Understanding and Managing
Pain
Insensitivity to pain = many
injuries
Somatosensory System
• Moves info. From body to brain
Neurons
• Afferent (sensory) neurons
• Interneurons - Connect sensory
neurons to motor neurons
• Efferent (motor) neurons
Somatosensory cortex
PET and fMRI scans
• Can see brain at work
Pain
Definition of pain
• Sensation + emotional reaction to
sensation
Types of pain
• Acute
– Occurs when injured - cut, burn, childbirth, surgery
– Adaptive
– Warns of further injury
• Chronic
–
–
–
–
Lasts months or years
Not adaptive
No biological benefit
Reinforced by environmental factors
• Sympathy
– It is still real pain
The experience of pain
• Anzio beachhead
– Carrying severed arm
– People not realizing they were shot
Expression of pain
• Cultural background & social context
– E.g. Childbirth
– Rites of passage
Theories of pain
Specificity theory of pain
• Pain = amount of tissue damaged
– Pain largely uninfluenced by psychological
forces
• Problems
– No specific skin receptors devoted to
relaying pain
– Phantom limb pain
– Injury without pain
• E.g. in war
Gate control theory of pain
• Sensory input is not the only factor
– Changes in the spinal column and brain
control the flow of neural impulses
– Parts of spinal column can either
• increase (open the gate) or
• decrease (close the gate)
Measurement of pain
• 1. Self-report
– Rating scales (e.g. 0-10)
– MMPI
• 2. Behavioral assessments
– Observing a patient’s behavior
• 3. Physiological measures
– Electromyography (EMG)
• Muscle tension
• Not a very good method (Poor validity)
Phantom limb pain
• Common following amputation
• Decreases with time
Managing pain with medicine
• Self-paced administration of narcotics
– E.g. morphine pump
• Limits are programmed in
– Avoids undermedication
– Patients use less medication
– Higher satisfaction
Managing pain with behavior
• Relaxation training
– Reduces
• Headaches
• Rheumatoid arthritis
• Low back pain
• Behavior modification
– Based on operant conditioning
– Positive reinforcers for pain - e.g. sympathy
• Increase pain
– Reinforcing desirable (non pain) behavior
• Reduces pain
Managing pain with behavior
• Cognitive behavioral therapy (CBT)
– Changing your thinking patterns
– E.g. “Reframing” - “Pain is weakness
leaving the body” - Used in the military