JUNE 1979 P H Y S I O T H E R A P Y 39 White, J. C. and Sweet, W. H . (1955): Pain. Its m echan­ isms and neurosurgical control. Springfield: C. C. Thom as. Wierzinga, H . (1975): V erzoening m et h et Lijden? Baarn: Ten H ave. W ittgenstein, L. (1963): P hilosophical Investigations. O xford: Blackwell. W olff, H. G. (ed.) (1943): Pain. Baltim ore: W illiams and Wilkens. W olff, H . G . and H ard y , J. D. (1947): On the nature o f pain. Physiological R eview , 27, 167- 198. W olff, H . G. a n d W olf, S. (1958): Pain. Blackwell Scientific Publication. Oxford. W ood, E. (1962): A study of pleasure and pain. Theos publishing H ouse. W ordsw orth, J. C. (1954): Pain and other Problem s. L ondon: Allen an d U nwin. Zborow ski, M. (1969): People in Pain. San Francisco: Jossey Bass. Z em ach, E. M. (1971): Pains and Pain-feelings. R atio, 13 N r. 2, p p 150- 157. T H E NATURE OF A CU TE PAIN P. A. FO STE R * As an anaesthetist I w ould say th a t you should not a ssu m e th a t the anaesthetist is necessarily a n expert on acute pain sim ply because this speciality controls — usually successfully — p a rt o f th e pain caused by th e surgeor): ’T h e reaso n is th a t th e very routine n a tu re of the surgical assault encourages a narro w ap p ro ach to the handling of pain relief w hich often, unfortunately, does n o t extend m uch beyond th e operating theatre. T he treatm en t of postoperative pain in fact often leaves m uch to be desired. T o avoid th e an aesth etist’s close-up view o f pain, 1 w ould like to pain t fo r you a b ro ad er picture including som e perspective and even a horizon. T o begin som ew here in the fo reg ro u n d , let us first state th a t th e anim al body stays in contact w ith and reacts to its environm ent by circuits in th e nervous system we call reflex arcs. T hese a re b u ilt according to the simple p la n o f — R E C E P T O R SE N S O R Y N E R V E C E N ­ T R A L L Y L O C A T E D SY N A PSE M O T O R N E R V E ->■ E F F E C T O R O R G A N . P ain is p a rt o f a com plex e lab o ratio n o n this them e w hereby an acutely received stim ulus th a t exceeds a certain threshold m ust be perceived to be so unpleasant th a t im m ediate avoidance is dem anded. A t this p o in t may I em phasise th a t A cute P ain is an essential an d valuable indicator fo r th e body, which we should only ignore u n d er special circum stances — .such as during surgery. ) C hronic pain does no t necessarily play such a valuable Jxunction. . . T h e first step in th e consideration of acute p ain is to look a t the pathw ays in th e pain m echanism . T his not only helps to u n derstand th e n a tu re o f pain b u t gives an insight in to how to tre a t it. T o re-em phasize the p oint already m ade, pain, in all its aspects, is an elab o ratio n of th e basic reflex arc w hich m ay be divided into — D A T A A C Q U IS IT IO N D A T A P R O C E S S IN G -► E X E C U T IV E M O T O R P R O G R A M M IN G . W e can look at these th ree phases separately an d then see how they m ay interact. T h ere are a few o f th e sim ple facts ab o u t pain th a t need to be clearly understood. T h ere are tw o types of pain — a “fast p a in ” , som e­ times called th e “first p a in ” th a t arises fro m the skin, localizes the site o f injury, leads to the initial w ith­ draw al reflex and does not outlast the stim ulus. I t is conducted along th e A a group o f fine m yelinated * P rofessor an d H ead, D e p a rtm e n t o f A naesthesia, U niversity of Stellenbosch an d T ygerberg H ospital, t P ap er read a t P ain Sym posium , preceding 13th N atio n al C ouncil M eeting 23 - 27 A p ril 1979. fibres, an d is appreciated in th e cerebral cortex afte r passage in th e spinothalam ic tracts. F ollow ing this comes th e “slow p a in ” or “ real p a in ” , the persistent pain th a t follow s in ju ry an d leads to a different so rt of reflex response — th e guarding, rigidity o r spasm th a t protects an injured part. T h e p a th ­ w ay here is along unm yelinated fibres w hich are^ slow conductors, hence the descriptive nam e. A p preciation is in subcortical b rain areas subserved by the spinoreticulo- diencephalic tracts. “R eal p ain ” pathw ays arise fro m skin a n d deeper tissue, an d autonom ic pain fibres m ingle w ith th e som atic fibre input w hich makes it possible to feel pain fro m deep organs referred to the surface of th e body. T he th ird spatial dim ension of pain — d ep th — is often not as accu rate as th e surface location. Perhaps the m ost im p o rtan t reason fo r th e distinction betw een th e tw o types o f pain is because m orphine is only effective in slow p ain pathw ays. T hus m orphine on its own cannot be an effective anaesthetic, since it does not influence “fast p a in ” , but only pain fro m injury alread y sustained. P ain is p roduced by fo u r sorts o f stim uli— (a) M echanical injury either to nerves o r th e ir endings; (b) T h e therm al extrem es of h eat an d cold; (c) E lectrical stim uli w hich directly fire