J. Neurol. Neurosurg. Psychiat., 1949, 12, 251.

CRAMP IN CASES OF PROLAPSED INTERVERTEBRAL DISCBY

LIONEL WOLMANFrom the Department of Nervous Diseases, Royal Sheffield Infirmary and Hospital

Although cramp has been mentioned as a symp-tom by several writers on the subject of prolapsedintervertebral discs (Bradford and Spurling, 1941;O'Connell, 1943; Lenhard, 1947) no study hashitherto been made of its exact nature, frequency,and relationships. It was not until the routinefollow-up of cases of sciatica, which had beentreated surgically, was begun that it was noticed thatthe symptom of painful cramps in the leg was fairlycommon in postoperative cases. This served tofocus attention on the symptom, and an inquiryabout it was therefore made in all cases, both beforeand after operation. The purpose of this paper isto record these observations, and if possible torelate the' symptom to conditions found at, orproduced by, the operation, and to discuss thesymptom in relation to theories now held on theatiology of muscle cramp.

MaterialThe observations recorded here were made in the

Department of Nervous Diseases, Royal SheffieldInfirmary and Hospital, in a series of 204 cases of back-ache and sciatica which were thought to be due toherniation of an intervertebral disc and were subjectedto operation. The patients were operated on betweenthe years 1939 and 1946 by Mr. James Hardman, and aroutine follow-up examination was carried out in 1947,at least twelve months and up to seven years afteroperation. The figures given below are extracted fromthe complete follow-up survey carried out by the writer,the results of which will be published in a later paper.

Type of Operation.-The operation performed waseither a laminectomy or a hemilaminectomy, withexploration of the disc spaces between the fourth andfifth lumbar vertebra and the lumbosacral articulation.As much prolapsed material as possible was removed,and if exploration was negative further spaces wereinvestigated if this wa's thought necessary by theoperating surgeon. In about two-thirds of the casesdivision of one or two sensory roots, either at the samesegmental level as the disc or at the segment above, wasmade. This procedure was adopted in' an attempt tobe certain that pain was relieved (Walker, 1945) and to-avoid further root pressure if more material shouldprolapse.

This procedure has since been abandoned in favourof complete curettage of the disc space. Of the 204patients, 142 had division of one or more p6sterior ro6ts,while the remaining sixty-two had no such division.The surgeon's decision whether to section the posteriorroot was influenced by his estimate of the completenessof the disc removal and to a lesser extent by the severityof root pain.

Type of Cramp.-In most cases the cramp cameon at night while the patient was in bed. It affectedthe calf alone, the thigh alone, the foot alone, orcombination of these. There was always associatedpain, and the patient could always feel the muscleharden or, in the case of the foot, see and feel thetoes being drawn down under the sole. Thesesymptoms were always verified before a pain in theleg was-called cramp.When there had been cramp before operation,

this symptom began after the onset of sciatica andnever before. The most characteristic thing aboutthe postoperative cramps was that they were veryfrequent immediately after operation, occurriignightly or every other night for the first few weeks,and gradually becomi'ng less frequent so that theyoccurred about weekly or monthly twelve toeighteen months after operation. With a furtherlapse of time they became very infrequent, occurringonly once every three or- four months. Thisinfrequency made observations on actual attacksof cramp difficult. None have yet been recordedas occurring more than five years after operation.

Incidence of Cramp.-Cramps occurred as a pre-operative symptom in sixteen out .of the 204 casesin the series (8 per cent.). It occurred afteroperation in fifty-two cases (26 per cent.). Ofthese postoperative cases, in the group of sixty-twocases not having a sensory'root divided, nine (15per cent.) developed cramps, whereas, in the 142cases having a posterior root division, forty-three(30 per cent.) developed cramps. Thus crampsappear twice as commonly in the cases havingdivision of sensory roots as in those not havingthis performed.

