J . ment. Defic. Res. (1973) 17, 89 89

EVALUATION OF PHYSICAL MATURITYIN ADOLESCENT MENTALLY RETARDED BOYS

A. T. RUNDLE and P. E. SYLVESTER

St. Lawrence's Hospital, Caterham, Surrey

Bourtourline-Young, GreuHch, Gallagher, Cone and Heald (1968), in a studyof physical maturity at adolescence derived a formula for puberal maturity, stated as;

0.5 (pubic hair rating) + 0.4 (testicular voiume rating) + 0-3 (axillary hair. rating) -f 0.5 = puberal age. . . . . , _ . _

This equation, according to the authors, gives a quick and precise method forcalculating puberal maturity and correlates very highly with the clinical assessmentmade by five independent experienced investigators.

The equation was derived from data on normal children of West Europeanorigin, and we considered that in view of the reported widespread abnormalities inmaturation of mentally retarded children (Rundle and Sylvester 1962, 1963 and1965; Sylvester and Rundle, 1962; Flory 1936; Mosier, Grossman and Dingman 1962;Dooren, 1967) its applicability to such an abnormal population should be assessed.

METHODSPubic hair

The five standards of Tanner (1962) were adopted since they correspond to the0-4 stages used by Bourtourline-Young et al. (1968).

Axillary hairIn our original publication (Rundle and Sylvester, 1963) axillary hair was

assessed by the four stage standards of Quaade (1955), i.e.,Stage 1 Lanugo during infancyStage 2 Occasional, pigmented and non-curlingStage 3 Sparse, pigmented and curlingStage 4 Fully developed axillary hair.As it appears that the first two stages correspond to the first three stages of

Bourtourline-Young et al. (1968), some re-evaluation of our data was necessary.

Genital developmentThe five standard ratings of Tanner (1962) were used.

Testicular volumeOur methods for the estimation of testicular volume are reported in detail

elsewhere (Rundle and Sylvester, 1962) which, briefiy, involve the measurement ofthe length and breadth and width of the testis through the scrotum by means ofmodified Harpcndcn skinfold calipers and the subsequent application of the formulaof Lambert (1951):

Testicular volume =0 .71 X length X breadth X width.

Received 26th January, 1973

90 MENTALLY RETARDED BOYS

The testicular volumes so obtained were then transposed into the scale rating ofBourtourline-Young et al. (1968) using the volume quoted by them.

Skinfold thicknessSkinfold thickness was determined by means of the Harpenden skinfold calipers

(Edwards, Hammond, Healy, Tanner and Whitehouse, 1955; Tanner and White-house, 1955) at the triceps and subscapular sites. For the purpose of this communica-tion only the triceps values have been included, but the findings derived from theseare equally applicable to those of the subscapular region.

Skeletal ageStandardised X-rays of the hand and wrist were compared with standards

(Greulich and Pyle, 1959) either blind on at least two occasions or until the differencesbetween consecutive assessments were less than one standard.

Miscellaneous anthropometric dataStanding heights, sitting heights, biacromial widths and pelvic widths were

measured to the nearest 0.1 cm using standard anthropometric techniques. Weightwas measured to the nearest 0.1 kg by a precision balance.

Subject material

Sixty-nine mentally retarded boys were selected after the elimination of thosecases where genetic, metabolic, traumatic or infiammatory mechanisms could be thecause of their mental retardation. An age range of ten to seventeen was taken sincethe lower limit would include any cases with an early onset of puberty (as suggestedby Dooren, 1967) and the upper limit would include some cases who had achievedfull puberty (Rundle and Sylvester, 1963).

