The document discusses pain and its sensory and central mechanisms. It defines pain and classifies it as acute, subacute, and chronic. It describes the peripheral and central mechanisms of the pain sensory system, including primary afferent nociceptors and ascending pathways. It discusses sensitization, modulation, and theories of pain including the gate control theory and neuromatrix theory. It also covers neuropathic pain, assessment of pain, multidisciplinary treatment approaches, analgesic agents and their mechanisms and uses, and adjunctive therapies.

2. PAIN
• THE INTERNATIONAL ASSOCIATION FOR THE
STUDY OF PAIN (IASP) DEFINES PAIN AS
“AN UNPLEASANT SENSORY AND EMOTIONAL
EXPERIENCE ASSOCIATED WITH ACTUAL OR
POTENTIAL TISSUE DAMAGE, OR DESCRIBED IN
TERMS OF SUCH DAMAGE.”
IT MAY BE ACUTE, SUBACUTE AND CHRONIC.
• PAIN SENSORY SYSTEM:
PERIPHERAL MECHANISM
CENTRAL MECHANISM

4. PERIPHERAL
PRIMARY AFFERENT NOCICEPTOR
• THE LARGER DIAMETER A BETA FIBERS
• SMALL DIAMETER MYELINATED A DELTA AND
UNMYELINATED C FIBERS
• RESPONSES TO INTENSE HEAT, INTENSE
COLD, INTENSE STIMULI, CHANGES IN pH,
APPLICATION OF CHEMICAL IRRITANTS.

6. SENSITISATION
• WHEN PROLONGED, REPEATED AND INTENSE
STIMULI ARE APPLIED TO THE INFLAMMED
TISSUE THEN THE THRESHOLD FOR
ACTIVATION OF PRIMARY AFFERENTS IS
LOWERED.
• THE MEDIATORS ARE BRADYKININ, NGF, PGS
AND LTS .

7. • TWO TYPES OF SENSITISATION– PERIPHERAL
AND CENTRAL
• PERIPHERAL- WHEN OCCURS IN PERIPHERAL
NERVE TERMINALS,
• CENTRAL- WHEN OCCURS AT DORSAL HORN
CELLS OF SC.
• CONTRIBUTES TO TENDERNESS, SORENESS
AND HYPERALGESIA.

9. CENTRAL
• REFERRED PAIN- THE CONVERGENCE- PROJECTION
HYPOTHESIS

10. ASCENDING PATHWAYS OF PAIN

12. PAIN MODULATION
• PLACEBO EFFECT
• NOCEBO EFFECT
• BEECHER’S CLASSIC WORLD WAR 2 SURVEY
• BRAIN CIRCUIT FOR MODULATION INVOLVES
HYPOTHALAMUS, MEDULLA AND MIDBRAIN.
• IT IS OPIOID MEDIATED.

13. GATE CONTROL THEORY OF PAIN

14. NEUROMATRIX THEORY (DR.MELZACK 1990)

15. NEUROPATHIC PAIN
• DIRECT DAMAGE OR LESION IN THE CENTRL
AND PERIPHERAL PATHWAYS RESUTS IN PAIN.
• IN DIABETIC NEUROPATHY, HERPES ZOSTER,
TRAUMA TO BRAIN STEM, THALAMUS AND
SPINAL CORD

16. CHARACTERISTICS OF NEUROPATHIC
PAIN
• UNUSUAL BURNING, TINGLING OR ELECTRIC
SHOCK LIKE PAIN
• SENSORY DEFICIT IN AREA OF PAIN
• HYPERPATHIA- FROM PAINFUL STIMULI
• ALLODYNIA –FROM NON PAINFUL
STIMULI(TOPICAL LIGNOCAIN PATCH 5%)

17. SYMPATHETICALLY MAINTAINED PAIN
PERIPHERAL NERVE INJURY
ADRENERGIC RESPONSE ACTIVATION BY
NOCICEPTORS
DELAYED DEVELOPMENT OF PAIN
(HRS TO DAYS AND WEEKS)

18. • ALSO KNOWN AS CRPS-COMPLEX REGIONAL
PAIN SYNDROME
• CRPS 1- IDEOPATHIC- REFLEX SYMPATHETIC
DYSTROPHY
• CRPS 2- DEFINITE NERVE INJURY-POST
TRUMATIC NEURALGIA

