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TREATMENT OF LUMBARINTERVERTEBRAL DISC PROLAPSE

By VALENTINE LOGUE, M.B., B.S., M.R.C.P., F.R.C.S.Neurological Surgeon to St. George's Hospital and Royal National Orthopaedic Hospital.

It is now 18 years since the prolapse of a lumbarintervertebral disc came to be recognized as thecommon pathological cause of sciatica, andalthough through the intervening years the clinicalfeatures of the condition have become well knownand the diagnosis a commonplace, the treatmenthas tended to remain a controversial subject.Recently, however, several detailed follow-upstudies of large numbers of patients have beenpublished which illustrate the results of both sur-gical and conservative treatment, so that it is nowpossible to draw accurate conclusions regardingthe long-term merits of any particular line oftherapy and to lay down general rules for themanagement of the individual case. These rulescan, of course, serve only as rough guides, for thetreatment of lumbar intervertebral disc prolapseis almost entirely the treatment of pain, and theemotional reaction of the individual patient to thepain he is experiencing will have a considerableinfluence on the management of the condition, aswell as social and economic factors such as thelength of time a patient can remain off work andthe type of work to which he must return.Another point which must be borne in mind is

that a complete relief of symptoms either by con-servative or operative methods cannot be offeredto the patient, because the basic pathological con-dition is essentially that of degeneration and dis-organization of an intervertebral joint, of whichthe sciatica is merely a chance complication. Sur-gical treatment in particular tends further to dis-rupt the joint and although remarkable efforts toheal, and compensate for it, may be made bynature, restoration to normal is not possible andsome symptoms not infrequently remain.

In fact it is a matter for some surprise that theresults of treatment can be as good as they are whenone considers the sequelae of disc prolapse (Fig. i);those of a narrowed disc space, sclerosis of theadjacent vertebral surfaces with spur formation andmal-alignment of the posterior intervertebral

joints; to these must be added the changes whichare often present in the affected nerve root con-sisting of distortion and thickening of the rootowing to intrinsic fibrosis from tension andischaemia, and adhesions to the damaged disc.

Fie. i.-X-ray of the lumbar spine of a patient withsciatica, who had been treated conservatively, toshow the late results of disc degeneration. TheL 4/5 disc space is narrowed and there is spur for-mation from the bodies of the adjacent vertebrae.The spine shows slight angulation forwards at thislevel, which, combined with the approximation ofthe vertebrae, must disturb the alignment of theposterior intervertebral joints.

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May 1953 LOGUE: Treatment of Lumbar Intervertebral Disc Prolapse 235

Types of PainThe symptoms of prolapsed lumbar inter-

vertebral disc are predominantly those of pain,which may be felt either in the lower part of theback or in the leg or in both sites together. It isnow generally accepted that sciatic pain (and an-terior crural pain in higher disc lesions) is due todirect impingement of a prolapse on a nerve rootand not to ' referred' pain from disorganizedjoints or subluxated vertebrae. Why tension ona root in its dural sheath in this situation shouldproduce pain, whereas similar stimulation of aperipheral nerve merely produces paraesthesiae, isnot accurately known, but the fact that the nerveroot is exquisitely painful can easily be confirmedat operation under local analgesia.

If however, a prolapse does not happen to be soanatomically situated as to come in contact with anerve root it can give rise solely to low back pain.The sites where this can occur are: (i) In the mid-line of any of the five lumbar discs (until the pro-lapse reaches such a size as to extend laterally toimpinge on a nerve root); (ii) Laterally from thefirst, second or third lumbar discs, for at this highlevel the nerve roots arise just below the discitself and are not involved as a rule except by thelarge protrusions.

