SYSTEMATIC VENTRICULOGRAPHIC STUDIES ININFANTS BORN WITH MENINGOMYELOCELE AND

ENCEPHALOCELE*THE INCIDENCE AND DEVELOPMENT OF HYDROCEPHALUS

BY

JOHN LORBERFrom the Department of Child Health, University of Sheffield

(RECEIVED FOR PUBLICATION JANUARY 5, 1961)

Increasing experience and the introduction of newtechniques in the treatment of congenital hydro-cephalus demand its earliest possible recognitionand knowledge of its natural history. By far thecommonest type of congenital hydrocephalus is theone associated with a meningomyelocele or en-cephalocele. The presence of hydrocephalus insuch infants should be suspected at birth, simplybecause the association is so common.

Present InvestigationAn investigation was started on January 1, 1959,

in the Children's Hospital, Sheffield. Its firstpurpose was to determine the incidence and degreeof hydrocephalus in infants who were born withmeningomyelocele or encephalocele, and to relatethis incidence to various clinical features. Thesecond purpose was to determine what effect, ifany, early operation on the meningomyelocele wouldhave on the development of hydrocephalus, and todetermine the prognosis for those who had nohydrocephalus at the first examination. Its thirdpurpose was to include those infants, who werefound to have a hydrocephalus, in a controlledtherapeutic trial. This paper deals with theresults of the first two aspects of the investigations.

MethodsInfants with meningomyelocele or encephalocele were

subjected to full clinical examination. The main methodof investigation was ventriculography, which was oftenassociated with dye penetration studies and sometimeswith pneumoencephalography. The term 'hydrocephalus'in this paper refers to the radiological diagnosis of apathologically distended ventricular system on ventriculo-graphy irrespective of any other feature. Ventriculo-

* Based on a paper delivered at a Joint Meeting of the Swedish andBritish Paediatric Association in Uppsala, in September 1959.

graphy was performed through the right side of theanterior fontanelle. The depth of the cerebral cortexwas measured by using a graduated needle for ventricularpuncture. The cerebrospinal fluid pressure was measuredin millimetres of water, while the infant was lyingplacidly, with the help of a sweetened dummy. Thiswas followed by an injection of 20-40 ml. of sterile air.Radiographs were then taken in different positions ofthe head, including the head down position, to outlinethe whole ventricular system, as far as possible.. Hydro-cephalus was diagnosed if this system was unequivocallydilated, the angles of the lateral ventricles were roundedoff, and the margins of the ventricles were convex. Ifhydrocephalus was found, it was arbitrarily graded intothree groups. Grade 1 was the mildest, with considerableresidual brain tissue, whereas in Grade III the cerebralcortex was, at the most, a few millimetres thick. Grade IIfell between these two extremes (Fig. 1).

Case MaterialThis investigation is based on the study of 172 out of

214 infants who had been born with a meningomyeloceleor an encephalocele, and who were admitted to theSheffield Children's Hospital between January 1, 1959',and November 30, 1960 (Table 1). All were under9 months of age on admission. There were 86 boysand 86 girls. Eighty-five infants were admitted on thefirst day of their life, 39 were between 2 and 7 days old,25 were up to 8 weeks of age, and the last 23 were older(Table 2). These infants were admitted under thesurgical care of Mr. Zachary, whose policy was to repairthe lesion as soon as possible after admission. Theexcised segments were examined histologically by Dr.J. L. Emery. The diagnosis of meningomyelocele isbased either on the presence of paralytic lesions in thesegments involved by the spina bifida cystica or thepresence of neural elements in the excised sac. In a fewof the older infants the meningomyelocele had alreadybeen repaired at other hospitals, before they were trans-ferred to us for the treatment of hydrocephalus. In58 infants the meningomyelocele or encephalocele wasrepaired during the first day of life, in 60 between the

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ARCHIVES OF DISEASE IN CHILDHOOD

FIG. 1.- -Diagrammatic representations of Grades 1, 2 and 3 hydro-cenhAnq-s

TABLE 1214 CONSECUTIVE CASES OF MENINGOMY

ENCEPHALOCELE UNDER 9 MONTHS(Admitted January 1959-November 1'

Ventriculogram not performed:Died before or soon after operation on

meningomyeloceleRecent admissions, awaiting ventriculographySurvived, over I year of age, no apparent

hydrocephalus

Total

Ventriculogram performed:No hydrocephalusHydrocephalus.

