Myelination increases the speed of transmission and so sudden, sharp pain gets transmitted to the cerebral cortex faster than dull or aching pain. This may be important for survival. The motivational and affective elements of pain appear to be influenced strongly by the C-fibers. They project onto the thalamus, hypothalamus, and amygdala. The A-delta fibers project onto particular areas of the thalamus and sensory areas of the cerebral cortex. Neurotransmitters are also involved, in particular, substance P.
Colored portrait picture of a white woman, shoulder length brown hair with a worried look on her face . She is on the right side of the page.
Studies show depression and anxiety create more pain and stronger pain. Pure psychologic pain. Poor under report pain for fear of being a burdn, mistrust of richer docs, addiction running around neighborhood. Subtle cultural diffenences – ex – Eastern European rate pain worse than Asians or African Amer. Gender – females tolerate visceral pain better, males – somatic. Spiritual suffering can increase pain and different religions have different meaning behind physical suffersing – “cruxifixion complex”
Episodes of neuralgia occur suddenly and without apparent cause. Someone with causalgia may report that it feels like my arm is pressed against a hot stove. Typically follows a traumatic injury like a gun shot wound or stabbing and occurs at the site of injury. Is experienced well after the wound has healed. Phantom limb pain – example might be burning sensation in your toes after the limb and foot has been amputated. Person can experience a sense of their limb moving. Can persist for months and years. Pain can be felt as shooting, burning, or cramping (e.g., feel like hand is clenched with finger nails digging into the hand).
Poor pain control is based on misperceptions of pain controlling medications – e.g., fear of addiction. Children, for fear of needles or lack of knowledge about pain-killer medications, may request medications less.
Capsaicin (Zostrix) – red hot chili pepper juice – used for centuries in S. America, burns for first few days then wears out substance P in pain receptors PT/chirpracter/massage/yoga/acupuncture in some studies equally effective in certain conditions like low back pain NSAIDs – beware of GI side effects and platelet effects, though the Salcylate class and Diflunisal have less of these effects. NSAIDs in studies shown to decrease narcotic use by up to 40% in things like wide-spread boney mets Relaxants – soma, flexeril, benzodiazepines
Biofeedback for the treatment of chronic pain appears to be no more effective than relaxation methods. Relaxation may work in two ways: 1) reducing muscle tension; and 2) helping the patient better manage stress and anxiety. Relaxation exercises are frequently used in preparing a pregnant women for the delivery of her child. Relaxation may also stimulate the release of endogenous opioids, as well as boosting immune function. Evidence suggests that its effects are modest but useful in combination with other methods. Mechanism by which hypnosis works for some pain conditions, particularly acute pain such as that during surgery, is not well understood. Cognitive methods of pain control appear to be as effectives as hypnosis.
Chronic pain management
Dr.P.NARASIMHA REDDY M.D D.A
Professor And H.O.D
Narayana medical college hospital
Pain is defined by international association for
study of pain as “An unpleasant sensory and
emotional experience associated with actual or
potential tissue damage or described in terms
of such damage”.
Pain is always a subjective experience
Everyone learns the meaning of “pain” through
experiences usually related to injuries in early life
As an unpleasant sensation it becomes an
Pain is a significant stress physically, emotionally
Somatic pain:caused by the activation of pain receptors in either
the cutaneous (the body surface) or deeper tissues (musculoskeletal
Visceral pain: pain that is caused by activation of pain receptors
from infiltration, compression, extension or stretching of the thoracic,
abdominal or pelvic viscera (chest, stomach and pelvic areas).
Neuropathic pain: caused by injury to the nervous system either
as a result of a tumor compressing nerves or the spinal cord, or
cancer actually infiltrating into the nerves or spinal cord.
Although descriptive, does not provide correct
information, perhaps these should be used to modify
acute and chronic pain indications to allow patients to
understand, but how do you measure what is mild,
moderate, severe: ultimately it is the bias of the agency,
investigators, sponsors to suggest which is which.
Acute pain: short-lasting and manifesting in objective ways
that can be easily described and observed. It may be clinically
associated with diaphoresis and tachycardia. It can last for
several days, increasing in intensity over time (subacute pain),
or it can occur intermittently (episodic or intermittent pain).
Usually related to a discreet event for onset: post op, post
truama, fracture, etc
Chronic pain: Long-term and typically defined if it lasts for >
three months. It is more subjective and not as easily clinically
characterized as acute pain and is more psychological. This
kind of pain usually affects a person's life, changing personality,
their ability to function, and their overall lifestyle.
Chronic pain has a psycho-social component that
must be dealt with before depression becomes a part
of the clinical picture. Chronic pain should be
recognized as a multi-factorial disease state requiring
intervention at many levels.
Normal or Nociceptive pain – includes
acute,subacute & inflammatory pain.
Abnormal or pathophysiologic pain –
Neuropathic and central pain.
Nociceptors : are free nerve endings,
innervated by A-delta and C nerve fibers, that
respond to intense ,potentially damaging
stimuli that exist throughout the body.
Found in skin in form of
High threshold mechanoreceptors
Local release of prostaglandins potentiate the
action of bradykinin and acts as sensitiser to
First order neurons:Nociceptive afferent fibers
terminate in spinal dorsal horn on the same
side as the dorsal root ganglion where primary
sensory neural cells are located.
Second order neurons:
1. Wide dynamic range neurons.(WDR)
2. Nociceptive specific neurons.
WDR neurons are located in laminae V of
Occurs at Nociceptor, spinal cord or in supra
It can either facilitate or inhibit pain.
At the spinal level modulation is via “GATE
CONTROL THEORY” by MELZACK & WALL.
Described physiological mechanism by which
psychological factors can affect the experience
Neural gate can open and close thereby
Gate is located in the spinal cord.
Counter stimulation (e.g., heat, message)
Intense concentration or distraction
Involvement and interest in life activities
A-delta fibers – small, myelinated fibers that
transmit sharp pain
C-fibers – small unmyelinated nerve fibers that
transmit dull or aching pain.
Hypothalamus, pons and somatosensory cortex
: stimulation of these areas causes analgesia
Three endogenous systems involved in the
inhibitory pathways for pain: (1) the opioid
system, (2) the noradrenergic system, and (3)
the serotonergic system
Increased catabolic demands: poor wound
healing, weakness, muscle breakdown.
Decreased limb movement: increased risk of
Respiratory effects: shallow breathing, tachypnea,
cough suppression increasing risk of pneumonia
Increased sodium and water retention (renal)
Decreased gastrointestinal mobility.
Tachycardia and elevated blood pressure
Negative emotions: anxiety, depression
Existential suffering: may lead to patients
seeking active end of life.
Decrease natural killer cell counts
Effects on other lymphocytes not yet defined.
Chronic pain is pain that:
continues a month or more
beyond the usual recovery
period for an injury or illness or
goes on for months or years
due to a chronic condition.
The pain may not be constant but
disrupts daily life.
It also can interfere with sleep,
keeping you awake a night.
Nociceptive,Neuropathic or both.
Psychological mechanisms play a major role.
Attenuated neuroendocrine stress response
and have prominent sleep and affective
Neuropathic pain: Paroxysmal and
lancinating,has a burning quality and is
associated with hyperpathia.
Deafferentation pain: neuropathic pain
associated with loss of sensory input into the
Sympathetically mediated pain:sympathetic
system plays a major role.
Psychologic factors – depression, anxiety, somatization
Socioeconomic factors – cultural differences, urban
Spiritual factors – spiritual suffering, meaning of pain
Physical factors – VERY complex neuroanatomy creating
the pain sensation, from pain receptors to afferent
nerves to spinothalamic tract, to thalamus to cortex with
modulators all along the way
Therefore best approach is multi-disciplinary
Neuralgia – an extremely painful condition
consisting of recurrent episodes of intense shooting
or stabbing pain along the course of the nerve.
Causalgia – recurrent episodes of severe burning
Phantom limb pain – feelings of pain in a limb that is
no longer there and has no functioning nerves.
Response to previous treatments.
and emotional status.
Plain radiographs,CT,MRI, bone scans.
