Morphometric Evaluation of Sutural Patterns at the Pterion and Asterion in Dry Indian Skulls: Surgical Relevance.

INTRODUCTION: The pterion and asterion serve as crucial landmarks on the skull, representing the antero-lateral and postero-lateral fontanelles in neonates, respectively. In clinical practice, these points play a pivotal role in guiding the understanding of deeper structures and their relationships to the head's surface. The thin calvarium at these junctures is susceptible to fractures, and the underlying vessels are prone to tear, often leading to extradural hematoma formation, necessitating burr hole surgery for evacuation. MATERIAL AND METHODS: The study involved 40 human dry skulls in Indians (n= 27 male (10.8%), n= 13 female (5.2%)) of unknown age, evaluating morphometric characteristics of 80 pterions and asterions. Measurements were conducted using a digital caliper (SKADIOO±0.2mm/0.01") in millimeters on both sides of each skull. The investigation also included an examination of sutural patterns in Pterion and asterion. RESULTS: Three types of sutural patterns were identified in the pterion, the most common being the sphenoparietal variety (75% on the right, 70% on the left), followed by the epipteric variety, which was the second most common (11.3% on the right, 12.5% on the left), and then the frontotemporal type (1.3% on the right, 2.5% on the left). Two sutural patterns were observed in the asterion: type 1 (presence of sutural bone) in 17.9% of skulls and type 2 (absence of sutural bone) in 82.1%. CONCLUSION: The differences in pterion and asterion positions across various populations explored in previous studies motivated us to conduct this research in the Indian population. Our findings revealed that among Indians, the predominant pterion type is predominantly sphenoparietal, whereas type 2 is the most prevalent in asterion. Understanding the clinical significance of the pterion and asterion is crucial for healthcare professionals to ensure precise and safe surgical procedures, particularly for the effective treatment of head trauma patients.

Dermoid cyst, unusual location of the pterion: About a case and review of literature.

Intracranial dermoid cysts are benign tumors of congenital origin. The intradiploic forms are rare, exceptional at the pterional level. We report the case of a 10-year-old girl who presented with a cutaneous fistula in the left frontotemporal region. The blind end of the fistula was an intradiploic dermoid cyst in the rare location of the pterion confirmed by imaging and histopathology. Once this lesion is suspected, it is important to identify its location and morphology using imaging techniques and to complete excision of the cyst to avoid complications associated with infection and to mitigate the risk of subtotal resection.

Analysis of the Variations in the Morphology, Topography of the Pterion, and Their Implications in Neurosurgery: An Osteometric Study.

Objective Pterion is an "H" shaped formation of sutures located in the temporal fossa of the skull. It is an important anatomical landmark and a craniometric point. The thinness of the skull and its inner relation with the middle meningeal artery make this anatomical landmark clinically significant. Variations in the pterion are imperative, especially for neurosurgeons in order to have the most suitable craniometric point to be minimally invasive. Materials and Methods One hundred pterions were studied to report the variations in the type and location of the pterion. Murphy's classification was used to classify the pterion into four types on the basis of bone articulation-sphenoparietal, frontotemporal, stellate, and epipteric. Results All four types of pterions were observed, sphenoparietal being the most common. No significant gender difference was observed in terms of type and laterality of various pterions. The mean distance between the center of pterion to the superolateral point of zygomaticotemporal (PZT) suture and the anterolateral point of the frontozygomatic (PFZ) suture were 3.91 ± 3.79 cm and 3.68 ± 3.79 mm, respectively. Correlation analysis showed a strong positive relation between PZT and PFZ sutures. Conclusion Accurate data on the morphology and morphometry of bony anatomical points are crucial, while performing intracranial surgery using them as recognizable landmarks. The morphometric parameters may help in determining the soundness of the pterion as an identifiable landmark for performing interventions like burr hole and other neurosurgical procedures in this area.

Does diploic venous flow drain extracranially in the pterional area? A magnetic resonance imaging study.

Background: To the best of our knowledge, no study using neuroimaging modalities has documented calvarial diploic veins (DVs) connected to the extracranial sites. This study aimed to characterize them using magnetic resonance imaging (MRI). Methods: A total of 88 patients underwent thin-sliced contrast MRI. In addition, the DVs coursing through the pterional area were observed on three injected cadaver heads. Results: On postcontrast MRI, the DVs of the pterional area directly drained into the temporalis muscle or supplied branches coursing into the muscle in 43% on the right side and 40% on the left. The DVs and their branches were highly variable in diameter and number. In 9% of cases, the DV of the pterional area was found to drain into an extracranial site and connected to large venous channels distributed in the temporalis muscle. Furthermore, in 17% of cases, the DVs drained into the extracranial sites in the frontal skull region, followed by 9% in the parietal, 2% in the occipital, and 1% in the temporal regions. The DVs coursed superficially in the pterional area on both sides of all three cadaver heads. On one side, the DV in the area was open to an extracranial site. Conclusion: Part of the diploic venous flow drains extracranially in the pterional area. This area may provide an important interface between the calvarial DVs and the extracranial venous system.

