Pain

PAIN CONTENTS 1) Definition of Pain 2) Types of Pain 3) The Pain receptors and their Stimulation 4) Different types of Pain stimuli 5) Classification of nerve fibres 6) Receptor nerve ending 7) Pain pathway 8) Pain theories(Neurophysiologic explanation of pain control) 9) Pain modulation 10) Pain Assessment 11) Pain Management Definition of Pain: Pain is defined as unpleasant sensory and emotional experience that is associated with actual or potential tissue damage Pain is a protective Mechanism, It occurs whenever any tissue damaged and causes the individual to respond to remove the Pain stimulus. Eg: Prolonged sitting on the Escher can cause tissue damage due to lack of blood flow to the skin. The perception of pain in turn prevents potential damage by making us respond with an alteration of posture. Types of Skin Pain has been classified into 2 major types i) Fast pain ii) Slow pain Fast pain It occurs within 0.1 second after the pain stimulus is applied. It is also described by many alternate names such as Sharp pain Prickling pain Acute pain Electric pain This type of pain felt when a needle is stuck into the skin or when the skin is cut with a knife. It is felt only superficial tissues of body. Slow Pain It begins only after a second or more and then increase slowly over many seconds and sometimes even minutes. It is also called by names such as: Burning pain Aching pain Throbbing pain Nervous pain Chronic Pain 1 Purusotham chippala MPT

It is associated with tissue distruction. It can occur both in the skin and almost any deep tissue or organ. Fast type of pain – A d fibers Slow type of pain – C fibers PAIN RECEPTORS AND THEIR STIMULATION: All pain receptors are free nerve endings that line the skin tissues. Pain receptor’s Classification includes: i) Touch Sensitive- Meissner’s corpuscles ii) Cold sensitive- Krausels end bulb iii) Heat Sensitive- Ruffinie’s end organ iv) Pain sensitive- free nerve endings v) Pressure sensitive- Pacininian Corpuscles Different types of Pain stimuli: 1) Based on physical energy source: a) Electro magnetic b) Chemical c) Gravity d) Mechanical displacement e) Sensibility f) Mechanical g) Thermal h) Others -Social - Psychology -Behavioral Classification of nerve fibers Fiber A Fiber B Fiber C Myelinated Myelinated unmyelinated Afferent pre ganglionic somatic Efferent sympathetic efferent Pattern Theory:The sensation of pain results from an appropriate intensity (or) frequency of stimulation of receptors that also respond to other stimuli such as touch, pressure, or temperature. This theory denotes pattern or coding of sensory information is the key element the coding is temporal and spatial sequency of action – potentials are generated in periphery. This theory considers the intense stimulation of non specific receptors as the adequate stimulus for eliciting pain sensation. A touch stimulus applied to a receptor produces a particular pattern of action potentials the resultant sensation is touch. A potentially damaging touch stimulus applied to the receptors produces a different pattern of action potentials resulted sensation is pain. 2 Purusotham chippala MPT

Fig: shows (a & b) pattern of action potentials resulting in sensation of pain According to this theory neural impulses from the periphery are combined and modified to summate in CNS structures, where the pain is then localized and interpreted. According to pattern theory, Temporal and spatial summation of impulses along the pathway from the skin to the cerebral levels determines the individuals sensation of pain (fig B)

Gate Control Theory: Postulated by Melzack & Wall, 1965 Dorsal horn of spinal cord act like a gate that can increase or decrease the flow of nerve impulses, from peripheral fibers to spinal cord cells that project to the brain. (Pre synaptic inhibition of pain) Stimulation of A B receptors mechano receptors (Deep pressure like massage manual theory) Pre synaptic inhibition Suppression of pain from A δ and C fibers (Nociceptors) Stimulation of A δ fiber (Low Tens) Interneuron (Encephalin) Presynaptic inhibition of C fiber pains

Assessment of pain:OPQRST Format Origin\ onset

: Normal musculoskeletal Examination : Gradual\sudden How did pain started.

