Post on 04-Apr-2018
transcript
7/29/2019 117404156 Pain and Pain Pathways
1/43
Pain and pain pathways
7/29/2019 117404156 Pain and Pain Pathways
2/43
CONTENTS
Introduction
History
Levels of pain processing
Neural pathways of pain
Theories of pain
Types of pain
Measurment of pain
Management of pain
Studies
References
7/29/2019 117404156 Pain and Pain Pathways
3/43
The most fundamental and primitive sensation
Pain impairs the lives of millions of people
In 1984 Bonica reported that 1/3 of the worlds
population suffers from pain of some etiology
We dentists are concerned with teo of the most
common pains:
1st
Acute orofacial pain arising from teeth andassociated structures
2nd Chronic orofacial pain , which is belived to
account for 40% of all chronic pain problems
7/29/2019 117404156 Pain and Pain Pathways
4/43
Responsibility of the dentist:
To identify the cause
To treat ( by dental or multidiciplinary
approach)
7/29/2019 117404156 Pain and Pain Pathways
5/43
History
Root : from greek word Poin derived from latin
Poena
Dorlands Medical dictionary defined pain as A
more or less localised sensation of discomfort,distress or agony, resulting from stimulation of
specialised nerve endings.
It serves as a protective mechanism in so far as
it induces the suferer to remove or withdraw
from the source
7/29/2019 117404156 Pain and Pain Pathways
6/43
An unplesant sensation associated with acuteor potential tissue damage and mediated by
spefic nerve fibers to the brain wheere its
conscious appreation may be modified byvarious factors
Pressure to seek aid for pain increases when
patient is under greater than usual stress
Degerr of pain is not related to amount of injury.
. . . . . But on attention given by patient
7/29/2019 117404156 Pain and Pain Pathways
7/43
Levels of pain processing
Nociception
Pain
Suffering Pain behaviour
Pain is presently recognised as anexperience rather than a sensation
7/29/2019 117404156 Pain and Pain Pathways
8/43
Neural pathways of pain
Feilds has noted that subjective experience of
pain arises from 4 distinct processes
Transduction Noxius stimuli electric activity in sensory neuron
Transmission 1st order neurons: sensory organ spinal chord
2nd order neurons: spinal chord thalamus
3rd order; interaction
Modulation
Perception
7/29/2019 117404156 Pain and Pain Pathways
9/43
Fibers carrying pain impuls:
A delta fibers:
Myelinated
Mechanical stimulus
C fibers
Unmylinated
Chemical and thermal stimuli
7/29/2019 117404156 Pain and Pain Pathways
10/43
Theories of pain
Intensity theory When sensation is beyond a level
Speficity theory Spefic nociceptors + center in brain
Pattern theory Nan specialised receptors; excitation thresholds,
adaptation ranges,distribution of branches
Protopathic and epicritic theory Primitive system + advanced system
7/29/2019 117404156 Pain and Pain Pathways
11/43
Gate control theory 1965, Melzack and Wall
Activity in several interacting neural pathways
Cells in substantiagelatinosa
Dorsal column fibersthat project towards
the brain
First central transmission(T) cells in spinal chord
Gate control system
modulates efferent
paterns before they
influnce T cells
Central control trigger
activates areas in brain
influnces modulating
prop of GCS
Activates neural
mechanism for perception
- Threashold
7/29/2019 117404156 Pain and Pain Pathways
12/43
Orofacial pain classification: Axis I (Physical conditions)
I. Somatic pain
Superficial somatic pain
Cutananeous pain
Mucogingival pain
Deep somatic pain
Musculoskeletal pain
Muscle pain
Protective co contraction Local muscle soreness
Myofacial pain
Myospasm
Centrally mediated myalgia
Temporomandibularjoint pain
Ligamentous pain
