PAIN AND ITS MANAGEMENT

D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY

SOMATOSENSORY CORTEX

SOMATOTOPIC ORGANIZATIONMORE AREA TAKEN BY SENSITIVE

REGIONS (GREATER RECEPTOR DENSITY-SMALLER RECEPTIVE FIELDS)

CELLS RESPONDING TO ONE TYPE OF SENSATION IN VERTICLE COLUMNS(FOR EXAMPLE..PACINIAN CORPUSCLES IN A FINGERTIP)

THE ANTEROLATERAL PAIN AND TEMPERATURE PATHWAY

SENSORY NEURONS SYNAPSE IN SUBSTANTIA GELATINOSA

SECONDARY NEURONS CROSS MIDLINE AND ASCEND IN ATEROLATERAL COLUMN

BRANCHES GO TO THE RETICULAR FORMATIONTERMINATE IN VENTROBASAL NUCLEUS OF

THALMUSTERTIARY NEURONS GO TO SENSORY CORTEX

THE ANTEROLATERAL PATHWAY

SUBSTANTIAGELITANOSA

THE SENSATION OF PAIN

FAST PAINSLOW PAINMECHANICAL PAINCHEMICAL PAINTHERMAL PAIN

PAIN NERVES:

TYPE DIAMETER(m)

CONDUCTIONVELOCITY(m/s)

SENSORYINFORMATION

III(A) 5 15 LIGHTLYMYELINATED:

TOUCH,PRESSURE, AND

PAINIV(C) 1 2 UNMYELINATED:

PAIN ANDTEMPERATURE

FAST PAIN

OCCURS IN ABOUT 0.1 SECONDS SUBJECTIVE DESCRIPTION:SHARP, ACUTE,

ELECTRIC OR PRICKING A FIBERS SYNAPSE ON CELLS IN LAMINA I

(LAMINA MARGINALIS) IN THE DORSAL HORNS SECONDARY NEURONS CROSS AND TRAVEL

THROUGH THE ANTEROLATERAL PATHWAY TO THE VENTROBASAL COMPLEX OF THE THALAMUS

TERTIARY NEURONS GO TO THE PRIMARY SENSORY CORTEX

FAST PAIN PATHWAY

III

IIIIV

VVI

IX

VII

VIII

SUBSTANTIAGELITANOSA

LAMINAMARGINALIS

VENTROBASALNUCLEUS

ANTEROLATERALPATHWAY

SLOW PAIN

OCCURS AFTER A SECOND OR MOREOFTEN ASSOCIATED WITH TISSUE

DESTRUCTIONSUBJECTIVELY DESCRIBED AS BURNING,

ACHING,THROBBING, NAUSEOUS, OR CHRONIC

C FIBERS WHICH SYNAPSE IN THE SUBSTANTIA GELITANOSA

FINAL PROJECTION IS THE FRONTAL CORTEX

SLOW PAIN PATHWAY

III

IIIIV

VVI

IX

VII

VIII

SUBSTANTIAGELITANOSA

LAMINAMARGINALIS

VENTROBASALNUCLEUS

ANTEROLATERALPATHWAY

MECHANICAL, CHEMICAL AND THERMAL PAIN

FAST PAIN IS GENERALLY MECHANICAL OR THERMAL

SLOW PAIN CAN BE ALL THREECHEMICAL PAIN RECEPTORS: BRADYKININ,

SEROTONIN, HISTAMINE, POTASSIUM IONS, ACIDS, ACETYL CHOLINE AND PROTEOLYTIC ENZYMES

PROSTAGLANDINS ENHANCE PAIN SENSATION

BRAIN STRUCTURES AND PAIN

COMPLETE REMOVAL OF THE SENSORY CORTEX DOES NOT DESTROY THE ABILITY TO PERCIEVE PAIN

STIMULATION OF THE SENSORY CORTEX EVOKES A SENSATION OF PAIN

PAIN CONTROL (ANALGESIA)