Position\pattern

:Constant\ periodic Localized\ Radiating Aggravating & Relieving factory Improving\ non screening\ remaining

Quality of pain

: Mechanical – pressing – bursting - stabbing Chemical – burning Neural – Numbness\ pins & needles Vascular – Throbbing

Quantity of pain

: Intensity of pain.

Radiation - Characteristics of pain radiations 3 Purusotham chippala MPT

Symptom\signs – Functional\ Psychological Treatment – previous Rx, Current Rx effectiveness 2) Pain Rating Scales. 3) Body diagram scale - used to show location 4) Sickness impact profile scale 5) Visual Analog scale (VAS scale) 6) MCGILL pain Questionnaire - Examines Quality and Complexity of pain experience 7) (OSTDS pattern - Onset, Site, Type, Time, Duration, Severity, Aggravating and relieving factor) Neurobiology and Molecular Biology of Pain: Chemical agents released as a result of local tissue damage mainly stimulate nociceptors 1) Substances that stimulate nociceptors a) Protons b) Neuro transmitters Serotonin Histamine Ach c) Poly peptides - Bradykinin Kallidin d) Prostaglandins e) Cellular Metabolities f) Spicy plants – Capacin (red pepper) Capsicum (Black pepper) Chemical Class Amino Acids Peptides

Facilitation/ Excitations Neurotransmitter Aspartate Glutamate Substance P Vaso Intestine Peptide Histamine Seratonin Ach Bradykinin Kallidin Prostaglandin

Inhibitory Neurotransmitter GABA Glycine Enkaphalis Dynorphilis Endorphins

Leukotrins

Physiotherapy in Pain Management: Such as 4 Purusotham chippala MPT

• • • • • • • • • •

Heat – superficial heat –Hot pack Ice/Cold/Cryotherapy TENS IFT UVR Ultra Sound Therapy MWD SWD IRR Laser

Heat: Pain decreases Ischemic Pain is relieved by the influx of oxygen – rich blood into the dilated vessels’' and Muscle tension pain is decreased by inhition of the pain/spasm cycle. 1) Conductive heating – Moist heat packs Paraffin Wax bath 2) Corrective heating - Hydrotherapy Contrast bath 3) Radient heat

Superficial Deep

1) Infra. Red 2) Ultraviolet Diathermy- Short - Micro Micro therm

PT Treatment of patient with pain Successful treatment of pain involves identifying and connecting its cause. Numerous physical modalities can be applied to the tissues to relieve pain. These include 1) Superficial heat 2) Deep heat 3) Cryotherapy 4) Phonophoresis 5) Iorstophoresis 6) Laser therapy 7) Tens 8) Point stimulation (Electro Acupuncture) 9) Joint mobilisation 10) Therapeutic touch 11) Myofacial release (MFR) 12) Massage and as well as effective cognitive measures 5 Purusotham chippala MPT

Moist Heat Moist heat is a safe analgesic muscle relaxant a) Mechanism for pain relief i) Heat is gamma fibre activity by decreasing muscle spindle activity via the direct effect of heat on skin receptors. ii) Quick worming of the spindles causes a temporary complete inhibition of the firing of the spindles. iii) Central proprioception mechanism is also affected by reflex action of heat. Raising the body temperature causes decreases gamma activity. b) Heat reduces the conduction velocity of the ‘C’ Nerve fibres. Injury/disease alters the thermal threshold of pain – Heat alters this thermal threshold of pain thereby decreasing pain. C) Counter irritant effect of heat also relieves pain. d) Rise in a temperatures also causes circulation, which in turn removes pain metabolities thus breakdown of the vicious cycle of pain and muscle spasm. Effect of heat of pain relief 1) increased metabolism: Output of waste products from the cells in ed 2) Heat has a direct effect on the blood vessels: Causes vasodilatation of blood vessels, flow of blood through the area, so necessary oxygen and nutritive materials are supplied and waste products are removed less pain. 2. CRYOTHERAPY: i) ii) iii) iv) v)