19. PSYCHOLOGICAL FACTORS
AFFECTIVE
FACTORS-
• DEPRESSION
• ANXIETY
• ANGER
COGNITIVE
FACTORS-
• NEGATIVE
THOUGHTS
LEARNING
FACTORS-
• OPERANT
LEARNING
• FEAR OF
MOVEMENT

20. ASSESSMENT OF PAIN
• PAIN INTENSITY-
VISUAL ANALOGUE SCALE
VERBAL RATING SCALE
NUMERIC RATING SCALE
• PAIN AFFECT-
Mc GILL PAIN QUESTIONNAIRE
BELIEF PAIN INVENTORY
• PSYCHOMETRIC ANALYSIS

21. IASP CLASSIFIES PAIN TREATMENT
PROGRAMME INTO FOUR CATEGORIES
1. MULTIDISCIPLINARY PAIN CENTRE
2. MULTIDISCIPLINARY PAIN CLINIC
3. PAIN CLINIC
4. MODALITY ORIENTED CLINIC

22. • PHYSIATRIST
• PHYSICAL
THERAPIST
•
OCCUPATIONAL
THERAPIST
• PAIN
PSYCHOLOGIST
• SOCIAL
WORKER
•
RECREATIONAL
THERAPIST
• BIOFEEDBACK
SPECIALIST
• NURSING
EDUCATOR
• VOCATIONAL
COUNSELOR
INTERDISCIPLINARY PAIN
TEAM MEMBERS

23. TREATMENT
• PHYSICAL THERAPY AND OCCUPATIONAL
THERAPY
• PAIN PSYCHOLOGY ASSESSMENT AND
INTERVENTIONS
• VOCATIONAL COUNSELLING
• NURSE FACILITATOR
• MEDICATIONS

24. ANALGESIC AGENTS
• NARCOTIC AND NON NARCOTIC AGENTS
• NON NARCOTICS INCLUDE ASPIRIN,
ACETAMINOPHEN, PROPIONIC ACID
DERIVATIVES, AND CYCLOOXYGENASE II [COX
II] INHIBITORS, OXICAM DERIVATIVES, ACETIC
ACID DERIVATIVES, PARA AMINO PHENOL
DERIVATIVES, BARBITURATE DERIVATIVES

25. • COX 2 INHBITORS- CELECOXIBS
• OXICAM DERIVTIVES- MELOXICAM
• PROPRIONIC ACID DERIVATIVES- IBUPROFEN,
NAPROXEN
• ACETIC ACID DERIVATIVES- ETODOLAC,
KETODOLAC, DICLOFENAC
• SALICYLATE DERIVATIVES- ASPIRIN, SALSALATE
• PARA AMINO PHENOL DERIVATIVES-
ACETAMINOPHEN
• BARBITURATE- BUTALBITAL

26. PRECAUTIONS IN PAIN MEDICATION
1. DIAGNOSIS WITH APPROPRIATE DIFFERENTIAL.
2. PSYCHOLOGICAL ASSESSMENT, INCLUDING RISK OF ADDICTIVE
DISORDER.
3. INFORMED CONSENT.
4. TREATMENT AGREEMENT.
5. PREINTERVENTION AND POSTINTERVENTION ASSESSMENT OF PAIN
LEVEL AND FUNCTION.
6. APPROPRIATE TRIAL OF OPIOID THERAPY WITH/WITHOUT
ADJUNCTIVE MEDICATIONS.
7. REASSESSMENT OF PAIN SCORE AND LEVEL OF FUNCTION.
8. REGULARLY ASSESS THE FOUR A’S OF PAIN MEDICINE (ANALGE-SIA,
ACTIVITIES OF DAILY LIVING, ADVERSE EFFECTS, AND ABERRANT
BEHAVIOR).
9. PERIODICALLY REVIEW PAIN DIAGNOSIS AND COMORBID
CONDITIONS, INCLUDING ADDICTIVE DISORDERS.
10. DOCUMENTATION.