Total

TABLE 2172 CASES OF MENINGOMYELOCEL

ENCEPHALOCELE

Age

1st Day 2-7of Life Days

On admission .85 39Meningomyelocele repaired* 58 60Ventriculogram .. .. 4

* Ten were not operated on.

second and seventh days, in 26 during the next sevenweeks, and in 18 at a later date. In 10 infants no attemptwas made to repair the meningomyelocele (Table 2).

Ventriculography was performed in 17 infants beforethe repair of the meningomyelocele, in 80 within threeweeks and in 75 more than three weeks after the operation(Table 3). Ventriculography was performed in 55%either before or at most three weeks after operation.Longer delays were usually due to late referral, themeningomyelocele having been repaired elsewhere, or topost-operative illness, including meningitis, which delayedthese investigations. In seven infants ventriculographywas again performed on a later occasion.

Forty-two other infants were admitted into hospitalduring the same period with spina bifida cystica; 30 ofthese died shortly after admission, and were never fitfor ventricular studies. Eight were discharged fromhospital soon after operation on their spina bifidacystica. None of these had paralytic lesions and therewere no neural elements in the excised sac. They wereall seen later and did not develop clinical hydrocephalus.These infants had a simple meningocele. Ventriculo-graphy was not ethically justifiable. Finally, four recentadmissions have not yet reached the stage of ventriculo-graphy. These 42 infants are not included in this study.

ResultsVentriculography showed that 30 (17%) infants

had either normal or only doubtfully enlargedventricular systems and 142 (83%) infants had

ELOCELE AND hydrocephalus (Table 4). Of these the hydro-OF AGE cephalus was trivial (Grade 1) in six, but the large

960) majority had more serious ventricular dilatation,

this being extreme in 51 (30% of 172 cases). Table 3No. of Cases shows that the ventriculograms on infants who had

no hydrocephalus were performed about the same30 interval after the surgical repair (average 25 days)

as in those with hydrocephalus (average 29 days).8 The latter figure does not include 16 infants whose

42 (20 '%) meningomyelocele was repaired after ventriculo-graphy, or not at all.

30142 Head Circumference Related to Hydrocephalus.172 (80%) Ventriculograms were performed on these infants

irrespective of whether the size of their head waslarge or not at the time, and irrespective of whetherthere was fullness or bulging of the fontanelle,separation of the sutures or other signs of hydro-

_E AND cephalus. Table 5 shows that the head circum-ference of the 30 infants who had no hydrocephalusat the time of the ventriculography was below the

1-8 8 Weeks 10th percentile at the time of examination in 20%,Weeks + it was within the normal range* in 63% and was

25 23 slightly above the 90th percentile in 17%. In26 18 contrast to this, 61% of the infants with hydro-126 42

* For the purpose of this investigation the head circumference isregarded as normal if it falls within the 10th and 90th percentile.

)</ GRAD/E 2

\ j GRADE 3 "

"I,

382

4W;V..a.tub.

SYSTEMATIC VENTRICULOGRAPHIC STUDIES IN INFANTSTABLE 3

TIMING OF FIRST VENTRICULOGRAM IN RELATION TOREPAIR OF MENINGOMYELOCELE

Ventriculography

Result of All 0-21 Days 22 Days or Aver-Ventriculogram Cases Before After More After age

Repair Repair Repair

No. No. % No.

Normal .. 30 1 3 18 60 11 37 25Hydrocephalus 142 16 11 62 44 64 45 29*

Total 172 17 10 80 47 75 43

* Excluding 16 infants whose meningomyelocele was not repaired.

cephalus had an enlarged and often considerablyenlarged head at this stage. It is more interestingto note, however, that the head circumference waswithin the normal range in 48 of the 142 hydro-cephalic infants (34%) and in seven babies it waseven below the normal in size, although the ven-triculogram showed a considerable degree of hydro-cephalus (Figs 2 and 3). The same data show thatof the 92 infants whose head circumference wasover the 90th percentile 87 (95%) had hydrocephalus.It is important to note, however, that of the 80whose head circumference at this stage was normalor below the normal range, 55 (69%) had ventriculo-graphic evidence of hydrocephalus (Table 6). It isclear from these figures that although an abnormallylarge head almost always indicates hydrocephalus,a normal or small head in infants with meningo-myelocele or encephalocele certainly does notexclude hydrocephalus which is present in almosttwo-thirds of such cases.

