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Melzack's Gate Theory is revolutionary, helpful, but wrong. - PowerPoint PPT Presentation


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Neuromodule Approach to Pain. Melzack's Gate Theory is revolutionary, helpful, but wrong. Some people experience pain without ANY injury. Doesn’t explain injury-less pain, such as Quinlan Phantom limb pain Pain occurs only because of CNS activity—neuromodules.

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slide1

Neuromodule Approach to Pain

Melzack's Gate Theory is revolutionary, helpful, but wrong.

Some people experience pain without ANY injury.

Doesn’t explain injury-less pain, such as Quinlan

Phantom limb pain

Pain occurs only because of CNS activity—neuromodules.

Neuromodules are like software programs, or tracks on CDs

Should be triggered by major event (i.e., serious injury) but for some people are trigged by minor event (i.e., bad mood).

slide2

Neuromodule Approach to Pain

Fred. Lenz: Locates brain cells  panic attacks.

Smell and memory

Emotions launched via peripheral activity: Bite that pencil!

Neuromodules may explain "pain epidemics”

Neuromodule confirmed by new pain killers that reduce brain excitability.

Anti-epileptic drugs

Sea snail venom

ABT-594—from frogs. 70X more powerful than morphine.

Take home point: Pain is "all in the head"

slide3

Early Trauma and Increased Pain Sensitivity

  • 1. Infant rats have paw injected with irritant, or not.
  • 2. Mature rats exposed to hot surface:
  • * To injured paw
  • * To uninjured paw
  • * "Control" rats
  • 3. Injured rats respond quicker, but only for hurt paw
  • 4. Injured rats have more pain-nerve endings
  • 5. Implications for humans:
  • * Surgery w/o anesthesia
  • * Treatment of premature infants
slide4

Neuromodule Model

Memories of previous injuries

Emotions

YOWW!!

Injury to Periphery

slide5

Phantom Limb Pain

I placed a coffee cup in front of John and asked him to grab it. Just as he said he was reaching out, I yanked the cup away. "Ow!" he yelled. "Don't do that!" "What's the matter?" "Don't do that," he repeated. "I had just got my fingers around the cup handle when you pulled it. That really hurts!" Hold on a minute. I wrench a real cup from phantom fingers and the person yells, ouch! The fingers were illusory, but the pain was real - indeed, so intense that I dared not repeat the experiment.

V.S. Ramachandran Phantoms in the Brain

Phantom limbs will: Itch, twitch, gesticulate during conversation, and will take actions “on their own”.

Phantom limb paralysis: Brain “learns” that attempts to move missing limb fail, translate it into paralysis, creates excruciating cramps.

slide6

Alleviating Phantom Limb Pain

1. Patient places healthy limb and stump into mirror box.

2. Look through top, at angle, “see” two limbs.

3. Move healthy limb in “mirror symmetric movement”, like orchestra conductor or clapping hands.

4. Creates artificial visual feedback of phantom limb being intentionally controlled.

5. Patient then instructed to clench good hand, tightly—sees both hands clenched.

6. Patient told to slowly unclench “both hands”, and phantom limb relaxes, providing relief to chronic pain.

7. Repeated trials led one patient to “loose” phantom arm, but phantom hand now attached to shoulder!

Mirror Box

slide7

Phantom Limb Patient Using Mirror Box Ramachandran, Phantoms in the Brain

Philip rotated his body, shifting his shoulder, to "insert" his lifeless phantom into the box. Then he put his right hand on the other side of the mirror and attempted to make synchronous movements. As he gazed into the mirror, he gasped and then cried out, "Oh, my God! Oh, my God, doctor! This is unbelievable. It's mind boggling!" He was jumping up and down like a kid. "My left arm is plugged in again. It's as if I'm in the past. All these memories from so many years ago are flooding back into my mind. I can move my arm again. I can feel my elbow moving, my wrist moving. It's all moving again.

V. Ramachandran

slide8

Can Healthy Limbs Be “Fooled”?