Morphological types and localization patterns of pterion in the skulls of adults from southeastern China.

PURPOSE: To study the morphological types and relative location of the pterion and its precise relationship with the middle meningeal artery (MMA) in the skulls of adults from southeastern China. METHODS: Dry skulls (n = 250) of adults were obtained from a university specimen bank and analyzed. The morphological types of the pterions were observed. The distances from the center of the external pterion (Pec) to the relevant intracranial and extracranial marker points were measured using a digital vernier caliper. The anterior, middle, and posterior end points of the external pterion were drilled perpendicular to the bone surface. The precise relationships of the external pterion with the internal pterion and the groove of the frontal branch of the MMA were observed and measured after sawing the skull. RESULTS: The morphological types of the pterion in the skulls of adults from southeastern China were sphenoparietal suture (SP) (85%), epipteric (12.4%), frontotemporal suture (1.4%), and stellate (1.2%) types. The mean widths of the external and internal pterions were R, 10.68 ± 4.22 mm; L, 11.13 ± 4.40 mm and R, 14.66 ± 4.04 mm; L, 14.14 ± 4.29 mm, respectively, and the width of the internal pterion was slightly longer than that of the external (P < 0.05). No significant difference in pterion width was found between the genders or sides of the skull (both P > 0.05). The distances from the Pec to the posterolateral aspect of the frontozygomatic suture, zygomatic process of the frontal bone, midpoint of the zygomatic arch, and external acoustic meatus were 29.95 ± 3.75 mm, 34.88 ± 4.08 mm, 40.86 ± 3.59 mm, and 53.79 ± 3.82 mm, respectively. These distances were slightly longer on the right side of the skull than on the left side (P < 0.01) and longer in men than in women (P < 0.01). The distances from the Pec to the frontal crest, optic canal, and anterior clinoid process were 62.79 ± 1.15 mm, 45.39 ± 2.48 mm, and 45.47 ± 2.05 mm, respectively. The external and internal pterions were not on the same level, and all the internal pterions were located below the external ones. In the vast majority of the skulls, the groove of the frontal branch of the MMA passed through the posterior end of the external pterion (Pep) or the area between the Pec and Pep. CONCLUSION: The morphology of the pterion in the skulls of adults from southeastern China is predominantly of the SP type, mostly symmetrically distributed. The distance from the pterion to the extracranially relevant marker points differs among the ethnic groups, between the genders, and between the sides of the skull. All the internal pterions are located below the external ones. Most of the frontal branch of the MMA is located below the mid-posterior segment of the lateral pterion. The characterization of the morphology, the relative position of the pterion and the precise relationship of this structure with the MMA in the skulls of adults from southeastern China may provide an anatomical basis for teaching and clinical practices.

Classification and Morphometric Features of Pterion in Thai Population with Potential Sex Prediction.

Background and Objectives: The landmark for neurosurgical approaches to access brain lesion is the pterion. The aim of the present study is to classify and examine the prevalence of all types of pterion variations and perform morphometric measurements from previously defined anthropological landmarks. Materials and methods: One-hundred and twenty-four Thai dried skulls were investigated. Classification and morphometric measurement of the pterion was performed. Machine learning models were also used to interpret the morphometric findings with respect to sex and age estimation. Results: Spheno-parietal type was the most common type (62.1%), followed by epipteric (11.7%), fronto-temporal (5.2%) and stellate (1.2%). Complete synostosis of the pterion suture was present in 18.5% and was only present in males. While most morphometric measurements were similar between males and females, the distances from the pterion center to the mastoid process and to the external occipital protuberance were longer in males. Random forest algorithm could predict sex with 80.7% accuracy (root mean square error = 0.38) when the pterion morphometric data were provided. Correlational analysis indicated that the distances from the pterion center to the anterior aspect of the frontozygomatic suture and to the zygomatic angle were positively correlated with age, which may serve as basis for age estimation in the future. Conclusions: Further studies are needed to explore the use of machine learning in anatomical studies and morphometry-based sex and age estimation. Thorough understanding of the anatomy of the pterion is clinically useful when planning pterional craniotomy, particularly when the position of the pterion may change with age.