In order to explain the cause of the back paincertain anatomical and physiological features ofthe intervertebral disc require brief mention.The Nerve Supply of the Intervertebral DiscThe only parts of the intervertebral disc in

which nerve fibres, probably subserving pain,have been demonstrated are the annulus fibrosusand the posterior longitudinal ligament (whichshould be regarded as part of the disc covering).These fibres arise from a recurrent branch (Fig. z)which is given off just beyond the ganglion andreturns through the intervertebral foramen to rundown the spinal canal and supply the ligaments ofthe disc two segments below the nerve root fromwhich it arose. At operation under local analgesia,pressure on the annulus and posterior ligament willproduce the same back pain of which the patientcomplains, whereas the nucleus pulposus and thecartilaginous plates applied to the upper and lowersurfaces of the disc are insensitive. It would seemthat the back pain must have its origin in theposterior longitudinal ligament and annulusfibrosus.The nucleus pulposus is mainly composed of

water and therefore behaves as a liquid and, beingvirtually incompressible, performs its shock-absorber task by transmitting the considerableforces applied to it equally in all directions to theenclosing multi-layered annulus fibrosus which isthe elastic structure of the disc. Degeneration or

premature senescence of the nucleus pulposus andannulus fibrosus is probably an intermittentlyprogressive affair (except in certain massive centralprotrusions) and only a circumscribed part of thenucleus softens at one time, tending at the in-stigation of trauma to be detached from the re-mainder of the nucleus and squeezed through aweakened area of annulus, thus coming to lieunder the posterior longitudinal ligament, stretch-ing it and its contained nerve fibres and so givingrise to low back pain.Fate of the Prolapse

If the patient with back pain or sciatica is nowtreated by rest in bed or immobilization of thespine in a plaster jacket, it will frequently befound that the symptoms improve or even dis-appear completely. He may, if fortunate, thenhave no symptoms for the rest of his life, orfurther attacks may occur at shorter or longerintervals and the question arises as to why thepain gets better and what happens to the prolapse.Two observations have some bearing on this.Firstly, it has been shown that in patients treatedby bed-rest, although the pain may clear upentirely and the spinal movements return tonormal, the prolapse as revealed by myelographydecreases only slightly in size. Secondly, it some-

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FIG. 2.-Semi-diagrammatic drawing to illustrate thecourse and distribution of the recurrent (sinu-vertebral) nerve.

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POSTGRADUATE MEDICAL JOURNAL

times happens when operating on a patient witha recent disc prolapse and who has had sciaticasometime previously in the opposite leg, that ifthis side of the disc is exposed, a hard prolapse,often of considerable size, will be seen. The nerveroot may show marked kinking around it, butdespite this it apparently functions normally andcertainly painlessly. It seems clear, therefore, thatwith a relief of symptoms the prolapse does notchange greatly in size and certainly does not ' re-duce itself' back within the disc space, whichconfirms the obvious theoretical objections to sucha process taking place.Although the main bulk of the prolapse remains

there is some slight shrinkage in size and thisshrinkage is due partly to reduction of tension onthe disc and prolapse, as a result of recumbencyand immobilization of the spine, and partly to theprocess of desiccation (the nuclear material iscomposed of 80 per cent. of water), and this seemsall that is necessary to relax the tension on theposterior longitudinal ligament and so relieve theback pain. If the prolapse happens to be incontact with a nerve root producing sciatica, theslight reduction in size permits the nerve to slipoff the summit of the protrusion or else gives ittime to stretch and so adapt itself to the sub-jacent prominence. This ability of the nerve rootto stretch has been confirmed experimentally incats.

In addition to the slight changes in size of theprolapse there is also an attempt at healing of thetorn fibres of the annulus fibrosus and posteriorlongitudinal ligament, but this plays little part incontaining the protrusion for, as mentioned earlier,the size of the prolapse is predetermined by theextent of the degenerated area of nucleus and therelief of pain is due to adaptation of the localsensitive structures to the tension. However, itmay happen at a variable time later that anotherportion of the nucleus degenerates and becomessoft enough to be squeezed through the weakenedarea in the annulus, so producing a sudden in-crease in size of the prolapse and stretching of theposterior ligament or the nerve root, and a furtherattack of back pain or sciatica.The reason why all cases do not clear up and

some patients are left with persistent pain despiteadequate bed rest (in fact those cases that come tosurgery) is not clear, but is probably bound upwith such factors as a steady progressive de-generation of the nucleus and continuous ex-trusion of material and enlargement of the prolapse,or the fact that the initial protrusion is too largefor the sensitive ligaments to adapt themselves toit. Jn the case of sciatic pain additional factorsare concerned, i.e. the shape of the prolapse andthe relationship of the nerve root to it, so that the

root may be unable to slip off the summit. Inother cases the nerve may be fixed to the prolapseby the formation of adhesions.