Retrodiscal pain
Capsular pain
Arthritic pain
Osseous /periosteal pain
Soft connective tissue pain
Periodontal dental pain
Visceral pain
Pulpal dental pain
Vascular pain
Neurovascular pain
Visceral mucosal pain
Glandular, ocular, auricular pain
7/29/2019 117404156 Pain and Pain Pathways
13/43
II Neuropathic pain
Episodic neuropathic pains
Paroxysmal neuralgia pain
Trideminal neuralgia
Glossopharyngeal neuralgia
Geniculate neuralgia
Superior laryngeal neuralgia
Nervus intermidus
Occipital neuralgia Neurovascular pain
Continuous neuropathic pain
Peripherally mediated pain
Entrapment neuropathy Deafferentiation pain
Traumatic neuroma pain
Neuritic pain
Peripheral neuritis
Herpes zoster
Centrally mediated pain
Burning mouth disorder
Atypical odontalgia
Postherpetic neuralgia
Metabolic polyneuropathies
Diabetic neuropathy
Hypothyroid neuropathy
Alcholic neuropathy
Nutritional neuropathy
Axis II (psychologic conditions)
Mood disorders Anxiety disorders
Somatoform disorders
Other conditions
7/29/2019 117404156 Pain and Pain Pathways
14/43
Measurment of pain
Pain perception threashold (PPT)
Severe Pain Threashold (SPT)
Variability
Scales for measurment
Category scale Rupee analog scale
Numeric rating scale
Visual analog scale
7/29/2019 117404156 Pain and Pain Pathways
15/43
Visual analog scale:
Pain score
No pain Worst possible pain10 cms
0- no pain
1 Probabaly no pin
2 Mild discomfort
3 Mild pain or discomfort
4 Mild to moderate pain
5 Moderate pain
6 Increased moderate pain
7 moderate to severe pain
8 Severe pain
9 Severe to excruciating pain
10 Worst possible pain
7/29/2019 117404156 Pain and Pain Pathways
16/43
Management of pain
Therupatic modalities:
Pharmacologic therapy
1) Analgesic agents
2) Anesthetic agents
3) Anti inflamatory agents
4) Muscle relaxants
5) Antidepressants
6) Anti anxity agents
7) Vasoactive agents8) Non epinephrine blockers
9) Antimicrobial agents
10) Antiviral agents
7/29/2019 117404156 Pain and Pain Pathways
17/43
11) Antihistamine agents
12) Anticonvulsants
13) Neurolytic agents
14) Uricisuric agents15) Dietary considerations
Physical therapy Psychologic therapy
1) Modalities 1) Counclling
Sensory stimulation 2) Behaviour modification
Ultrasonic * Stress releiving training
Electrogalvanic stimulation * Relaxation training
Deep heat * Physical self regulation
2) Manual techniques Massage
Spray and streach technique
Exercise
Physical activity
7/29/2019 117404156 Pain and Pain Pathways
18/43
Analgesic agents:
Shouldnt eliminate pain. . . . But make it tolerable
Non narcotic analgesics:- 4 basic actions
- Inhibition of COX PG E2 formation
- PGs induce hyperalgesia
- Temperature in fever
- Inhibits PGE2 formation in hypothalamus
- Prolongs bleeding time
- Synthesis of platelet aggregator factor TXA2
- No tolerance, physical dependence
- Have celing effect
- Toxicity: gastric mucosal damage, bleeding, Renal blood flow,
aggrevates Asthma &anaphylactoid reactions
Eg: Asprin, Iboprofen, Ketoprofen (short t1/2)
Nabumetone, naproxen (long t1/2)
Acetaminophen (adv)
7/29/2019 117404156 Pain and Pain Pathways
19/43
Most commonly used for acute dental pain
Mild-moderate pain + inflamation : Paracetamol + low
dose Iboprofen
Post extraction pain : Ketorolac/ diclofenac / nimesulide/asprin
Gastric intolerance to NSAIDs: Celecoxib/ Raficoxib/
Paracetamol
With history of asthma; anaphylaxis to NSAIDs:Nimesulide
Children: only Paracetamol/ Asprin/ Ibuprofen(asprin in
viral infections: Reyes syn)
Pregnancy: paracetamol is safest; 2nd choice low doseasprin
7/29/2019 117404156 Pain and Pain Pathways
20/43
Asprin dose: 300-500 mg TDS/QID
ASSPRIN, DISPRIN 350 mg tabS
Paracetamol: 500mg-1g TDS CROCIN 500mg; 1g, METACIN,PARACIN 500mg
