Dr.P.NARASIMHA REDDY M.D D.AProfessor And H.O.D Dept.Of AnesthesiologyNarayana medical college hospitalNellore.

Good Evening

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

emotional experience 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 tissues).

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.

Mild: ?? Moderate: ?? Severe: ??

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.

1. Normal or Nociceptive pain – includes acute,subacute & inflammatory pain.

2. 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- Polymodal receptors- Silent receptors.

Chemical mediators:

Local release of prostaglandins potentiate the action of bradykinin and acts as sensitiser to nociceptors.

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.

Rexed laminae:

Second order neurons:1. Wide dynamic range neurons.(WDR)2. Nociceptive specific neurons. WDR neurons are located in laminae V

of dorsal horn.

Occurs at Nociceptor, spinal cord or in supra spinal structures.

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 of pain.

Neural gate can open and close thereby modulating pain.

Gate is located in the spinal cord.

Physical conditions Extent of injury Inappropriate activity level

Emotional conditions Anxiety or worry Tension Depression

Mental Conditions Focusing on pain Boredom

Physical conditions Medications Counter stimulation (e.g., heat, message)

Emotional conditions Positive emotions Relaxation, Rest

Mental conditions 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 DVT/PE Respiratory effects: shallow breathing, tachypnea,

cough suppression increasing risk of pneumonia and atelectasis.

Increased sodium and water retention (renal) Decreased gastrointestinal mobility.

Tachycardia and elevated blood pressure

Negative emotions: anxiety, depression Sleep deprivation 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.

Loneliness

HostilitySocial Factors

Anxiety Depression

Psychological Factors

Pathological Process

Physical Factors

TIM

E

Nociceptive,Neuropathic or both. Psychological mechanisms play a major

role. Attenuated neuroendocrine stress

response and have prominent sleep and affective disturbances.

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 CNS.

Sympathetically mediated pain:sympathetic system plays a major role.

Psychologic factors – depression, anxiety, somatization Socioeconomic factors – cultural differences, urban poor, gender 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

Episodic pain syndromes: Headaches – migraine, tension, cluster… Ischemic episodes – claudication, angina, sickle

cell disease Visceral pain – biliary colic, irritable bowel, pre-

menstrual syndrome, renal colic Somatic pain - gout

Chronic pain syndromes: Somatic – low back pain ,degenerative and inflammatory

arthitis, lumbosacral radiculopathy,Failed back surgery, vertebral compression fractures, bony metastases, Myofascial pain syndrome.

Visceral – abdominal cancers, chronic pancreatitis.

Neuropathic – CRPS,Post herpetic neuralgia,Trigeminal neuralgia,diabetic neuropathy, phantom limb pain, spinal stenosis/sciatica, spinal mets,

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 pain.

Phantom limb pain – feelings of pain in a limb that is no longer there and has no functioning nerves.

MEDICAL EVALUATION: Location,onset. Quality,radiation. Response to previous treatments. h/o

past,personal,social,economic,psychological and emotional status.

Plain radiographs,CT,MRI, bone scans.

PSYCHOLOGICAL EVALUATION:1. Clinical interview.2. A structured pain inventorya. Mc Gill pain questionnaire.b. Psychosocial pain inventory.c. Westhaven - Yale multidimensional

pain inventory.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 studies:

Useful for confirming diagnosis of entrapment syndromes,neural trauma and polyneuropathies,radicular syndromes.

Can distinguish b/n neurogenic and myogenic disorders.

Reliable quantitation of pain severity helps determine therapeutic interventions and evaluate the efficacy of treatments.

PAIN SCALES:- Numerical rating scale.- Faces rating scale- Visual analog scale.- McGill pain questionnaire.

VISUAL ANALOGUE SCALE

McGill Pain questionnaire: It is a checklist of words describing

symptoms. Attempts to define the pain in 3 major

dimensions.1. Sensory – discriminative.2. Motivational – affective.3. Cognitive – evaluative.

Contains 20 sets of words that are divided into 4 groups.

1. 10 sensory.2. 5 affective.3. 1 evaluative.4. 4 miscellaneous.

Low back pain:

Treatment: Bed rest widely recommended but

shown to impede recovery. Current consensus – maintenance of

activity and work status. If beyond 4-wks – refer to

multidisciplinary pain centre.

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 intervertebral foramen.

Narrowing can be caused by spondylolisthesis,osteoarthritis of spine,degenerative disk disease.

Also called as post laminectomy syndrome.

One of the most difficult groups of chronic pain patients.

Exhibits strong nociceptive and neuropathic characteristics.

Pain may be sharp and shooting ,burning,dydesthic.

Iatrogenic and due to development of fibrous scarring.

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 stretching,cold spray,compression massage,injection of 0.5% lidocaine at the trigger point,botulinum toxin injection.

Common complaint.

Neuropathic pain that involves upper and lower extremities.

Reflex sympathetic dystrophy and causalgia are replaced by CRPS I ,CRPS II.

CRPS type I: follows minor trauma. Preceeding events are

trauma,surgery,sprain,fracture,dislocation.

3 phases.

CRPS type II: also called as causalgia. Burning pain,follows high velocity

injuries to large nerves. Pain immediate in onset. Associated with

allodynia,hyperpathia,vasomotor and sudomotor dysfunction.

Treatment: Sympathetic blocks. 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 is compromised.

Typically presents with unilateral pain in dermatomal distribution.

