Estimation of Cranial Volume in Dissecting Room Cadavers

Transcription

1 168 J Anat. Soc. India 51(2) (2002) Estimation of Cranial Volume in Dissecting Room Cadavers K.Y. Manjunath Department of Anatomy, St. John s Medical College Bangalore Abstract. It is natural that there exists some relationship between the head size and the size of the brain. Several investigators have estimated the cranial volume in the past which indirectly reflects the brain volume. Most of these studies have been made on the dry skulls using linear dimensions, packing methods or occasionally radiological methods. In the present study the cranial volume has been estimated in 50 dissecting room cadavers (33 males; 17 females) using linear dimensions of the head (using Lee-Pearson's formula) measured with spreading caliper and Todd s head spanner. Following the removal of the calvaria the cranial volume was again estimated using spheroid formula after subtracting the linear dimensions from scalp/soft tissue thickness. The estimated mean cranial volume was as follows : by Lee-Pearson's formula: Males : ± cc; Females : ± cc.; by spheroid formula: Males-mean: ±239.98; Females-mean : 1081± Our results are almost similar to other studies on the cranial volume of macerated skulls available in the Indian literature. Key words : Anthropometry; craniometry; cranial volume; skull. Introduction : It is natural that there exists some relationship between the head size and the size of the brain. Several investigators have estimated the cranial volume in the past which indirectly reflects the brain volume. Most of these studies have been made on the dry skulls using linear dimensions, packing methods or occasionally radiological methods. A few studies have been made on living subjects as well Berry and Porteus-1920; Estabrooks-1928; Oliver- 1932; Jorgensen, Paridon, Quade-1959; Verdun & Bourdial-1962). Of late a fairly large group of 1,058 Caucasian subjects of 7 days to 20 years of age have been examined for cranial volume and related indices using modified spheroid formula (Dekaban- 1977). Although a few studies on the estimation of cranial volume do exists in the Indian literature (Shukla 1966; Thomas, Janakiram, Rajangam, Amar-1980; Routal, Pal, Bhagawat-1984), these studies are based on examination of macerated skulls. Hardly any study of cranial volume based on the examination of living subjects or cadavers exists in the Indian literature. Hence an attempt has been made in the present study to estimate the cranial volume of the dissection room cadavers using the linear dimensions of the head. Material and Methods : The material for this study consisted of 33 male and 17 female dissection room cadavers (Total 50). The cadavers were of South-Indian origin (they all were unclaimed cadavers acquired through police sources within Bangalore city limits.) In each case the following linear dimensions of the head were measured before the calvaria was cut for the removal of the brain : 1. Occipito-frontal circumference (OFC/head circumference) using a steel tape. 2. Maximum head length (Glabella inion length) 3. Maximum head breadth (measured between parietal eminences.); 2 and 3 measured with a spreading caliper. 4. Head height (external acoustic meatus to the highest point of the vertex) using an auricular head spanner (Todd's). Each measurement was taken to the nearest millimeter at least three times and the average was considered for computation. The cranial volume was calculated using the following formula given by Williams, et al, (1995) Males : (L-11) x (B-11) x (Ht-11) ; Females : (L-11) x (B-11) x (Ht-11) Following the removal of the calvaria the thickness of the cranial vault and the soft tissue were measured using a sliding calliper to the nearest millimeter. Using the soft tissue/cranial vault thickness the cranial volume was computed using the modified spheroid formula derived by Dekaban (1977). i.e (L-2t) x (B - 2t) x (Ht - t), where t-thickness of the cranial vault and the soft tissue. Results : Table 1 and 2 show the details of the measurements of the head of the cadavers and the cranial volume computed by both the methods. The mean

2 Manjunath, K.Y. 169 TABLE-1 : CRANIAL VOLUME OF MALE CADAVERS Sl. Head Head Head Head Cranial Volume (C 3 ) no. circ Length Breadth Height (Cm.) (Hl) (Hb) (Hht) Lee Spheroid mm. mm. mm. Pearson Formula 2 V=Hlx78 3 Formula 1 (t=7.95mm) (L-11X(B-11)X(H-11) ; (L-2t)x(B-2t)x(Ht-t); 3 head length after subtracted from twice the skull/scalp thickness.