Site of Meningomyelocele and Encephalocele andIncidence of Paraplegia Related to Hydrocephalus.One infant had an anterior encephalocele (pro-truding through a cleft palate), and 15 had occipital

TABLE 4RESULTS OF VENTRICULOGRAPHY IN 172 INFANTS WITH

MENINGOMYELOCELE(January 1959-November 1960)

No. %No hydrocephalus .. .. 30 17

Grade1 .. 6 3Hydrocephalus f Grade 2 .. 85 50

i Grade 3 .. 51 30

TABLE 5HEAD CIRCUMFERENCE AT TIME OF FIRST

VENTRICULOGRAM

Percentile

Result of All Below 10th 1Oth-90th Over 90thVentriculogram Cases

No. % No. % No. %

No hydro-cephalus .. 30 6 20 19 6 5 17l

Hydrocephalus.. 142' 7 5' 48' 63, 87L 61Treated .. 61 2 22 37'Control .. 54 3 21 30Advanced .. 27 2 5 20

encephaloceles. The meningomyelocele was cer-vical in two, thoracic in 10 and sacral in 15. Thelumbar segment was involved in 129 infants (75%).These included 48 thoraco-lumbar, 51 lumbar and30 lumbo-sacral meningomyeloceles (Table 7).The site of the encephalocele or meningomyelocele

TABLE 6HEAD CIRCUMFERENCE AT TIME OF VENTRICULO-GRAPHY RELATED TO INCIDENCE OF HYDROCEPHALUS

Percentile Total No Hydro- Hydrocephaluscephalus

Below 10th 13) 6 76i80 55 (69%)

10-90th .. 67 j 19 48Over 90th.. 92 5 87 (95%)

TABLE 7RELATION OF SITE OF MENINGOMYELOCELE OR ENCEPHALOCELE TO INCIDENCE OF

HYDROCEPHALUS ON VENTRICULOGRAPHY

(January 1959-November 1960)

Site ofMeningomyeloceleor Encephalocele

Palatal ..

Occipital ..Cervical ..Thoracic ..Sacral

Thoraco-lumbarLumbar ..

Lumbo-sacral

All

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ARCHIVES OF DISEASE IN CHILDHOOD

..:~~~~~~~~~~~~~~~~~~~~~~~~. .:.:. X

=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...... ... .. ...*sNE_ ~~~~~~~~~~~~..

32g.}:R3,:u !:: :? i::.

FIG. 2a and b.-Clinical photographs of an infant whose head cir-cumference was normal and who showed no other clinical evidence of

hydrocephalus.

had an important relationship to the incidence ofhydrocephalus. The incidence of hydrocephalusaccording to the site of the lesion was as follows:thoraco-lumbar 96% (46 of 48), lumbar 86% (44 of51), lumbo-sacral 83% (25 out of 30), occipital73% (11 out of 15), thoracic 70% (seven out of 10)

TABLE 8SITE OF MENINGOMYELOCELE AND ENCEPHALOCELE

AND INCIDENCE OF PARAPLEGIA(January 1959-November 1960)

NoSite Paraplegia Paraplegia Total

No. NNo.

Lumbar (including thoraco-lumbar and lumbo-sacral) 108 84 21 16 129

All other sites. 9 21 34 79 43

All .117 68 55 32 172

FIG. 2c and d.-Ventriculograms of the same infant on the same day,showing Grade 2 hydrocephalus and craniolacunia.

and sacral 60% (nine out of 15). When themeningomyelocele involved the lumbar region theincidence of hydrocephalus was 89%, as comparedwith an incidence of 63% when only other siteswere involved.

Cases with lumbar involvement are not onlyassociated with a higher incidence of hydrocephalus,but usually they also have more serious neurologicaldefects. The incidence of paraplegia in this groupwas 84% (108 out of 129), as compared with 21%in those 45 whose lesion did not involve the lumbarsegments. Altogether 117 out of 172 infants hadsome partial or complete flaccid paralysis of theirlower limbs (68%) (Table 8).

There was a close relationship between paraplegiaand the incidence of hydrocephalus. Of 117 infantswith paraplegia 109 (93%) had an associated hydro-cephalus, as compared with an incidence of only

384

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SYSTEMATIC VENTRICULOGRAPHIC STUDIES IN INFANTS

60% among 55 infants without paraplegia (Table 9).If these two sets of circumstances are combined

(Table 10) it is seen that if an infant had a lumbarmeningomyelocele with paraplegia, the incidence ofan associated hydrocephalus was 96% (104 out of108). If there was no paraplegia, or if the meningo-myelocele did not involve the lumbar segments,then the chance of hydrocephalus was much less.Of 64 such infants 38 (60%) had hydrocephalus.

