Page Two P H Y S I O T H E R A P Y January, 1954. International Congress Lecture The Pathology of Lower Motor Neuron Disturbances in Relation to Treatment By H . J . SE D D O N , C.M .G ., M .A ., D .M ., F.R .C.S. Director o f Studies, Institute o f Orthopaedics, University o f London, and Clinical Director o f the R oyal National Orthopaedic Hospital. WH E N a peripheral nerve has been severed the patient exhibits familiar and rem arkably constant changes. W ithin th e distribution o f the nerve there is complete m otor an d sensory loss. Percutaneous stim ulation o f the nerve shows th a t its conductivity rapidly disappears; w asting o f the affected muscles begins within a few days, fibrillation in these muscles begins o n ab o u t the eighteenth day and th e reaction o f degeneration is fully established by the twenty-first. In the nerve itself W allerian degeneration takes place, a breaking up an d disappearance o f th e axons an d their myelin sheaths. I f th e paralysis , is extensive th e lim b is likely to become oedem atous; this is due to the vasom otor paralysis, but still m ore to the paralysis o f the muscles themselves which play a n im portant p a rt in the return o f venous blood an d lym ph from the limb. The muscles show tw o striking progressive changes, shrinkage o f th eir fibres and interstitial fibrosis. But they are n o t in any peculiarly delicate state, such as th at im agined by K eith, an d do not require particularly gentle handling. Prolonged stretching is, however, harm ful and it is chiefly for the prevention o f it th a t splints o r other form s o f support are used. In the absence o f appropriate treatm ent contractures will develop and they are due to a num ber o f factors: 1. T he unopposed pull o f norm al muscles. 2. T he shortening o f th e paralysed muscles, which is a consequence o f the tendency to shrinkage o f the fibrous tissue deposited in them.. 3. C apsular' shortening on the relaxed side o f a jo in t an d corresponding capsular lengthening on the stretched side. 4. A diffuse fibrosis involving m any structures— joints, muscles, tendon sheaths and subcutaneous tissues— which is the result o f th e deposition o f collagen fibres (fibrous tissue) in the stagnant oedem a fluid o f the swollen limb. T he first an d second types o f co ntracture cannot, o f course, co-exist, an d th e second is usually due to in ­ a p p ro p riate splinting, undertaken w ith the laudable in ­ tention o f preventing th e contracture o f norm al muscle but unaccom panied by regular passive m ovem ent o f the affected part. I t is still, alas, one o f th e com m onest types o f contracture an d one o f the m ost difficult to deal with. Prevention o f contractures is the first and m ost im portant duty o f the physiotherapist, and there are three simple m ethods o f treatm ent th a t m ust invariably be applied : 1. Elevation o f the limb if the paralysis is a t all extensive. In a com plete lesion o f the brachial plexus this m ay have to be m aintained for several m o n th s; on the o th er han d in a simple ulnar paralysis there is rarely, if ever, need fo r it. I t is designed to assist in the return flow o f blood an d lym ph. 2. Passive m ovem ent o f the affected part. T his has three consequences: , (a) I t assists in the prevention o f oedem a by augm ent­ ing the return circulation. .(b) It m aintains all muscles a t their p ro p er length. (c) It prevents capsular contractures. 3. Splinting. Splints a re frequently necessary to prevent stretching o f the affected muscles and jo in t capsules and also to prevent shortening o f norm al muscles. B ut I fo r the reason th a t I have already given the splinting must not take th e form o f rigid im m obilization. Sometimes the splint m ust itself be rigid, but the possible evil consequence o f this—namely, contracture o f th e relaxed paralysed muscles—can be prevented by passi.ve movement o f the limb o u t o f th e splint twice and, if necessary, m ore times a day. A better solution, where some power is retained in the affected part, is to give th e p atient w hat C apener has called a lively splint, an apparatus with a spring o r elastic in it which allows the norm al muscles a limited but highly beneficial range o f activity. T he muscles themselves call for special attention in addition to the m aintenance o f their proper length. As was shown experimentally by G uttm ann and others and clinically by Shirley Jackson, regular galvanic stim ulation, a t least daily, m aintains muscle bulk to a rem arkable degree and, it would appear, actually prevents interstitial fibrosis. T here is no longer any doubt ab o u t the value o f this treat­ m ent in conditions where re-innervation o f the muscles may be expected. A fter division o f a nerve this re-innervation will occur only as a result o f well-executed surgical repair, but ai considerable period m ust elapse before re-innervation begins; th e new axons travel distally from the site o f suture a t the rate o f ab o u t one m illim etre a day—an inch a m onth if you wish— so