Peripheral nerve conduction velocity decreases by 2.4m/s per degree Celsius. Peripheral receptors become less excitable Muscle spindle responsiveness to stretch decreases as a result muscle spasm decreases. Circulatory effects – Lewis’s hunting reaction –following the application of cold there is initial vasoconstriction, followed by vasodilatation. Cellular metabolic activity: The oxygen required for the cell

Indications: i) ii) iii) iv) v) Contra Indication: i)

pain and muscle spasm Acute inflammation following trauma PRICER protocol Chronic inflammation following trauma Spasticity Facilitation of movement. PVD’s 6

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ii) iii) iv) v)

Cardiac disease Loss of sensation Cancer and sickle cell anemia Brief icing over the posterior primary organs of the trunk

Disadvantages: i) Impaired skin sensation ii) Burns iii) Neurological pain cryotherapy is better than thermotherapy

TENS HIGH TENS High frequency, low intensity (100HZ, 50usec, 0-30mA) Stimulates large diameter affrents( A B) produces “Pre Oynaptic Inhibition” of Aδ and C fibers at the level of SG(DHS) Onset Pain relief: Fast Relief is short lived Resistance is more Neural accommodation develops Good for acute pain relief

LOW TENS Low frequency, high intensity (2H2, 200usec, 30-80ms) It gives a nociceptive stimulus acts by descending pain inhibiting pathway by stimulation of the release of enkephalinus and endarphis Onset pain relief: Slow Relief lasts for hours or days Good for chronic pain

4. IFT (Inter ferential Therapy) Effects: i) Activation of pain gate control mechanism ii) Activation of nociceptive fibres iii) Physical block iv) Blood flow v) The placebo effect Advantages: i) ii)

It is effective if pain is radiating type. Can penetrate skin by means of medium frequency currents.

5. UVR (Ultra Violet Radiation) Effects: Counter irritant effect relieves pain, enhances healing of pain 6. ULTRA SOUND THERAPY Deep heat also accomplished through use of ultrasound. 7 Purusotham chippala MPT

Therapeutic effects are: 1) Selectively raise tissue temperature at the interfaces without causing substantial change in the surrounding tissues. 2) The amount of heat produced depends directly on the dosage. At les than 1.0 watt there is aminimal in tissue temperature. At 1.5 watt the superficial tissues are geated and at greater than 2.0 watt temperature of the deeper tissues is raised. 3) Ultrasound therapy of C fibres yields pain relief distal to the point of application 4) Ultrasound therapy of large diameter Aδ fibers brings relief of spasm by changing gamma fiber activity.

7. Microtherm Microtherm converts electrical energy into the electrical magnetic energy that can be focused on the tissue of choice. Temperature results when the electromagnetic waves are absorbed by the tissues. Microwave is far more exact than diathermy and is indicated where getting of individual deep structure is desired. 8. PHONOPHORESIS Molecules of a pain relieving chemical substance into the tissues. Once substance molecules are broken down into ions and taken up into the cells, where they participate in intracellular chemical reactions. Chemical solutions + a conducting gel = conducting media 9. SHORT WAVE DIATHERMY 1) relief of pain: localized tissue temperature, blood circulation to that part, metabolism processed, nutrients are supplied, ever already accumulated, metabolities noxious substances are washed away from the part 2) by acting on superficial: sedative effect, muscle relaxation, pain 3) strong superficial heating probably relieves pain by counter irritation 4) S.W.D does the effecting resolution of inflammatory process, so indirectly relieving pain. 10. INFRA RED RADIATION Therapeutic uses i) ii) iii)

Relief pain When healing is mild the relief of pain is probably due to the sedative effect on the superficial sensory nerve ending. Stronger heating stimulates the superficial sensory nerve endings.

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iv)

It has been found that pain may be due to the accumulation in the tissues of waste products of metabolism and ed blood flow through the part removes these substances and relieves pain.

In some cases the relief of pain is probably associated with muscle relaxation. Pain due to acute inflammation/ recent injury is relieved effectively with mild heating.

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