sensory nerves an d can produce pain w ithout m uch injury; (d) C hem ical pain, p roduced by m any substance? eith er applied to tissue o r liberated in tissue. The first three are d irect effects on o rd in ary nerve fibres or nerve endings, th ere being no specific pain receptors. Pain is th e in terp re tatio n o f the intensity and d u ratio n o f a w ide variety of stim uli carried along ordinary nerves. . . C hem ical pain is significant because it is also an indirectly produced p ain secondary to tissue damage. It m ay be caused by the potassium liberated fro m injured cells, an d by acid m etabolic substances, o r by the horm ones o f injury an d inflam m ation. Substances such as histam ine, bradykinins an d prostaglandins a re fo r us extrem ely im p o rtan t in acute pain because we have the chem ical antagonists to use against them . A spirin is a specific brad y k in in antagonist an d a n in h ib ito r of prostaglandin synthesis. T he recent in troduction o f in tra ­ venous aspirin into South A frica is thus a n exciting new a d d itio n to our arm am en tariu m against pain. So also, one should u nd erstan d th a t oxygen lack, inade­ quate b lo o d supply, venous congestion, swelling, are causes of pain th a t are treatab le by simple physical means such as massage, positioning, m obilization, cold or an oxygen mask. Surely this is how pain should be ideally treated — at its source w ith physical m eans and R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) 40 specific drugs, ra th e r th an centrally w ith shotgun blasts from anaesthetists, m orphine-like drugs and the like. O ver one aspect there is some confusion. Pain per­ ception thresholds of nerves vary very little in people. Pain tolerance levels differ greatly betw een people and in the sam e person fro m tim e to tim e, b u t this is v ariatio n in interpretation or processing, not in the feeling o r acquisition. PR O C E SS IN G T H E IN F O R M A T IO N T o und erstan d the difference betw een perception and tolerance, one m ust look to see how the inform ation is processed objectively and subjectively. Pain in fo rm atio n , a fte r being received and sorted when it enters the spinal cord, ascends to the b rain along tw o m ain routes fo r processing — the first, one m ight say, fo r objective assessment, th e second fo r subjective assessm ent. A lready in this first sorting station in the spinal c o rd '1 there is th e blending of inputs fro m the som atic an d visceral structures th a t can lead to referred pain a n d som e of the a b n o rm al pain syn­ drom es. F o r the objective appreciation of the p ainful stim ulus, one m ust d etect it accu rately : W here is it? H ow long did it la st? W h at is the context? T h e subjective pathw ay — the spino-reticular pathw ay w ith its m odulating circuits — is ap p aren tly m ore co n ­ cerned w ith allotting significance to the stim ulus as som ething h arm ful and to be avoided: A rousal of b ra in activity fo r assessm ent and effective response. Setting a n d detecting the th reshold at which “ p ain ” becomes p ainful In terp retin g the significance of the pain. D eciding w hat to do. It is suggested th a t there m ay be c o n tro l m echanism s interacting betw een th e tw o pathw ays. O ne of these runs from the brain back along the real pain pathw ay to a “g ate” , proposed by M elzack an d Wall in 1965, w hich is present a t the p oint o f entry o f the sensory nerve into the spinal cord in the sub stantia gelatinosa. T here are o th er m oderating pathw ays in the m id-brain itself th a t do not descend to spinal cord level. These are negative feedback o r inhibitory path vays o f a type com m on in th e organization of the central nervous system, which can reduce sensory input fo r various good reasons, such as greater priorities, directed atten ­ tion, strong suggestion. We know w hat chem ical tran s­ m itters are involved, and can mim ic them with m orphine­ like drugs. T h e inhibition can be selective,', so th at a person m ay not react to severe threatening injury, b u t com plain a b o u t non-significant and trivial pain. T hus one sees inh ib itio n and disinhibition on the one hand o f input, and on the o th er hand o f interpretation. F in ally there is th e appreciation of m en tal p ain : danger, guilt, fear, grief, loss and m em ory, conceived ra th e r th a n felt. Often the responses are sim ilar. U n d o u b ted ly pre-existing m ental p ain strongly influ­ ences the later perception o f physical pain. A most significant brain region concerned w ith p ain apprecia­ tion is the lim bic area in w hich also em otion is a p p re ­ ciated. T H E R E SPO N S E In looking at the responses to a stim ulus th a t has been judged painful, the m o to r side o f the reflex a rc is found to have m any facets: V ocalization: the w arning call, the cry o f subm ission o r fear. V iolent m uscular m ovem ent, or the inhibition of m ovem ent. Secretion o f adrenaline and from o th er glands. Changes in the b lo o d ’s