E!!!!!’!l!.?f ~~!!I•Pain is tansmi tted. from the penphery in a code which1s translated in the centra, nervous system. Thismessage moves along a oomplex system of relaysli””;’!!’er1pherfarlee nerve end1nga reapon”lible tor painperc.ption.- Pain fibres, fast A-d~lta and slow C fibvee •c81’ry the message to the spinal cord •• Sensations are carrled to the central nervoussyst ••• through the drosal oolumn end the anterolateraltracts of the spinal cord. Gating takesplace at the level of the subatancia gblatinoaa._.Spinal asoend1ng pathways inolude· Ioligosynaptic systems like the spinotectal,spinoreticular and spinovestibular path....-;”ysT.heyform the spInothalamic tract. f.lultisynlipticsystewJ like the spinal reticu.lar corH and Lissauer’s..•h.2y a.l ao C&e 1”y impul.ses to thalaudc .nuclei.iiigher pI’ojections reach the cerebral cortex.- Downsi:ream dea ..ending coutT;)l ”,xist;Jat all levelscoming from the cortex, diencephaloll brain otem.Inhib:ltion takeEl place through activation of theendogenous opiate mechuniam._~¥.i.1•1._es--o~f’_&”’a_.i-.n--:Pain CWl be classit:ied eccor dr.ng ttl its acurce andlocalillatLm :- Visceral pain, mainly tL’an’,’mitted througb tll..,sympathetic nervous Gistam, the cazdd ac and splancbnic- Deep iiloma+.· Lc p:xll1 :l.llclud1ng pein from prolcmged~---_._---177 -different types.Disorder of the perception of pain including aHyera1gesia. cnusa1gia. central pain like neuralgiasand the thalamic sync1,.ome.- Psychological rain whioh should be exclude4and tr”!ated.The c1in:foal classification of pain include. IAcute pain such as postoperative pain.- Chronic pain such as neuralgias. phantom limb pain,rheumatic pain and the L. r-actable pain of malignantdiseases.Me:’1agement of pain·~:”:’~===r==:===.Z’l:=.•a• :(1) Medical Tentment I -----------------This inc1u”.s thfl different analgesic drugs and theiradjuv~ts :- a) MiJ n~n-addictive drugs. This includesanalgef’ cs With anti-pyretic and anti-inflammatoryRetio’ • l’he ;.:’r[ef application of these drups i8 torthe , mtrol of low intenai ty pain and disoomfort arisingfro’. certain struc tures such as headaohes, arthra1gil!lsan my·1g:l.e.s.The main example of this group of drugs• b) Narcotic analgesir’ J. These drugs cause addiotion.The b(}st example of this group is morphine. Theyare uned to relievr severe pain~ In chronio painoonditions they ar~ better avoided because of thedarger of addiction. their use should be restrlQtedto intractable pain oonditions in patients having ashort expectation ot life. Amongthese drugs arepethidine.Th~y~~e~~i~!yn~e~~~; -, ’in chrom c V8,in cc
.d:;’ti,o,ns whe:re pgtleut.e maysuffer from agii;a’f:;ioann.xiety, depression andpainful muscle ~pasms. They include tricylioantidepressants, monoamine oxidase inhibitors,tranquilizers, hypnotics and musole relaxants itneeded.(2) Regional blocks :They may be performed using local analgesic agents,which produce reversible block, to control acutepostoperative pain or as diagnostic and prognostic ,- ”. - ’- i.;~.::~.~’~Neurolytic solutions cause destruction of nerve fibres •.. .’ (:,j J,.’l : ’.’ ~id....l n ,.:;,’~: i”.~ ’.’:’;_~.J , .l dTt~y are Qsed mainl~ ~? ~~lieve ~he ipt~~?t~.~~ p~ncaused by inoperable neoplasms. These solutionsinclude :- Absolute alcohol used intrathecally for malignantped.n-Phenol used in 5 - 10% solution in glycerine •..•Chlorocresol used as 2% solution in glycerine.There are several forms of local blocks :,’, 1 - Local infiltration by injecting O.~ lignocaine ?r25% Bupivacaine into the painful tissues to treatsu~gical incisions·2 - Injection of autonomic nerves and ~~ia. Th~seare used in pain ca:l:’ried by sympa.thetic pathways,like vascular disorders of the limbs. cardiac andcancer pain. These techniques include :tllllellateganglion block’- Lumbar sympathetic block” ,I -.19 -~ ,<, ;t.::~;,:-J;,:,-:. . .;tor both acute’ amI-,chronic pain’ conditions.The techni~~e ~ncludes blocks of the ~rigeminal,aervical or brachial plexus, thoracic and lumbarnerves.4 - f.pinal blocks : Intrathecal block is .ot great valuebecause of itil speed and.,,,~~lJc;ity,in acute pain conditions.using localNlalges,ics Injections .of neurolyt’ic solutions is a valuable lIIeans6!producing pain relief specially in malignancy.~~his can be done by injectiq either:- Intrathecal absolute alcohl (1 ml)- Intrathecal phenol inj ection (5 - 7% solution).5 - Epidural injections :Temporaryetfective, p~!J.:,r~:Liefcan e.c¥rleud inpatients suffering from acute postopertive painand severe intractable pain, by inseting an epidurallatheter and controlling the pain by repeat.a top-upinjections of local anaesthe.t, ics~Bupiva,oaine is the most suitable drug used, whileneurolytic solutionare used to achieve prolonged,pain relief in intractable pain.,,) Neuros~rg1Cal procedures : ------Many neurosurgical procedUres are available toalleviate severe forms of chronic pain by interruptionof the pain conduction pathways. They inolude :- P~rcutaneous cervical cordotomy: This is useful intreating patients with inoperable conditioneccmplaining of severe intractable pain. Radiofrequencypercutaneous coagulation of the anterolateralquadraqt of the spinal cord is performed at the C 1 - 2’- 8Q ’~used for hormone dependant tumours. The trans-nasal,trans-sphenoid rout •.·.is used. At o·f.a1dose or I m1absolute alehol is injected in increments of 0.1 m1.- Destruction of the gasserian ganglion and roots :This is the treatment of choice in cases of ilrigeminalnEuralgia resisting medical treatment. This can beperformed by neurolytic inje,ptionsor better byr~dio-~requency coagulation.-(_4) Cryoanalgesia: •..._------------Freesing a nerve percutaneously for about I -2 minutes,at .~ temperature between -5 and -20 °C,using a gasexp~aion cryoprobe ca~ses p~olonged ~8vcrBib10anS:’,gesia.by:l,nterrupt,~~,P:~r.ve.cqnquQti9n~ The, b~•.c•kduration ~aries from few days to few months.(5), Electrical Neuromodulation : ---~----------------------------Thi3 techninqe is based on the ”gate control” theory,whioa advocates that stimulation 0f large peripheralnerve fibres close the spinal ga~e and thus preventspainful peripheral stimulation from gaining acoe •• tothe ascending transmission system. Endorphins arealso involved in this method of analgesia.This technique has proved to be of value in the control(6) Acupuncture analgesia: ------------------------This is based on classical chinese medici1ll8which statesthd a vital rorce er lifeenergytlowli through the bodyin confined channels calJ.,edlmeridians”. !he abnormalflow of disease and pain can be corrected by insertingDeedleaaloWl: tile liJ:lea oLtile ,concemed ••tidian.~, .8·1 -The point of insertion is caJ.led the acupuncture point.1’! r • •. IThis approach is of value in chronic musculo-skeletalpains, arthriti~ B.’1d .. aome sciatic and low baok pain.
