652

BODY-FLUIDS IN EPILEPSY

THERE has been a good deal of discussion about îthe relation of the water and acid-base balance of

Iepileptic patients to their fits. Lately the observa- 1tion that antidiuretics and a large fluid intake increase r

while diuretics and restricted ’fluids decrease the anumber of fits has supported an earlier finding. One 1of the characteristic changes previously described is j

that body-weight rises before a fit and falls after it. 1Greville, Jones and Hughes have worked out the j

relations between body-weight, fluid intake and output, (

gain and loss of metabolic water, variations of 1insensible water loss and such like in detail for three patients and a normal control over a period of months,during which all four were kept on standard diets. ,

They suggest that the weight changes observed are ,

due to changes in the water content of the body, andthat the retention is most probably in the blood- ,stream, because the total nitrogen and total solids ofthe blood fall as the water excretion rises and viceversa. The rise and fall in weight before and after afit occurred however in rather less than half the fitsobserved; in the remainder there was a negative waterbalance. This inquiry settles the relation betweenweight changes and body hydration, but it does notexplain the relation between hydration and seizurefrequency.

Gibbs, Lennox and Gibbs 2 have investigated thecarbon-dioxide content of arterial and venous bloodin epileptics. They divide their case material intothree classes-the grand-mal type, the petit-mal type,and a mixed type, in which there are both grand- andpetit-mal fits. They found that the grand-mal typehave a high carbon-dioxide content in the blood, thepetit-mal type a low one, and the mixed type a rangesimilar to that of the normal controls. There is alsoan abnormal fluctuation in the carbon-dioxide of theblood in epileptics. A simultaneous study of the

oxygen content shows that the abnormally low levelof carbon-dioxide before a petit-mal fit and the riseafter it do not depend on changes in blood-flow or intissue oxidation in the brain. With grand mal thereis a steady rise for several days before a fit whenthere is a fall; they could not determine whether thefall takes place with or before the fit. The carbon-dioxide level then rises again until another fit occursand so on. The grand-mal picture is thus the converseof the petit-mal, and this is strikingly borne out bythe electroencephalograph. The records from thisinstrument are distinct for the two types of seizure.In the grand-mal type there is a train of fast waves,while the energy in the petit-mal encephalogram liesin the slow waves. Moreover, raising the carbon-dioxide content of alveolar air or internal jugularblood increases the frequency of the brain waves, andlowering it reduces their frequency, whether the wavepattern is normal or abnormal. The fluctuation incarbon-dioxide content is elaborated by Nims and hiscolleagues who have demonstrated that on over-

breathing the carbon-dioxide level of the blood dropsfurther and stays low longer in the epileptic than inthe normal person. Overbreathing is known to be afactor in precipitating petit mal, and they have tracedthe course of the three variables, base bicarbonate, pH,and carbon-dixoide tension, by plotting them triaxially(using the method of Shock and Hastings) after a

period of overbreathing. Blood samples were takenat short intervals, and the course of the three variables

1. Greville, G. D., Jones, T. S. G. and Hughes, W. F. G. J. ment.Sci. 1940, 86, 195.

2. Gibbs, E. L., Lennox, W. G. and Gibbs, F. A. Arch. Neurol.Psychiat. February, 1940, p. 223.

3. Nims, L. F., Gibbs, E. L., Lennox, W. G., Gibbs, F. A. andWilliams, D. Ibid, p. 262.

was found to be typical. The normal traces out aloop which is small and narrow, showing relativelylittle alteration in the acid-base balance, while the

petit-mal epileptic produces a loop which is large andwide, indicating a shift toward a fixed acid acidosis.The mechanisms which regulate the physico-chemicalstate of the fluids of the body, and hence of the

brain, are thus impaired in petit mal so that they arenot able quickly and adequately to adjust the acid-base balance when it is disturbed. These two papersmake it clear that in epilepsy there is an instabilityof the acid-base balance, with different pictures for thetwo types of epileptic fit. Moreover, they have estab-lished that there is some inherent difference in thereaction of the epileptic since the physico-chemicalchanges produced by overbreathing will precipitate anattack of petiti mal in an epileptic but not in a normalperson. Finally, artificial changes in carbon-dioxidecontent will not precipitate a fit unless they are moreextensive than those observed in a spontaneous fit.

EYESTRAIN IN INDUSTRY

THE illumination of factories and workshops is atlast receiving the attention it deserves from industrialwelfare officers, and it formed the subject of a leadingarticle in the February number of Aircraft Produc-tion, the journal of the aircraft manufacturingindustry. The lighting requirements of various typesof work are very variable and it is essential thatengineers and architects planning the lighting ofworkshops and offices should be guided by the need ofindividual workers or teams of workers rather thanby the claims of symmetry. For instance, theintensity, quality and background of the lightingrequired are quite different for workers who are paint.ing aeroplane wings and for those engaged on fineadjustments of parts of an engine against a micro-meter. For the former a diffuse even illumination ofmoderate intensity is adequate, whereas the latterneed powerful focal illumination from an appropriatesource near the work but not shining directly intothe worker’s eyes, with a subdued background. Forwork requiring concentrated visual attention to detailcareful photometric readings should be taken of theintensity and quality of light that allows the workmanto do his job efficiently with the least fatigue. Glareand too great an intensity of illumination as well asinsufficient lighting are causes of retinal fatigue.Laymen often express concern about the possibility ofcausing progressive and permanent damage to eyesightby working under artificial light. It is true that someadult ’myopes may have their refractive disorderincreased by long hours of close work under insuffi-cient illumination when their general health is belownormal, but in the case of low and moderate degreesof myopia this does not impair their sight when cor-rected by appropriate glasses. It is also a fact thatpeople with unstable binocular muscle balance andconvergence and accommodation weakness who havehad no symptoms when employed out of doors maysuffer from headaches, eyestrain and inability to concentrate when their occupation is changed to closework. These muscular deficiencies do not lead to

impairment of vision but are the cause of a break-down and inability to continue close work. Theworker’s general health, in particular his opportuni-ties for outdoor exercise, regular meals of good food,relaxation, sleep, interest in his work and his psycho-logical make-up, as well as the air and lighting of hisworkshop, are factors in causing an ocular break-down. Certain ocular aids such as polaroid glasses,for use on highly polished surfaces, binocular magni-fiers, tinted lenses and other protective devices serve

653

a useful purpose in industry. The ideal could berealised by a thorough and careful preliminary eyeexamination of all workers to detect refractive errorsand muscle imbalances and insufficiencies as well asocular disease. Workpeople could then be groupedaccording to their ocular fitness for certain types ofwork. Industrial investigations should be made onthe optimum conditions of lighting and posture forthe workman. Many data would have to be collectedbefore any definite opinion could be passed aboutthe effect of certain forms of work on the eyes andthe incidence of industrial ocular fatigue. Such astudy would require the cooperation of the physio-logist, physician, psychologist, ophthalmologist andsocial-welfare worker.

SHAPE OF THE FEMALE PELVIS

FOR some years there has been a growing realisationthat all was not well with the accepted classification ofpelvic deformity in women. Certainly knowledge waslacking about the effect of the bony pelvis on thecourse of labour. For practical purposes the pelvishas been looked upon as consisting of an inlet and anoutlet. Any variation in the size and shape of theformer has commanded attention, especially in regardto its measurement and relationship to the positionof the foetal head, and a special but rarely seen

mechanism was devised for the passage of the foetalskull through the flat pelvic brim. The contractedpelvic outlet received less attention, probably becauseit was more difficult to detect. Usually the diagnosiswas made at the time of an obstructed labour. Forsome reason it was thought to be associated for themost part with a kyphosis of the spine, an entirelyerroneous supposition. This was the state of affairsin the majority of teaching centres before Caldwelland Moloy began to publish their papers on the

subject. Their investigation was aided by pelvic radio-graphy and they made use of the precision stereo-

scope, whose value is now established wherever it hasbeen employed. The variations of the female pelvis,they suggest, should be classified into four main types,the anthropoid, gynecoid, platypelloid and android,intermediate types being common. This classificationin itself is important, but Caldwell and Moloy nextdirect attention to the necessity for considering thepelvis not merely as an inlet and an outlet but as abony birth-canal, in which deformities or obstructionsmay be met with at any level or plane. They putforward a plan for the accurate analysis and assess-ment of information obtained by radiography of theshape and capacity of the whole bony canal. Lastlythey consider the influence of the pelvic shape on thecourse of labour and any obstetrical manipulationsthat may be necessary to assist delivery. Their viewsprovide an explanation, hitherto absent in textbooksof obstetrics, of phenomena that have been observedtimes without number. For example, it has beenaccepted that the foetal skull only assumes the per-sistent occipito-posterior position if it is poorly flexedwhen it reaches the pelvic floor. Yet all who practiseobstetrics have constantly had to examine and deliverthe foetus in that position when the head was most cer-tainly fully flexed. This has not been an error injudgment or diagnosis. The explanation is forth-coming in a study of the bony birth-canal in theandroid pelvis. Caldwell and Moloy have made a

useful contribution to our knowledge of pelvic varia-tions and have also brought out the necessity for athorough and intelligent investigation of each bonypelvis. Neverthelessi they have made it clear that too

1. Caldwell, W. E. and Moloy, H. C. Edinb. med. J. 1939, 46,Transactions 1, 37.

much attention need not be directed to minor deformi-ties. These will usually give rise to no trouble, pro-vided that strong physiological uterine action is notreplaced by the feeble, irregular contractions that areoften the products of misguided attempts.at the induc-tion of premature labour.

LIGATURE OF THE PATENT DUCTUS

ARTERIOSUS

CONGENITAL deformities supply an obvious field forconstructive surgery, and much has been achieved init, especially by plastic and orthopaedic surgeons. Butthe problems of cardiac malformation have remainedwithout a single solution until Gross 1 announcedsuccessful ligature of the patent ductus arteriosus in4 cases, more than thirty years after Munro 2 firstsuggested its possibility. The ductus Botalli commonlyremains patent to compensate for some more seriousabnormality, and then its surgical obliteration wouldclearly be undesirable, but in 92 of the 242 cases

reviewed by Abbott it was the sole cardiovascularlesion. As many as 28 of these patients died ofinfective endocarditis, 40 of heart failure and 2 ofrupture of the ductus, and their average age at deathwas twenty-four years. Apart from its threat to lifethe lesion may shunt enough blood from the aorticcircuit seriously to impair a child’s nutrition. Fromthese considerations Gross formulates his criteria foroperation, and rightly insists that the mere diagnosisof an uncomplicated patent ductus is not enough towarrant intervention. In short, he requires evidencethat the ductus is enlarging, that a child is notdeveloping properly or that the heart is carrying anincreased burden. The threat of infective endocarditisalways remains to be thrown into the scale againstdelay.

Gross worked out his method of approach by studyof the human cadaver and experiments on living dogs.He found that a good view of the ductus was obtainedby entering the thorax through the left pleural cavityand temporarily collapsing the lung. The mediastinal

pleura is then incised to expose the pulmonary arteryand aortic arch, and dissection of the fat and areolartissue filling the sulcus between them follows, a pro-cedure requiring great care and patience which inone case took nearly two hours. It was found crucialhere to isolate the recurrent laryngeal nerve, not onlyto avoid injuring it but also because it leads surely tothe ductus. Added difficulty may be caused by a highreflection of the pericardium or by the ductus beingunusually thin-walled. In one case the wall tore, anddeath was only averted by superb nerve and skill andby an immediate blood-transfusion. Before actualligature a temporary occlusion for two or threeminutes was practised in order to gauge its effect onthe circulation. Gross’s four patients, who were agedseven, eleven, seven and seventeen years, all recoveredrapidly, and there were no postoperative complications.The thrill disappeared in every case. In the first twoa faint to and fro murmur persisted, but in the secondtwo, with a change in technique from single to doubleligature, the murmurs were abolished. In every casethe low preoperative diastolic pressure was restored tonormal, and the heart lost its tumultuous action. Intwo cases blood-flow studies were made by takingsamples of blood for oxygen content from the aorta,the ductus, the main pulmonary artery and the leftpulmonary artery before and after ligature of the

1. Gross, R. E. Trans. Amer. surg. Ass. 1939, 57, 8.2. Munro, J. C. Ann. Surg. 1907, 46, 335.3. Abbott, M. E. Congenital Heart Disease. Nelson’s Loose

Leaf Living Medicine, vol. iv, p. 207.