TreatmentIt has been known since ancient times that bed

rest will frequently cure lumbago or sciatica, andsome recent surveys of patients treated conserva-tively reveal that about four out of five patientswith sciatica, and an even higher proportion withlumbago, will get partially or completely betterwith non-operative treatment, some permanently,some to experience further attacks months oryears later. In any patient therefore with aninitial attack of sciatica or lumbago, the first re-course is to conservative treatment, with twoexceptions: (i) The early appearance of a severefoot drop, indicating considerable damage to themotor root of one or more nerves (milder motorsymptoms appear in about io per cent. of all casesof sciatica), and (ii) A massive central extrusioncausing a cauda equina compression. Both theseconditions require prompt surgery.The important principle in conservative treat-

ment is immobilization of the spine and relief ofweight bearing by rest in bed, which relieves tosome extent the extruding tension on the pro-lapse and so gives the ligaments or nerve root timeto adapt themselves to the pressure. Immobiliza-tion of the spine by a plaster jacket without bedrest can be used for milder cases.Some details of bed rest require emphasizing.

Firstly, if must be rigidly enforced and thisusually means admission to hospital. The patientshould not get out of bed for any purpose and forthe first week he should not be permitted to situp. The mattress should be a firm one and shouldnot sag, if necessary it can be supported byfracture boards. Traction on the leg by means ofa weight and adhesive strapping is sometimesbeneficial in some cases with very severe pain. Itis important that analgesic drugs be administeredin adequate quantities to make the pain bearableduring the early stages.The next question is how long should bed rest

be continued? Experience has shown that themajority of cases which are going to improve withthis treatment will have shown some responsewithin three weeks, and this should be the mini-mum time that the patient remains in bed. If atthe expiration of this time the pain has abatedcompletely the patient can start getting up atonce. If some symptoms still persist but it isevident that the condition is improving steadily,then a further period of rest up to about fourweeks is advised. If mild symptoms continue heshould then get up in a plaster jacket or a support-ing corset of the Goldthwaite type. In any event

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LOGUE: Treatment of Lumbar Intervertebral Disc Prolapse

activity should be restricted and he should avoidheavy lifting for a further three months.On the other hand, if at the end of three weeks

the symptoms have shown no signs of abating, thenoperative treatment will have to be considered.

This assessment of the problem after a threeweeks' trial of recumbency is an important step,for even if the decision is made and successfulsurgery is undertaken at this stage it will still besome seven to eight weeks before the patient canreturn to light work and Io to 12 weeks before hecan return to heavy manual labour, if not longer.It is important not to let conservative treatmentdrag on for six, eight or. ten weeks without realimprovement and then present the unfortunateand often demoralized patient with the prospect ofanother two or even three months following opera-tion before he can resume work. Therefore, ifthere has been little response to bed rest at theexpiration of three weeks the position should beexplained to the patient and the chances of cure orimprovement by surgery on the one hand and thedwindling chances of further conservative treat-ment on the other defined, and the patient thenleft to decide what he wants done. If the pain isstill very severe, or if the patient has had previousattacks, there is usually little doubt about theanswer. However, if the symptoms are not par-ticularly bad, but still capable of preventing work,economic factors may then come into play. Ifthere is nlQiurgent necessity for the patient towork he may prefer to continue with bed rest fora longer time, even at the risk of it being eventuallyunsuccessful, and likewise the patient who is moreapprehensive of surgery than of his pain, or per-haps has. a friend who has had an unsuccessful discoperation, will prefer to continue with conserva-tive measures until he finally convinces himselfthat his symptoms will not clear up withoutsurgery.

Plaster JacketThe use of the plaster jacket is reserved (i) for

those patients whose symptoms are not severeenough to demand bed rest and who are anxiousto remain ambulant, (ii) for continuing im-mobilization of the spine after a period of re-cumbency, or (iii) for those unfortunate few whofind that their pain is relieved in the erect postureand is made worse by lying down.The plaster should be applied with the spine in

the position it has naturally adopted and thereshould be no attempt by head traction to straightenthe spine. It should fit snugly and is best appliedover two layers of stockinette, with protective padsover the iliac crests and the lumbar spinous pro-cesses, and should extend in front from the pubesto the upper third of the sternum and at the back

