Folia Morphol. Vol. 77, No. 4, pp. 730–735 DOI: 10.5603/FM.a2018.0030 O R I G I N A L A R T I C L E Copyright © 2018 Via Medica ISSN 0015–5659 www.fm.viamedica.pl Morphology of cranial sutures and radiologic evaluation of the variations of intersutural bones S. Çalışkan1, K.K. Oğuz2, S. Tunalı3, M.M. Aldur4, B. Erçakmak4, M.F. Sargon4 1Department of Anatomy, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey 2Department of Radiology, Faculty of Medicine, Hacettepe University, Ankara, Turkey 3Department of Anatomy, Faculty of Medicine, TOBB ETÜ, Ankara, Turkey 4Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey [Received: 19 December 2017; Accepted: 1 March 2018] Background: As far as our literature searches showed us, morphological characte- ristics of cranium such as sutures, sutural bones and fontanelles had been examined in the skulls in the museums and dry specimens until now. As a modern method, three-dimensional virtual reconstruction of cranial bones by using multidetector computed tomography-computed tomography angiography (MDCT-CTA) can display in vivo morphological characteristics. In our study, we aimed to determine the presence and incidence of these morphological characteristics that can be clinically significant in our population, by using radiologic methods. Materials and methods: We examined head and neck regions of 185 patients via MDCT-CTA. We evaluated radiologically detectable variations of the metopic sutures, lambda, bregma, asterion and pterion, which can be very easily confused with fractures. Additionally, the differences between the genders and incidence of coexistence of these variations were evaluated. Results: According to our study, the incidence of persistent metopic suture was 8.1% and the incidence of lambda variations was 5.9%. Variations were most commonly encountered on the left asterion, and least commonly on the bregma and left pterion. In the evaluation of the coexistence of the parameters and combinations, the Wormian bones located at the right and left asterions were detected. There were no statistically significant differences between genders. Conclusions: Variations of the sutures and sutural bones can be easily misdia- gnosed with the fractures of related bony regions in unconscious patients with multiple traumas. During surgical interventions in these patients, surgeons must take this fact into consideration in order to make differential diagnosis of fractures and intersutural bone variations. (Folia Morphol 2018; 77, 4: 730–735) Key words: Wormian bones, MDCT-CTA, Inca bone, sutural bones, three- -dimensional reconstruction INTRODUCTION older adults’ craniums are composed of 22 bones. Cranium is the osseous structure of the head and Most of these bones are held together by the joints also it is the most complex bony structure in the termed as sutures [13]. Sutures and the junctions of body. While the young adults’ craniums consist of sutures undergo a series of morphological changes 28 separate bones, many of which are paired, the from birth to adulthood. The ossification of the cra- Address for correspondence: Dr. S. Çalışkan, Department of Anatomy, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Bilkent, 06800 Ankara, Turkey, tel: +90-312-3241555, e-mail: [email protected] 730 S. Çalışkan et al., Radiologic evaluation of cranial variations nial bones is incomplete at birth. Most of the bones the study. The MDCT scans were performed with are united by fibrous or cartilage tissue [3, 4, 6, 13]. Somatom Sensation 16 Scanner (Siemens Medical During all this process, additional ossification centres Solutions, Erlangen, Germany). The records of the appear in or near the sutures, which are the potential patients were retrospectively reviewed. Cranial and sites of Wormian bones. Wormian bones (alternative cervical CT scans that were obtained from 16 slice- name of sutural bones) are isolated sutural bones MDCT were evaluated for each patient. As a routine which are various in shape and size [13]. While they procedure, CT procedure was explained to each pa- frequently occur at fontanelles (especially the pos- tient before scanning. As all the patients underwent terior fontanel) and pterion, the lambdoid suture is MDCT for vascular imaging, iodinated contrast media the most frequent location of Wormian bones [5, 7]. had been applied. The images of each patient were The isolated sutural bone in lambda is named as re-evaluated and computer-aided 3D reconstructions ‘Os Incae’. The morphological significance of sutural were performed. Reconstructions were generated at bones is negligible. Sometimes associated with the Leonardo Workstation using Syngo 2007 software. rapid cranial expansion e.g. hydrocephaly, sutural Then, 5 images showing the superior, anterior, pos- bones appear in great numbers [13]. terior, right and left lateral sides of the craniums Some researches support that sutural bones are were considered. All of the patients were older than associated with central nervous system anomalies. 