RESULTSFig. 1 shows the puberal maturity index as determined by the formula of

Bourtourline-Young et al. (1968) of all cases plotted against chronological age. The

Table 1Coefficients of correlation of seven variables against age [inyears), puberal

maturity index [see text), and puberal maturity index with ageeffect partialled out

Puberal IndexVariable Age Puberal Index {age partialled out)

0.810.490.420.350.16

0.29

WeightStanding heightSitting heightBiacromial widthPelvic widthPuberal indexSkeletal age

0.600.750.700.230.70

0.870.790.740.390.63

0.69

A. T. RUNDLE and P. E. SYLVESTER 91

P 10 11 12 13 U IS U 17

Chronological age (yrs)

Fig. 1. Puberal maturity index (see text) of sixty-nine menially retarded boys,aged ten to seventeen years, plotted against chronological age.

curve represents the yearly means smoothed by eye and demonstrates the pubertalspurt from thirteen to seventeen years which is in agreement with data on a similargroup of boys presented elsewhere (Rundle and Sylvester, 1962 and 1963). Althoughthere appears to be considerable scatter about the means, this is not so marked aswhen trsticular volume is used as the criterion (Fig. 2). The same data, i.e. puberalindex, is presented in Fig. 3, but plotted against skeletal age. The curve for the mean inFig. 3 resembles that of puberal index against age (Fig. 1), but the degree ofscatter isreduced, and more closely resembles the curve for testicular volume against skeletalage (Rundle and Sylvester, 1962). In Fig. 4 the triceps skinfoldthicknessofoursample(with some additional cases aged five to ten years) is plotted against age. The degreeof scatter not only reflects the low correlation between this variable and puberty(also shown in the data of Bourtourline-Young et al.^ 1968), but is probably greaterthan that which would be found in normal boys due to the heterogeneity of oursample. Fig. 4 casts serious doubt on the value of single estimates of this parameter ina cross-sectional survey.

To make this study comparable to that of Bourtourline-Young et al. (1968),simple correlations between the puberal index and the seven variables are shown inTable 1. The two sets of correlations are not strictly comparable as the originalauthors correlated their variables with a puberal maturity judgement, but since theseauthors give a correlation between the clinical judgement and the puberal index as0.99, we consider that the degree of error arising from such a comparison is negligiblesince only general conclusions are drawn. Comparison of our correlations with those

92 MENTALLY RETARDED BOYS

Fig. 2. Testicular volume (deter-mined by the method of Rundleand Sylvester, (1962) of sixty-ninementally retarded boys, aged tento seventeen years, plotted againstchronological age.

7 V

Chronological age (yrs)

£" 4

toE— 3«

.n

• •

7 B 9 U 12 13 U

Skeletal age (yrs)

Fig. 3. Puberalmaturity index (seetext) of thirty-threementally retardedboys plotted againstskeletal age.

of the original authors shows that, with the exceptions of skeletal age and weight, ourdata do not correlate as well as theirs. Weight is notoriously inaccurate and mostinfluenced by exogenous factors, and skeletal age has been shown not to differsignificantly from normal boys (Rundle and Sylvester, 1963), but it is difficult tosuggest a reason why, of all the variables investigated, these two parameters shouldbe contrary to the general trends. Also included in Table I are the intercorrelationsbetween puberal index and the several variables with the age effect partialled out.The effect of this procedure is, in all cases with the exception of the weight, to reducethe coefficient of correlation considerably. It is suggested that the lower correlationin our data is a measure in our sample of a core of abnormal rate of maturation, orpossibly both.

In Fig. 5 the three physical maturity standards (pubic hair, genitalia and axil-lary hair) are plotted against testicular voiume. The horizontal bars indicate the

A. T. RUNDLE and P. E. SYLVESTER 93

Fig. 4. Triceps skinfold thick-ness (mm) of sixty-two boys,aged five to seventeen years,plotted against chronologicalage.

Age in years

U 1> l« 17

25th, 50th and 75th percentile, and the two most mature ratings in each case havebeen combined since it is our experience that the separation of these requires thegreatest degree of experience and is most open to error. Analysis of this data rulesout the use of means and standard deviations as the results were fotind to exhibit aconsiderable degree of positive skewness, particularly in the first two (most immature)stages. Differences between the three variables and the differing degree of overlapbetween stages is further evidence of individual differences in rates of maturation.