Prognosis. In this section those 115 infants willbe considered who had been admitted up to andincluding March 1960. The survivors have beenobserved for a minimum of eight and a maximumof 23 months at the time of this analysis in December1960.

FIG. 3a and b.-Clinical photographs of another infant withoutclinical evidence of hydrocephalus.

TABLE 9

RELATION OF PARAPLEGIA TO INCIDENCE OF HYDRO-CEPHALUS ON VENTRICULOGRAPHY

(January 1959-November 1960)

All Hydro- No Hydro-Cases cephalus cephalus

No. % No. ° No. %

Paraplegia .. .. 117 68 109 93 8 7No paraplegia .. .. 55 32 33 60 22 40

Total .. 172 100 142 83 30 17

FIG. 3c and d.-Lateral views (one in the erect and one in the upsidedown position) of the same infant, on the same day, showing con-

siderable dilatation of all parts of the lateral ventricles (Grade 2hydrocephalus and craniolacunia).

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ARCHIVES OF DISEASE IN CHILDHOODTABLE 10

INCIDENCE OF HYDROCEPHALUS RELATED TO SITE OFMENINGOMYELOCELE OR ENCEPHALOCELE AND TO

PARAPLEGIA

All HydrocephalusSite Paraplegia Cases

(No.) No. %

Lumbar .. .. + 108 104 96Lumbar .. .. 21 11 52

All other sites ..22

63

(a) Infants with No Hydrocephalus. It was ofconsiderable importance to watch the physical andmental development of those infants who did nothave hydrocephalus at the time of the ventriculo-graphy. Of the 22 followed for eight months ormore, none developed clinically detectable hydro-cephalus. One infant died at 8 months of age,and all the others are 1 year old or more. Thehead circumference at 1 year of age was slightlyover the 90th percentile in three, it was normal (10thto 90th percentile) in 11 and it was only slightly ormoderately below the 10th percentile in five. One

of these infants had a most extensive thoraco-lumbar meningomyelocele which could be onlypartly repaired. Nevertheless, she has no para-plegia, and did not develop hydrocephalus. At1 year of age her head circumference was only171 in. (43 * 5 cm.) (Fig. 4a and b). She had anormal intelligence.

Finally, three infants with occipital encephalocelesbecame obviously microcephalic. One of these diedin another hospital at 8 months of age with broncho-pneumonia. The autopsy was not detailed, but noevidence of hydrocephalus was found. The headcircumference of the other two extremely retardedinfants was only 16 in. (40 5 cm.) at 12 months ofage. One of these has very poor vision, and thedevelopmental quotient of both is well below 50.Only these three infants with occipital encephalocelehad an intellectual defect.

It would have been of great interest to repeat theventriculogram in all 22 of these infants to provethat they did not develop hydrocephalus. In viewof their good clinical progress this would have beenunjustifiable. The ventriculograms, however, wererepeated in three infants whose head circumference

FIG. 4a and b.-A 12-month-old infant whose extensive thoraco-lumbar meningomyelocele could only partlv be repaired, but who hada normal ventriculogram. No hydrocephalus had developed by 18 months of age.

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SYSTEMATIC VENTRICULOGRAPHIC STUDIES IN INFANTS

FIG. 5a and b.-Ventriculograms of an infant with a lumbo-sacral meningomyelocele repaired when she was 1 day old. The ventriculogramswere performed at 6 and 35 weeks of age respectively.

exceeded the 90th percentile. None of them showedhydrocephalus at the second examination. Fig.5a and b shows the ventriculograms of such aninfant with a lumbo-sacral meningomyelocele whichwas repaired on the first day of life. The firstventriculogram was performed at 6 weeks, and thesecond at 35 weeks of age.