it m ay be nine o r twelve m onths before any return o f voluntary pow er can be expected. This I recovery follows a fairly regular" anatom ical order, the order in which the m o to r branches a re given off by the p aren t nerve trunk. So, as recovery progresses, th e physio­ therapist is required to continue the treatm ent ap propriate fo r completely paralysed muscles in the distal distribution o f the nerve while she is starting on the re-education o f the proxim al muscles th at are beginning to show signs o f life. N o m atter how carefully a nerve has been repaired m any o f th e outgrow ing axons a t the site o f suture find their way into the w rong peripheral nerve tubes, and there is w hat we call an axonal confusion. A m otor fibre may grow dow n a sensory tube, in which case it is completely useless. It m ay grow into a m otor tube belonging to a muscle different from the one originally innervated by th a t particular axon. So we find th a t after, say, suture o f the ulnar nerve th e interossei have lost their delicate independent action, though they may act well enough together, as in the m otion o f grasping. This loss o f indepen­ dent m ovem ent is a great handicap, and the physiotherapist m ust do the best she can to restore a little independent m ovem ent by training the patient to contract the affected muscles individually. There is a strict biological limit to 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. ) January, 1954. P H Y S I O T H E R A P Y Page Three the success o f such training, but it is none th e less necessary to undertake it and at this stage occupational therapy th a t calls for fine individual movem ents o f digits is especially valuable. I now come to a second type o f nerve dam age which is very com m on but n o t perhaps quite so clearly recognized as the first, one th a t we have called axonotmesis, in which the axons o f a nerve are completely interrupted but the tubes th at contain them rem ain in continuity. I f a nerve is squeezed very hard with sm ooth forceps the axons are interrupted ju st as'c o m p le te ly as if the nerve had been cut across; a complete paralysis is produced with all the consequences th at I have ju s t described. W allerian degen­ eration in th e peripheral pa rt o f th e nerve is indistinguishable from th a t following division o f the nerve. But there is a striking difference at the site o f injury. T he tubes con­ taining the nerve fibres are incredibly tough and will resist an immense am ount o f compression. Thus, when the compressing force has been removed the continuity o f the nerve is m aintained by these little tubes an d they perm it the axons to grow down them again along their old paths. ^Surgical repair is unnecessary because regeneration is ^spontaneous. Furtherm ore, there is no axonal confusion a t the site o f injury, and as the axons grow down they travel in their proper channels tow ards their appropriate destinations. Thus, although the im m ediate effects o f the injury are indistinguishable from those following division o f the nerve the ultim ate recovery is very good indeed because there is a retu rn o f independent movem ent in the affected muscles and, sometimes equally im portant, o f full sensibility in the previously denervated skin. There is no need, therefore, for th e physiotherapist to bother so much ab o u t treatm ent designed to restore independent muscle action; it will return anyway. This is the sort o f injury th a t comm only follows a fracture o f the hum erus involving the radial nerve. There is a third and m uch m ore benign type o f damage which we call neurapraxia. Y ou are fam iliar with the comparatively transient paralysis th a t may follow the application o f a tourniquet or the use o f crutches th at press too hard in the axilla. It is predom inantly m otor, there is little muscle wasting, th e nerves retain their excita­ bility below the level o f injury an d the muscles show no reaction o f degeneration. The whole picture suggests a lesion in which the continuity o f the axons is preserved, and we now know th a t the essential dam age is loss o f the myelin sheaths. These regenerate with com parative rapidity and the paralysis clears up within a m atter o f days or k week s. Furtherm ore, since there is no W allerian degen­ e r a t i o n and, therefore, no outgrow ing o f axons, there is no progressive rqarch o f recovery from the centre o t the periphery. Recovery usually occurs simultaneously thro u g h ­ out the distribution o f th e nerve. H ere is a sum m ary o f the physiotherapeutic measures necessary in the three basic types o f nerve injury, and it might be described as the ABC o f the treatm ent o f lower m otor neuron disorders. Treatment Nerve Axonotmesis Neurapraxia Divided Prevention of oedema Yes Yes N o Passive movements Yes Yes Yes Splinting Yes Yes N o Electro-therapy Yes Yes N o Muscle Re-education Yes N o N o I would like now to consider poliomyelitis, which is the comm onest and m ost im portant o f all spinal-cord disorders affecting the lower m otor