Anatomical characteristics and significance of the metopism and Wormian bones in dry adult-Chinese skulls.

BACKGROUND: This study aimed to investigate the incidence, topographical distribution, morphology, and interrelationship of the metopism and Wormian bones (WBs) in dry adult-Chinese skulls. MATERIALS AND METHODS: In this study, 285 dried adult-Chinese skull specimens from the Department of Anatomy at the Southern Medical University were examined. The incidence of different types of metopism and WBs were recorded. The length of the metopic suture was measured using a flexible ruler. Additionally, the lengths and widths of the WBs were measured using a vernier calliper. RESULTS: The incidence of metopism and WBs in Chinese adults were estimated at 10.18% (29/285) and 63.86% (182/285), respectively. The metopism always accompanied WBs (26/29, 89.66%), but the WBs did not necessarily accompany metopism (26/182, 14.29%). The locations of the WBs in the order of decreasing incidence were the lambdoid suture (78.57%, 143/182), pterion (34.62%, 63/182), asterion (12.09%, 22/182), lambda (8.24%, 15/182), sagittal suture (4.95%, 9/182), and Inca bone (3.85%, 7/182). These locations differed in topographical distribution and morphological patterns. CONCLUSIONS: Chinese adults differ in incidence of metopism and WBs from adults of other races, indicating racial differences. The characteristics of WBs vary depending on the cranial site of occurrence. The metopism always accompanies WBs, but the WBs do not necessarily accompany metopism.

Influence of persistent metopic suture on sagittal suture closure.

BACKGROUND: Metopic suture lies between the halves of the growing frontal bone and usually closes in early infancy. If the metopic suture fails to close it persists in adulthood and could be considered an anterior continuation of the sagittal suture (SS). This study aimed to investigate if the metopic suture persistence is related to any significant deviations from the normal SS maturation. We also aimed to elaborate linear regression models for age-at-death prediction of the metopic crania and to compare their accuracy with the models developed on the control ones. METHODS: The SS was investigated in a total of 122 dry adult contemporary male crania of known age-at-death divided in a metopic series (n = 34) and a control one (n = 88). The crania were scanned and high-resolution volumetric images were generated using an industrial µCT system. The SS closure degree was assessed on cross-sectional tomograms using a scale of grades. Both series were compared and linear regression models for age-at-death prediction were elaborated. RESULTS: The comparison between both series showed that the degree of SS closure differs significantly in all SS sections and bone layers and it is considerably lower in the metopic series. The elaborated linear regression models showed that the error in the age-at-death prediction of the metopic crania is almost two times bigger than that in the control. CONCLUSIONS: The SS closure in metopic crania is significantly delayed compared to the control, which means that it is entirely unreliable and misleading as an indicator for age-at-death prediction.

Incidence of persistent metopic suture in Australia: findings from 1034 three-dimensional computed tomography scans.

PURPOSE: To investigate the incidence of persistent, open metopic sutures in contemporary Australians aged 24 months and older. METHODS: Metopic suture evaluation was conducted on retrospective cranial/cervical computed tomography scans of patients aged 24 to 252 months who presented to the Women's and Children's Hospital in Adelaide, Australia, between 2010 and 2020. Suture ossification was graded according to Lottering scoring system based on 4 stages, on three-dimensional volume-rendered reconstructions (stage 1: fibrous tissue interface, stage 2: commenced fusion, stage 3: complete fusion and stage 4: obliterated suture). The complete persistent sutures were classified as stage 1. Partially closed sutures were classified into stages 2 and 3, while completely closed sutures were defined as stage 4. RESULTS: One thousand thirty-four patients (61.2% male and 38.8% female) were included, with a mean age at scan of 66 months. More than half of patients were subject to scanning due to closed-head injuries. The incidence of persistent (completely open) metopic suture was 4.8% (2.3% in males and 2.5% in females). In comparison, a partially closed metopic suture was found in 6.3% of the study cohort, with the remaining sutures located along the metopic suture line, at the glabella, mid-part of the suture, bregma and glabella-bregma areas. CONCLUSION: The prevalence of persistent metopic sutures in our study of the Australian population is 4.8%, and it is equally distributed between the genders. The pattern of suture closure can commence from any location along the suture line, which is in contrast to the existing literature.