To test this further, thirty-four cases from our sample aged 10-13.5 years werere-examined to determine which physical criterion or combination of criteria firstindicated onset of puberty. Although it may be open to criticism, a testicular volumein excess of 5 ml, and in the other three criteria one or more stages above the pre-pubertat, were taken as evidence that the pubertal spurt had started. These resultsare given in Table 2. The variability in the criteria first presenting evidence ofpuberty is evident from Table 2, and confirms similar findings on mentally retardedboys and girls by Dooren (1967).

DISCUSSIONSuperficially at least, data on growth and niaturation appear to be simple to

collect, simpler to evaluate and give a reliable indication of normal physiologicalfunction, but experience soon indicates that this is not the case. Failure of growth andmaturation is regularly suggested as one of the most constant concomitants of mentalretardation with very little attention being paid to the nature of the group beinginvestigated other than their reduced intelligence. Most anthropometric surveys onthe mentally retarded have been criticised as either not segregating the sample into

94 MENTALLY RETARDED BOYS

Fig. 5. Pubic hair, genitaldevelopment and axillary hairratings of sixty-nine mentallyretarded boys, aged ten toseventeen years, plotted againsttesticular volume. The upperand lower horizontal barsrepresent the 25th and 75thpercentile, the middle horizon-tal bar represents the 50 thpercentile. In all three criteriathe two most advanced ratingshave been combined. Thenumber of cases in each ratingis indicated above the 75thpercentiie.

38

36

34

32

30

26

26

24

22

20

18

16

14

12

10

8

i

4

2

•

11

•

38

r

t

am

m

4

1

-L : 4

0

•

8

34 'Y

12

I.L T

2 3 4 - 5

Pubic hairrating

1 2 3 4 * 5

Genital deveiopmentrating

0 1 2 3 - 4

Axiliary hairrating

reliable diagnostic or aetioiogical categories, or, if such segregation has been made, thesubdivisions have little meaning in terms of pathology and at best could be regardedas of mixed aetiology (Marshall, 1966).

The present authors have shown elsewhere {Rundle and Sylvester, 1965) thateven after the elimination of those cases of known aetiology (and hence one supposesthe most abnormal) the remainder, often termed unclassified, can be shown in bothgrowth and maturation to consist of two distinct populations, a group whose growthconforms to a normal distribution and a second group whose growth is retarded, i.e.dwarfed in a pathological sense. The finding of this bimodality has been subsequentlyconfirmed by other authors (Roberts and Clayton, 1969). The proportion of cases ineach mode will vary considerably due to varying proportions of subjects of differingethnic origin and social background and it will vary from survey to survey due tolocal priorities in patterns of admission to the institution for the mentally subnormal.

There is little doubt that the equation for puberal maturity adduced by Bourtour-line-Young et al, (1968) can be of great use to the paediatrician dealing with normalchildren, whether he is using the index as a single unrelated test or as a comparisonin a longitudinal study, but its widespread use in populations where abnormalitiesarising from divergent causes are to be expected is not to be recommended.

A. T. RUNDLE and P. E. SYLVESTER 95

Table 2

Signs of first appearance of puberty in 34 boys aged 10-13.5years

Criteria J^umber Percentage

Prepubertal 8 23.5Testicular volume only 2 5.9Pubic hair only nil nilAxillary hair only 9 26.5Genital development only nil —Testes genital development 3 8.8Testes axillary hair 12 35.3

Total 34 100

We are of the opinion that if anthropometry is to be used in the study of mentalretardation there can be no short cuts, at least that can be envisaged in the presentstate of knowledge. Not only must a large number of variables be investigated (thepresent authors have adopted eighteen, but realise this number is probably too few),but even then the data must be analyses in the most stringent manner and the finalconclusions can only Ije, at best, information supporting data for the clinician, patho-logist and geneticist.