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252' LIONEL- WOLMANTABLE I

AGE AND SEX INCIDENCE OF CASES-

Series ino Average Age of Aof Men Womenseries age youngest e est

Pre- operativecramps .. .. 16 38 20 54 15 1

Postoperativecramps . . .. 52 36 17 50 43 9

Cases withoutcramp .. .. 136 36 17 68 112 24

Whole series .. 204 36 17 68 170 34

Of the sixteen patients complaining of crampbefore operation, ten were relieved of this symptomafter operation, while in the remaining six thecramps were6 more frequent and severe afterwardsin all but one, whose cramps persisted at about thesame frequency and intensity. It has been men-tioned already that the cramp in these cases tendsto come on at night while the patient is in bed,thus differentiating the pain from that of inter-mittent claudication. A further point of differenceis the age incidence, which is shown in Table I.It will be seen that the average age of the -atientswith cramp was approximately the same as in thewhole series of sciatica cases; this suggests thatvascular factors of a degenerative type play nopart in the causation of the cramp.

Sex Incidence.-The sex of the patients withcramp is shown in Table I. Although pre-operativecramps were commoner in men than in women, thesex distribution in the group with cramp afteroperation was similar to that for the whole series(about five men to one woman); this suggeststhat sex has no part in the aetiology of these cramps.

- TABLE II

PRECIPITATING FACTORS IN CRAMP

No. with No. withPrecipitating factor pre- post-

operative operativecramp cramp

In bed at night .. .. .. 7 32

While bending or kneeling .. 0 3

While sitting .. .. .. 2 3

Stretching leg .. .. .. 2 0

While standing with weighton leg.. .. .. .. 0 3

No definite cause-cramp atany time of day or night .. 5 11

Total . .. .. 1 6 52

Precipitating Cause of Cramps.-AII the patientswere asked what factors brought on the cramp.The replies (Table II) showed that nocturnal crampoccurred in more than half the cases.

Factors Relieving Cramp.-The cramp passed ofspontaneously in all the patients in whom itoccurred pre-operatively, but could be relieved byrubbing the affected part or by pressing the footagainst something firm. In the fifty-two patientsin whom cramp was postoperative, changing -theposition of the leg was most effective and relievedcramp in fifteen cases, pressing the foot to theground was successful in ten, and six found thatrubbing the affected part gave relief. Three patientsthougzht they could relieve cramp by taking aspirinbefore going to bed, and eight cases used'a combina-

TABLE 1IIMUSCLES AFFECTED BY CRAMP

Pre-operative cases Postoperative cases

Part Weak- Weak-affected Weak- ness Weak- ness

No. % ness and No. % ness andonly wast- only wast-

ing ing

Thigh .. 2 13 0 1 3 6 1 2

Thigh andcalf .. 1 6 1 0 6 11 0 1

Calf .. 9 56 5 4 29 56 10 5

Calf and foot 1 6 1 0 5 10 0 0

Foot and toes 3 19 1 0 9 17 2 2

Total.. 16 100 _-52 100

tion of all these methods to obtain relief. Theremaining ten adopted no particular measures butallowed the cramp to pass off spontaneously.

Site of Cramp.-The muscles affected by crampare indicated 'in Table III. As many observershave previously noted, the calf m'uscles are -by farthe commonest site for muscular cramps. In thesixteen pre-operative cases, wasting of the affectedmuscles was found in five patients, while in allexcept three there was definite weakness of thesemuscles compared with the opposite side. Fibrilla-tion was seen in the calf in two patients only. Inthe fifty-two postoperative cases weakness andwasting were less frequently found in the affectedmuscles, there being ten patients with wasting andtwenty-three with weakness. As cramps werefairly infrequent by the time of the follow-up, thisobservation is of doubtful significance. The dis-tribution of the weakness and wasting is shown inTable III.

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CRAMP AND PROLAPSED DISC

TABLE IVRELATIONSHIP OF CRAMP TO THE LEVEL OF THE

PROLAPSED DISC

Cases with Cases with Remainderpre- post- of cases

Site of prolapsed operative operative withoutdisc tramp cramp cramp

No. % No. % No. %

L3-L4 ..' 0 0 0 0 4 3

L4-L5 .. . 5 31 16 31 50 36

L5-Sl .. 9 56 31 60 72 54

L4-5 and L5-S1 0 0 4 8 6 5

No disc found atoperation , .. 2 13 1 2 4 3

Total .. 16 100 52 101 136 101

The degree ofweakness and wasting ofthe musclesliable to develop cramp was not significantlydifferent from that seen in cases not developingcramp either before or after operation.