(From Ramachandran)

1. Purchase a realistic but fake arm/hand

- Sit at table with one hand resting on the table, the other beneath the table.

- Position the fake arm/hand on the table in the corresponding position as though both hands/arms are resting on the table.

- Have associate tap both real hand that is beneath table and the fake hand in synchrony as you watch the fake hand.

- Notice how sensations appear to originate from the fake hand/arm.

2. Carry out the same on naïve associate.

- Once the effect has been achieved for a while, pull out previously hidden hammer and hit the fake arm/hand.

- Run!

slide10

Musings on Responses to Others’ Pain

Why ”oooohhhhh!!!!”?

Why is others’ pain funny?

slide12

Types of Chronic Pain

a. Benign pain

1. Lasts for at least 6 mos.

2. Non-responsive to Tx

3. Example: lower back pain

b. Recurrent acute pain

1. Repeated episodes of sharp, acute pain, with pain free periods in between.

2. Last for at least 6 mos.

3. Example: Migraine headaches.

c. Chronic progressive pain

1. Duration: at least 6 mos.

2. Increases in severity over time

3. Example: Cancer, degenerate diseases

slide13

Life Meaning of Chronic Pain

You are in car accident, suffer chronic back pain that severely reduces your freedom of movement. What areas of your life would be affected?

Emotional toll: Depression

Work / Independence

Social / interpersonal implications

Leisure activities

Income / Standard of Living

Declined ability to deal with other life stresses

slide14

Psycho-social Complications of Chronic Pain

  • 1. Counterproductive coping
  • a. Isolation
  • b. Negative beliefs
  • 2. Social Support:
  • a. Hazards of positive support
  • b. Hazards of no support
  • Negative stereotypes
  • Medical complications and risks
  • 5. Double binds (1-4, above)
slide15

Pain Prone Personality

Are some personalities more prone to experiencing, reporting pain?

MMPI = Minnesota Multiphasic Personality Inventory

a. Acute pain pats: Hypochondriasis – overly attend to body Hysteria – extreme emotionality/exaggerate symps.

b. Chronic pain pats: Neurotic triad: Hypcondriasis + hysteria + depression

Secondary gain: What are social benefits of pain?

Attention, special identity

“Functional type”: neurotic triad + schizo / psychopathology / paranoia

Danger of “Pain Prone Personality” concept?

1. Negative stereotypes 2. Causal direction

slide16

Pain and Depression

Wrong model:

Pain  Depression --- What’s missing?

Correct model:

Pain ↓ activity ↓ mastery ↓ control  Depression

slide17

“MECHANICAL” PAIN REDUCTION TECHNIQUES

Drugs

Surgery

Sensory Control: Counter-irritation

Counter-irritation stim. Dorsal horn cells  inhibit pain-transit cells.

slide18

“PSYCHOSOCIAL” PAIN REDUCTION TECHNIQUES

Biofeedback

Relaxation

Hypnosis

Acupuncture

Distraction

Guided Imagery

Cognitive Reframing

Pain Management Programs

slide19

Pain Relief Through Virtual Reality

Severe burns one of most painful conditions to treat: cleaning, re-bandaging excruciating.

Pennebaker symptom research suggests that distraction should do what to pain?

Reduce it.

Why?

Competition of cues.

SnowWorld: Virtual Reality program designed for pain relief.

Patients enter SnowWorld during procedures

Shoot snowballs at snowmen, penguins

Report pain reductions 30%-50%

Note SnowWorld colors. Why?

slide20

Pain Management Programs

1. Evaluation

a. pain

b. functional status: life style changes, limitations

c. Emotional and mental functioning

2. Treatment plan

a. Pre-set time. Not indefinite.

b. Specific goals.

c. Contract

3. Program

a. Education

1. Nature of pain: physio, psychological

2. Pain reduction techniques

b. Therapy

1. Psycho therapy

2. Cognitive therapy:

c. Family therapy

d. Relapse prevention