THE ANALGESIA SYSTEMTHE BRAIN’S OPIATE SYSTEMINHIBITION OF PAIN BY TACTILE

STIMULATIONTREATMENT OF PAIN BY ELECTRICAL

STIMULATIONREFERED PAIN

THE ANALGESIA SYSTEM

PREAQUEDUCTAL GRAYRAPHE MAGNUS NUCLEUSPAIN INHIBITORY COMPLEX IN

DORSAL HORNS

PAIN INHIBITORY COMPLEX: PRESYNAPTIC INHIBITION

PAINRECEPTOR

BRAIN STEM.NEURON

INHIBITORY NEURON

ANTEROLATERALPATHWAY

DORSAL HORN OFSPINAL CORD

+

-

PAIN TRANSMISSION AND INHIBITION

SUBSTANCE P IS THE NEUROTRANSMITTER: BUILDS UP SLOWLY IN THE JUNCTION AND IS SLOWLY DESTROYED

PRESYNAPTIC INHIBITION BY INHIBITORY NEURON BLOCKS THE RELEASE OF SUBSTANCE P (ENKEPHALIN)

THE BRAIN’S OPIATE SYSTEM

OPIATE RECEPTORS EXIST IN MANY CENTERS OF THE BRAIN, ESPECIALLY IN THE ANALGESIA SYSTEM

AMONG THE NATURAL SUBSTANCES WHICH ACTIVATE THESE RECEPTORS ARE: ENDORPHINS, ENKEPHALINS, AND MORPHINE

INHIBITION OF PAIN BY TACTILE STIMULATION

STIMULATION OF LARGE SENSORY FIBERS FOR TACTILE SENSATION INHIBITS PAIN TRANSMISSION FOR SAME REGION

RUBBING OFTEN EASES PAINLINAMENTS, OIL OF CLOVE, ETC.POSSIBLE EXPLANATION FOR

ACUPUNCTURE?

TREATMENT OF PAIN BY ELECTRICAL STIMULATION

STIMULATION OF LARGE SENSORY NERVES

ELECTRODES IN SKIN OR SPINAL IMPLANTS

INTRALAMINAR NUCLEUS OF THALAMUS

REFERED PAIN

VISCERAL PAIN FIBERS SYNAPSE ON SAME SECONDARY NEURONS AS RECEIVE PAIN FIBERS FROM SKIN

CLINICAL ASPECTS OF PAIN

HYPERALGESIATHE THALAMIC SYNDROMEHERPES ZOSTER (SHINGLES)TIC DOULOUREUXTHE BROWN-SEQUARD

SYNDROMEHEADACHE

HYPERALGESIA

ENHANCED SENSITIVITY AROUND DAMAGED TISSUE

SENSITIZATION OF NOCICEPTORS BY SUBSTANCES RELEASED WHEN TISSUE IS DAMAGED

THE THALAMIC SYNDROME

LESION OF SOMATOSENSORY THALMUS

USUALLY A DISTORTED AND EXAGERATED SUBJECTIVE QUALITY

MAY CUT OFF PAIN TRASMISSION FROM PERIPHERY

HERPES ZOSTER (SHINGLES)

USUALLY AFFECTS THE DORSAL ROOT

ONE DERMATOME AND ONE SIDE

TIC DOULOUREUX

CHRONIC NEURALGIA OF TRIGEMINAL NERVE

SOMETIMES DUE TO INFLAMMATION (NEURITIS)

SOMETIMES TREATED SURGICALLY, BUT OFTEN RETURNS

THE BROWN-SEQUARD SYNDROME

CHARACTERISTIC PATTERN OF SENSORY LOSS DUE TO LOCALIZED DAMAGE ON ONE SIDE OF SPINE

USUALLY ACCOMPANIED BY MOTOR LOSS AS WELL

LESION ON RIGHT HALF OF SPINAL CORD

LOSS OF PAIN SENSATION ON LEFT SIDE BELOW LESION

LOSS OF TOUCH AND VIBRATION ON RIGHT SIDE BELOW LESION

LOSS OF BOTH ON RIGHT SIDE AT SAME LEVEL

NO LOSS ABOVE LESION

HEADACHE

SELDOM DUE TO BRAIN DAMAGE NO SENSORY NERVES IN BRAIN LIKE THERE

ARE IN PERIPHERY TENSION INDUCED MUSCLE TIGHTNESS SWELLING OF THE MUCOUS MEMBRANES EYE DISORDERS DILATION OF CEREBRAL BLOOD VESSELS INCREASED INTERCRANIAL PRESSURE INFLAMMATION AND SWELLING