Cramp and Level ofProlapsed Disc.-The relation-ship of cramp to the level of the prolapsed discfound at operation was also investigated. Table IVgives an analysis of the site of the prolapsed disc inthe various groups. From this it will be seen thatthe distribution is approximately the same in allthree groups, which suggests that the occurrence ofcramp is independent of the level of the prolapseof the disc.

Site of Cramp and Level of Prolapsed Disc.-InTable V the relationship between the site of crampand the level of prolapsed intervertebral disc isshown both for the group suffering from crampbefore operation and the group with postoperativecramp.As is to be expected from the fact that a pro-

lapsed disc can affect the nerve root either of itsown or of a higher segmental level according to its

TABLE VRFLATIONSHIP BETWEEN SITE OF CRAMP AND LEVEL

OF PROLAPSED DISC

Pre-operative J PostoperativePart cramp cramp

-affectedby No L5A Nocramp L4-L5 L5-SI disc L4-L5 L5-Sl and disc

found L5-S1 found

Thigh.. 1 1 0 3 0 0 0

and calf 0 1 0 1 5 0 0

Calf .. 2 6 1 8 19 2 1

Calf andfoot .. 1 0 0 1 1 1 0

Foot andtoes .. 1 1 3 6 1 0

medial or lateral position, there is no definitecorrelation between the muscle affected by crampand the level of the prolapsed disc. The type ofdisc found at operation, especially as regards theposition of prolapsed material, was thereforeinvestigated next. /

Relationship of Cramp to Type of Disc.-Thetype of disc found at operation had to be discoveredfrom the operation notes, but in some cases noparticular comments about the disc were found.,'It was possible to divide the cases in which specialcomment was made into four categories accordingto whether the prolapsed disc appeared as a slightmedial bulge, a large central prolapse, a smalllateral prolapse, or a large lateral prolapse. This

TABLE VIRELATIONSHIP OF CRAMP TO TYPE OF DISC

Pre- Post.operative operative Rest of

Type of cramps cramps seriesprolapsed

discNo. % No. % No. %

No evidence ofprolapse .. 2 13 1 2 4 3

Slight medianbulge.. .. 2 13 15 29 32 23

Large central pro-lapse . .. 3 19 21 41 56 41

Small lateral pro-lapse . .. 2 13 1 2 12 ,9

Large lateral pro-lapse.. .. 7 44 10 19 20 15

No mention madeof disc type .. 0 0 4 8 12 9

Total .. 16 102 52 101 136 100

is obviously an arbitrary and artifiial division, asthe static conditions seen at operation may notrepresent the true state of affairs, but it was the onlymethod possible. In Table VI the findings arecompared with those obtained in the 136 caseswithout cramps. The findings in the cases develop-ing cramp after operation resemble those in thegeneral series, but in those suffering cramp beforeoperation there was a higher proportion with largelateral prolapsed discs. These figures suggest,therefore, that cramps are more liable to developin cases having a large lateral prolapse of the disc.As the nerve root was often stretched over thesummit of the large prolapsed discs, attention wasnext focused on the posterior nerve root.

Cramp and the Posterior Root Section.-It wasfound that most of the fifty-two patients developingpostoperative cramp had one or more- posterior

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nere roots sectioned at operation. Thus, only,>nine patients (18 per cent.) -did not have a' rootdividedjwhile- 83 -per cent. did, 54 per cent. havingdivision of one sensory root and 29 per cent. havingtwo. Of the patients with cramp and withoutsensory root division, one had paraplegia beforeoperation which persisted afterwards and at opera-

tion the roots of the cauda equina were found tobe-matted together, three had very laterally placeddiscs with the nerve root stretched over the summitof -the disc, and the remaining five had nothingspecial recorded about the operation. It is worthnoting that in only one patient out of the fifty-twodeveloping cramp after operation was the cramp

bilateral in both calves. This patient was the onlyone in whom the posterior root was divided on bothsides. The patient who complained most bitterlyof all about painful cramps in the calf had only a

partial division of one posterior nerve root. (TableVII.)

