Nur Amalina Aminuddin Baki

082012100067

Pain Management

Classification of pain

Acute

Chronic

Evaluation of pain

Selected pain syndromes

Perception

Pain perception depends on specialized neurons

that function as receptors, detecting the stimulus,

and then transducing and conducting it to the central

nervous system.

PROTOPATHIC (NOXIOUS) EPICRITIC (NONNOXIOUS).

• pain • light touch, pressure,

proprioception,

• and temperature discrimination

• high-threshold receptors • low-threshold receptors

• smaller, lightly myelinated (Aδ)

and unmyelinated (C) nerve

fibers

• large myelinated nerve fibers

Term Description

Allodynia Perception of an ordinarily nonnoxious stimulus as pain

Analgesia Absence of pain perception

Anesthesia Absence of all sensation

Anesthesia

dolorosa

Pain in an area that lacks sensation

Dysesthesia Unpleasant or abnormal sensation with or without a stimulus

Hypalgesia Diminished response to noxious stimulation (eg, pinprick)

Hyperalgesia Increased response to noxious stimulation

Hyperesthesi

a

Increased response to mild stimulation

Hyperpathia Presence of hyperesthesia, allodynia, and hyperalgesia usually

associated with overreaction, and persistence of the sensation

after the stimulus

Hypesthesia Reduced cutaneous sensation (eg, light ,touch, pressure, or

temperature)

Neuralgia Pain in the distribution of a nerve or a group of nerves

Paresthesia Abnormal sensation perceived without an apparent stimulus

Classification of pain

Acute and chronic pain.

Pathophysiology

nociceptive or neuropathic pain

Etiology

arthritis or cancer pain

Affected area

headache or low back pain

ACUTE PAIN

Caused by noxious

stimulation

Usually nociceptive.

Post-traumatic,

postoperative, obstetric

pain and pain associated

with acute medical

illnesses

Self-limited or resolve

with treatment in a few

days or weeks.

Types of acute pain

Somatic

Visceral

Somatic pain

Intensity and duration of the stimulus affect the

degree of localization.

Superficial Deep

skin, subcutaneous tissues,

and mucous membranes

muscles, tendons, joints, or

bones

well localized less well localized

sharp, pricking, throbbing,

or burning sensation.

dull, aching quality

Visceral pain

Due to a disease

process or abnormal

function involving an

internal organ or its

covering

Four subtypes are

described:

Localized visceral pain

Localized parietal pain

Referred visceral pain

Referred parietal pain

Referred pain are due to

:

Embryological

development and

migration of tissues

Convergence of visceral

and somatic afferent input

Visceral Parietal

dull, diffuse, and

usually midline.

sharp and

stabbing

sensation

localized or

referred

associated nausea,

vomiting, sweating,

and changes in

blood pressure and

heart rate.

CHRONIC PAIN

Pain that persists beyond the usual course of an acute

disease or after a reasonable time for healing to occur(1

to 6 months.)

May be

Nociceptive (musculoskeletal disorders)

Neuropathic (pain associated with peripheral or central neural

disorders)

Mixed (Cancer and chronic back pain)

Psychological and environmental factors play a major

role.

Attenuated or absent neuroendocrine stress responses

and have prominent sleep and mood disturbances.

Mechanism of chronic pain

Maybe caused by

combination of :

Peripheral

Spontaneous discharges;

Sensitization of receptors to

stimuli;

Up-regulation of adrenergic

receptors.

Central

Loss of segmental

inhibition,

Spontaneous discharges in

deafferentated neurons,

Reorganization of neural

connections.

Psychological

Psychophysiological

Learned or operant

behavior in which chronic

behavior patterns are

rewarded

Psychopathology

Pure psychogenic

mechanisms (somatoform

pain disorder)

Neuropathic Pain Mechanism

Involve peripheral-central and central neural mechanism.

Associated with lesion of peripheral nerves, dorsal root

ganglia, nerve root.

Mechanisms:

Spontaneous self sustaining neuronal activity in primary afferent

neuron.

