Download Pain - You Can Do It!

Pain
Pain: is a subjective sensation that accompanies the activation of
nociceptors which signals actual or potential tissue damage.
Pain is stimulated by many factors:
 Mechanical
 Thermal
 Electrical
 Chemical
Cognitive Influences that affect the feeling of pain:
 Duration of pain
 Type of personality
 Age
 Gender
 Cultural background
 Expectation and previous experiences
Types of pain:
 Acute pain
 Chronic pain
 Somatogenic pain
 Neurogenic pain
 Referred pain
 Psychogenic pain
 Phantom pain
Acute Pain (1 day  1 week):
 Pain that is sharp (Like a hit with a knife)
 Functions to limit movement and prevent further injury
(withdrawal reflex)
 After 1 week it is called subacute until 3 months.
Examples:
 Appendicitis
 Heart attack
Chronic Pain (Exceeds 6 months):





Results from injury
Could have a cause and could have no cause!
It's latent (comes after a while)
Slow, aching, dull
Could set a pathway in the nervous system for its own and
sends signals with no ongoing tissue damage and the brain
misfires and creates pain
Examples:
 Back pain
 Osteoarthritis
Somatogenic pain:



A pain coming from viscera or sclerotome
Not well localized
Could be referred
Neurogenic Pain:




It has a neural origin (compression, cut, etc…)
Can be from the nerve itself or from the root
Pain will be felt either at the site in earlier stages
In later stages it is felt along the pathway of the nerve
Example:
 Sciatica
Description of pain:
Burning, lighting, tingling
Referred Pain:
Originating in one site radiating to another side,
Why???
Because, the dorsal root of the spinal cord receives input from both skin
and viscera, so the connection between signals from skin and viscera
results in that the brain can not tell which is which.
Examples:



Heart  pain is felt in the left shoulder
Kidney  pain is felt in the groin
Gall bladder  pain is felt in the right upper quadrant of the abdomen
Psychogenic Pain:
 Most of the time there is no pathology!
 Try talking to them
 Patient with this kind of pain are better sent to the social worker.
Phantom Pain:




Sensation of limb that is felt while the limb is amputated nerves are
destroyed
Physiologically there is no signals going to the brain
Abnormal discharge in the peripheral nerve fibers are conceived by the
brain as pain
Signals from the stump are going to the brain
Description of pain:
Burning, electric, cramping.
Pathways of Pain:
Stimulus  Nciceptors  A-Delta & C fibers Dorsal horn  Higher
centers.
Types of neurons:



First order
Second order
Third order
Types of receptors:




Nciceptors
Thermoreceptors
Mechanoreceptors
Proprioceptors
Neural Transmission:
1.
2.
Afferent: Form the periphery to the brain.
Efferent: From the brain to the periphery.



1st order neurons start at the periphery and end at the
dorsal horn
2nd order neurons start at the dorsal horn and end at the
thalamus and brainstem
3rd order neurons start the thalamus and brainstem and
end in the sensory cortex



Signal move from one neuron to another or from a neuron
to a muscle.
We need a neurotransmitter in the presynaptic membrane
synaptic cleft postsynaptic cleft
Examples of neurotransmitters: ACTH, Substance P,
Serotonin, norepinephrine, B-endorphins, enkephalin.
Pathway of pain:
Injury in periphery  prostaglandin and bradykinin are produced a
primary hyper algesia  secondary hyper algesia  receptors are
stimulated  substance P is produced  C fibers and A-Delta
fibers send signals to the spinal cord  higher centers
 A-Delta Fibers:
1.
2.
3.
4.
5.
6.
Myelinated
Faster (530 m/s)
Sharp pain
Localized pain
Last for a short while
Withdrawal reflex
 C Fibers
1.
2.
3.
4.
5.
Unmyelinated
Slower (0.52 m/s)
Thropping, Burning, Dull
pain
Poorly localized
Difused
Controlling pain:
1.
Ascending way:
Stimulation of A-Alfa and A-Beta fibers stimulates substantia gelatinosa in
the spinal cord  enkephalin is produced  inhibition of A-Delta and C
fibers  transmission of A-Delta and C fibers is cut off  no pain!
2. Descending pathway (1):
By training the patient that the pain is not important
Training the patient's cognitive thinking and changing their behavior
3. Descending pathway (2):
Using TENS  stimulate higher centers  chemicals are produced 
stimulates the spinal cord  cut transmission between 2nd order
neurons and 1st order neurons  no pain!
Pain Assessment:
Pain is assessed by:
 Visual Analog Scale: the scale consists of a line usually 10cm
long , the extremes represents the limits of pain experience, one
is defined as "NO PAIN" and the other as "SEVER PAIN", the
distance between them represents the pain severity.
 Pain Charts: can be used to establish spatial properties of pain.
 McGill Pain Questionnaire: is a tool with 78 words that describes
pain.
 Numeric Pain Scale: the patient is asked to rate their pain on a
scale from 1 to 10.
 I Wish You All The Best 
of Luck 