Pathophysiology

Pathophysiology Study Guide

©2018 of 131 6.7 Pain Pain is the feeling that is triggered by the central nervous system in the body. Pain can be mild, sharp, acute, and chronic. One may feel pain in any particular body part or even in the entire body. It is a tool to communicate the occurrence of a problem within the body. Types of Pain There are different types by which pain can be classified. Common types of pain are nociceptive, neuropathic, and inflammatory. Nociceptive pain is the kind of pain that occurs in response to an injury to tissues or noxious insult. Examples of nociceptive pain include somatic pain (like joint pain, myofascial pain) and visceral (like pain in smooth muscles). Neuropathic pain is the response of a lesion or disease-causing agent in the somatosensory nervous system. Sensory abnormalities can be numbness, paralysis, and hypersensitivity. Examples of neuropathic pain are diabetic neuropathy, spinal cord injury pain, and post stroke central pain. Inflammatory pain is caused by the activation and sensitization of nociceptive pain pathways through the mediators released at the site of tissue inflammation. Pain can also be categorized by the intensity, which can be divided into mild pain, moderate pain, and severe pain. It is also possible to categorize pain as per the time course and can be acute pain (lasts for less than three to six months), or chronic pain (lasts for more than three to six months or even after the healing of tissue is complete). Pain Assessment Pain should be assessed by using a multi-dimensional approach so that chronicity, severity, and quality of the pain, along with contributing factors, etiology of pain, mechanism of injury, and barriers to pain assessment, can be ascertained. A "0 to 10" numerical scale is the most widely used measure to assess pain intensity. When using the Numerical Rating Scale (NRS), patients are asked to rate their pain from 0 to 10, with "0" equaling no pain and "10" equaling the worst possible pain. There is no instrument to objectively measure pain intensity therefore the only valid measure of pain is the patient´s self-report. There are various other scales used to assess pain in patients who are unable to express their pain level verbally. In infants, pain should be assessed using a blend of behavioral and physiological factors. One such tool to assess pain among infants is “CRIES,” which is a way to evaluate five major factors including crying, oxygen requirement, increased vital signs, expression, and sleeplessness on a scale of zero to two. Another tool is the modified behavioral pain scale that uses three factors, which include facial expression, cry, and movements to assess children between two to six months. Among young children, pain can also be assessed through limitations in cognitive skills. For children older than three years, self- reporting becomes a valid measure. Pain Mechanism (Pathway) When the brain receives a pain signal (ascending pathways), the signals travel to the motor cortex, followed by the spinal cord, and finally to the motor nerves. This influences the contractions of the muscles. For the ascending pathways, there are two major tracts that carry the nociceptive signals to Achieve Page 101