20 years and none of them had neurosurgical treatment Otherwise, some authors claim that these bones are or history of head trauma. No demographic charac- linked with genetic factors [10, 11]. Also, osteogen- teristics except the age and sex were mentioned in esis imperfecta and cleidocranial dysostosis can be the study. SPSS for Windows 11.5 software package accompanied by Wormian bones [7]. Sutural bones was used for statistical analysis. The significance have clinical importance during the interpretation of of the differences between the groups in terms of radiographs of patients with head trauma. In such gender, was assessed by Student’s t test. The cate- cases, the radiologists have to make the differential gorical variables were examined by using Pearson’s diagnosis between sutural bones and fractures. Su- χ2 or Fisher’s exact χ2 test. P values < 0.05 were tural bones may also lead to complications in pos- considered as significant. terior and lateral approaches to the cranial cavity. All the procedures of our study were approved Therefore, to know the presence and incidence of by the Ethical Committee of Hacettepe University these structures is essential for neurosurgeons and Faculty of Medicine on 28 September 2010 (Number radiologists [10, 11]. Persistent metopic suture is an- HEK: 410-01-2587). other clinically important structure which is present in 0–7.4% in different populations and it may lead RESULTS to abnormal development of frontal sinuses [13]. Of 185 patients included in this study, 109 (58.9%) All these morphological features of the cranium had were male and 76 (41.1%) were female. The age range been examined in the craniums that are found in of the participants was in between 22 and 91 and the museums. These anatomical features of cranial median age was 62.7. According to our study the structures can also be evaluated on three-dimensional prevalence of persistent metopic suture was 8.1%. (3D) models reconstructed from computed tomog- Of the 15 patients with metopic sutures, 7 were male raphy (CT) scans. and 8 were female (6.4% of male and 10.5% of female The aim of this study was to recognise the 3D patients had metopic sutures; Table 1). This anatomical morphology and the incidence of all these clinically variation was more often observed in female patients. important structures in Turkish population. However, as a result of statistical analysis there wasn’t any statistically significant difference between gen- MATERIALS AND METHODS ders. The persistent metopic suture of a patient can be One hundred and eighty-five patients (109 males, seen in Figure 1. In this study, lambda was found mor- 76 females) who underwent dual source multidetec- phologically normal in 174 (94.1%) patients. Eleven pa- tor computed tomography (MDCT) were included tients had variations in this region. Also, 7.3% of male in this retrospective study. The patients who were and 3.9% of female patients had variations of lambda. younger than 22 years old and those with a history We classified the variants of lambda region as shown in of cranial surgery and trauma were excluded from Figure 2. We defined five groups: type A, type B, type C, 731 Folia Morphol., 2018, Vol. 77, No. 4 Table 1. Difference of anatomical variations between genders Male (n = 109) Female (n = 76) P Age 63.3 ± 13.1 61.7 ± 14.8 0.433 Metopic suture 7 (6.4%) 8 (10.5%) 0.314 Lambda 0.529 Normal 101 (92.7%) 73 (96.1%) Abnormal 8 (7.3%) 3 (3.9%) Type A 2 (1.8%) 1 (1.3%) – Type B 2 (1.8%) 2 (2.6%) – Type C 2 (1.8%) – – Type D 1 (0.9%) – – Type E 1 (0.9%) – – Pterion-right – – – Pterion-left – 1 (1.3%) 0.411 Bregma 1 (0.9%) – 1.000 Mendosal suture – – – Asterion-right 8 (7.3%) 5 (6.6%) 0.842 Asterion-left 11 (10.1%) 8 (10.5%) 0.924 Coexistent 8 (7.3%) 6 (7.9%) 0.888 variations Figure 2. Types of lambda variations. Figure 1. Persistent metopic suture. Figure 3. Type A lambda variation. type D, type E (Fig. 2). As presented in Table 1, the most commonly found was type B. Of 4 patients in type B, 2 patients were male and 2 of them were female (Table 1). Figure 3 presents type A, Figure 4 — type B, Figure 5 — type C, Figure 6 — type D and Figure 7 shows type E. Of the all patients included in this study, only one female has Wormian bone in left pterion. No Wormian bones were detected in right pterion. Because the transverse sections that were passing through the vertex were not available in 24 patients’ MDCT images, bregma couldn’t be evaluated in these participants. As a result of the evaluation of the re- Figure 4. Type B lambda variation. 732 S. Çalışkan et al., Radiologic evaluation of cranial variations Figure 5.