3 170 Estimation of Cranial Volume TABLE 2 : CRANIAL VOLUME OF FEMALE CADAVERS Sl. Head Head Head Head Cranial Volume (C 3 ) no. circ. Length Breadth Height (Cm.) (Hl) (Hb) (Hht) Lee Spheroid mm. mm. mm. Pearson Formula 2 V=Hlx7 3 Formula 1 (t=9.25mm) (L-11)X(B11)X(H-11) ; (L-2t)x(B-2t)x(Ht-t); 3 head length after subtracted from twice the skull/scalp thickness (t). cranial volume as computed by Lee-Pearson formula was as follows. Males : ± cc (range : ) cc; Females : ± cc(range : cc). the cranial volume as computed by spheroid formula (Dekaban- 1977). : Males - mean: ± (range cc); Females-mean: 1081±111.6 (range: cc). The cranial volume was also calculated by multiplying the maximum length (after subtracting from scalp the cranial vault thickness) with the figure 78 (MacKinnon,-1955) and the results are listed in table 1 and 2. Discussion : According to Hooton (1926), the racial characters are best defined in the skull. Cranial capacity constitutes one of the most important characters for determining the racial difference. It is also an indirect approach to evaluate the size of the brain. Lee and Pearson (1901) used external measurements of the skulls to calculate the cranial capacity which has an added advantage as it can be used in case of living persons, as well as where skulls have been slightly broken or damaged. The cranial capacity of skulls belonging to different races has been determined by several authors (Morant, 1922; Szombathy, 1934; Hooton, 1963). Chaturvedi and Harenja (1962) have done it on the Indian skulls. Estimated cranial volume according to three different formulae showed a wide range of variation: males-1). Pearson's formula vs. spheroid formula mean difference ± C 3 (range

4 Manjunath, K.Y C 3 );2) spheroid formula vs. head length x ± C 3 (range C 3 ); (3) Pearson s formula vs. head lengthx78-mean difference ± C 3 (range C 3 ). females- 1) Pearson s formula vs. spheroid formulamean difference-82.5 ± 68.2 C 3 (range c 3 ) ; 2) spheroid formula vs. head lengthx78 mean difference ± C 3 (range C 3 ); 3) Pearson s formula vs. head length x78-mean difference ± 81.2 C 3 (range C 3 ). The author encountered a number of problems during the collection of the data which is the basis of the large difference observed between the cranial volume estimated by three different formulae: (a) the head of the cadaver could not be oriented in the Frankfurt plane. (b) on many occasions the scalp was stripped of while removing the calvaria, hence soft tissue thickness could not be taken into account. (c) the sectioning of the calvaria was not always uniform, on some occasions it was very low and on some, it was very high hence the cranial vault thickness could not be measured uniformly at the same spot so the thickness of the cranial vault shows wide variations. When the cranial volume was computed using the skull vault/soft tissue thickness of each cadaver individually the results with the spheroid formula was still more variable when compared to the Pearson s formula. Hence the mean of thickness of vault/soft tissue of all cadavers was used. According to some Indian studies the cranial volume of adult crania has been found to vary between: 950 C C 3 (Shukla-1966; Thomas et al 1980; Routal, Pal and Bhagavat-1984). Pal, Bhagawat and Routal (1986) in their further studies of 370 Gujarati (Indian) crania have estimated the cranial volume as ranging from cc (mean: 1252 ± ) Our findings are almost similar to these studies. The mean cranial volume of Caucassians as computed by Dekaban (1977) shows higher value than ours (males-1548 C 3 ; females-1425 C 3 ) because the skull vault/soft thickness was measured radiologically in living subjects in his series. His subjects belonged to a homogenous group where as subjects used in present series are likely to be heterogeneous and socio-economically poor some 171 even being mentally deficient. Of late cranial capacity of adult Korean crania has been estimated (Hwang, et al -1955) by filling these with rice seeds and measuring in a graduated cylinder. Later these measurements were compared with volume estimated by linear dimensions. The mean cranial capacity in males was: 1470±107cc and in females: 1317±117cc. Some attempt appears to have been made to estimate the cranial capacity of Indian cadavers by Venkatesan and Copper (1975). These authors used the calvarial displacement volume as a guide to cranial capacity: heads of fresh cadavers were immersed up to glabella-inion level in a specially constructed apparatus and the volume of water displaced was noted. The procedure was repeated after removal of the scalp and the scalp volume was estimated. Further the calvarium and brain volume were estimated by the same method after removal. The data was correlated with Lee-Pearson and the spheroidal formulae. No details of this study could be traced in the form of published report for comparison. Post-mortem estimation of cranial capacity has acquired some significance because of its potential applications in estimating brain atrophy: Variations of brain weights and volumes often reflect pathological states. However, these parameters are more meaningful when related to intracranial volume. The most useful derived parameter is the difference between intracranial volume and brain volume expressed as a percentage (potential intracranial space). Previously described techniques to determine intracranial volume have been unsatisfactory for routine application in the autopsy room (Harper et al 1984). A technique has been described by Harper et al (1984) based on the production of a permanent polyurethane cast of the cranial cavity. The casts can be formed in about 20 min with little modification of standard autopsy technique. The cast provides a permanent record of the size and shape of the cranial cavity and can be used to determine intracranial volume or other intracranial dimension. The usefulness of the derived parameter, potential intracranial space, was evident in some of the cases studied. Shukla (1966) has mentioned in his study clas-