(b) Infants with Hydrocephalus. It is not withinthe scope of this paper to discuss in detail the outlookof the infants who had hydrocephalus. The naturalhistory of their disease was influenced by variousoperative procedures, and more than half have beentreated by a ventriculo-caval shunt. It is relevant,however, that 36 infants with hydrocephalus werenot subjected to operative treatment immediatelyafter ventriculography, but 11 were operated onlater, because their head circumference showed aprecipitous rise, well above the maximal normalrange. There were only three infants in the 36whose head circumference remained within thenormal range (8%) and six whose head circum-

ference pattern rose only moderately above the90th percentile line (16%). All these had onlyslight or moderate hydrocephalus on ventriculo-graphy. Most of the moderate and all the severecases of hydrocephalus showed a gross or precipitateincrease in head size, resulting in obvious clinicalhydrocephalus in 25 of the 36 (70%) before theyreached their first birthday (Table 11).

DiscussionBefore this study there were reports of large series

of cases of spina bifida cystica (meningocele andmeningomyelocele) and cranium bifidum (encephalo-cele) in which the site of the lesion was correlatedwith the incidence of hydrocephalus and in whichthe diagnosis of hydrocephalus was made either onclinical grounds or on autopsy evidence. Thedevelopment of hydrocephalus either as a sequelto the operation on the meningomyelocele or in-dependent of such procedures has also been dis-cussed at length.

TABLE 11HEAD CIRCUMFERENCE PATTERN OF INFANTS AFTER VENTRICULOGRAPHY

NormalTotal Micro- 1St9th Range 95th Grossly Died

cephalic Percentile I Oth-90th Percentile Enlarged EarlyPercentile

Infants with no hydrocephalus .. .. 22 3 5 11 3 - -

Infants with hydrocephalus who werenot operated upon .36 _ _ 3 6 25 2Grade I 2 - I I - -

Grade 2 .26 - - 2 5 17 2Grade 3 .8 _ - - - 8 -

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ARCHIVES OF DISEASE IN CHILDHOOD

Ingraham and Matson (1954) studied 1,433 casesof spina bifida cystica and cranium bifidum in thecourse of some 20 years. Of these, 187 were casesof encephalocele, 396 were considered to be simplemeningoceles and 754 were meningomyeloceles.The proportion of simple meningoceles (in whichthe sac does not contain neural elements) was muchhigher than in the present series. The very lowincidence of meningoceles in our material corre-sponds well with the series of Laurence (1960)who found only 9% of cases of meningocele in aseries of 407 cases of spina bifida cystica seen inLondon.

In this series the incidence of hydrocephalus, asshown by ventriculograms, was closely linked withthe site of the meningomyelocele. This observationis similar to that of Laurence, who estimated that theoverall incidence of hydrocephalus in his series was62% (based presumably on clinical signs and autopsyevidence). He too found that the incidence ofhydrocephalus was highest when the meningo-myelocele involved the lumbar (80%) or thoraco-lumbar region (70%) and less common in purelysacral (50%) or thoracic (43%) lesions. Ingrahamand Matson (1954) considered that internal hydro-cephalus was probably present in some degree inalmost all patients with the Arnold Chiari mal-formation and that the hydrocephalus was of thecommunicating variety.

There has been no conclusive evidence so far toshow whether the hydrocephalus is an essential partof the developmental disorder, and is present atbirth, or whether the hydrocephalus develops laterduring the first year of life possibly as a result ofoperative interference or of meningitis resultingfrom an ascending infection.Macnab (1958), discussing 200 cases (a part of

the 407 reported by Laurence in 1960), found that32% showed evidence of hydrocephalus at birth,in 16% the onset was between the 2nd and 3rdmonths and in 7% progressive hydrocephalus onlybecame evident after about one year of observation.The criteria of the diagnosis of hydrocephaluswere not stated, and it seems that the diagnosis wasbased on clinical evidence. Schaffer (1960) statedthat many meningomyeloceles were associated withhydrocephalus at the onset, while in some infantshydrocephalus made its appearance early and pro-gressed speedily.Our findings indicate that hydrocephalus is

frequently present in those infants whose head is notenlarged at the time and who show none of the otherclinical signs which are accepted as evidence ofhydrocephalus. We found this in 55 (39%) out of142 infants with hydrocephalus. A similar obser-

vation on a smaller scale was made 20 years agoby Shapiro and Tosti (1940) who found ventriculo-graphic evidence of hydrocephalus in six consecu-tive infants before the operation on their meningo-myeloceles and whose head circumferences werenormal at the time of the examination.The ventriculograms in this series were performed