27. MOA
SALICYLATES AND PROPRIONIC ACID
DERIVATIVES-
• INHIBIT COX1 &2
• INHIBIT MIGRATION OF LEUKOCYTES
• STABILISE LYSOSOMAL ENZYMES
• PENETRATE JOINT FLUID TO MAINTAIN
ANTIINLAMMMATORY ACTION MORE THAN
THE HALF LIFE

28. CLINICAL USES-
– ANTI INFLAMMATORY
– ANTIPYRETIC
– ANTIPLATELET EFFECT- STROKE AND IHD
SIDE EFFECTS-
– GASTRIC IRRITATION
– RENAL SIDE EFFECTS
– ANGIONEURETIC EDEMA
– REYE’S SYNDROME
– HSN REACTIONS (ASPIRIN INDUCED ASTHMA)

29. COX2 INHHIBITORS
(-COXIBS)
• LOW GASTRIC SIDE EFFECTS. AS COMPARABLE
TO SALICYLATES AND PROPRIONIC ACIDS
• BUT HAS SIDE EFFECTS – ASPIRIN LIKE
ASTHMA AND ALLERGIES AND RENAL
COMPROMISE

30. ACETMINOPHEN
(PARACETAMOL)
• WEAK EFFECT ON COX.
• EXCRETED BY HEPATIC
GLUCURODINATION(60%)AND SULFATION(35%)
• POTENTIAL ANTIPYRETIC AND ANALGESIC
EFFECT(UPTO 2 GM PER DAY)
• SAFEST FOR GASTRIC IRRITATION AND ALLERGIC
REACTIONS

31. • SIDE EFFFECT-
DOSE DEPENDENT FATAL HEPATIC NECROSIS-
EXCESS NABQ FORMATION BY MICROSOMAL
ENZYMES CAUSES CELLULAR NECROSIS (>4GM
A DAY)
• SIGNS- NAUSEA, VOMITING AND PAIN
ABDOMEN- IN 2-4 DAYS OF INGESTION OF
TOXIC DOSES.
• CAUTIONS IN ALCOHOLICS

32. NARCOTIC AGENTS
• OPIATE RECEPTORS IN DORSAL HORN,
PERIAQUEDUCTAL AREA, VENTRAL MEDULLA
AND THALAMIC NUCLEI
• RECEPTORS ARE MU, DELTA AND KAPPA.
• MU RECEPTOR- LIGANDS ARE MORPHIN,
ENDORPHINS AND OTHER SYNTHETIC
• DELTA RECEPTOR- LIGAND- ENKEPHALINS
• KAPPA RECEPTORS- DYNORPHINS

33. CELLULAR EFFECT- BINDING TO OPIATE RECEPTORS
IN CNS AND PERIPHERY
• PRESYNAPTIC- REDUCES EFFLUX OF CALCIUM
• POST SYNAPTIC- INCREASES POTASSIUM EFFLUX
CNS EFFECT- ANALGESIA IN SPINAL AND
SUPRASPINAL REGION- MU RECEPTOR
PERIPHERL EFFECT- VASODILATION AND HISTAMINE
RELEASE, CONSTIPATION AND BILIARY COLIC
PHYSICAL DEPENDANCE.

34. DRUGS
• NATURAL DERIVATIVES- MORPHIN, CODEIN
• PHENANTHRENE DERIVATIVES-
HYDROCODONE, OXYCODON
• DIPHENYL HEPTANE- METHADONE
• PHENYLPIPERIDINE- FENTANYL
• OTHERS- TAPENTADOL

35. • MILD OPIOIDS: CODEINE, HYDROCODONE,
OXYCODONE.
• MAJOR OPIOIDS: MORPHINE, MEPERIDINE,
HYDROMORPHONE, FENTANYL, METHADONE.

36. ADJUVANTS-
• ANTICONVULSANTS
• ANTIDEPRESSANTS

37. ANTICONVULSANTS
FOR NEUROPATHIC PAIN-
• GABAPENTIN, PREGABALIN (POST HERPETIC
NEURALGIA, DIABETIC NEUROPATHY)
• CARBAMAZEPIN(TRIGEMINAL NEURALGIA)
• LAMOTRIGINE(CENTRAL POST STROKE PAIN)
• OXCARBAZEPIN (POST HERPETIC NEURALGIA,
HIV-NEUROPATHY)

38. ANTIDEPRESSANTS
• TCA- DOXEPIN, AMITRIPTYLINE, IMIPRAMINE,
NORTRIPTYLINE
• SSRI-FLUOXETINE, ESCITALOPRAM,
CITALOPRAM, SERTRALINE
• SNRI- MIRTZAPINE, VENLAFAXINE,
DULOXETINE, MILNACIPRAN

39. SLEEP AND PAIN
MEDICATION FOR INSOMNIA-
• BENZODIAZEPINS- ESZOPICLONE,
• TCA
TOPICAL ANALGESIA(VANILLOID RECEPTORS)-
• MENTHOL (KAPPA RECEPTOR),
• LIGNOCAINE PATCH,
• NSAIDS

40. WHO PAIN LADDER
•