Marked mechanosensivity

Short circuits between pain fiber and other type of fiber.

Functional reorganization of receptive filed in dorsal horn neurons.

Spontaneous electrical activity in dorsal horn cell or thalamic nuclei.

Release of segmental inhibition in spinal cord.

Lesion of the thalamus or other supraspinal structures

Systemic Responses To ACUTE

Pain

Cardiovascular (hypertension, tachycardia, enhanced myocardial irritability, and increased systemic vascularresistance.).

Respiratory (hypoxemia, hypoventilation, impair coughing and clearing of secretions.)

Gastrointestinal and Urinary (increases sphincter tone and decreases intestinal and urinary motility, stress ulceration and nausea, vomiting, and constipation)

Endocrine (negative nitrogen balance, carbohydrate intolerance, and increased lipolysis, sodium retention, water retention)

Hematological (Stress-mediated increases in

platelet adhesiveness, reduced fibrinolysis, and

hypercoagulability)

Immune (Stress-related immunodepression )

Psychological (anxiety and sleep disturbances )

Systemic Responses To Chronic

Pain

Observed only in patients with :

Severe recurring pain due to nociceptive mechanisms

Prominent central mechanisms (pain associated with

paraplegia0.

Absent in most patients with chronic pain.

Sleep ,depression, changes in appetite and stresses

on social relationships.

Evaluation of chronic pain

Pain measurement

Numerical rating scale,

Wong-Baker FACES rating scale,

Visual analog scale (VAS),

McGill Pain Questionnaire (MPQ)

Imaging studies

Pyschological

Minnesota Multiphasic Personality

Inventory (MMPI)

Beck Depression Inventory.

Electromyography and nerve

conduction studies

SELECTED PAIN

SYNDROMES

Entrapment syndrome

Neural compression

Narrow passage , genetic factors ,repetitive trauma

Diagnosis :

Electromyography and nerve conduction studies.

Neural blockade of the nerve with local anesthetic

Treatment :

Oral analgesics

Temporary immobilization

Surgical decompression.

Myofascial pain

Characterized by aching muscle pain, muscle

spasm, stiff ness, weakness, and autonomic

dysfunction.

Have trigger points in muscles or connective tissue

(levator scapulae, masseter, quadratus lumborum,

and gluteus medius muscles)

Palpation : tight,ropy bands over trigger points.

Pain radiates in a fixed pattern (not follow

dermatomes)

Gross trauma or repetitive microtrauma

Diagnosis: character of the pain and palpation of

discrete trigger

Treatment:

Spontaneously resolve

Local anesthetic (1–3 ml) trigger point injections.

Topical cooling with ethyl chloride / fluorocarbon spray can

also

Physical therapy

Fibromyalgia

Chronic widespread pain, fatigue, sleep disturbance, and heightened pain in response to tactile pressure

Diagnosis: 1. Widespread Pain Index (WPI) score of 7 or higher, and Symptom

Severity (SS) scale score of 5 or higher, or WPI of 3–6 and SS scale score of 9 or higher.

2. Symptoms present at a similar level for at least 3 months.

3. Absence of another disorder that would otherwise explain the pain.

Treatment: Cardiovascular conditioning, strength training, improving sleep

hygiene, cognitive behavioral therapy, patient education

pregabalin ,duloxetine ,and milnacipran

Low back pain and related syndromes

Paravertebral muscle and

lumbosacral joint

sprain/strain

Buttock pain : coccydynia,

piriformis syndrome

Degenerative disc disease:

herniated intervertebral

disc ,spinal stenosis

Facet syndrome , cervical

pain

Congenital abnormalities (lumbarization of S1 , spondylolysis,spondylolisthesis)

Tumors Benign (hemangiomas, osteomas, aneurysmal bone cysts)

Malignant (osteosarcomas, Ewing’s sarcoma, and giant cell tumors.)