tabs; CROCIN PAIN RELIF: paracetamol 650mg+
Caffine 50mg tabs
Diclofenac 50 mg TDS VOVERAN, DICLONAC, MOVONAC 50 mg entric
coated tabs
Celecoxib 100-200 mg BD
CELACT, REVIBRA 100mg 200mg caps
7/29/2019 117404156 Pain and Pain Pathways
21/43
Narcotic analgesics
- Act through CNS receptors. . . . . Induce peripheral
analgesia
- Depress nociceptor neurons
- Have inhibitory influnce on release of substance P
- Tolerance should be noted- May cause constipation, physical dependence, addiction,
Acute morphine poisoning (R naloxone)
- Should be given on strict time schedule
- Used only for severe acute pain, chronic cancer pain- Eg ; morphine, codine, Pentazocine, Tramadol
7/29/2019 117404156 Pain and Pain Pathways
22/43
Anesthetic agents :
- For diagnostic and therupatic
Topical anesthesia- Solutions / spraya / lozenges
- Alovera juice inflamatory pain
- Analgesic balms : Balsam of peru, eugenol, guaiacol .- Use
- Eg: Xylocaine 4% topical solution
- Topical LA mixed with other medication
- Eg: Peripheral neuropathy: lignocain + amitriptyline +
Carbamazepine (Tegretol)
Injectable LA
7/29/2019 117404156 Pain and Pain Pathways
23/43
Injectable LA
Low potency short duration: Procaine
Intermediate Potency and duration: Lignocaine
Prilocaine
High potency, long duration : TetracaineBupivacaine
Ropivacaine
Mechanism of action: Reduces Na entry during AP
depolarization dosent reach threashold no APRate of rise of action potential
Lignocaine2% + adrenalin :commonly used
pulpal anesthesia obtained in 2-3 mins; lasts for 40-60 mins
Soft tissue anesthesia 2-3 hrs
Analgesia may not be acheived in very sensitive teeth, marked
inflamation
Lignocaine10% spray: for impressions
Bupivacaine 2% + adr 1: 200000
High lipid soluble- low bone penetrationanesthesia in >5 mins lasts for
7/29/2019 117404156 Pain and Pain Pathways
24/43
Anti Inflamatory agents
By inhibiting PGs
Devar reported that locally applied steroidrapidly and eeffectively arrested pain
Corticosteroids potent; but immune system
Uses: reccurent oral ulcers;
Phemphigus;erosive lichenplanus; pain from
exposed dental pulp; Hydrocortisone may be
injected into TMJ to relive refractory pain and
stifness Contraindicated in systemic fungal and herpesinfections
7/29/2019 117404156 Pain and Pain Pathways
25/43
Muscle relaxants
- in myogenous pain
- Potential agents (succinyl choline, methocarbamol)restricted to hospitalised pts
Anti depressants
- In Chronic pain with depression- Tricyclic anti depressants action: availability of 5HT,
norepinephrine, dopamine in CSF
- Eg: low dose of amitryptaline before sleep on
prolonged use reduces chronic pain ( nt acute pain)- Amitryptaline : post herpetic neuralgia
- Newer antidepresants SSRIs eg: fluoxetine, venloflaxine
7/29/2019 117404156 Pain and Pain Pathways
26/43
Antianxity agents
Reduces modulating effect of pain and
apprehension Major tranquilizer : Phenothiazine
Minor tranquilizers: Diazepam,Meprobamate
Have muscle relaxant action also
Potential for drug tollerance,dependence
When used for analgesia best prescribed for
limited period
Clonazepam
Has analgesic effect in certain neuropathic pains
Effective in burning mouth syndrome
7/29/2019 117404156 Pain and Pain Pathways
27/43
Vasoactive agents:
In neurovascular pain
Somatostatin has inhibitory action on substance P
B adrenergic blockers are proven effective in
phantom limb pain, migrane
adrenergic blocking drugs( eg: ergotamine
tartarate) : stimulating effect on b.v Used in cluster headache
Caffine has enhancing effect on its action
7/29/2019 117404156 Pain and Pain Pathways
28/43
Norepinephrine blockers:
Block reuptake of norepinephrine