biochem istry. T h e em otional response. I suppose it is a philosophical p o in t as to w hether the existing em otional state influences the significance th a t we read in pain, or w hether it is the bringing together of th e tw o judgem ents on the context of the pain and its significance as a th reat th at directs the p attern of the em otional response. C ertainly the emo­ tio n al response generated by m ental pain o r indifference determ ines how we feel physical pain. P robably this is o f no g reat im p o rtan ce here as long as we rem ember the one m ost significant point, th at the b rain area for pain appreciation is inextricably interm ingled w ith em o­ tion. Because em otional response is the basis of the richness and com plexity o f th e hum an experience pain becom es by its association, the m ost com plex symptom we have to treat. M uch of this com plexity lies in the a p p ro a c h to chronic pain and is outside the scope of this discussion, b u t one m ust never fo rg et: th a t apprehension of pain m akes its appreciation more intense; th a t frequently apprehension is based on fear o f an unknow n and undefined experience, which we can reduce; th a t strong em otion o r m otivation can also reductl the significance and the appreciation of pain. ™ All o u r non-specific centrally acting pain relieving drugs are accom panied in th e ir effects by psychical responses as well. Such psychical effects are usually pleasan t — w ith these drugs addiction is a problem . L ooking forw ard to pain, either positively o r nega­ tively, can influence w hat one feels. So does looking back on the p ast experience. I t is p a rt of the cultural heritage o f m ost civilizations to use pain to m ould personalities, to establish beh av io u r patterns, to reinforce codes of m orality, to discipline com m unities to con­ fo rm ity to a rb itra ry standards. H ow often is it the rem em brance o f unpleasant things past th a t make people toe the line. If the significance of pain is so bound up w ith the fu tu re and the past, m aybe we, the anaesthetists, have com e u pon a new app ro ach to pain control. Tw o im­ p o rta n t properties of m any of o u r new and p o te n t drugs a re those of strong am nesia coupled w ith tranquilliza- tion. T hese drugs are beginning to replace th e classical anaesthetic drugs w hich have ad d itio n al widespread effects in the body. D o o u r new techniques w ith o u r new drugs perhaps expose the p atien t to the exquisite reality o f present pain whilst a t the sam e tim e elim inating any anxiety fo r w hat will happen in the next m om ent of time, and giving a calm forgetfulness of the pai ) th a t has just p assed? Will this becom e the new f o n n of successful anaesthesia — living only in an excruciating present? w hich one can never rem em ber? Is pain a fe a r th at w hat has happened will again happen? H ow will we ever be able to find out? T R E A T IN G A C U T E P A IN It m ust be ap p aren t from looking at acute pain m echanism s th a t there is a m ultitude o f treatm ents. A purely anatom ical ap p ro ach will suggest various levels o f attack from skin receptor up to the brain where the understanding of m echanism s is n o t so clear. O n an o th er ap p ro ach level there are exciting possibilities to explore in controlling thresholds of pain, attitudes and our in terp re tatio n of the significance. We m ay m odify the em otional response. W e m ay also m odify the m otor response to pain and find th a t it influences o u r per­ ception. T h e Sensory N erve T his has been blocked fo r m any years by locally applied cold an d later by the local anaesthetics, either a t the nerve ending o r along the nerve fibres- as they run to th e spinal cord. F o r as long, b u t on a less well JUNIE 1979F I S I O T E R A P I E R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) understood basis, we have blocked the tissue horm ones with aspirin. N ow th a t we have so m any m ore drugs to control th e release o r effects of tissue horm ones we can achieve considerable pain relief by controlling the tissue response to trau m a — swelling, inflam m ation and the liberation of chem icals fro m the dam aged cell. In o u r age of burgeoning pharm acology we som e­ times overlook th e value of treatm ents th a t restore norm al function to an area of the body. Ischaem ia causes pain; is th ere adequate oxygen supply o r nu trien t supply to the injured p art? D istu rb ed function in one area m ay disturb an o th er area to cause pain. T his is a very large subject and in large m easure it is w hat physiotherapy is about. The Spinal Cord M any of the m ost effective nerve blocks available to us are on the spinal cord a fte r the first reception station of pain inform ation. T hese spinal and ex trad u ral blocks xthat we do offer an o th e r possibility of blocking different itypes of nerves so th a t fast pain m ay be separated from slow pain and m uscle pow er can be unaffected w hile we produce graded sensory block. It is