Treatment: Sympathetic blockade during attack Antidepressants,anticonvulsants,opioid

s. TENS.

TIC DOULOUREUX 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 varying periods.

Treatment: Carbamazepine. Invasive treatment- Glycerol

injection,Radiofrequency ablation of gasserian ganglion

Microsurgical decompression of trigeminal nerve.

Improvements in nociception, not curing.

Decrease pain and suffering Increase daily activity. Instill hope

1. PHARMACOLOGICAL.2. PHYSICAL MEASURES/NON

PHARMACOLOGICAL.3. PSYCHOLOGICAL MEASURES.4. INVASIVE TECHNIQUES.

About half of hospitalized patients who have pain are under-medicated.

Children are at particular risk of poor pain control methods.

Medications are given as: PRN – “as needed” As a prescribed schedule

NSAIDS, COX INHIBITORS. OPIOIDS ANTI DEPRESSANTS ANTI CONVULSANTS CORTICOSTEROIDS LOCAL ANAESTHETICS – systemic

administration.

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 (Bextra)]

200-fold to 300-fold selectivity for inhibition of COX-2 over COX-1

Codeine Fentanyl Hydrocodone Hydormorphone

MethadoneMorphineOxycodoneOxymorphone

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.

PHYSICAL DEPENDENCE: 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.

PSYCHOLOGIC DEPENDENCE: 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.

PSEUDO-ADDICTION: Physical dependence confused with

psychologic dependence 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

Definition Agents which enhance analgesic efficacy,

have independent analgesic activity for specific types of pain, and / or relieve concurrent symptoms which exacerbate pain

Antidepressants Anticonvulsants Corticosteroids Neuroleptics Antihistamines

Analeptics Benzodiazepines Antispasmodics Muscle relaxants Systemic local

anesthetics

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 retention .

Ex. Amitryptiline,Clomipramine,Doxepine,Fluoxetine,Imipramine.

Antiepileptic drugs have been used for many years in the treatment of neuropathic pain particularly trigeminal neuralgia and diabetic neuropathy.

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 psychotic symptoms.

Fluphenazine,Haloperidol,Chlorpromazine and perphenazine are commonly used.

Action due to blockade of dopaminergic receptors.

Glucocorticoids are extensively used in pain management for their anti inflammatory and possibly analgesic actions.

Can be given topically,orally,parenterally.

Lidocaine Infusion 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 pathways. Can be given

epidurally,intrathecally,parenterally.

N-methyl-D-aspartate receptor antagonist (NMDA)

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

Pamidronate (Aredia) Zoledronic acid (Zometa) Strontium-89 (Metastron) Calcitonin (Calcimar) Not in cancer ? arthritis Capsaicin (Zostrix) scheduled in neuropathic

pain Cannabinoid (Marinol)

Pain

Step 1Nonopioid Adjuvant

Pain persisting or increasing

Step 2Opioid for mild to moderate pain

Nonopioid Adjuvant

Pain persisting or increasing

Pain persisting or increasing

Step 3Opioid for moderate to severe pain

Nonopioid Adjuvant

Invasive treatments

Opioid Delivery

Quality of Life

Proposed 4th Step

The WHOLadder

Exercises :Graded exercise program prevents joint stiffness,muscle atrophy and contractures.

Superficial heating modalities:- Conductive – hot packs,paraffin

baths,fluido therapy.- Convective- Radiant.

ULTRASOUND: for deep pain.

ACCUPUNCTURE: Useful adjunct for patients with chronic

musculoskeletal disorders and headaches.

Technique – insertion of needles in discrete anatomically defined points called “MERIDIANS”.

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 medication

Ice packs Chiropractic/osteopathic

manipulations Massage Yoga Topical agents (Ben

Gay/Icy Hot – with menthol, salcylates, Capcaicin)

Local injections (steroids, lidocaine)

Glucosamine shown to help with osteoarthritis

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

emotional components 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 pain management.

1. Self management techniques – cognitive methods,relaxation,biofeedback.

2. Operant techniques.3. Group therapy.

Cognitive methods: Based on assumptions that a patients

attitude towards pain can influence the perception of pain.

Maladaptive attitudes contribute to suffering and disability.

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 pain* Intractable side effects*

*Symptoms that persists despite carefully individualized patient management

SELECTION OF BLOCK: Depends on - 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- Facet blocks- Trans sacral nerve blocks etc.

Sympathetic blocks:- Stellate ganlion block- Celiac plexus block- Thoracic,lumbar sympathetic chain

block etc.

CELIAC PLEXUS BLOCK

EPIDURAL INJECTIONS:- Lumbar interlaminar epidural injections- Fluoroscopic injections- Transforaminal injections- Radiofrequency rhizotomy

SPINAL INJECTIONS: 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 cord.

Mechanism – activation of descending modulating systems and inhibition of sympathetic outflow.

Indications:- 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 breakage.

Deep brain stimulation may be used for intractable cancer pain and rarely for intractable neuropathic pain of nonmalignant origin.

- Electrodes are implanted stereotactically into periaqueductal and periventricular gray areas for nociceptive pain.

- Complications: intracranial hemorrhage and infection.

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 aggressively.

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 Anaesthesia.

Raj PP:Practical Management Of Pain . Wall PD,Melzack OC:Text book of pain. ISA Journal On pain. Gowri devi M;Chronic pain Management-

Psychological aspectsin current conceptsin pain management.CMEabstract 1998.