TABLE VIICRAMP AND POSTERIOR ROOT SECTION

Roots sectioned

Part affected by L4 L5

cramp L4 L5 S1adin None

5 Si

Thigh .: .. 1 1 0 1

Thigh and calf.. 1 3 1 0 0 1

Calf.. .

3 112 3 3 7

Calf and foot.. 1 1 0 2 1 0

Footand toes ..0. 3 0 3 3 0.

Total . 6 19 3 8 7 9(12%) (36%) (6%) (15%) (13%) (18%)

Site of Cramp and Posterior Root Section.-Anattempt was made to correlate the muscle affectedby cramp with the root divided. Although therewas a tendency for the thigh muscles to be affectedwhen the fourth lumbar root was divided and forthe foot to be involved when t1W fifth lumbar andfirst sciatic roots were divided, there were exceptions,as might be expected from the fact that there is an

overlap between the muscles and cord segmentssupplying them, each muscle being supplied bymore than one segment and each segnental levelsupplying several muscles.

Relatibnship of Cramp to X-Ray Appearamnes.-As muscular cramps are common in patients witharthritis of the knee, hip, or spine (Pem-berton,1935), the x-ray appearances were studied. It was

found that in the pre-operative group 44 per cent.showed no abnormality of the lumbar spine on

x-ray examination, while 38 per cent. had slightnarrowing of the disc space and none showedarthritic changes. In the postoperative group 46

VOLMAN - :

TABLE VIIIRELATIONSHIP OF CRAMP TO RESULT OF OPERATION IN

PATIENTS WrTH CRAMP BEFORE OPERATION-

Good BadSeries Number result resultin series -

No. % No. %

Cases with cramp beforeoperation >. .. 16 9 56 7 44

Remainder of series .. 188 120 64 68 36

Whole series .. 204 129 63 75 37

per cent. showed no abnormality, while 18 per cent.had narrowing of the disc space and 12 per cent.had arthritis. Of the 136 patients who neverexperienced cramp, 44 per cent. showed no abnorm-ality, 17 per cent. had narrowing of the disc space,and 14 per cent. had arthritic lipping. The radio-graphs in the group developing cramp after opera-tion and in the general series were taken at the timeof the follow up, when arthritic changes, if any,would be at their maximum. The fact that thex-ray appearances of the lumbar spine in the casesdeveloping cramp were roughly similar in type andfrequency to those of the general series suggeststhat arthritis had little or no part in the etiology ofthese cramps, while in the pre-operative group itplayed no part whatever. Radiographs taken atthe time were little or no different from those takenbefore operation, the variation being no more thanin the group not developing cramp.

Relationship of Cramp to Results of Operation.-An investigation was made into whether patientswho had cramp before operation did better or worsethan those without cramp at that stage. Moredetailed results will be published later, and here the'cases are merely divided into good and bad. Theresults are without significance. (Table VIII.)

TABLE IXRELATIONSHIP OF CRAMP TO RESULTS OF OPERATION IN

PATIENTS DEVELOPING CRAMP AFTER OPERATION

Good BadCases with cramp No. result result

No. % No. %

One or more root divided .. 43 28 65 15 35Norootdivided .. .. 9 5 56 4 44

Total with cramp .. 52 33. 64 19 36

Cases without cramp .. 136 87 64 49 36

Whole series .. .. 204 129 63 75 37

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CRAMP AND-PROLAPSED DISCTABLE X

OPERATIVE PROCEDURE ON SIXTEEN PATIENTS WITH CRAMPBEFORE OPERATION

DisofcNo discDccmremoval fDic .and fon;Totalremoval noonly pseirnerve

SectiononsectionNo. of cases withcramp beforeoperat-ion only 3 6 1 10

.No. of cases withcramp beforea n d a f t e roperation 0.. - 5 1 6

The next point investigated was whether, inpatients developing cramp after operation, thecramps occurred more commonly in the operativefailures or in the successes. It will be seen that theresults are approximately the same in the groupswith and without cramp as compared with the wholeseries and therefore the appearance of cramp afteroperation has no prognostic significance. (TableIX.)

Persistence of Cramp after Operation.-Of thesixteen patientk with cramp before the operation,only six had it afterwards, the remaining ten beingfree. The operative procedures carried out on thesepatients were as given in Table X.