The prevalence of persistent metopic sutures comparing the Nepalese bone collection with Korean bone collection / Prevalencia de suturas metópicas persistentes que comparan una colección de huesos nepaleses con una colección de huesos coreanos

SUMMARY: Metopic suture can be visualized from the nasion to the bregma along the arch of the frontal bone in mid-sagittal plane. Persistent metopic suture normally closing between 1st and 2nd year of life has also been related with ethnicity. The present study reports the presence of complete and incomplete metopic sutures in Nepalese and Korean population skulls which helps to shed light on its incidence rate. Out of 121 adult skulls in Nepalese population, metopic suture was found to be present in 33 skulls. Incomplete metopic sutures showed variations of morphology, like linear (6.61 %), V-shaped (8.26 %) and double incomplete (10.74 %) and two cases with complete metopic suture, which showed variation in interdigitation between its anterior and posterior ends. Korean population showed metopic suture to be present in 8 skulls out of 104 with metopism in 3 skulls. Incomplete metopic sutures like double incomplete (1.92 %) and linear (2.88 %) were also noted. Alterations to local strains could be the contributing factor for such variation and complexity of interdigitation, which occur during the growth of the braincase. The knowledge of the metopic suture and its variations according to ethnicity is important and should be considered to prevent wrong diagnosis. The presence of different types of metopic sutures as reported by the present study provides informative value on the presence and variation of such sutures in population depending on ethnicity and ought to be helpful in diagnostic sequences in emergency setting.

RESUMEN: La sutura metópica se puede visualizar desde nasión hasta el bregma a lo largo del arco del hueso frontal en el plano mediano sagital. La sutura metópica persistente que normalmente se cierra entre el primer y segundo año de vida, también se ha relacionado con el origen étnico. El presente estudio informa la presencia de suturas metópicas completas e incompletas en los cráneos de la población nepalesa y coreana, lo que además de entregar información sobre su tasa de incidencia. De 121 cráneos adultos en la población nepalesa, en 33 de ellos se encontró la sutura metópica. Las suturas metópicas incompletas mostraron variaciones de la morfología, como lineal (6,61 %), en forma de V (8,26 %) y doble incompleta (10,74 %), además de dos casos con sutura metópica completa, que mostraron variación en la interdigitación entre sus extremos anterior y posterior. De los 104 cráneos de la población coreana en 8 se presentó la sutura metópica y en 3 metopismo. También se observaron suturas metópicas incompletas como doble incompleta (1,92 %) y lineal (2,88 %). Las alteraciones en las etnias locales podrían ser el factor contribuyente para tal variación y complejidad de la interdigitación, que ocurre durante el crecimiento de la cráneo. El conocimiento de la sutura metópica y sus variaciones según el origen étnico es importante y debe considerarse para prevenir un diagnóstico incorrecto. La presencia de diferentes tipos de suturas metópicas según lo informado en el estudio, proporciona un valor informativo sobre la presencia y la variación de tales suturas en la población, dependiendo de la etnia, y debería ser útil en las secuencias de diagnóstico en situaciones de emergencia.

The metopic suture: Natural history.

The metopic suture (MS) is one of the main sutures of the calvaria; premature closure is responsible for trigonocephaly, while persistence (metopism) is considered a normal variant. The ages of onset and completion of MS closure and prevalence of metopism in normal children are poorly documented. We studied the pattern of MS closure on 3D-CT scans of 477 children admitted for head trauma since 2012. We also studied the prevalence of trigonocephaly and the sex ratio in our clinical series of patients with all types of synostosis diagnosed during the last 4 decades. In the majority of children, MS closure started at 4 months and was complete at 9 months. The prevalence of metopism was stable after 1 year of age, at 5.1%; it was more than twice as frequent in girls (F/M ratio 2.1, non-significant). Our trigonocephaly series and the literature show a steady increase in prevalence over recent decades. During the same period, the prevalence of metopism decreased steadily. Data from comparative anatomy and paleoanthropology suggest that postnatal MS persistence in our species results from the risk of dystocia caused by the closed pelvis associated with bipedalism. The increasing incidence of trigonocephaly appears to parallel the fall in prevalence of metopism. The increasing use of cesarean section may have eliminated a potent selection factor in favor of postnatal persistence of the MS.