neuron. T he essential dam age is in th e anterior h o rn cells, and it may range from a transient suspension o f function to com plete and irre­ parable destruction. It is well know n th a t some parts o f th e cord are m ore vulnerable th an others. W e do not know all the reasons fo r this, though it appears th at the virus itself has a particular affinity for anterior horn cells in certain regions. H ere you see the distribution o f lesions in cases seen in the M alta epidemic an d it is fairly characteristic W hat is more, certain muscles are more vulnerable than others. In the lum bo-sacral region, which is the p art most susceptible to damage, the tibialis anterior is the muscle m ost likely to suffer perm anent paralysis. M y colleague, Sharrard, has shown th a t this is due to the shortness o f the colum n o f anterior horn cells supplying i t ; other muscles with their anterior horn cells in th e sam e part o f the cord have longer cell stations. They are less likely to be com ­ pletely knocked o u t by a localized focus o f infection which we can liken in its effects to the explosion o f a small bom b. A cottage will be completely blotted o u t; a whole terrace o f houses will not. O f course, if th e dam age is over­ whelming, all cell stations, long and short alike, are com ­ pletely destroyed. Thus we find that if at the end o f six to eight weeks— during which active contraction o f the affected muscles has been attem pted—there is still complete paralysis o f all muscles in one segment o f a limb, say below the knee, the prognosis is very bad: no worthwhile recovery can be expected. The peripheral consequences o f the dam age to the anterior h o rn cells tak e two forms. I f all the anterior horn cells in, say, the lum bo-sacral region have been destroyed there is total paralysis o f the lower limbs indistinguishable from th a t produced by section of all the nerve roots, except th at sensibility is preserved. The m otor axons degenerate, their conductivity is lost, the muscles fibrillate, they show the reaction o f degeneration, they waste rapidly and become fibrotic. There is also a tendency to oedema, but not, perhaps, quite so great as after a nerve injury because there is no vasom otor paralysis. C ontractures, too, are prone to develop, though if there are no surviving muscles there can be no deform ity d u e to unopposed muscle action. O n th e other hand, where the anterior horn cells have been dam aged but are still capable o f recovery there is no axonal degeneration. Electrical excitability o f th e nerves is retained and is a rem arkably accurate indication o f the prospect o f recovery. So far as we know there is no interm ediate state in which axonal degeneration occurs and is followed by axonal regeneration, as after the repair o f a divided nerve. The tem poral pattern o f recovery is m uch the sam e in all muscles, irrespective o f their distance from the spinal cord. Furtherm ore, m ost o f the recovery occurs fairly early. These tw o facts are powerful evidence against the occurrence o f axonal regeneration, fo r if it were significant proxim al muscles w ould recover sooner th an the distal, and th e whole process would be much slower than it actually .is. F ro m th e thera­ peutic point o f view this is im portant. I f a muscle is de­ nervated it will rem ain so,' and therefore m aintenance o f its volum e by galvanic treatm ent is a waste o f time. If a muscle, o r part o f it, is going to recover, its axonal connections are intact and therefore galvanism is u n ­ necessary. T his form o f treatm ent has no place in the m anagem ent o f poliomyelitis. F rom this rather streamlined account o f the pathology o f poliomyelitis you might conclude that recovery is solely dependent on the extent and intensity o f the anterior horn cell damage, and th a t we can influence it but little. So far as the essential lesion is concerned I believe th at this is the case, but there are, nevertheless, many useful and necessary things to be done. Poliomyelitis is the most ferocious o f all deforming diseases. It is more crippling th an rheum atoid arthritis o r than jo in t tuberculosis; but fortunately we can do a great deal to prevent this evil consequence— indeed it is our first duty. The deformities produced by peripheral nerve injuries are trivial com pared w ith those caused by poliomyelitis, simply because a nerve 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. ) Page Four P H Y S I O T H E R A P Y January, 1954. injury affects a t m ost one limb whereas poliomyelitis can affect the whole body and produce a vicious and wide­ spread upset o f muscle balance. The measures that I have described to you for the prevention o f contractures after nerve injuries are strictly applicable in poliomyelitis and for the very sam e reasons. 1. The paralysed p a rt needs to be elevated in the early days in order to prevent oedema, and the fibrosis and stiffness resulting from it. This applies chiefly to the upper lim b: if th e lower is affected the patient will be (or should be) recum bent for a num ber o f weeks, and this suffices to prevent oedema. A t th is' po in t we may conveniently rem ind ourselves th at the only reason for using massage in the treatm ent o f poliomyelitis is a poor peripheral circulation. 