Cramp and Duration of Symptoms of ProlapsedDisc.-In order to see if there was any relationshipbetween the occurrence of cramp and the length ofhistory before operation, the average duration ofsymptoms of prolapsed intervertebral disc for thevarious groups was compared with that of the

TABLE XIAVERAGE DURATION OF SYMPTOMS OF PROLAPSED DISC

No. n Average durationSeries series of symptoms

-before oper'atio'n

Pre-operative cramps .. 16 3 yrs. 5 mths.

Postoperative cramps:with root section .. 43 4 yrs. 10 mths.

without root section . 9 5 yrs. 9 mths.

Total .. .. 52 4 yrs. 11 mths.

Cases without cramp pre-or postoperative .. 136 3 yrs. 9 mths.

Whole series .. .. 204 4 yrs. 1 mth.

G

whole series (Table XI). In the patients withcramp-before operation the duration of symptomswas slightly less than in those without it, suggesti'ngthat there was no relationship. In contrast, thepatients with cramp after operation had a muchlonger duration of symptoms before surgicaltreatment; this was especially so in the patientswho had cramp without root section. The longerduration of symptoms suggests the possibility ofmore damage to nerve roots by prolapsed material,but whether this is the correct explanation isdoubtful in view of the short histories in the patientswith pre-operative cramp. It seems likely that the-duration of stretching of nerve fibres by prolapsedmaterial is only one factor, and possibly of lessimportance than the size and site of prolapse.

Cramp and Type of Symptoms.-All the 204patients under review had sciatica, but there werefive without any backache and eleven with slightpain in the back compared with that along thesciatic nerve distribution. Of these five withoutbackache, two had cramps in the calfafter operation.All the remaining patients had both backache andsciatica; and, although it was difficult to estimateaccurately, the impression was that there was littleor no relationship between severity of sciatic painand the occurrence of cramp. It may be arguedthat the occurrence of cramps after operation wasmore dependent on the severity of pain due to nerveroot involvement than on root section, and thatthe latter procedure happened to be done only inthe patients with severe pain. The longer durationof symptoms in the patients with cramp afteroperation is compatible with the greater nerveinvolvement in these cases. Often, however, thenerve was sectioned irrespective of the severity ofpain,, and sometimes this was done because of thesmall amount of prolapsed material removed. Asthese cases also developed cramp, the essentialcause seems to be degenerative changes in thenerve root due to section or stretching by a prolapseddisc.

DiscussionFrom the results of this study, it seems that

cramp is more likely to occur in cases of prolapsedintervertebral disc when there is involvement of theposterior nerve roots by prolapsed material as inlarge lateral protrusions. That cramp can occuras a result of posterior root irritation is well knownand is an explanation of their frequency in such acondition as subarachnoid himorrhage. Gootnick(1943) believes that the cramps seen in arthritis ofthe hip or knee, in weak feet, or in intrinsic in-flammatory changes in nerves, such as sciatica,are clonic contractions of a muscle group due to

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256' LIONEL-

reflex bombardment of the myoneural junction bya stream of impulses from the neighbouring sourceof irritation, and he likens them to a variety ofsegmental visceromotor reflex, such as the abdominalrigidity in peritoneal inflammation. This theorywould explain the occurrence of cramp in thepre-operative patients. In the postoperative patientsthe cramp seems to be related to posterior rootdivision. Although posterior rhizotomy is anoperation which has been practised for a long timefor various painful conditions, no mention of theincidence of cramp after operation could be foundon perusal of the literature. After division of theposterior nerve root three possible series of changesmay occur: a peripheral, a central, and changesat the site of section. These will be considered inturn.