1. Clinical interview.
2. A structured pain inventory
a. Mc Gill pain questionnaire.
b. Psychosocial pain inventory.
c. Westhaven - Yale multidimensional pain
d. Pain profile.
3. Psychometric testing:
a. Minnesota multiphasic pain inventory(MMPI)
b. Symptom check list-90.
c. Million behavioural pain inventory.
d. The beck depression inventory.
e. The spielberger state-trait anxiety scale.
Electromyography and Nerve conduction
Useful for confirming diagnosis of entrapment
syndromes,neural trauma and
Can distinguish b/n neurogenic and myogenic
Reliable quantitation of pain severity helps
determine therapeutic interventions and
evaluate the efficacy of treatments.
Numerical rating scale.
Faces rating scale
Visual analog scale.
McGill pain questionnaire.
McGill Pain questionnaire:
It is a checklist of words describing symptoms.
Attempts to define the pain in 3 major
1. Sensory – discriminative.
2. Motivational – affective.
3. Cognitive – evaluative.
Contains 20 sets of words that are divided into
1. 10 sensory.
2. 5 affective.
3. 1 evaluative.
4. 4 miscellaneous.
Bed rest widely recommended but shown to
Current consensus – maintenance of activity
and work status.
If beyond 4-wks – refer to multidisciplinary pain
General term for congenital and acquired
disorders of spine.
Narrowing of the bony frame surrounding the
neural structures .
Can affect central spinal canal or lateral
Narrowing can be caused by
spine,degenerative disk disease.
Also called as post laminectomy syndrome.
One of the most difficult groups of chronic pain
Exhibits strong nociceptive and neuropathic
Pain may be sharp and shooting
Iatrogenic and due to development of fibrous
Soft tissue disorder that creates pain in tender
areas within muscle groups.
Diagnosis made on clinical trigger points .
Trigger points are painful regions in a taut band of
muscle that produces referenced pain with
application of pressure.
Painful area usually feels like a “rope”.
Created by events like trauma or prolonged
tension from poor posture.
Local prolonged ischemia may trigger the
formation of subsequent fibrosis.
Therapeutic modalities – passive
massage,injection of 0.5% lidocaine at the
trigger point,botulinum toxin injection.
Neuropathic pain that involves upper and lower
Reflex sympathetic dystrophy and causalgia are
replaced by CRPS I ,CRPS II.
CRPS type I: follows minor trauma.
Preceeding events are
CRPS type II: also called as causalgia.
Burning pain,follows high velocity injuries to
Pain immediate in onset.
Physical therapy plays major role.
Cure rate is high if Rx initiated within 1month of
symptoms and appears to decrease with time.
Intractable pain that develops as a sequel of
acute herpes zoster infection.(AHZ)
Pain from AHZ resolves usually within 3-4
weeks and if pain lasts longer than 4-6wks
PHN should be suspected.
In AHZ large myelinated fibers are destroyed
whereas in PHN pain processing by small fibers
Typically presents with unilateral pain in
Sympathetic blockade during attack
classically presents as a painful, unilateral affliction
of the face, characterized by brief electric-shock-like
pain, limited to the distribution of one or more
divisions of the trigeminal nerve.
Pain is commonly evoked by trivial stimuli, including
washing, shaving, smoking, talking and brushing the
teeth, but may also occur spontaneously. The pain
is abrupt in onset and termination may remit for
Invasive treatment- Glycerol
injection,Radiofrequency ablation of gasserian
Microsurgical decompression of trigeminal
Improvements in nociception, not
Decrease pain and suffering
Increase daily activity.
About half of hospitalized patients who have
pain are under-medicated.
Children are at particular risk of poor pain
Medications are given as:
PRN – “as needed”
As a prescribed schedule
NSAIDS, COX INHIBITORS.
LOCAL ANAESTHETICS – systemic
Traditional NSAIDs are effective in the treatment
of mild to moderate pain, but their use is limited
by potentially serious adverse effects
ketorolac : indicated only in the management of
moderately severe acute pain that requires opioid
level analgesics ; no more than 5 days
COX-2 selective inhibitors [celecoxib
(Celebrex), rofecoxib (Vioxx) and valdecoxib
200-fold to 300-fold selectivity for inhibition of
COX-2 over COX-1
Individualize route, dosage, and schedule
Administer analgesics regularly (not PRN) if
pain is present most of day
Become familiar with dose / time course of
several strong opioids
Give infants / children adequate opioid dose
Follow patients closely, particularly when
beginning or changing analgesic regimens
When changing to a new opioid or different route
Use equianalgesic dosing table to estimate new dose
Modify estimate based on clinical situation
Recognize and treat side effects
Be aware of potential hazards of meperidine / mixed
agonist-antagonists - particularly pentazocine
Do not use placebos to assess nature of pain
Watch for development of:
Tolerance - treat appropriately
Physical dependence – prevent withdrawal
Do not label a patient psychologically dependent,
“addicted”, if you mean physically dependent on /
tolerant to opioids
Be alert to psychological side of patient .
Constipation , no tolerance develops to constipation,
use stimulants (Senokot, Bisocodyl, Pericolace)
Nausea/vomiting – tolerance can occur in 2-5 days.
Sedation – tolerance can occur in 2-3 days.
Clonic jerks – usually high doses, can change drug or
diazepam can help
Respiratory suppression in toxic doses, never see it if
have pain or use the drugs the right way.
Can produce Hyperalgesia in certain individuals.
Tolerance (20-40%) – up-regulate opioid receptors to need higher
dose for sustained effect
Withdrawal (20-40%) – after 2 wks, withdrawing drug leads to
adrenaline response (sweating, tachycardia, tachypnea, cramps,
diarrhea, hypertension); avoid by decreasing drug 25% a day.
Addiction (0.1% in CA pain) – a need to get “high” where drug
controls your life, compulsive uncontrolled behavior to get the
drug; lie, cheat, steal.
Physical dependence confused with
Pain-relief seeking, not drug-seeking
When right dose used, patient functions
better in life, whereas opposite true with
the true addict
To help diffentiate: one MD controls the
drug under a specific contract with pt., one
pharmacy, frequent visits, pill counts
Agents which enhance analgesic efficacy, have
independent analgesic activity for specific types of
pain, and / or relieve concurrent symptoms which
Antidepressants are effective agents in the treatment
of neuropathic pain.
Action due to blockade of presynaptic reuptake of
serotonin,norepinephrine or both.
serious side effects , include anticholinergic effects
including dry mouth, confusion, and urinary
Antiepileptic drugs have been used for many
years in the treatment of neuropathic pain
particularly trigeminal neuralgia and diabetic
Blocks voltage gated sodium channels and can
suppress spontaneous neuronal discharges.
phenytoin, carbamazepine, and valproic acid
The newer agents, gabapentin appears to be the
most effective and well tolerated
Useful in patients with marked agitation or
perphenazine are commonly used.
Action due to blockade of dopaminergic
Glucocorticoids are extensively used in pain
management for their anti inflammatory and
possibly analgesic actions.
Can be given topically,orally,parenterally.
More effective in neuropathic pain but can be used for
all pain syndromes. Starting dose 0.5mg-2 mg/kg per hr
IV or SC. Some studies demonstrate long-lasting pain
relief even after drug has been stopped. Need to
decrease opioids when starting.
Lidocaine Patch (Lidoderm®)
On 12hrs off 12 hours (but can leave on 24)
Expensive (great indigent program however)
Alpha adrenergic agonist.
Action – activation of descending inhibitory
Can be given
N-methyl-D-aspartate receptor antagonist
Used as an anesthetic for years
Case reports show effectiveness when
traditional and invasive techniques fail
Starting IV dose 150mg qd (0.1-0.2mg/kg) with
reduction of opioid achieved or 10-15 mg q6
increasing by 10 mg dose each day
Appears to have a synergistic effect with opioids
Zoledronic acid (Zometa)
Calcitonin (Calcimar) Not in cancer ? arthritis
Capsaicin (Zostrix) scheduled in neuropathic pain
Quality of Life
Proposed 4 th
Pain persisting or increasing
Opioid for moderate to severe pain
± Nonopioid ± Adjuvant
Pain persisting or increasing
Opioid for mild to moderate pain
± Nonopioid ± Adjuvant
Pain persisting or increasing
Exercises :Graded exercise program prevents
joint stiffness,muscle atrophy and contractures.
Superficial heating modalities:
Conductive – hot packs,paraffin baths,fluido
Useful adjunct for patients with chronic
musculoskeletal disorders and headaches.
Technique – insertion of needles in discrete
anatomically defined points called
Used widely in chronic pain
All available trials used TENS as an adjuvant to
medication, and it’s possible the effects of
TENS was masked by the analgesic effect of
Topical agents (Ben Gay/Icy
Hot – with menthol, salcylates,
Local injections (steroids,
Glucosamine shown to help
Herbals/supplements – glucosamine shown to be useful in
osteoarthritis, certain herbs like chamomile useful for colicky pain
Homeopathies/flower essences – for relaxation, visceral pain
Healing touch/Reiki – using energy techniques, useful with
Neuro Emotional Technique – A chiropractic technique also
useful with emotional components
Mind – focusing therapies:
Meditation, yoga, guided-imagery, hypnosis, biofeedback
Art/music/humor therapy, pet therapy
By distraction, found to lower HR/RR and decrease pain up to 10-20%
Integral part of multidisciplinary approach to
1. Self management techniques – cognitive
2. Operant techniques.
3. Group therapy.
Based on assumptions that a patients attitude
towards pain can influence the perception of
Maladaptive attitudes contribute to suffering
Patient is taught skills for coping with pain
either individually or in group therapy.
Biofeedback – provides biophysiological
feedback to patient about some bodily
process the patient is unaware of (e.g.,
forehead muscle tension).
Relaxation – systematic relaxation of the
large muscle groups.
Hypnosis – relaxation + suggestion +
distraction + altering the meaning of pain.
OPERANT / BEHAVIOUR THERAPY:
Based on premise that behaviour in patients
with chronic pain is determined by
consequences of behaviour.
Positive reinforcers aggravate the pain,negative
reinforcers reduce pain behaviour.
Intractable side effects*
*Symptoms that persists despite carefully
individualized patient management
SELECTION OF BLOCK:
Location of pain
Its presumed mechanism
Skills of treating physician.
L.A ‘s can be applied locally,at peripheral
nerve,somatic plexus,sympathetic ganglia or
nerve root, centrally in neuraxis.
Somatic nerve blocks:
Trigeminal nerve blocks
Cervical,thoracic,lumbar paravertebral blocks
Trans sacral nerve blocks etc.
Therapeutic effects of spinal injections are a
combination of primary physiologic changes
that result from the procedure and the
secondary results arising from the enhanced
pain control that allow other treatments.
Also called dorsal coloumn stimulation.
Produces analgesia by directly stimulating large
A beta fibers in dorsal coloumns of the spinal
Mechanism – activation of descending
modulating systems and inhibition of
Sympathetically mediated pain
Spinal cord lesions
Phantom limb pain
Failed back surgery syndrome.
Technique: electrodes placed epidurally and
connected to an external generator.
Complications: infection,lead migration,lead
Deep brain stimulation may be used for
intractable cancer pain and rarely for
intractable neuropathic pain of nonmalignant
Electrodes are implanted stereotactically into
periaqueductal and periventricular gray areas
for nociceptive pain.
Complications: intracranial hemorrhage and
Pain is unnecessary.
Effective tools are available to help doctors evaluate pain in
their patients. Unrelieved pain should be treated just like any
other vital sign: with aggressive measures.
Effective therapies are available to treat pain. Use guidelines
to develop a rational plan to relieve pain.
Side effects are manageable. Anticipate side effects and treat
Addiction rarely occurs. Trust your patient when they report
pain. Tolerance and physical dependence can occur.
Plan and you will succeed. Take the initiative and focus on
relieving pain at your hospital. Your patients depend on it.
John C.Rowlingson – Chronic Pain.Miller’s
Raj PP:Practical Management Of Pain .
Wall PD,Melzack OC:Text book of pain.
ISA Journal On pain.
Gowri devi M;Chronic pain ManagementPsychological aspectsin current conceptsin
pain management.CMEabstract 1998.