Block stellate ganglion : control ofsympathetically maintained pains of orofacial
region
Guanethidine commonly usedAlso effective in rheumatoid arthritis
7/29/2019 117404156 Pain and Pain Pathways
29/43
Antimicrobial agents
Reduce pain by resolving
Intrinsic analgesic effect
Pain
Long term therapy - only if infection present
Antiviral agents
Effective in primirary infection of HSV, HZV
Eg Acyclovir, Famcyclovir Famcyclovir effectively reduces all symptoms
Drug of choice even in immunocompromised, HIV
7/29/2019 117404156 Pain and Pain Pathways
30/43
Anti histamine agents
In allergic reactions and neurovascular pain
Also has some analgesic effectAntihistamine + acetaminophen greater
analgesia than acetaminophen alone
Anticonvulsants Useful in neuropathic pain
Eg: Carbamazepine- primary mediator in
inflamatory pain
Neuropathic pain also treated by: Gabapentin;
oxycarbamazepine; Topiramate
7/29/2019 117404156 Pain and Pain Pathways
31/43
Neurolytic agents
Treat pain by destroying neves
Deafferentiation pain: Pain caused bydestroying nerves
Eg: 95% ethyl alchol (may not prevent
regeneration of peripheral axons) Glecerol injected into retro gasserian spc for
treating trigeminal neuralgia
It demyleanetes neurons responsible for trigeminal
neuralgia
7/29/2019 117404156 Pain and Pain Pathways
32/43
Uricosuric agents:
Used in hyperurecemia causing TMJ pain
Colchicine: subsides acute attacks of gout and relives
pain Probenicide: for for chronic gout arthritis
Acts by inhibiting reuptake of urates by kidney
Gout can involve TMJ
7/29/2019 117404156 Pain and Pain Pathways
33/43
Dietary considerations: Dietary supplementation of L-tryptophan : elevated pain
tollerence
Tryptophan competes with other amino acids for passage
across BBB
2% plasma tryptophan Tryptophan hydroxylase
. Tryptophan
Brady et al: 10 chronic pain patients included in study obtained
pain relif by taking 4g of L tryptophan per day and consuming
low-protein, low-fat, high carbohydrate diet for 8 weeks
CNS seratonergic neurons are actively involved in nociceptive
response
Seltzer et al: reduction in clinical pain and elevated pain
tolerance among randomly selected patients suferring from
chronic maxillofacial pain as a result of 4 weeks tryptophan
supplement therapy
Vit B6
7/29/2019 117404156 Pain and Pain Pathways
34/43
Physical therapy Sensory stimulation Cutaneous
Trans cutaneousPercutaneous
Cutaneous stimulation
Effect occurs by stimulation of thick mylinated afferents ;
A- neurons chiefly Many forms of cutaneous stimulation effectively
attenuate pain
Rubbing skin
Superficial massage
With alchol, menthol
Counter irrigation
Muster plaster
Mixture of aconite + iodine : stimulation of nociceptive fibers :
analgesic effect
Vapocoolant therapy
7/29/2019 117404156 Pain and Pain Pathways
35/43
Vapocoolant therapy
Useful in reliving myofacial trigger point pain
Interrmittancy is esseential
Act By stimulating cutaneous nociceptors and thicker A
fibers Eg: ethyl chloride spray
Alternative applications of heat & cold for brief periods
Eg : moist heat application over painful areas. When heat isnt
effective ice may be tried Infra red heat
Warm saline moutwashes for pain relif after chord insertion
for gingival retraction
Mechanical vibrations
Reported to give complete pain relif in 1/3 of patients with
dental pain
Hydrotherpy
Especially in neck & back pain of muscle origin
Effect of warm saline mouth washes on reduction of pain after packingchord for gingival retraction ;J of Mashhad dentistry 2007
Transcutaneous stimulation
7/29/2019 117404156 Pain and Pain Pathways
36/43
Transcutaneous stimulation
Low intensity current of high frequency
Mild tingling vibration