Dividing the posterior root should, theoretically,leave the dorsal root ganglion, its afferent sensoryfibres, and their terminal sensory endings in muscleintact, all degeneration occurring proximal to thecut. If there are efferent autonomic fibres in theposterior root, after section it is possible that someperipheral degenerative changes may occur, affectingeither the muscle fibres, the sensory endings, themyoneural junction, or the blood supply, andrendering the muscle fibres more liable to pass intospontaneous contraction. This might be trans-mitted to other fibres in the muscle until spasmresulted under various sets of conditions. Theexistence in man of sympathetic fibres in dorsalroots has not been proved, while the presence ofparasympathetic fibres arising in the lateral hornsof grey matter, and running to single end plates inmuscle via dorsal root and ganglion (Kure, 1931),is not universally accepted. Apart from thesepossibilities it is difficult to conceive how peripheralchang'es may occur by other known mechanisms,though their occurrence cannot be excluded.Dawson and Ladell, in a personal communication,stated that they found the cramp produced byacute salt deficiency was relieved by an intravenousinjection of salt, except in a leg from which thecirculation had been cut off by a pneumatic cuff.When circulatory arrest had abolished both theanlkle jerk and the reflex responses to electricalstimulation, cramp no longer occurred, either duringelectrical stimulation or duiring voluntary contrac-tion of the muscle. This suggests that an intactreflex arc is necessary for the objective and subjectivephenomena of cramp to be present together. 'Ifthis is true, the cramp in rhizotomy patients isdependent on intact reflex arcs in other segnents ofthe cord. Unfortunately, there is no muscle whichis innervated entirely by one.segmental level of thecord, so it is not possible to prove whether such a

WOLMAN

muscle will go into cramp after divisioni of itssensory root. The observations recorded in thispaper suggest that there may be some correlationbetween nerve root divided and muscle affected,but there were exceptions, as was expected from theoverlap between the segments and muscles inner-vated. Weddell'(1945) has shown in the case ofpain sensation in normal skin that there is a networkof nerve endings arranged so that any one area ofskin is supplied by several overlapping terminalsderived from different areas. In muscles the nerveterninals form a much looser meshwork, so thatindividual neural terminals in this meshwork areisolated from each other (Feindel, Weddell, andSinclair, 1948). The utilization of intact reflexarcs in cramp production might be possible withthis anatomical arrangement, while the reductionin pattern of afferent impulses after rhizotomymight form a basis for explanation of the painassociated with these cramps, as has been postulatedin the case of nerve nets and terminals subserving.cutaneous pain sensation when isolated from'neighbours, instead of interweaving with them as'in normal skin (Weddell, Sinclair, and Feindel,1948). The possibility that the painful element incramp is transmitted to the cord through intactposterior roots via sympathetic afferent sensoryfibres in these rhizotbmy cases cannot be excluded.The central changes would consist of degeneration

of the sensory fibres as they entered the cord as faras the intercalatory neurone in the posterior hornor even to the anterior horn cell. Loss of con-trolling action of afferent impulses would have aneffect on these neurones and might cause them tosend out impulses to the muscles, resulting in tkeirspasm. The pain of thle cramp would havee'toutilize intact sensory fibres at other levels as,described above. The poiterior root degenerationcould be compared with the pathological changesoccurring in tabes dorsalis. -In this disease, over90 per cent. of all cases exl*rience lightning painsand " an abrupt reflex or half-6onscious 'start' oflimb muscles may accompany the 'shoot' of 'thepain " (Wilson, 1940). The p6riodic occurrence ofpainful crises associated with spasm ofsmooth musclealso, demonstrates the motor accompanimnent'-ofchanges in the posterior nerve roots. It seems morelikely, therefore, that the' motor component of'thesecramps is dependent on central degenerative changesrather than hypothetical peripheral alterations.The third factor to be considered is the change in

the cut surface of the nerve root or in the cases withpre-bperative cramp the site of impingement ofprolapsed disc on nerve root. Granit and others(1944) showed that an "artificial synapse" couldbe formed in a mixed nerve either'by sectioning it

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CRAMP AND PROLAPSED DISC

or even ligating it without damaging it enough to studied in a series of 204 cases followed up one tostop normal distal conduction. This may be the *seven years after operation.mechanism of pain and cramp production in these 2. The incidence of cramp was found to becases, the affected nerve or the peripheral end of the higher after operation when, in addition to removalsectioned posterior root acting as a short-circuiting of the protruded disc material, a posterior nervepoint causing impulses to descend perhaps anti- root has been cut.dromally.One point needing further explanation is why the 3. The cramp occurring in these postoperative