SUMMARYIn an attempt to make a fair, statistical evaluation of the application of the

equation for maturity of Bourtourline-Young et al. i.e.puberal age ^ 0.5 (pubic hair rating) + (testicular volume rating) + 0.3

(axillary hair rating) + 0.5,to the mentally subnormal, sixty-nine boys aged ten to seventeen years weremeasured with respect to weight, standing height, sitting height, biacromial and pelvicwidths, triceps and subscapular skinfold thickness, skeletal age, genital developmentrating, pubic hair and axillary hair ratings.

From these measurements data are obtained confirming that puberty in thementally retarded is a more diffuse process, and that the sequence of events is morevaried than in the normal. On the evidence of this information it is suggested that theuse of short cuts, such as the above equation, are not applicable to individuals drawnfrom an abnormal population.

ACKNOWLEDGEMENTSThe authors wish to express their appreciation to the nursing staff of St.

Lawrence's Hospital for their generous assistance.

REFERENCES

BouRTOURLiNE-VouNG, H., GREULICH, W. W., GAI.LAGHER, J. R., CONE, T . and HEALD, F.(1968) Evaluation of physical maturity at adolescence. Develop. Med. Child ^feurot. 10, 338.

DOOREN, L. J. (1967) Groei en Geslachlelijke Rijpinal Bij Cerebraal Defects Kinderen.J.j. Groen enZoon, Leiden.

96 MENTALLY RETARDED BOYS

EDWARDS, D . A., HAMMOND, W . H . , HEALEY, M . J . R., Tanner,J. M. and Whitehouse, R. H.(1955) Design and accuracy of calipers for measuring subcutaneous tissue thickness.Brit.J.Nutr.9, 133.

FLORY, G. D . (1936) The physical growth of mentally deficient boys. Monogr. Soc. Res. ChildDevelop., 1, No. 6.

GREULICH, W . W . and PYLE, S. 1. (1959) Radiographic Alla.% of Skeletal Development of Hand andWrist. 2nd Edition. Stanford University Press, Stanford, Galifornia.

LAMBERT, B. (1951) The frequency of mumps and of mumps orchitis, and the consequencesfor sexuality and fertility. Acta. Genel. {Basel). Suppl. L

MARSHALL, W . A. (1966) Basic anthropometric measurements. In: Somatic Growth of the Child.H. E., Stenefert Kroses N.V., Leiden.

MOSIER, H . D. , GROSSMAN, H . J. and DINGMAN, H . F . (1962) Secondary sex development inmentally deficient individuals. Child Develop., 33, 273.

QUAADE, F . (1955) Obese Children. Anthropology and Environment. Danish Science Press, Gopen-hagen,

ROBERTS, G . E . and GLAYTON, B. E . (1969) Some findings arising out of mentally retardedchildren. Part I I : Physical growth and development. Develop. Med. Child Neurol., 11, 5B4.

RUNDLE, A. T. and SYLVESTER, P. E. (1962) The measurement of testicular volume. Itsapplication to the assessment of maturation and its use in the diagnosis ofhypoconadismArch. Dis. Childh. 37, 514.

RUNDLE, A. T. and SYLVESTER, P. E. (1963) Growth and development of young males. 7. mentDefic. Res., 7, 10.

RUNDLE, A. T. and SYLVESTER, P. E. (1965) Growth and development of young females.Amer. J. ment. Defic, 69, 635.

SYLVESTER, P. E. and RUNDLE, A. T. (1962) Endocrinological aspects of mental deficiency.II. Maturation status of adult males. J . ment. Defic. Res. 6, 87.

TANNER, J. M. (1962) Growth at Adolejicence. 2nd Edition. Blackwell Scientific PublicationsOxford.

TANNER, J. M. and WHITEHOUSE, R . H . (1955) The Harpenden Skinfoid Galiper. Amer. J.phys. Anthropol., 13, 743.