two distinct responses to a painful stimulus: a “first pain” and a “second pain.” Dr. Cabaluna explains that “The first pain is well localized and brief, the second is more diffuse and protracted. First pain is described as sharp and ‘pricking.’ It localizes to a well-defined part of the body surface. The receptors for this first pain are high-threshold mechanoreceptors. There appear to be specific nociceptors [or sensory pain receptors], which mediate pain, and only pain. Second pain is due to stimulation of receptors that exist in many tissues [but, paradoxically, not in the brain]. It is often described as dull [i.e. not sharp] and aching. It is poorly localized. Receptors for this second pain are termed polymodal nociceptors. This pain tends to last beyond the termination of an acute painful stimulus.”
Remarkably, thresholds for feeling pain are constant from one individual to another. And for all its dread associations, pain does have a distinct and even life-saving function. It alerts a person to the existence of a medical problem or an injury that needs treatment.
For the rest of the article, please see the July – September 2008 issue.