valuable to be able to do this in the investigation of unusual pain syn­ drom es, and to separate autonom ic pain from som atic ^ A u to n o m ic a lly active drugs are frequently overlooked in pain treatm ent. If you can relieve the spasm of an artery in m igraine, o r of the gut in the sum m er fruit season o r of the uterus during m enstruation, you relieve acute pain integrated at spinal cord level. O th er drugs reach th e spinal co rd in th e blood stream ; these the m orphine-like drugs are tcch y the m ost im portant. H ow ever, w ith new u nderstanding of the synaptic transm itters involved in pain pathw ays in the spinal cord, new drugs will w ithout d o u b t be developed. JUNE 1979 The Brain We have drugs th a t influence the objective response b u t do not serve as good analgesics, ra th e r producing sleep, by acting a p p aren tly only on th e cerebral cortex. M any of the drugs used in psychiatry have a place in treating pain which is not unexpected if you think 41 of m uch m ental disease as uncontrolled m ental pain. T h e e u p h o rian t drugs such as cocaine, benzedrine and m ethedrine, w hich we are not allowed to use, have p ro fo u n d effects on pain perception, making it less im portant, m ore bearable. A ntidepressant drugs likewise have an established place in treating chronic pain; un fo rtu n ately m ost are too slow acting to be of use w ith acute pain. If one looks fo r a fast acting antidepressant drug one comes back to m orphine w hich has been used from time im m em orial fo r this purpose. A m nesic drugs, whilst they m ay not ap p ear from the p a tie n t’s response to bring pain relief, are used never­ theless. “T w ilight sleep” with scopolam ine fo r “painless ch ild b irth ” is a n exam ple. W h at should be m ore fully explored is the use of com binations of drugs to suit individuals. W here m o r­ phine is insufficient we frequently com bine it with tranquillizers (diazepam , lorazepam , droperidol) o r a n ti­ depressants such as chlorprom azine and achieve a better effect. Still b etter is to com bine such a com bination w ith one of the peripherally acting drugs, such as in tra ­ venous aspirin. A naesthetics p robably act in a m orphine-like way and also affect fast pain perception by producing sleep. The Response H ow m uch does th e adrenaline secretion, o r the spasm of injured m uscle influence pain p ercep tio n . C ertain ly b o th are pow erful a ro u sal m echanism s of the reticu lar system which is associated with real pain p e r­ ception. W hilst n eith er curare n o r beta adrenergic blocking drugs are regarded as analgesics, they are used in drug com binations w hich m akes it look as it they m ight have analgesic effects. A naesthetists don t o ften think a b o u t this. . . Surely the greatest e rro r we m ake in treating pain is to believe th a t a single ap p ro ach m ust be effective. A nd the second e rro r arises fro m o u r inability to m easure pain in som eone else so th a t we d e c e iv e ourselves th at o u r treatm en t som etim es w orks b etter than it in rac d °If we regard pain as a com plex response w ith p a th ­ ways at all levels fro m the individual cell to the most highly integrated m ental function, then we may better control it. P H Y S I O T H E R A P Y T H E PSYCHOLOGY OF PAINf A. D. M U L L E R * M.A. (U .P.) D .L it. et. al. (A.M.S.T.) IN T R O D U C T I O N A fter all th e in fo rm a tio n you have already received this m orning it w ould seem unnecessary, perhaps even superfluous to add anything else at all, and seeing th at I am painfully aw are o f the fact th a t I will not be forgiven if I just reiterate w hat was said, very elo- quently, by previo us speakers, I m ust im m ediately d e c la re ’m y interests in this m atter. I am p articip atin g as a hum an scientist an d as such I think th a t I represent a certain perspective which m ay com plem ent w hat was already given to you, * P rofessor of In d u strial Psychology, U niversity o f the W estern Cape. V f P aper read at Pain Sym posium , preceding 13th N a tio n a l C ouncil M eeting 23 - 27 A pril 1979. in th a t way co n trib u tin g tow ards a fuller understanding o f th e vexing problem s surrounding he pain p h en o ­ m enon. As a hum an scientist, a psychologist in my case, I hold certain views w hich m ay differ in certain respects from those already given to you; no t in any way diam etrically opposed, perhaps only certain accents will be placed on different aspects. THE IM PORTANCE OF THE U N IT Y OF A PER SO N ’S EXISTENCE A lthough it is factually so th a t a h u m an being can be described in term s o f body, m ind, o r person lang­ uage as Prof. D egenaar in his excellent paper ex­ pounded, this introduces to m y way o f thinking a th re a t to the full understanding of the unity of a person’s existence n o t as a final product of all the separate approaches but as a starting point. Some protagonist o f th e sam e p oint o f view I hold, once R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )