Assessment of Gestational Age by Neurological Examination R
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Arch Dis Child: first published as 10.1136/adc.41.218.437 on 1 August 1966. Downloaded from Arch. Dis. Childh., 1966, 41, 437. Assessment of Gestational Age by Neurological Examination R. J. ROBINSON From the Nuffield Neonatal Research Unit, Institute of Child Health, Hammersmith Hospital, London W.12 In recent years there has been rapidly increasing ence in assessment of muscle tone, to be practicable interest in babies whose birthweight is low because for general use. The present paper reports a study their intrauterine growth has been retarded, and it of the presence and absence of a number of reflexes has been recognized that the clinical problems of in relation to gestational age. Certain of them were these 'small-for-dates' babies differ from those of found to have sufficiently predictable times of true prematures. They rarely die from respiratory appearance to provide simple and reliable indices of distress syndrome or intraventricular haemorrhage, gestational age. but are particularly susceptible to symptomatic hypoglycaemia and intrapulmonary haemorrhage Clinical Material and Methods (Gruenwald, 1963; Dawkins, 1965). It is, there- Eighty-five babies were studied in the Neonatal fore, a matter of practical importance to know Ward at Hammersmith Hospital. Since the aim was to whether a particular baby of low birthweight is truly analyse the behaviour of normal babies of known premature or small-for-dates, a distinction that gestational age, 23 were omitted from the analysis because either their gestational age calculated from the depends on accurate knowledge of the gestational copyright. age. This is most accurately measured by calcula- menstrual dates was uncertain or they had neurological abnormalities. Of the remainder, 37 (19 male, 18 tion from the first day of the mother's last menstrual female) were classified as 'normal weight' and 25 (13 period, provided her cycle is regular and her memory male, 12 female) as 'small-for-dates'. 7 of the normal correct. Often, however, these conditions do not weight group and 6 of the small-for-dates group were of hold, and some independent method of assessing mainly West Indian or African parentage. The birth- gestational age is required. Small-for-dates babies weights and gestational ages of both series are plotted in cannot be recognized from their general appearance Fig. 1. which is often indistinguishable from that of http://adc.bmj.com/ true prematures (Gruenwald, 1963). Most bodily +2SD dimensions are affected by the intrauterine growth +I SD retardation. Head circumference is a possible 4000 exception, but its normal variation is such that it Mean does not by itself give a sufficiently accurate estimate '," < -I SD of gestational age. Epiphysial development is a 3000 poor index of maturity since it is retarded in small- as for-dates babies (Scott and Usher, 1964; Wiggles- on September 24, 2021 by guest. Protected ._ worth, 1966). 2000 " * ° ') @ * . It has been suggested that the best criteria of 0 Babies Stuidied 4 0 0 maturity are based on neurological development I- / °,/. ' Normal weright to Small for cdates (Gesell and Amatruda, 1945) which is unaffected 1000 o *,,' , * *~~~ by intrauterine growth retardation (Bergstr6m, Gunther, Olow, and Soderling, 1955; Saint-Anne Lines derived trom Dargassies, 1955; Illingworth and Holt, 1963). / Perinotal Survey However, the methods so far proposed for 'dating' 28 32 36 40 44 babies by neurological examination have been Gestation (weeks), ow6t > insufficiently precise, or required too much experi- ~-2SD FIG. 1.-Birthweights and gestational ages of the normal weight and small-for-dates babies studied. The lines for mean and standard deviations are derivedfrom the data of Received February 10, 1966. the Perinatal Mortality Survey (Butler andBonham, 1963). 437 Arch Dis Child: first published as 10.1136/adc.41.218.437 on 1 August 1966. Downloaded from 438 R. J. Robinson Definitions. The lines for mean birthweight and group are of most interest and the other groups will standard deviations shown in Fig. 1 were derived from only be briefly reported in passing. the data of the Perinatal Mortality Survey (Butler and Bonham, 1963) by the late Dr. Michael Dawkins. He pointed out that the standard deviations were excessively Responses constantly or almost constantly high at the low gestational ages, because there were very present. The palmar and plantar grasp responses few babies and some had obviously incorrect gestational were present in all the observations on all the babies, ages. Consequently if 'more than two standard deviations though in babies of less than 30 weeks' gestation the below the mean birth-weight' is taken as the definition of palmar grasp consisted of flexion of the fingers only. small-for-dates, it is a far more stringent requirement The withdrawal response on stimulation of the sole of for babies below 36 weeks than above, and many infants the foot was present in 98% of all the examinations. whopresentthe clinical and post-mortempicture of'small- The abduction and extension phase of the Moro for-dates' are excluded. Small-for-dates has therefore reflex was present in 99% of examinations, though been arbitrarily defined as 'more than 25% below the mean birthweight for the gestational age'. Above 36 in babies less than 28-29 weeks' gestation the weeks' gestation this corresponds to more than 2 standard response was feeble and of low amplitude. The deviations below the mean. The normal weight group Galant response (lateral incurvation of the trunk on were all less than 20% below the mean birthweight. stimulation of the lumbar skin) was present in 870% of examinations and the blink response to light in Methods of examination. A standard neurological 82%. All these responses were obtained even in examination was devised in which the following 20 babies of 26 weeks' gestation. The slight variability reflexes and responses were tested: blink response to of the last 2 seemed partly dependent on the state of glabellar tap, palmar and plantar grasp, traction response, arousal and partly on undiscovered causes. The plantar reflex, withdrawal on stimulation of foot, crossed extensor reflex, abdominal and cremasteric reflexes, presence of the abdominal reflexes was very depend- tendon jerks (biceps, knee, and ankle), asymmetrical ent on state of arousal, but provided the baby was tonic neck reflexes, neck-righting reflex, Moro reflex, not moving or crying they were present in 95% of Galant reflex, head-tuming towards diffuse light, blink observations, including those on the most immature response to light, and pupil size and reactions to light. babies. copyright. (The meanings of these terms are explained where necessary in the results section.) The responses were Responses dependent on gestational age. tested as described by Prechtl and Beintema (1964) with The presence of 10 responses was found to show a slight modifications to reduce the amount of handling of positive correlation with gestational age. 5 of these the very small babies. The responses were recorded as present, doubtful, or absent on each side of the body (pupil reactions, glabellar tap, traction and neck- where appropriate. With the more complicated righting reflexes, and head-turning to light) responses each part was recorded separately. For each appeared at definite times in the gestational period, recording of a response, the 'state of arousal' of the baby which were the same in the normal weight and the http://adc.bmj.com/ at the time was recorded following the system of Prechtl small-for-dates groups. The other 5 responses and Beintema. Where there is a 'required state' for a (crossed extensor, adduction phase of Moro, reflex to be elicited, babies were only tested in this state. asymmetric tonic neck and cremasteric reflexes, and knee-jerks) behaved less predictably and the Times and numbers of examinations. Examina- correlation with gestational age was a looser one. tions were carried out 1 i-2 hours after feeds if possible. Where possible, serial examinations were done once or Methods ofanalysis and presentation ofdata. twice a week in order to obtain a longitudinal study of a on September 24, 2021 by guest. Protected particular baby. All examinations were made by the Certain methods are used in the analysis of results author; a total of 219 was performed (normal weight for each of the responses, and these will be explained group, 125; small-for-dates, 94). first. (1) Gestation from 25 weeks onwards is divided Results into 3 (or occasionally 4) periods-the first being the The responses studied fell into 4 main groups. period when the response is usually absent, the (1) Responses constantly or almost constantly second an intermediate period, and the third a period present whatever the state or gestational age of the when the response is usually present. For each baby. (2) Responses whose presence or absence period the number of occasions on which the depended mainly on gestational age. (3) Responses response was found present or absent respectively is that were very dependent on the state of arousal. counted from all the examinations on all the babies (4) Responses that were variable from baby to falling in that gestational period (whether they were baby and from time to time from undetermined born in it or attained it after birth). The results are causes. For the present purposes the second recorded as bar diagrams, the number of babies (N) Arch Dis Child: first published as 10.1136/adc.41.218.437 on 1 August 1966. Downloaded from Assessment of Gestational Age by Neurological Examination 439 on whom the observations were made being recorded under the bars. Results from the normal weight and small-for-dates groups are recorded separately and compared. This method has the advantage that it combines the 'longitudinal' studies of individual babies with the 'transverse' study of all the babies. It is open to the theoretical objection that since unequal numbers of examinations are I, made on different babies the results may be unduly weighted by many observations on a single baby.