from the posterior iliac spines to the angles of thescapulae. It should be trimmed in the groins andaxilla to allow a fairly free range of limb movement,The jacket is retained in the first instance for sixweeks and then renewed, for by this time it usuallywill have worked a little loose and in any event thespine may be taking up a new position as a result ofthe relief of pain and spasm. The second plastershould continue to be worn for about three weeksafter the symptoms have cleared up.Other Conservative TreatmentThere are some conservative measures which

still require mention. One is manipulation of thespine with or without anaesthesia, and althoughnow and again a dramatic cure of sciatic or backpain results (the reason why is not clear), moreoften the size of the protrusion is sharply in-creased and a number of patients date the onset oftheir sciatica from a manipulation for low backpain. A foot drop and even a cauda equina in-jury is not unknown. The consensus of opinionis that when a patient has unequivocal signs of aprolapsed disc causing either back or sciatic painit is a procedure best avoided. Epidural injectionof saline, with a small proportion of local an-aesthetic via the sacral foramen has had its vogue,but it is difficult to see how it can influence thedisc protrusion and its usual effect is to relievethe pain for a few hours only and then when thelocal anaesthetic has worn off the pain returns withundiminished severity.Surgical Treatment.The indications for surgery will be: (i) Failure

of an adequate trial of conservative treatment.(ii) Recurrent attacks of pain. Operation isusually advised at the start of a second attack if thefirst episode has been severe, but the decision mustbe left to the patient, who may wish to give con-servative treatment a further trial. (iii) Caudaequina compression or severe foot drop. Withregard to sciatica the indications under (i) and(ii) above are quite straightforward, but whenoperation is contemplated for a prolapse causinglow back pain alone, stricter criteria are necessary.At one time practically all low back pain was

attributed to disc prolapse and a rather uncriticalphase of surgery followed, with poor results.Recently more rigid criteria have been adopted,and as a rule few operations are performed for thiscondition, probably only i per cent. or 2 per cejit.of all operations for disc prolapse. Conseryativetreatment is usually persisted in for much longerthan for sciatica, as the pain is not so demoralizingand in only very few cases does it not clear upeventually, Before operation is advised, and thiswill only be after prolonged conservative therapy,

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238 POSTGRADUATE MEDICAL JOURNAL May 1953

it is essential that the symptoms conform to thewell-known clinical picture; pain which is ex-acerbated on coughing and straining; spasm ofthe spinal muscles with deformity of the spine,usually an obliteration of lumbar lordosis towhich may be added some degree of tilt to one orother side. Flexion and extension movements ofthe spine are restricted whereas lateral flexion androtation are comparatively free. If operations forback pain are confined to patients presenting thesesigns the results are as good as those for sciatica.

Pre-Operative InvestigationsOnce surgery is decided upon for sciatica or

back pain there are some further investigationswhich should be done.

Straight X-rays of the spine will already havebeen taken at the time of the original diagnosis,not so much with the idea of demonstrating anychange in the intervertebral disc, which oftentakes a considerable time to appear, but from apoint of view of recognizing certain anomalies,i.e. spina bifida, an increase or reduction in the

number of lumbar vertebrae, or a spondylolisthesis,and for excluding more serious conditions such astuberculous infection, primary and secondarytumours of the vertebrae and sacrum, or bonechanges resulting from tumours in the spinalcanal.The next point is whether myelography should

be undertaken before surgery. This method isaccurate in about 80 per cent. of cases. The 20per cent. of failures usually take the form of aninability to demonstrate a disc prolapse when oneis in fact present, and this more commonly ariseswith prolapses at the lumbo-sacral level (Fig. 3).This failure is often due to simple anatomicalreasons such as a lateral situation of the protrusionor the high termination of the dural sac, or a wideanterior extradural space. Clinical diagnosis ismore reliable than this 80 per cent. success rate,and both the lower disc spaces where 95 per cent.of the prolapses occur can be explored quite easilyso that myelography is not used as a routine, but isreserved (i) for those cases causing a cauda equinasyndrome (Fig. 4), (ii) for exclusion or confirma-tion of a suspected tumour, (iii) for localizing aprolapse from one of the higher disc spaces givingrise to anterior crural pain (Fig. 5), and (iv) forlocalizing a prolapse producing only low back

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FIG. 3.-Apparently normal myelogram in a patient who had suffered from left-sided sciatica for one year. Operationwas deferred for some months and when eventually performed a very large lumbo-sacral disc prolapse was foundextending from the midline to the intervertebral foramen and involving the first sacral nerve root sheath.