2. Paralysed and unaffected muscles alike must be m aintained a t their norm al length by regular passive move­ m ent. Lengthening o f paralysed muscles an d stretching o r shortening o f jo in t capsules must be prevented where necessary by the application o f splints, and here again the ‘lively’ splints devised by Capener are m ost valuable. In the adult simple support in bed is often all th at is neces­ sary; but a wriggling and unruly child requires splints if we are to avoid the contractures th a t come on with such astonishing rapidity in the early days o f the disease and th a t are capable, a t any rate in the child, o f producing the m ost grotesque deform ation. Now we com e to the much m ore debatable and, I am sure, unsettled question o f muscle re-education. T he difficulty is to know when to begin. There are three kinds o f people treating poliomyelitis. T here are the fixers, those who believe in putting on splints an d keeping the patient very, very quiet. There are the jloggers who get patients out o f bed early and chase them round the physiotherapy departm ent. • Then there are the good people, like myself, who are called festina-lentists who get the patients going very slowly. We do not really, know which o f the three is right about this. T o come to a con­ clusion, we require som e knowledge, o f w hat is happening in the spinal cord. H ow long is it before those cells that are going to recover are capable o f transm itting the impulses set up by the p atien t’s efforts to move th e paralysed part? Is it possible to fatigue these convalescent cells by pushing them to o h ard ? R itchie Russell has shown th a t fatigue is an im portant factor in aggravating the severity and extent o f cell damage during th e stage o f invasion. Is fatigue harm ful during the phase o f recovery? As I see it there are four ways o f approaching this question: 1. I t is possible to follow the actual histological changes in the anterior horn cells in post-m ortem material obtained from patients dying at different periods after the onset o f the disease. We are assured by B odian that the whole cycle o f changes in the cells th a t have survived is over five weeks after the onset, and so it might be assumed th a t treatm ent could safely be started a t this period. On the o ther hand, E inarson has found appearances suggesting th a t anterior ho rn cells are still abnorm al, yet perhaps capable o f recovery, as late as eight m onths after the onset o f thp disease. W hat are we to d o ? My own feeling is that we ought not to drive purely histological evidence too far. Here, for example, are some brain cells from a patient who died o f cerebral anoxia. She was completely unconscious and paralysed until her death three weeks later; yet although these cells had stopped working they look comparatively respectable. My own inclination is to err on the side o f conservatism. I am encouraged in this attitude by the fact th a t the cerebro-spinal fluid some­ times remains abnorm al for six weeks o r.m o re after the onset o f the disease, an indication th a t the inflam matory process in the spinal cord that follows the short sharp phase when the virus is active persists for some time. Furtherm ore, my colleague, Brooks, has shown th at the electrical reactions o f affected muscles do not settle down to a perm anent state until about four m onths after the onset: during this period the condition o f a proportion of the affected anterior horn cells is unstable. ^ Lastly, we have the evidence from treatm ent. T myself have found th a t early vigorous exercise o f paretic muscles sometimes causes them to become weaker, and my„experience is not unique. So until we know m ore ab o u t this awkward aspect o f poliomyelitis it is wise to m ake haste slowly and to build up exercises gradually, lest by going too fast we overburden neurom uscular units th at may barely have escaped dissolution. CHANGE OF ADDRESSES Mrs. M. Levy, the Journal T reasurer, has moved, to 105, Acacia Road, Blackheath, Johannesburg.- Mrs. D . Baumann has moved to 53/54, Colosseum Buildings, M arket Square, E ast L ondon. Mrs. G . L. H. D iering has moved to 8, Pine Street, Plantation, Bbksburg. ■ ( Miss D . G ibbon’s address is c /o S tandard B ank of S.A., B loem fontein. Mrs. J. K rogh’s address is c /o C apt. J. K rogh, M ilitary Camp, East London. Mrs. S. Lewis (nee Robinson), is now at P.O. Box 37, Benoni. Mrs. J. Medalie has moved to 15, Cyril Crescent, Cyrildene, Johannesburg. Mrs. E. Metz has returned from Israel to 6, Delville R oad, Germiston. C apt. F. G. Ogg is now at P.O. Southbroom , South Coast, N atal. M r. R. Parker’s address is c /o M rs. R obinson, 87, Kritzinger Avenue, Brakpan. Mrs. M. S. Robertson has moved to 455, 1st Avenue, Crown Deep, Crown Mines. 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. )