Chapter Seven Understanding and Managing Pain. This chapter focuses on five basic questions: 1. How does the nervous system register pain? 2. What is.

Chapter SevenUnderstanding and Managing Pain

• This chapter focuses on five basic questions:

• 1. How does the nervous system register pain?

• 2. What is the meaning of pain?

• 3. How can pain be measured?

• 4. What types of pain present the biggest problems?

• 5. What techniques are effective for pain management?

Five Questions

• Pain - unpleasant feeling caused by illness or injury– Pain is important for survival

Pain

• Pain and the Nervous System– Sense receptors located on the surface of the

body turn physical energy into neural impulses• These neural impulses can travel to the peripheral

nervous system toward the spinal cord and brain

Pain and the Nervous System

• Afferent neurons - sensory neurons that relay information from the sense organs toward the brain– Primary afferents - specialized receptors in

sense organs that convert physical energy into neural impulses and carry this information to the brain to be processed

Neurons

• Myelinated afferent neurons - neurons covered in myelin – A-fibers important in pain perception

• Responsible for “fast”, prickly pain

• C-fibers are unmyelinated afferent neurons– Responsible for slower, dull pain

Neurons

• Nociception - process of perceiving pain– Nocireceptors - receptors in the skin and organs

that are capable of responding to various types of stimulation

Perceiving Pain

• Spinal cord - pathway for ascending sensory information and descending motor information to and from the brain

The Spinal Cord

The Spinal Cord

• From the spinal cord, the brain receives information from afferent neurons

• Somatosensory cortex - part of the brain that receives sensory information that allows the entire surface of the skin to be mapped

The Brain

Somatosensory Cortex

• Neurotransmitters - chemicals that are synthesized and stored in neurons

• In the 1970s, researchers identified naturally occurring chemicals in the brain that affect pain perception

– Endorphins, enkephalins, and dynorphin modulate pain

– Glutamate, substance P, bradykinin, and prostaglandins produce pain

Neurotransmitters and Pain

• Periaqueductal gray - an area of the brain involved in modulation of pain • When this part of the brain is stimulated, pain relief

occurs

• Modulating pain may be important in some survival instances

The Modulation of Pain

The Modulation of Pain

• Pain is due to two factors: – The sensation – The person’s reaction to that sensation

Defining Pain

• Pain can be viewed in terms of three stages:• Acute pain - normally brief from a cut, burn, injury;

adaptive in that it signals the person to avoid further injury

• Chronic pain - endures over months; no adaptive reason or biological benefit

• Prechronic pain - occurs between acute and chronic pain

Defining Pain

• The experience of pain is individualized, subjective, situational, and cultural– Individualized differences in pain– Cultural differences in pain

• African Americans and Hispanic Americans show higher sensitivity to pain than European Americans

Experiencing Pain

• Gender Differences in Pain Perception–Women report pain more readily than men

• May be due to gender roles and socialization

Experiencing Pain

• The first theory of pain was the specificity theory; however, this theory is too simplistic

• Currently, the gate control theory of pain is used to understand pain

Theories of Pain

• Gate Control Theory of Pain - pain perception is subjected to a number of modulations that influence the experience of pain– Structures in the spinal cord as a gate for the

sensory input that the brain interprets as pain

Gate Control Theory of Pain

Gate Control Theory of Pain

• Gate Control Theory also suggests that pain has motivational and emotional components – Gate control trigger - nerve impulses that descend

from the brain and influence the gate mechanism• For example, distraction or relaxation could cause the

gate to close, causing a decrease in pain

Gate Control Theory of Pain

• Pain can be measured in a number of ways:– Self-report ratings– Behavioral assessments– Physiological measures

The Measurement of Pain

• Self-reports ask people to evaluate and make ratings of their pain using:– Rating scales, such as the Visual Analog Scale, where

people rate their pain – Pain questionnaires, where people are asked to make

certain distinctions about their pain– Standardized psychological tests, where dishonesty

about pain can be assessed

Self-Reports

• Behavioral assessments of pain use observation of the patient to assess pain– Record body movements and facial expressions

looking for signs of pain– This method may be especially useful for children

and elderly who may not be able to accurately self-report on pain

Behavioral Assessments

• Physiological Measures – Electromyography (EMG) - measures level of muscle

tension, as pain may increase tension– Heart rate - predicts perception of pain, but only for

men– Overall, physiological assessments may not be as

valid as self-report or observational methods

Physiological Measures

• More than 30% of people in the US experience chronic or intermittent persistent pain

• Chronic pain is categorized as a syndrome - symptoms that occur together

Pain Syndromes

• Headache pain–Most common of all types of pain; 90% of people

will experience headaches– Three primary types of headaches:

• Migraine headaches• Tension headaches• Cluster headaches

Headache Pain

• Low back pain• Approximately 80% of people will experience low

back pain • Injuries, pregnancy, infections, degenerative

diseases, and malignancies all can cause lower back pain

Low Back Pain

• Arthritis Pain– Rheumatoid arthritis - an autoimmune disorder

characterized by swelling and inflammation of the joints

– Osteoarthritis - progressive inflammation of the joints; affects mainly older adults

– Fibromyalgia - characterized by tender points throughout the body; not considered arthritis

Arthritis Pain

• Pain is present in 44% of all cancer cases– Almost half of all cancer patients’ pain is left

untreated

Cancer Pain

• Phantom Limb Pain - the experience of chronic pain in a part of the body that is missing– Reports vary but it may be that 90% of amputees

experience phantom limb pain– Pain is more likely to occur when a person experienced

much pain before the amputation– There may be an emotional basis to this pain but also

the CNS and PNS may make maladaptive adaptations after the amputation

Phantom Limb Pain

• Treatment for pain varies– Acute pain is easier to treat as the source of the pain is

clear– Chronic pain is more difficult because there is not

usually an obvious source• Relief can be sought by two methods:

– Medical approaches– Behavioral management approaches

Managing Pain

• One of the most common medical approaches is the use of drugs– Analgesic drugs - relieve pain; most likely to be opiates

or nonnarcotic analgesics – Limitations to using drugs to treat pain:

• Tolerance and dependence on drugs• Overmedication

Medical Approaches

• Another medical approach used to manage pain is surgery– Surgery aims to repair the source of the pain or alter

the nervous system to alleviate the pain– Limitations of surgery:

• It may not always repair damaged tissue• It may not provide patients with relief• Expensive

Medical Approaches

• Several behavioral approaches have been used to help manage pain:– Relaxation therapy– Behavioral therapy– Cognitive therapy– Cognitive-behavioral therapy

Behavioral Approaches

• Relaxation Therapy - systematic tensing and relaxing of muscles– used successfully to treat tension and migraine

headaches, rheumatoid arthritis, low back pain

Relaxation Therapy

• Behavioral Therapy/behavioral modification - process of shaping behavior through the application of operant conditioning principles– Removal of reinforcers that may have been

prompting “pain traps”– Has been effective in decreasing pain intensity and

improving quality of life

Behavioral Therapy

• Cognitive Therapy - based on the principle that people’s beliefs, personal standards, and feelings of self-efficacy strongly affect their behavior– Identify irrational thoughts or “catastrophizing” and

eliminate or change them

Cognitive Therapy

• Cognitive Behavioral Therapy (CBT) - type of therapy aimed at developing beliefs, attitudes, thoughts, and skills to make positive changes in behavior – One form of CBT is acceptance and commitment

therapy (ACT) which encourages acceptance of pain by focusing attention on other valuable goals and activities

Cognitive Behavioral Therapy

Effectiveness of Therapies