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May 1953 LOGUE: Treatment of Lumbar Intervertebral Disc Prolapse 239

pain (Fig. 6). As mentioned earlier the pro-trusions giving rise to back pain may occur in oneof several widely separated situations and they aremuch more difficult to localize clinically thanthose giving rise to sciatica (for the mere complaint-of sciatica immediately localizes the prolapse tothe lower two lumbar space discs) so that myelo-;graphy is of very real value.

One simple investigation before surgery whichis well worth carrying out as a routine is that oflumbar puncture and examination of the cerebro-spinal fluid, not so much to confirm disc prolapse,but to exclude such occasional causes of sciatica asa cystic arachnoiditis when a rise of cell count willbe present, or a spinal tumour when a consider-able rise of protein will be observed. As a roughguide, a protein above Ioo mg. is more suggestiveof tumour, such as a neurofibroma or ependy-moma, than prolapse, and in the presence of such

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FIG. 4.-Myelogram showing a complete obstructionjust above the L 4/5 disc with the appearance of aconical termination to the theca, indicative of anextra-dural compression, which was due to amassive herniation. The patient had symptoms ofa cauda equina lesion which had steadily progressedover two years, simulating a tumour. This is anunusual presentation for a massive prolapse, themajority having an acute onset with a rapid,episodic progression.

a figure myelography should be seriously con-sidered.

Operative TechniqueThe position of the patient on the operating

table is important. Any compression of theabdomen and the intra-abdominal veins will betransmitted to the extradural veins which dilateto a phenomenal size, obscure the prolapse andmay give rise to furious bleeding. This can beavoided by operating on the patient either on hisunaffected side or, if prone, with supports onlyunder the chest and pelvis so that the abdomen isfree. There is some controversy about the ex-posure of the prolapse, whether it should be donethrough an interlaminar approach with removal ofthe ligamentum flavum or through a laminect6my,

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FIG. 5.-Myelogram showing a large filling defectopposite the L 3/4 disc, indicating a protrusionwhich had given rise to anterior crural pain,Myelography is a more reliable investigation forherniations at these higher levels than for thelower two lumbar discs. (The marker wire usedpre-operatively to identify the tip of the thirdlumbar spinous process can also be seen,)

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240 POSTGRADUATE MEDICAL JOURNAL May 1953

partial or complete. There should, however, be norigid rule about this. It will be found that themajority of protrusions of the lumbo sacral jointcan be removed through an interlaminar approachbut at the L4/5 level owing to the wider lamina ofthe fourth lumbar vertebra bone usually needsremoval from the adjacent laminal margins, whichis best accomplished with an ethmoidal punchforceps. If the opening in either situation is notadequate to expose the prolapse clearly, thereshould be no hesitation in removing a half laminaor more, for a great deal of harm can be done tothe theca and nerve root by too forceful retractionin order to obtain a better view. For a disc pro-lapse that is known to be centrally placed a hemi-lamina should be removed at once.The details of operation are briefly as follows:

The fifth lumbar spinous process is identified pre-operatively by placing an opaque marker on theskin and taking an X-ray. The incision is thencentred over this point. The muscles are separatedunilaterally from the spines and laminae, thesmooth sloping surface of the sacrum is located asa guide and from this the requisite interlaminaspace is identified and cleared. The ligamentum

flavum is incised and removed (hinging it and re-placing it at the end of the operation as advisedby some surgeons has no particular merit) toexpose the nerve root and prolapse.The protrusion may be situated medial or

lateral to, or in front of the root, and is usually asmooth glistening projection covered by theposterior longitudinal ligament. Sometimes itwill be found to have extruded through the liga-ment and be lying free in the spinal canal as stringywhite material, or to have migrated down alongthe nerve root to the intervertebral foramen.Occasionally there may be no obvious protrusionbut only some vascularization of the posteriorligament perhaps with the root adherent to it,but on pressure the disc will be found to be soft.This variety is often referred to as ' concealed'or ' intermittent' protrusion. The nerve needsto be accurately identified for it may be stretchedas a thin band over the top of the prolapse andincised in the belief that it is the capsule, withresultant damage to some of the fibres and thebrisk escape of c.s.f. The prolapse is incised andusually softened portions of mucleus extrude.The opening in the annulus will be seen and en-larged and then a thorough curettage of thenucleus carried out with spoon and rongeur so