on very young infants, either before or very soonafter the repair of the meningomyelocele or en-cephalocele. No hydrocephalus developed sub-sequently in any infant who showed no hydro-cephalus at this examination, in spite of the repair oftheir meningomyelocele or encephalocele. It hasbeen shown that hydrocephalus, therefore, is anintegral part of the clinical syndrome and is probablypresent right from the beginning in all those infantswho subsequently develop clinical signs of thecondition. In a very few cases the hydrocephalusremains subclinical throughout, but in the largemajority this becomes manifest within the first twomonths of life. In view of these observations it ishardly necessary to discuss the mechanism of thedevelopment of the hydrocephalus following opera-tive removal of the meningomyelocele. Neverthe-less, Ingraham and Matson (1954) may well be rightin their judgment that in some cases of meningo-myelocele the associated Arnold-Chiari malfor-mation in which the cerebrospinal fluid circulationis impaired only to a minor degree, may be disturbedby removal of the meningomyelocele. The operationmay precipitate a more severe degree of obstructionof the cerebrospinal fluid's pathway and this may befollowed by acute or slowly progressive hydro-cephalus. They consider that this is the cause ofthe hydrocephalus after surgery, and not the de-crease in the available absorptive surface, resultingfrom the removal of the sac. I would like to modifythis view by suggesting that even in these cases thehydrocephalus was already present at the time of theremoval of the sac, but that its progression to clinicalhydrocephalus might have been accelerated.

It is possible, of course, for hydrocephalus todevelop in those infants who did not have hydro-cephalus before, or whose hydrocephalus was oftrivial degree, if they should develop a pyogenicmeningitis. This unfortunately is a commoncomplication of meningomyelocele and may welloccur in the mildest cases with disastrous results.In Macnab's (1958) series of 200 cases the incidenceof meningitis was 18%. The meningitis usuallyoccurs very early, and is often fatal. In this study,ventriculograms were either never performed inthese infants or were done only after recovery fromthe meningitis, by which time evidence of grosshydrocephalus was usually available. Pyogenic

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SYSTEMATIC VENTRICULOGRAPHIC STUDIES IN INFANTS 389

meningitis will, of course, also aggravate existinghydrocephalus. This has been shown in severalinfants in this series.

Summary and ConclusionsThe following conclusions can be drawn from

this investigation: (1) There is an 80% incidence ofhydrocephalus in association with meningomyeloceleand encephalocele in infants. This hydrocephaluscan usually be detected in the first few days or weeksof life, even if the size of the head is not larger thannormal, and other signs of increased intracranialpressure are not present. (2) The incidence ofhydrocephalus is far higher in infants whosemeningo-myelocele involves the lumbar region, than whenit involves other sites, and is far higher if there isassociated paraplegia; 96% of infants with para-plegia and a lumbar meningomyelocele, and 95%of infants whose head circumference was over the90th percentile in the first few weeks of lifehad radiologically demonstrable hydrocephalus.(3) There is no evidence that repair of the meningo-myelocele in the early neonatal period influencesthe development of hydrocephalus. No infant

who did not have hydrocephalus at the first exami-nation developed clinical or other evidence of hydro-cephalus during a period of follow-up lasting up to23 months. (4) It is desirable to perform routineventriculography in babies with meningomyeloceleas soon as possible after birth. This is of greatprognostic value and is useful as a guide to treatment.

I have great pleasure in thanking Mr. R. B. Zachary forhis constant co-operation and for making this investiga-tion possible, Dr. T. Lodge and Dr. R. G. Grainger forthe radiographs and help in their interpretation; andmany paediatricians from a wide area who are kindlyreferring their cases to us; Mr. P. Rickus for the photo-graphic work, and many resident doctors and the nurseswho bear the brunt of the day-to-day care of thesedifficult patients, and Professor R. S. Illingworth forhis critical comments.

REFERENCES

Ingraham, F. D. and Matson, D. D. (1954). Neurosurgery ofInfancyand Childhood. Thomas, Springfield, Illinois.

Laurence, K. M. (1960). The natural history of spina bifida cystica.Proc. roy. Soc. Med., 53, 1055.

Macnab, G. H. (1958). Spina bifida cystica. In Recent Advancesin Paediatrics, ed. D. Gairdner, 2nd ed., chap. 7, pp. 201-13.Churchill, London

Schaffer, A. J. (1960). Diseases of the Newborn. Saunders, Phila-delphia.

Shapiro, B. and Tosti, V. G. (1940). Ventricular dilatation in spinabifida. J. Pediat., 16, 318.