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Reserch Article III

Spheno -Occipital Synchondrosis for the estimation of age in a Forensic Con-text : A preliminary case series study on a sample of Sinhalese in Sri Lanka.

Induwara Gooneratne

Sri Lanka Dental Journal 2017; 47(01) 109-115

Dr Induwara Gooneratne (Correspondence)

Department of Forensic Medicine, Faculty of Medicine, University of Perad-eniya, E mail : induwarag@yahoo.com

AbstractIntroduction- It is evident that there are numerous approaches employed by many different research-ers to ascertain the age of the unknown. Among those, the examination of the spheno- occipital synchondrosis has also been an area of focus by both forensic scientists as well as anatomists. However, despite many number of studies avail-able in the literature for many different other populations, for Sri Lanka, up to now there are no published studies using spheno- occipital synchondrosis as a marker to estimate the age of an individual.Aim- This study therefore aims at obtaining a crude idea about the ages at which the spheno- occipital joint completes among a Sri Lankan sample. As the available literature does not cover Sri Lankan Sinhalese adults, the results of this case series evaluation will undoubtedly provide a forensic practitioner a rough idea regarding the chronological ages at which the fusion occurs at the joint.Methods- Twenty one Sinhalese male skulls and eleven Sinhalese female skulls collected over the years for anatomical and autopsy purposes whose ages were known and ranged between twenty years to sixty five years were examined for this study using the method described by Moore and Jenson et al.Results and Conclusion- With the preliminary findings it is evident that the spheno- occipital synchondrosis of Sinhalese are fused at the age of

20 or above when evaluated ectocranially under naked eye. However, this may be a crude opinion where a larger representative sample needs to be studied prior to generalising the age of fusion

IntroductionEstimation of age is one important aspect in forensic practice especially of an unknown vic-tim. The age estimation in a forensic context is primarily carried out with a view to ascertain the identity of the victim. The investigatory process leading to the positive identification of the victim is further simplified if the age of the unknown can be estimated accurately. It is evident that there are numerous approaches employed by many different researchers to ascertain the age of the unknown. Among those, the examination of the spheno- occipital synchondrosis has also been an area of focus by both forensic scientists as well as anatomists. However, despite many number of studies available in the literature for many different other populations, for Sri Lanka, up to now there are no published studies using spheno- occipital synchondrosis as a marker to estimate the age of an individual1. As the term suggests, the spheno – occipital syn-chondrosis is a cartilaginous joint, a growth centre found in the base of the skull between the basilar part of the occipital bone and the body of the sphe-noid bone joining them together with a hyaline cartilage (See Fig 1). This joint is important in cranio facial development for both vertical axis

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Spheno -Occipital Synchondrosis for the estimation of age in a Forensic Context : A preliminary case series study on a sample of Sinhalese in Sri Lanka.

and horizontal plains, resulting in the increase of facial height and width. The hyaline cartilage, as usual, is gradually replaced by bone with age and this very process has been used as a method to estimate the age of an unknown victim in forensic practice2. Much research has shown that the age at which the spheno- occipital synchondrosis closes or fuses depend largely on the ethnicity of the population and gender3. This means that the chronological data that of a different population may not be applied to a Sri Lankan without a grave affront of error.

Fig 1 – A diagrammatic representation of the Spheno- Occipital Synchondrosis

shown in a square. The AimWhile a systematic and a large study is required for Sri Lankan ethnic groups evaluating the spheno- occipital synchondrosis, this study aims at obtaining a crude idea about the ages at which the spheno- occipital joint completes among a Sri Lankan sample. As the available literature does not cover Sri Lankan Sinhalese adults, the results of this case series evaluation will undoubtedly provide a forensic practitioner a rough idea re-garding the chronological ages at which the fusion occurs at the joint.

Materials and Methods Twenty one Sinhalese male skulls and eleven Sinhalese female skulls collected over the years for anatomical and autopsy purposes whose ages were known and ranged between twenty years to sixty five years were examined for this study using the method described by Moore and Jenson et al4. In the process, the spheno occipital synchondrosis of each skull was directly examined and evaluated ectocranially and a specific score was given by the researcher in accordance to the Moore Jenson guidelines. The joint was scored as unfused /open ( 0), fusing/closing (1) and fused/closed (2). As the scoring is described ‘in an unfused synchon-drosis, the gap contains no bone, and there is complete separation between the basilar portion of the occipital and the adjacent sphenoid. A fusing synchondrosis shows fusion activity when the gap begins to fill with bone as fusion proceeds from the endocranial to the ectocranial surface, but some form of hiatus exists in the suture. The synchondrosis was scored as fused when the gap was completely filled with bone, and the ectocra-nial surface between the occipital and sphenoid is continuous’. It is important that a fusion scar is distinguished if present at the suture, as it may misguide an untrained examiner.The direct visualization method this study used is the routine method used in forensic applications and it is easy to use and cost effective. Although there are other studies that had utilised other meth-ods such as radiological methods or other imaging methods for example computed tomography ( CT) or histology, the direct visualization method still remains unaffected especially in forensic contexts due to its cost effectiveness and easy accessibility.