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FIG. 6.-Myelogram showing a central prolapse from the lumbo-sacral disc in a patient who suffered from severe andpersistent low-back pain without sciatica. This appearance of a narrowed band of contrast material in the midlineis thought to be due to the nerve root bundles being displaced to either side off the summit of the prolapse, leavingonly a thin channel in the centre for the contrast,

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LOGUE: Treatment of Lumbar Intervertebral Disc Prolapse

that there is no loose nuclear tissue left to prolapseat a later date, and- the chances of fibrous ankylosisoccurring between the vertebrae are increased.Special attention must be paid to portions of thenucleus just anterior to the annulus and lateral tothe operative opening in it. If a satisfactory re-moval cannot be obtained from one side theopposite side should be exposed and the remainderof the nucleus excised. The introduction of in-struments into the disc space has to be done withcare for there are some reports of damage to thecommon iliac veins and arteries by an instrumentpenetrating the anterior portion of the annulusfibrosus. If an unequivocal prolapse is found it isnot necessary to explore the disc space above orbelow, despite the anatomical evidence in cadaversof multiple protrusions, for in practice multiplesymptomatic disc protrusions are very uncommon.,If, however, there is any doubt whatsoever aboutthe validity of a protrusion, the next space shouldbe explored before the disc is incised. In somecases no prolapse can be found in either space andit is then that the search should be extended far outinto the intervertebral foramen, where a smallprotrusion may be found. It is unnecessary tounroof the foramen by excising the facets formingits posterior wall and thus weakening the spine.

'Negative' explorations do occur, however,and this varies in modern series from 2 to IO percent. of cases. Fortunately a proportion even ofthese patients benefit from exploration, despite theabsence of any obvious disc pathology. ' Hyper-trophy of the ligamentum flavum' or ' varicosityof the extradural veins' are pathological mythssometimes put forward to explain these successes,but they are merely innocent variations of thenormal.

Division of the affected posterior nerve root issometimes advised but this should never benecessary at a primary exploration. It may beconsidered in a patient at re-exploration for per-sistent sciatic pain where the root is found to beextensively adherent, without much evidence ofrecurrent prolapse.Another problem is the question of spinal fusion

at the time of laminectomy on the eminentlyreasonable grounds that as one is dealing with adisorganized joint immobilization of it by meansof a graft should prevent any back pain afteroperation. Many varieties of spinal arthrodesishave been devised. One type aims at fusing thelamina and spinous processes with grafts from theilium or tibia, and this is the popular method inthis country. A second variety depends on fusionof the posterior intervertebral articulations,Another one consists of a complete removal of thenucleus and cartilage plates so that the cancellousvertebral surfaces come into close contact, some-

times reinforced by the insertion of bone pegs.Yet another variety depends on this same principlebut the approach is by an anterior extraperitonealone to the fronts of the vertebral bodies!There are, however, many points against

primary fusion at the time of disc removal: (i)Only few patients have back pain after operationsevere enough to incapacitate them, probably only2 per cent. or 3 per cent. of all operative cases.It is impossible to recognize this small percentagepre-operatively, either on clinical or radiologicalgrounds. Often the cases with gross ar-thritic changes on X-ray have painless backs.(ii) The operation is made more serious andcarries a higher risk. (iii) Fusion necessitates thepatient staying in bed between 6 to 12 weeks andthen wearing a plaster jacket for a further 6 toI2 weeks, and even then firm union cannot beguaranteed. It is therefore the accepted practicein this country to remove the prolapse and nucleuspulposus thoroughly and then wait and see whathappens. If severe incapacitating back pain fromintervertebral arthritis still persists after 6 to 12months then a further operation with fusion isjustified. Milder back pain is often kept undersatisfactory control by using a Goldthwaite corset.

Post-Operative TreatmentThe patient should get up on the seventh to

tenth day and be ready to leave hospital during thethird week.