cramps diminish with time. If they are due to cases gradually diminished with time.changes in the muscle fibres or in sensory endings, 4. The significance of these findings is discussedare these changes reversible with -the passage of in relation to the mechanism of cramp production.time, or do other intact fibres take over their 5. The occurrence of cramp, whether before orfunctional connexions ? If the cramps are -due to after operation, is of no prognostic significance aschanges in the cord, is their gradual diminution regards the operative resultdue to co'mpletion of degenerative changes in the readthopaivrsu.dyeocopletono degneraive hangs inthe 6. While,not helping in elucidating the mechanism

cut fibre and its connexions, or is it due to the time of cramp thesfdg ifconfime mustnbeneeded for other fibres and nerve endings in the ofcapthsfidn,ifofrm ,mutbneeddfroherfibes nd nrveendngsin ~hetaken into account in any comprehensive theory ofcord to take over completely the functional con- camp.nexions with released neurones? Such questionscannot be answered at present, and further specula- My thanks are due to Mr. James Hardman, F.R.C.S.,tidon would be unprofitable. Thus, the observations without whose work and original suggestion, thismade in this paper, though interesting, do not help investigation would not have been undertaken.in thp elucidation of the problem of cramp. Never- This work was carried out by the author while holdingthe E. G. Fearnsides Research Scholarship, Universitytheless, if they are confirmed, they would have to of Cambridge.be taken into account in any theory of the mechanism REFERENCESof cramp. Bradford, F. K., and Spurling, R. G. (1941). "The

Quinine, which was suggested by Gootnick (1943) Intervertebral Disc." First Edition. Charles C.as being effective in cramp due to reflex irritation, Thomas, Springfield, Illinois. p. 74.was not tried in the present series. By the time Feindel, W. H., Weddell, G., and Sinclair, D. C. (1948).these patients were seen the cramps had become J. Neurol. Neurosurg. Psychiat., 11, 113.infrequent, .so that no therapy was necessary; Gootnick, A. (1943). Arch. int. Med., 71, 555.

Granit, R., Leksell, L., and Skoglund, C. R. (1944).even if quinine had been given, its efficacy would Brain, 67, 125.have been difficult to assess owing to the natural Kur6, K. (1931). "Die vierfache Muskelinnervationimprovement that was taking place. einschliesslich der Pathogenese und Therapie derInonepatientseenaftethisfollprogressiven Muskeldystrophie." Urban and Schwar-

In one patient seen after this fOllOW-Up, in whom zenberg. Berlin.severe cramp was a prominent symptom and in Lenhard, R. E. (1947). J. Bone Jt. Surg., 29, 425.whom it persisted after the response of the sciatica O'Connell, J. E. A. (1943). Brit. J. Surg., 30, 315.to conservative treatment, quinine was very effective. Pemberton, R. (1935). " Arthritis and RheumatoidThis patient later needed surgical treatment owing Cox, London. p. 51.to the recurrence of sciatica. Walker, E. (1945). South. med. J., 38, 832.

Summary and Conclusions1. -The occurrence of cramp as a symptom in

sciatica due to prolapsedd iervertebral disc was

BOOK IRObservationSeon the Pathology of Hydrocephalus. By

Dorothy S. Russell. 1949. M.R.C. Special Report.Series No. 265. London, H.M. Stationery Office.Pp. 138. Price 6s. net.

This monograph is the result of seventeen years ofpost-mortem study of hydrocephalus in the child and theadult. There are three possible causes for hydro-cephalus: (1) excessive formation of the cerebrospinalfluid; (2) interference with the circulation of the fluid;

Weddell, G. (1945). British med. Bull., 3, 167.-, Sinclair, D. C., and Feindel, W. H. (1948). J.

Neurophysiol., 11, 99.Wilson, S. A. K. (1940). "'Neurology." Edward Arnold,London. p. 491.

IEVIEWSand (3) failure of adequate absorption of fluid into theblood and lymph channels. Recent work discounts thefirst possibility, as it seems unlikely that either hyper-trophy of the choroid plexuses or increased capillarypressure in them, for example, as a result of thrombosisof their efferent veins, ever result in hydrocephalus.About the third possible cause there is no certainknowledge, but a number of clinical cases of dilatationof the ventricles, as a sequel to extensive sinus throm-

257

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