Chapter 11 - Acute and Chronic Pain

Abstract

This chapter presents a study on acute and chronic pain. The International Association for the Study of Pain (IASP), relates pain as an unpleasant experience and although invariably associated with a nociceptive focus. The definition of pain by IASP, which is undergoing minor modification, is stated as an unpleasant sensory or emotional experience associated with actual or potential tissue damage or described in terms of such damage. The chapter discusses neurobiology of pain, principles of therapy, drug therapy, and several other types of therapy. Nonsteroidal anti-inflammatory drugs (NSAIDs), NSAIDs plus opioids, corticosteroids are also discussed. The subdivision of pain into either acute or chronic pain is common although somewhat arbitraryand depends on the situation. Acute pain includes postoperative pain, myocardial infarction, injury, or infrequent migraine/other headaches, biliary/renal colic, and so on. Pain that persists for longer than the normal time of healing or for longer than 3–6 months is then regarded as chronic pain, including regular or indeed irregular episodic acute pain conditions. There are some treatment differences between acute and chronic pain, particularly in the pharmacological algorithms used but a return of as much function as possible is a key feature common to both types of pain. Substantial progress has been made in improving the treatment of acute pain by re-evaluating routes of administration, modes of administration, and drug combinations and by prioritizing pain as an important treatment requirement in its own right. The steps and philosophy contained in the WHOanalgesic ladder provides a logical basis for the pharmacological treatment of chronic cancer and non-cancer pain.