Digital radiomorphometric analysis of the frontal sinus and assessment of the relation between persistent metopic suture and frontal sinus development.

OBJECTIVES: This study aimed to establish the frequency of the frontal sinus (FS) aplasia, to compare metopic and nonmetopic series and thus to assess the relationship between the preservation of metopic suture and FS development. MATERIALS AND METHODS: FSs were investigated in 230 dry skulls of adult males distributed into control (137) and metopic (93) series. They were visualized through industrial digital radiography. RESULTS: In the control series, the FS aplasia was observed in 12.41% of the skulls, and it was mostly unilateral (8.76%) than bilateral (3.65%). The left-sided aplasia (5.11%) slightly prevailed over the right-sided one (3.65%). In the metopic series, the aplasia was observed with a frequency of 19.35%, and the bilateral aplasia (7.53%) was rarer that the unilateral one (11.83%), while the right-sided aplasia was clearly predominant (9.68%) compared to the left-sided one (2.15%). DISCUSSION: The significant differences between both series showed a tendency for the persistence of metopic suture to be frequently related with FS underdevelopment in the vertical plate of the frontal bone, but in cases of pneumatization, it was preferentially on the left side. Taking into account that the cranial hypertension leads to suture diastasis and hinders development of the FS, it could be suggested that persistence of the metopic suture along with underdevelopment of the FS in nonsyndromic adults could be an expression of an elevated intracranial pressure during early development as an after-effect of certain condition.

Incidence of metopism in adult Thai skulls / Incidencia de metopismo en cráneos tailandeses adultos

The persistent metopic suture on adult skull (also known as metopism) can confuse the clinicians during diagnosis of the frontal bone fractures in emergency conditions. The incidences of metopism have been documented in many populations except in Thais. Therefore, this study was aimed to determine the incidence of metopism in adult Thai skulls. The identified 706 Thai dried skulls (481 males and 225 females) were carried out for metopic suture observations. The results showed that 53 skulls (7.51%) were present of the metopic sutures. The metopism observed could be classified into major two types (complete metopic suture (20 skulls [2.83%]) and incomplete metopic suture (33 skulls [4.67%]). For the incomplete metopic suture could be further classified into two subtypes, bregma-incomplete metopic suture and nasion- incomplete metopic suture. This incidence maybe a basic information for Thai radiologists to concern about metopic suture in emergency diagnosis of frontal bone fractures.

La persistencia de la sutura metópica en el cráneo adulto (también conocido como metopismo) puede provocar confusión en los médicos durante el diagnóstico de las fracturas de los huesos frontales en situaciones de emergencia. La incidencia de metopismo se ha documentado en muchas poblaciones, excepto en individuos tailandeses. Por lo tanto, este estudio tuvo como objetivo determinar la incidencia de metopismo en cráneos tailandeses adultos. Se identificaron 706 cráneos secos (481 hombres y 225 mujeres) y se llevó a cabo la observación de ls sutura metópica. Los resultados mostraron que en 53 cráneos (7,51%) estaba presente la sutura metópica. Según nuestras observaciones, el metopismo podría ser clasificado en dos tipos principales: sutura metópica completa (20 cráneos [2,83%]) y sutura metópica incompleta (33 cráneos 4,67%). A su vez, la sutura metópica incompleta podría ser clasificada en dos subtipos: sutura metópica incompleta "bregma" y sutura metópica incompleta "nasion". Consideramos que la indicedencia de metopismo registrado en este trabajo configura una información de relevancia para los radiólogos tailandeses en relación a la sutura metópica y el correcto diagnóstico en la emergencia de fracturas óseas frontales.