50 70% pain relif Action is immediate , restricted to segment
Acupuncture
By stimulating endogenous antinociceptive system
Electro acupuncture: low intensity, high frequency
current
Acupoints
Stimulates muscle nociceptors anti
nociceptive system
Induction period: 15-20 mins. Effect segmental or
generalised
Acupoint of oral cavity: inte orbital bridge + Ho Ku
point
Per cutaneous stimulation:
7/29/2019 117404156 Pain and Pain Pathways
37/43
Per cutaneous stimulation:
By electrodes that penetrate skin:
Subcutaneous nerve stimulation
Prolonged analgesia, no tollerance
Lawrence :
electric stimulation of perriosteum by insulated needles
9 122 V at 100-300 Hz for 45 mins Reported it was better than EA &TENS for chronic pain
Ultrasound
tissue temperrature at interrface
blood flow, seperates collagen fibers
Has better effect on deeper tissueskin
Phonophoresis: ultrasound used to administer drugs
through
Eg 10% hydrocortisone cream + Ultrasound
7/29/2019 117404156 Pain and Pain Pathways
38/43
EGS:
Uses electric stimulation to cause muscle contracture
Repeated involuntary contraction+ relaxation of muscles
Help in breaking up myospasm and increasing blood flow tomuscles
Reported to yield good results in MPDS
Deep heat therapy
Phisiotherapy in form of penetrating heat
Especially useful inflamatory pain
In form of ultrasound and diathermy
In myospasm and myofacial trigger point pain
Manual techniques:
Massage:
Gentle massage
Deep massage preceeded by 10 15 mins deep moist heat
effective in releiving trigger point pain and relaxing muscles
7/29/2019 117404156 Pain and Pain Pathways
39/43
Spray and streach technique
Muscle is streaxhed short of pain
Vapocoolant is applied in parallel sprays in one
direction travelling towards refrence area
Procedure
After 3 sweeps muscle is rewarmed
After treatment moist heat applied and range of
movement exercise done
Exercise
Forceful contraction of anagonist muscle causes
reflex relaxation of agonist Used for treating masticatory muscle spasm
For mucle to maintain normal resting length occational
stimulation of receptors is necessary
7/29/2019 117404156 Pain and Pain Pathways
40/43
Studies
A study to determine prevelence of joint diseases in 2
forms of myofacial pain( with limited mouth opening and
without) showed that patients with myofacial pain and
limited mouth opening often had joint diseases that were
not detected with clinical examination Study on modulation of myofacial pain by reproductive
harmones showed that pain levels were constant when
harmone levels were constant wheras they varied with
harmone levels in nonusers Posture corrections when given along with cognitive
behaviour intervention were seen to treat myofacial pain
better
7/29/2019 117404156 Pain and Pain Pathways
41/43
Maping of pressure pain threasholds (ppt) in edentulous
mucosa showed that ppt from ant post alveolus but
decreased from ant palate to post palate. Ppt reduced
from ridge crest to buccal vestibule
Another study conducted in 1993 showed that intraoralappliance (IA) was more effective than BF/SM in treating
TMJ disorders with pain and depression but after 6 mnts
IA group significantly relapsed wheras BF/SM
maintained and continued improvement Neeraj Madan, ijdr, 2001 :Denture wearing patients with
pain in oral musculature &tmj could be attributed to
improperly recorded vertical jaw relations
7/29/2019 117404156 Pain and Pain Pathways
42/43
O.gabbert 2005 : case report of pt who developed
neuropathic pain after implant placement: underwent
multiple RCTs, extraction, long term opoid therapy .
Finally CT,MRI showed perforation of mandibular cannal
by implant.
7/29/2019 117404156 Pain and Pain Pathways
43/43
Thank you