Download Title Reliability of Nasion-bregma length measurement in

Title
Reliability of Nasion-bregma length measurement in identification of sex of skull.
Authors
Dr. Narashimha Murthy
Assistant professor, Department of Forensic Medicine and Toxicology,
J. J. Medical College, Davangere, Karnataka
Dr. Nagesh Kuppast
Assistant professor, Department of Forensic Medicine and Toxicology,
S. S. Institute of Medical Sciences and Reasearch Center, Davangere, Karnataka.
Dr. Manjunath T. H.
Assistant professor, Department of Forensic Medicine and Toxicology,
Subbaiah Institute of Medical Science and Research Center, Shimoga, Karnataka.
Dr. Dileep Kumar R.
Department of Forensic Medicine and Toxicology,
S. S. Institute of Medical Sciences and Reasearch Center, Davangere, Karnataka.
Dr. Umesh S. R.
Professor and HOD, Department of Forensic Medicine and Toxicology,
M. R. Medical College, Gulbarga, Karnataka.
Dr. Shradha Iddalgave
Assistant Professor, Department of Anatomy,
S. S. Institute of Medical Sciences and Reasearch Center, Davangere, Karnataka
Corresponding author
Dr. Narashimha Murthy
Assistant professor, Department of Forensic Medicine and Toxicology,
J. J. Medical College, Davangere, Karnataka.
[email protected]
Abstract
Determination of sex from the skeletal remains is of medico legal importance for establishing
the identity of an individual. The determination of deceased sex is first step in skeletal analysis
since estimation of age at death, race, and stature depends on sex of deceased. Total 100 adult
human skulls (50 male and 50 female) of known sex available in department of anatomy and
Forensic Medicine of M. R. Medical College and K. B. N. Medical College, Gulbarga were
studied. Nasion-bregma length was measured. The demarking point (D.P.) and identification
point (I.P.) is calculated and then percentage of bones identified by D.P. and I.P. is recorded. The
results were compared with the available literature. Considering the Identification point, 14% of
female skulls and 6% of male skulls can be sorted out by this single parameter alone.
Key words
Nasion, Bregma, Demarking Point, Identification Point, Sexing of Cranium.
Introduction
Several forensic anthropologists have described qualitative sex differentiation using
many bones, but sexing from single bone is difficult task. Almost all the elements of human
skeleton show some degree of sexual dimorphism, but reliable indicators can be obtained from
specific bones like hip bone, skull and sacrum. The determination of deceased sex is first step in
skeletal analysis since estimation of age at death, race, and stature depends on sex of deceased.
The identity of the sex of the deceased is the first question to be answered. Various studies have
been done earlier by different workers like Pearson
Krogman2 (1949) and Armitage 3 (1971).
1
(1950), Fisher (1936), Washburn,
Various methods of sex determination of human skeletal are:
1. Traditional non metrical method (morphological)
2. Metrical methods
a. Pearson’s univariate analysis
b. Demarking point (Jit and Singh 4, 1966)
c. Identification point (Washburn, 1968)
d. Use of various indices on the basis of significant measurements.
e. The multivariate discriminant function analysis technique of Armitage
3
(1971).
Traditional method is non metrical and morphological. Morphological features of bones
depend upon nutrition, occupation, race and geography of the region, so the traditional method is
not reliable in the study of bones.
In this study nasion-bregma length of 100 adult human skulls of known sex (50 male and
50 female) was studied. They were analyzed statistically by applying routine statistical data like
identification point and demarking point. Similar works were conducted earlier by Keen (1950) 5
on cape colored population of South Africa, Deshmukh (2006) 6 and Hong Wei Song
7
(1992)
studied on Chinese skull.
The available literature shows that the Indian skull has not been studied widely except by
Deshmukh AG and Devarshi DB 7 (2006). Hence, the present study was undertaken with a view
to study the sex differences in skull of Hyderabad-Karnataka region of Karnataka.
Materials and Methods:
The materials for the present study consisted of 100 adult human skulls of known sex (50
male and 50 female) available in the Department of Forensic Medicine and Toxicology and
Department of Anatomy of M. R. Medical College and K. B. N. Medical College Gulbarga,
Karnataka. Following parameter was studied:
Nasion-Bregma Length: It is the distance between nasion and bregma. It was measured
with the help of sliding caliper.
As the first part of the study, all the values were tabulated and analyzed statistically by
routine statistical methods using SPSS software. The value of Range, Mean, Standard Deviation
(SD), Calculated Range (mean ± 3SD), Demarking Point and Identification Point were obtained.
Maximum value of female range was considered as identification point for male. Minimum value
of male range was considered as identification point for female. Maximum value of female
calculated range was considered as demarcation point for male. Minimum value of male
calculated range was considered as demarcation point for female. In case where female range /
calculated range maximum value of male range / calculated range was considered as
Identification point / Demarcation point for female and minimum value of female range /
calculated range was considered as identification point / demarcation point for male.
Subsequently ‘t’ is applied.
Observations
The Range, Mean, Calculated Range (mean + 3 S.D.), Demarking Points (DP) and Identification
Point (IP) of parameter, and the percentage of bones in which sex could be identified by them,
are given in table no 1.
Table No. 1: Showing statistical analysis of Nasion-Bregma length of skull
Details of measurement
Male (mm)
Female (mm)
125.98
121.28
8.16
10.92
110-139
108-138
>138
<110
Percentage of skulls identified by IP
6%
14%
Standard error
1.15
1.54
101.85-150.45
88.53-154.03
>154.03
<101.85
0%
0%
Mean
SD
Range
Identification Point (IP)
Calculated range (Mean±3SD)
Demarking Point (DP)
Percentage of skull sexed correctly by DP
‘t’ test: p<0.05
*significant
Discussion
The female skull retains the gracile attributes seen in prepubescent skull. Male cranium
becomes markedly rougher in adulthood, the differentiating features of sex become more
prominent after puberty, again towards old age there occurs blurring of sexually dimorphic traits.