Back extension exercises can be commenced assoon as the pain from the incision has cleared up,usually about the seventh day. In some clinicsspinal exercises are promoted vigorously with theaim of having a full range of spinal movement bythe time the patient leaves hospital. This isusually a rather arduous performance for thesufferer and if a long-term view is taken has noreal merit.No form of support such as a Goldthwaite

corset is necessary unless the patient has a gooddeal of back pain.The patient should be encouraged to live as

normal a life as possible and restriction on hisactivity should be confined to heavy lifting andany pursuits involving acute flexion of the spine.

Post-Operative SequelaeDespite a satisfactory disc removal, some

patients are left with residual sciatic pain, whichis not as a rule as severe as the original pain andis usually due to fibrosis in the root as a result ofprolonged tension on it by the disc, by too heavytraction at the time of operation or by adhesionswhich bind the disc to the rent in the annulus andposterior.longitudinal ligament,

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242 POSTGRADUATE MEDICAL JOURNAL May 1953

Cramps in the affected leg are quite common andpersistent although sciatic pain may have dis-appeared completely.A small proportion of patients develop a true

recurrent prolapse (prolapse from the same disc)months to years later. This varies in individualstatistics, but is probably in the neighbourhood of4 per cent. to 5 per cent. These recurrent attacksof sciatica, due to a further protrusion, are dealtwith in the same way as the primary attacks,except that one will tend to persist with conserva-tive treatment for a much longer period before sub-jecting the patient to a second laminectomy.There is also a 2 per cent. risk of developing afurther disc prolapse at another level.

Results of SurgeryTable i gives the results in disc surgery at the

hands of experienced surgeons. The figures arean average gathered from several large series.The overall results of treatment of sciatica or

TABLE I

TABLE SHOWING THE RESULTS OF OPERATION FORPROLAPSED LUMBAR INTERVERTEBRAL DISC

Percent.

Completely relieved of sciatic or back pain.. about 40Greatly improved, mild sciatic or back

pain; at full work ..V .. .. 30Improved, more severe sciatic or back pain;

at full or light work .. .. .. 20No improvement, or worse; unable towork . .. .. .. .. ,, 10

back pain can now be summed up. Out of 0oopatients about 80 will be improved or cured oftheir symptoms by the conservative measures ofbed rest or plaster immobilzation, and 20 will failto respond. Of these 20 who will eventually cometo operation i8 will be made fit to return to work,and of these eight will be completely relieved ofsymptoms. Two patients will fail to derive anybenefit from surgery.

SUBPHRENIC INFECTIONBy A. B. BIRT, F.R.C.S.

Norwich

The pathology and surgical importance of sub-phrenic infection cannot be fully understood with-out a thorough appreciation of the anatomy of thesubphrenic space.AnatomyThe subphrenic space is defined as being that

portion of the abdomen which lies between thediaphragm above and the transverse colon andmesocolon below.The space is divided into two parts by the liver;

the supra-hepatic and infra-hepatic portions.The supra-hepatic portion is divided into right

and left sides by the falciform ligament of the liver.The right side is itself divided into an anterior andposterior space by the right lateral ligament of theliver. The left lateral ligament of the liver runsvery close to the posterior margin of the left lobeof the liver so that it does not divide the left supra-hepatic area but forms the posterior part of theboundary between the supra- and infra-hepaticparts on the left side. There is, therefore, only onesupra-hepatic space on the left side, In addition

there is one small extra-peritoneal space in thesupra-hepatic part, namely the bare area of theliver, between the leaves of the lateral and falciformligaments. The supra-hepatic portion of the sub-phrenic area therefore contains two intra-peritonealspaces on the right and one on the left and onesmall extra-peritoneal space. These spaces areusually referred to as the right superior anteriorsubphrenic space, the right superior posterior sub-phrenic space, the left superior subphrenic spaceand the bare area of the liver.The infra-hepatic portion is divided into right

and left parts by the free edge of -the lesseromentum and the descending part of the duo-denum. There is only one space on the right inthe infra-hepatic region, but on the left there aretwo spaces, an anterior one and a posterior one,being separated from each other by the stomachand the lesser omentum. All the infra-hepaticspaces are intra-peritoneal, there is no extra-peritoneal space below the liver. The infra-hepatic portion of the subphrenic area thereforecontains one space on the right and two spaces on

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