5 172 sification of skulls into four morphological types but no details are mentioned hence no attempt was made in the present study in that direction. Most of the anthropologists while studying crania of various races on the basis of morphological and metrical features have concluded that the population of a country is no more formed by one homogeneous element but instead is constituted by heterogeneous elements (Shukla-1966). This explains how there can be a wide range of variation of cranial capacity within a population group. Summary & Conclusions : Using linear dimensions of the head the cranial volume was computed by Lee-Pearson formula in 33 male and 17 female dissection room cadavers. Following the removal of the calvaria the cranial volume was once again estimated by spheroid formula proposed by Dekaban (1977). The estimated cranial volume was comparable to other similar studies in the Indian literature. The technique of estimating the cranial volume needs to be refined and modified as it may be of potential application in estimating brain atrophy or reconstruction of the cranium in anthropological studies. References : 1. Berry, R.J.A. and Porteus, S.D. (1920): Intelligence and social valuation. Vineland training School Publications, No Chaturvedi, R.P. and Harenja, N.K. (1962): Cranial capacity, gnathic index, and facial angle in adult human skulls. Journal of Anatomical Society of India. 11: Dekaban, A. (1977): Tables of cranial and orbital measurements, cranial volume and derived indices in males and females from 7 days to 20 yrs of age Annals of Neurology. 2(6): Estabrooks, G.H. (1928): Cranial capacity and intelligence. Journal of Applied Pshychology. 13: Harper, C. Kril, J. Raven, D. Jones, N. (1984): Intracranial cavity volumes: a new method and its potential applications. Neuropathology Applied Neurobiology. 10(1): Hooton, E.A. (1926): A method of racial analysis. Science 44: Hooton, E.A. Up from the Ape. New York: Macmillan & Co., New York.: pp (1963). 8. Hwang, Y.I. Lee, K.H. Choi, B.Y. Lee, K.S. Lee, H.Y. Sir, W.S. Kim, H.J. Koh, K.S. Han, S.H. Chung, M.S. (1995) : Study on Estimation of Cranial Volume the Korean adult cranial capacity. Journal of Korean Medical Science. 10(4): Jorgensen, J.B. Parison, E., Quade, F. (1959): The external cranial volume of normal children. Acta Paediatrica. 48: Lee, A. and Pearson, K. (1901): Data for the problem of evolution in man- a first study of the correlation of the human skull. Philosophical Transactions of Royal Society, London. 196a: MacKinnon, I.L. (1955): The relation of the capacity of the human skull to its Roentgenological length American Journal of Roentgenology, Radium therapy and Nuclear Medicine. 74(6): Morant, G.M. (1922): The first study of Tibetan skull. Biometrika, 14: Oliver, R.A.C. (1932): The comparison of abilities of races with special references to East Africa. East African Medical Journal 9: Pal, G.P. Bhagawat, S.S. and Routal, R.V. (1986): A study of sututral bone in Gujarati (Indian) crania. Anthropologischer Anzeigher. 44(1) Pearson, K. (1902): Correlation of the intellectual ability with size and shape of head. Proceedings of the Royal Society. 69: Routal, R.V., Pal, G.P., and Bhagawat, S.S. (1984): Relationship between endocranial volume and the area of the foramen magnum. Journal of Anatomical Society of India. 33(3): Shukla, A.P. (1966): A study of cranial capacity and cranial index of Indian skull. Journal of Anatomical Society of India 15: Szombathy, J: in The races of Europe. Macmillan & Co., New York: p 656 (1934). 19. Thomas, I.M., Janakiram, S., Rajangam, S. and Amar, D.S. (1980): Cranial capacity of crania from Karnataka. Journal of Anatomical Society of India 29(3): Todd, W. (1923): Cranial capacity and linear dimensions, in White and Negro. American Journal of Physical Anthropology. 6: Venkatesan, B. and Cooper, M.M. (1975): Calavarial displacement volume as a guide to cranial capacity. Journal of Anatomical Society of India. 24(1): Verdun M. Bourdiol R. (1962): Les disproportions du volume cranien (Disproportions of cranial volume. Anthropometric criteria. Mental and Psychosocial correlations. Etiological research based on the study of 281 male subjects from 9 yrs to the adult age) Bulletin de I'Academie Nationale de Medicine (Paris) 146: Williams, P.L; Bannister, L.H; Berry, M.M; Collins, P; Dyson, M; Dussek, J.E; Ferguson, M.W.J. Gray s Anatomy. In: skeletal system, Soames, R.W. Edn 38th. Churchill Livingstone London: p. 612 (1995).