So the determination of sex from bones should ideally be limited to 15-55 years of age.8
Krogman WM 9 (1978) analyzed 750 skeletons and came to a conclusion that the determination
of sex is possible with accuracy of about 100% if whole skeleton is available, 92% when skull
alone and 98% when both pelvis and skull are available. A great number of measurements of the
skull have been proposed and used by different investigators during the past. Martin and Saller
used eighty one measures; Howell described seventy; Hrdlicka lists thirty two; Bass gives twenty
three. In the present study parameter, Nasion-Bregma Length was studied in hundred skulls of
known sex, and the results are statistically significant. The results are compared with those of
previous workers.
Table no-2. Comparison of Nasion-Bregma length of skulls of present study with previous
workers.
Sl
Name of
no
worker
1
2
Male
Female
SS
N
M
R
SD
N
M
R
SD
P
Keen (1950)
50
129.3
112-145
6.6
50
126
112-142
7.0
--
Hong wei
30
130.1
--
7.3
30
122.5
--
6.5
<0.001
40
125
114-143
7.04
34
123
104-131
8.17
>0.05
50
125.98
110-139
8.16
50
121.28
108-138
10.92
<0.05
Song (1992)
3
Deshmukh
(2006)
4
Present
study (2009)
Where N- no of skull, M- Mean. SD – Standard deviation, R – Range. SS – Statistical
significant, scale in mm.
The mean nasion-bregma length of male skull was 125.98 mm ranging between 110-139
mm. The mean nasion-bregma length of female skull was 121.28 mm with the values ranging
between 108-138 mm. The identification point of male skull was >138 mm and of female skull
was <110 mm and the percentage of skull identified by IP alone was 06% of males and 14% of
females. The SD for male and female were 8.16 and 10.92 respectively. The calculated range of
mean ± 3SD in males and females was 101.85-150.45 mm and 88.53-154.03 mm respectively.
The demarking point for males was >154.03 mm and for female it was <101.85 mm and the
percentage of skull identified by DP alone was 0% for both male and female. ‘t’ test was
significant with p <0.05.
Conclusion
Considering the Identification point, 14% of female skulls and 6% of male skulls can be
sorted out by this single parameter alone that is Nasion-bregma length.
Acknowledgement:
I thank Dr. Mallikarjun B., dean M. R. Medical College, Gulbarga for encouraging and
securing me the all the required facilities for the work.
I express my humble gratitude to all the staff members of Dept. Of Forensic Medicine
and Toxicology, M. R. Medical College, Gulbarga for their motivation and constructive ideas
during the study.
Source of funding: Self
Ethical clearance: Taken
Conflict of Interest Statement
“The undersigned author / authors hereby declare that the article is original, neither the
article nor a part of it is under consideration for publication anywhere else and has not been
previously published anywhere. We have declared all vested interests. We have meticulously
followed the instructions. The article, if published, shall be the property of the Journal and we
surrender all rights to the Editors. We agree to provide the latest follow up of cases prior to the
publication of case reports when requested”.
Authors
Dr. Narashimha Murthy*
Dr. Nagesh C. Kuppast**
Dr. Manjunath T. H.***
Dr. Dileep Kumar R. ****
Dr. Umesh S. R. *****
Dr. Shradha Iddalgave******
*Assistant professor, Department of Forensic Medicine and Toxicology,
J. J. Medical College, Davangere, Karnataka
**Assistant professor, Department of Forensic Medicine and Toxicology,
Karuna medical college,Palakkad Kerala.
***Assistant professor, Department of Forensic Medicine and Toxicology,
Subbaiah Institute of Medical Science and Research Center, Shimoga, Karnataka.
**** Assistant professor,Department of Forensic Medicine and Toxicology,
Siddhartha medical college , Tumkur, Karnataka.
*****Professor and HOD, Department of Forensic Medicine and Toxicology,
M. R. Medical College, Gulbarga, Karnataka.
***** Assistant professor, Department of Anatomy,
. Karuna medical college,Palakkad Kerala.
Signature
References
1. Parsons FG. Sexual differences in the skull. J Anat. 1920;54:58-65, cited by Krogman
WM (1962), vide Supra.
2. Krogman WM. The human skeleton in legal medicine, medical aspects. In
symposium on medical problems – series 11, Levingson, SA editor.
3. Saukko P, Knight B. Knight’s Forensic Pathology. 3rd ed. London: Edward Arnold
Ltd; 2004. P. 108.
4. Jit I, Singh S. The sexing of adult clavicles. Ind J Med Res. 1966;54:556-7.
5. Keen JA. Sex differences in skull. APJA. 1950;8(1):65-79.
6. Hong Wei Song, Zi, Qing Lin, Jing Tao Jia. Sex diagnosis of Chinese skulls using
multiple stepwise discriminant functional analysis. Forensic Sci Int. 1992;54:135-40.
7. Deshmukh AG, Devershi DB. Comparison of cranial sex determination by univariate
and multivariate analysis. Joint Anatomy Society of India. 2006;55(2):48-51.
8. Pillay VV. Text book of forensic medicine & toxicology. 14th ed. Hyderabad: Paras
Publication; 2004. P. 56.
9. Krogman WM. The human skeleton in forensic medicine. Springfield: Charles C
Thomas pub Ltd; 1962.