Infections ( spinal TB)

Neuropathic pain

Pain associated with diabetic neuropathy, causalgia, phantom limbs, postherpetic neuralgia, stroke, spinal cord injury, and multiple sclerosis.

Lancinating with a burning quality

Treatment: Anticonvulsants(eg, gabapentin, pregabalin)

Antidepressants (tricyclic antidepressants)

Antiarrhythmics (mexiletine)

Α 2 -adrenergic agonists (clonidine)

Topical agents (lidocaine or capsaicin)

Analgesics (NSAIDs and opioids)

Diabetic neuropathy Symmetric ,focal /

multifocal, affecting peripheral cranial, or autonomic nerves.

Most common syndrome = peripheral polyneuropathy

Complex regional pain syndrome (CRPS) Neuropathic pain disorder

with significant autonomic features

Alterations in sweating ,color, and skin temperature, and by trophic changes in the skin, hair, or nails.

Two variants: CRPS 1, formerly known as

reflex sympathetic dystrophy (RSD),

CRPS 2, formerly known as causalgia.

Headaches

Classic headache syndromes Migraine,Tension,Cluster

Vascular disorders Temporal

arteritis,Stroke,Venousthrombosis

Neuralgias Trigeminal,Glossopharyngeal,

Occipital

Intracranial pathology Tumor, Cerebrospinal fluid

leak, Pseudomotor cerebri, Meningitis, Aneurysm

Eye disorders Glaucoma, Optic neuritis

Sinus disease Allergic, Bacterial

Temporomandibular joint disease

Dental disorders

Drug-induced Acute ingestion,Withdrawal

(eg, caffeine and alcohol)

Systemic disorders Infections

Metabolic(Hypoglycemia, Hypoxemia)

Trauma

Miscellaneous Cold stimulus (swallowing cold

liquid)

Tension headaches Migraine headaches

Tight bandlike pain or discomfort

Frontal, temporal, or occipital,

Bilateral / unilateral.

Lasting hours to days.

Associated with emotional stress or depression.

Nsaids.

Associated with photophobia,

nausea and vomiting, and

aura

Lasts 4–72 h

Family history , certain foods

menses, and sleep

deprivation

Treatment: Oxygen, Sumatriptan ,

Dihydroergotamine

Prophylactic treatment Β-adrenergic blockers, calcium

channel blockers, valproic acid,

Cluster headaches Temporal Arteritis

Unilateral and periorbital,

Occurring in clusters of one to

three attacks a day over a 4- to 8-

week period.

Burning or drilling sensation

Each episode lasts 30–120 min.

Red eye, tearing, nasal stuffiness,

ptosis,

Males (90%).

Treatments:

Oxygen and sphenopalatine block.

Prophylaxis.

Lithium and verapamil

Inflammatory disorder of

extracranial arteries.

Develops over a few hours, is

dull in quality and worse at

night and in cold weather.

Scalp

Tenderness is usually present.

Accompanied by fever, and

weight loss.

Common in older patients (>55

years), with an incidence of

about

Early diagnosis and treatment

with steroids is important

because progression can lead

Trigeminal neuralgia

Unilateral.

Electric shock quality lasting

from seconds to minutes

Facial muscle spasm middle-

aged and elderly,

Common causes : Compression of the nerve by the superior

cerebellar artery or multiple sclerosis.

Treatment Carbamazepine,phenytoin or baclofen

Glycerol injection, radiofrequency

ablation, and microvascular

decompression of the trigeminal nerve.

Cancer related pain

Give drugs at fixed

interval and by oral

Parenteral if patients

have refractory pain,

cannot take medication

orally, or poor enteral

absorption

Adjuvant drug therapy

:anti depressant

,anticonvulsants,

ziconotide (CCB)

Surgery, radiation

therapy, and

chemotherapy

ACUTE PAIN CHRONIC PAIN

Somatic

Superficial

Deep

Visceral

Localized visceral pain

Localized parietal pain

Referred visceral pain

Referred parietal pain

Conclusion

Referances

Morgan and Mikhail’s textbook of Anesthesiology,

5th edition.