Results and Discussion The international literature on spneno- occipital synchondrosis clearly indicates that it can be uti-lised as a useful indicator of age of an individual5. However, the ages at which this joint fuses is at

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controversy and as expected, the authors do not seem to arrive at a consensus10. The primary rea-son for the variations opined in the chronological ages and fusion at this joint can be attributed to the different methodologies and approaches different studies have utilised as their tool to visualise the joint. For example, some studies have used laminectomy while others have used X ray films of the joint to visualise the growth plate at the synchondrosis. Further, other studies have used CT images and histological slides of the joint to understand the degree of fusion at the joint. Of course, this very reason of different methods used, provides different ages for fusion5,12. Certainly, a CT study will provide a more detailed outline of the inner and outer aspect of the joint resulting in a more precise opinion on fusion in comparison to a study conducted using a direct observation method10. Besides, within the same method too, researchers have found variations of the ages of fusion of this joint owing to ethnic and gender affiliations of the victim/individual. For example some studies have shown that the complete fusion occurs even at the age of 13 years while some others have seen the complete fusion at the age of 20. Further, an equally significant aspect to note in regard to the direct observation method which was used in this study can provide different ages when the joint is observed ectocranially and endocranially. The reason for this is that as liter-ature suggests, the fusion of this joint originate endocranially and extends towards outside.

As the results show in this case series study ( table 1) , all skulls in the sample was completed /fused . In other words, all skulls were scored 2 .All skulls were observed ectocranailly as per Moore and Jenson method using direct method revealed that the spheno-occipital synchondrosis are fused in the entire sample. As the sample had skulls belonging to individuals over 20 years, the results are consistent with many published

studies. As studies of Scott( 1958), McKern and Steward(1957) suggests the completion of fusion occurs between the ages of 17 to 25 years for both sexes when conventional methods were used to visualise the joint.

However, it is not possible to opine about any sexual dimorphism in fusing ages of the sample studied owing to the limited number of skulls available given in different age ranges. Further, this case series does not provide an opinion regarding the age at which the fusion begins or ends as the sample is limited. Nonetheless this study provides an important contribution to the existing literature and more importantly for the forensic practitioner in Sri Lanka which suggests a crude estimate that if the individual’s spheno –occipital synchondrosis is fused when exam-ined ectocranially using conventional methods, and that it can be scored 2, then the individual is likely to be around 20 years. This opinion is further substantiated with the evidence available on other international populations where it is es-timated the individual to be around 17-25 years when this joint is examined ectocranially using conventional method. Yet appreciating the fact that in some other populations internationally the age of fusion has been observed to be even at the age of 13 years when the joint is evaluated using advanced methods such as CT imaging. On the other hand, in a Sinhalese skull, if one finds that the spheno occipital synchondrosis observed ec-tocranially is unfused , then it is possible that the individual is below the age of 25 years. However, these opinions have to be substantiated with other more credible age indicators such as development of teeth or long bones, but in the absence of those which is not an uncommon scenario in a forensic context, it is perhaps possible to opine based on these findings until further elaborated study with a large sample is carried out.

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With these preliminary findings it is evident that the spheno- occipital synchondrosis of Sinhalese are fused at the age of 20 or above when evaluated ectocranially under naked eye. However, as indi-cated, this may be a crude opinion where a larger representative sample needs to be studied prior to generalising the age of fusion. Nonetheless, in the absence of even a crude idea about the age

References1. Gooneratne I (2016) A Review of the use of

spheno-occipital synchondrosis as an age indicator and its implications for Sri Lanka. SLJFMSL 7(2) 29-33

2. Kishnan K and Kanchan T (2013) Evaluation of spheno occipital synchondrosis J Forensic Dental Science 5(2) 72-76

3. Akhlahgi M Taghaddosinejad F (2010) Age at Death estimation based on macroscopic examination of the spheno -occipital suture. Journal of Forensic and Legal Medicine. Vol 17(6) 304-308

4. Moore-Jansen PM, Ousley SD, Jantz RL. Data collection procedures for forensic skeletal material, 3rd edn. Knoxville, TN: The University of Tennessee Department of Anthropology and Forensic Anthropology Center, 1993

of fusion of this joint for Sri Lankan Sinhalese, this finding can be a guideline for the forensic practitioner to evaluate the age of an unknown along with other more reliable age indicators as well as this may induce further research in this area unstudied so far in Sri Lanka.

5. Bassed RB, Briggs C, Drummer OH. Analy-sis of time of closure of the spheno-occipital synchondrosis using computed tomography. Forensic Sci Int. 2010;200:61–4.

6. Shirley NR, Jantz RL. Spheno-occipital synchondrosis fusion in modern Americans. J Forensic Sci. 2011;56:580–5

7. Scott JH. The cranial base. Am J Phys An-thropol 1958;16:319–48

8. McKern T, Stewart T. Skeletal age changes in young American males analysed from the standpoint of age identification. Natick, MA: Quartermaster Research and Development Center, Environmental Protection Research Division, 1957

Age Range in years Number of Skulls Score

male female20 - 25 2 225-50 9 4 250-65 10 7 2

Table 1 – Details of the sample studied : the age ranges, gender and the scores given.

Spheno -Occipital Synchondrosis for the estimation of age in a Forensic Context : A preliminary case series study on a sample of Sinhalese in Sri Lanka.

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9. Akhlaghi, M., Taghaddosinejad, F., Sheikhaz-adi, A., Valizadeh, B., Rezazadeh Shojaei, S.M.Age-at-death estimation based on the macroscopic examination of Spheno-occipi-tal sutures J of Forensic and Legal Medicine 2010(40) 325-328

10. Kahana, T., Birkby, W.H., Goldin, L., Hiss, J. Estimation of age in adolescents - The basilar synchondrosis J of forensic Sciences 2003.(48) 504-508

11. B. Ingervall, B. Thilander The human sphe-no-occipital synchondrosis I. The time of closure appraised macroscopically Acta Odontol. Scand., 30 (1972), pp. 349–356

12. Powel V T Brodie A G Closure of the sphe-no-occipital synchondrosis The Anatomical Record 1963 147(1) 15-23