Transcript class06.pain II

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).
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"
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
Neuromodule
Model
YOWW!!
Injury to Periphery
Memories of
previous injuries
Emotions
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.
Alleviating Phantom Limb Pain
1. Patient places healthy limb and stump into mirror box.
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!
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. V. Ramachandran
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.
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!
Class 6: Pain II
Musings on Responses to Others’ Pain
Why ”oooohhhhh!!!!”?
Why is others’ pain funny?
Acute Pain vs. Chronic Pain
Causes
Self Limiting?
Duration
Responsive to pain killers?
Acute Pain
Chronic Pain
specific injury -->
tissue damage
Acute episode
Yes
No
Less than 6 months
6 + months
Yes
Minimally
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
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
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
3. Negative stereotypes
4. Medical complications and risks
5. Double binds (1-4, above)
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
Pain and Depression
Wrong model:
Pain  Depression
--- What’s missing?
Correct model:
Pain  ↓ activity  ↓ mastery  ↓ control  Depression
“MECHANICAL” PAIN REDUCTION
TECHNIQUES
Drugs
Surgery
Sensory Control: Counter-irritation
Counter-irritation stim.
Dorsal horn cells  inhibit
pain-transit cells.
“PSYCHOSOCIAL” PAIN REDUCTION
TECHNIQUES
Biofeedback
Relaxation
Hypnosis
Acupuncture
Distraction
Guided Imagery
Cognitive Reframing
Pain Management Programs
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?
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