Metopismo: bases morfológicas, implicancias clínicas y reporte de caso / Metopism: morphologic basis clinical implications and case report

Durante la vida fetal y la infancia, los huesos planos de la bóveda craneal están separados por membranas densas de tejido conectivo que constituyen articulaciones fibrosas conocidas como suturas; las cuales tienen como objetivo durante los primeros estadios de la vida favorecer el desarrollo encefálico. Eventualmente estas suturas con el paso de los años se cierran formando una sinostosis entre los huesos del cráneo. Una de estas es la sutura frontal, que une los 2 huesos frontales en la época embrionaria y en el recién nacido. Esta sutura puede persistir en el tiempo generando el cuadro conocido como metopismo. Alteración que muestra distintas presentaciones e incidencias según sea el grupo étnico estudiado. El propósito de este artículo es mostrar las características que presenta esta condición, frecuencias, descripciones, variedades, etc., analizando distintas bases de datos, junto a la descripción de un caso. Se plantea la importancia que posee a nivel clínico a la hora de invadir quirúrgicamente esa zona, o la confusión que se puede presentar a nivel radiográfico lo cual eventualmente puede generar alguna complicación, por lo cual es de real relevancia el conocimiento de las bases morfológicas de esta condición con el fin de realizar un correcto diagnóstico y procedimiento quirúrgico si este lo amerita.

During fetal life and infancy, flat bones of the cranial vault are separated by dense connective tissue membranes, fibrous joints called sutures, which are aimed early on in life to promote brain development. Eventually these sutures close over the years to form a synostosis between the bones of the skull. One of these is the frontal suture, which joins the two frontal bones in the embryonic period and the newborn. This suture may persist over time, generating the condition known as metopism. Alteration showing different presentations and incidents depending on the ethnic group studied. The purpose of this paper is to show the features found in this condition, frequency, description, varieties, etc. This analysis was performed on different databases and the description of a case. It raises the importance that clinicians approaching the area at the time of surgery consider possible confusion at the radiographic level which can lead to subsequent complications. Therefore, real knowledge of the morphological bases of this condition is important for correct diagnosis and surgical procedure if warranted.

Metopism in Adult Skulls from Southern Brazil / Metopismo en Cráneos del Sur de Brasil

The metopic suture is found between the frontal bone tubers, there being divergences concerning the precise time of its closure, varying from the first to tenth year of life, and it can persist until adult age (metopism). A study was conducted in 71 dry skulls of adult Brazilian subjects of both sexes (43 males and 28 females), with ages ranging from twenty five to eighty years from the bone collection of the Laboratory of Human Anatomy of the Paranaense University ­ UNIPAR, Brazil. It was observed the occurrence of metopism in 7.04% (05/71) of the studied skulls, of which 80% (4/5) were female and only 20% (1/5) male. The incomplete metopic suture was found in 32.39% (23/71), with higher frequency in female skulls, 60.86% (14/23), when compared to the male ones, that reached 31.13% (9/23). Sutures showed variations of morphology, the linear type being the most frequent, with 69.56% (16/23). Different incidences of metopic suture were found in the different antrophometric types of skulls. Incomplete metopic sutures were predominant in the brachycranics, while complete metopic sutures had the same incidence in mesocranics, 40% (2/5) and dolichocranics, 40% (2/5).

La sutura metópica se encuentra entre las tuberosidades del hueso frontal, existiendo variaciones en relación a la fecha exacta de su cierre, ocurriendo entre el primero y el décimo año de vida, pudiendo persistir hasta la vida adulta (metopismo). Se realizó un estudio en 71 cráneos secos, de individuos adultos, brasileños, de ambos sexos (43 masculinos y 28 femeninos), con edades variando entre 25-80 años de edad, pertenecientes a los osarios del Laboratorio de Anatomía Humana de la Universidad Paranaense - UNIPAR, Brasil. La presencia de metopismo fue observada en el 7,04% (05/71) de los cráneos estudiados, siendo 80% (4/5) femeninos y sólo 20% (1/5) masculinos. La sutura metópica incompleta fue encontrada en el 32,39% de los casos (23/71), siendo más frecuente en el sexo femenino, 60,86% (14/23) que en el sexo masculino 39,13% de los casos (9/23). Las suturas metópicas presentaron variaciones en su morfología, siendo la forma más frecuente la del tipo linear, 69,56% (16/23). Fueron observadas distintas suturas metópicas en los diversos tipos antropométricos de cráneo. Las suturas incompletas predominaron en los braquicráneos y las suturas metópicas completas tuvieron la misma incidencia en los mesocráneos de 40% (2/5) y dolicocráneosde 40% (2/5).