Positions and Types of Pterion in Adult Human Skulls: A Preliminary Study.

BACKGROUND: A trauma to the skull in the area of the pterion usually causes rupture of the middle meningeal artery leading to life- threatening epidural hematoma. The objective of the study is to assess the prevalence of different types of pterion and to determine its location using valuable bony landmarks. METHODS: On 90 dry adult human skulls of unknown sex, age and nationality the distance of different landmarks from pterion was measured using stainless steel sliding Vernier caliper. The data were analyzed using SPSS version-20 and an independent t-test analysis was implemented. A value of P< 0.05 was considered as statistically significant. RESULTS: A higher occurrence of sphenoparietal type of pterion with the absence of frontotemporal type was noted. About 23% and 77% of the suture types are found to be unilateral and bilateral, respectively. There was a statistically significant difference between right and left sides of the skull in distances from the center of pterion to frontozygomatic suture, root of zygomatic arch, inion and in central thickness pterion. CONCLUSION: This study showed that the most prevalent type of pterion is sphenoparietal, and revealed asymmetry in the distances from center of pterion to frontozygomatic suture, root of zygomatic arch and inion, and its central thickness. Such findings could offer worthy information about the type and location of pterion, which could be relevant to anatomists, neurosurgeons, forensic medicine specialist and anthropologists.

Anatomical variations and morphometric study of pterion in a Thai population associated with clinical implications / Variaciones anatómicas y estudio morfométrico del pterion en una población tailandesa asociada con implicaciones clínicas

SUMMARY: The objective of this study was to consider the type of variation and to estimate the landmarks for localizing the pterion. One hundred twenty Thai dry skulls were selected randomly from the Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University. The distances of the parameters were measured via Vernier caliper. The sphenoparietal type is the most dominant in the Thai population with 88.75 %. In the male, the distance of the midglabella to the pterion was 9.94?0.64 mm The distance of the frontozygomatic suture to the pterion was 35.41?4.38 mm The distance of the zygomatic arch to the pterion was 39.39?4.69 mm and the distance of the mastoid process tip to the pterion was 86.88?4.44 mm In the female, the distance of the midglabella to the pterion was 9.27?0.63 mm The distance of the frontozygomatic suture to the pterion was 33.08?4.12 mm The distance of the zygomatic arch to the pterion was 33.08?4.12 mm and the distance of the mastoid process tip to the pterion was 83.62?5.16 mm. The pterion approach is the most popular method for neurosurgical procedures, and it provides anatomical variations in the pattern. The sphenoparietal type of pterion is the most common form and the stellate type of pterion is the least common form in Thai skulls. Sex influences the location of the pterion. These findings will be of importance to predict the pterion type in Thai skull and estimate the localization of pterion by using a bony landmark. Knowledge of the precise location of the pterion is an important landmark in the neurosurgical approach.

RESUMEN: El objetivo de este estudio fue considerar el tipo de variación del pterion y estimar los puntos de referencia para localizarlo. Se seleccionaron al azar 120 cráneos secos de individuos tailandeses del Centro de Investigación de Osteología Forense de la Facultad de Medicina de la Universidad de Chiang Mai. Las distancias de los parámetros se midieron mediante un caliper Vernier. El tipo esfenoparietal es el más dominante en la población tailandesa con 88,75 %. En el hombre, la distancia de la glabella al pterion fue de 9,94 ? 0,64 mm. La distancia de la sutura frontocigomática fue de 35,41 ? 4,38 mm La distancia del arco cigomático fue de 39,39 ? 4,69 mm y la distancia del ápice del proceso mastoideo al pterion fue de 86,88 ? 4,44 mm. En la mujer, la distancia de la glabella al pterion fue de 9,27 ? 0,63 mm. La distancia de la sutura frontocigomática al pterion fue de 33,08 ? 4,12 mm. La distancia del arco cigomático al pterion fue de 33,08 ? 4,12 mm y la distancia del ápice proceso mastoideo al pterion fue de 83,62 ? 5,16 mm. El abordaje del pterion es el método más utilizado para procedimientos neuroquirúrgicos y proporciona variaciones anatómicas en el patrón. El tipo esfenoparietal del pterion es la forma más común y el tipo estrellado del pterion es la forma menos común en los cráneos tailandeses. El sexo influye en la ubicación del pterion. Estos hallazgos serán importantes para predecir el tipo de pterion del cráneo en tailandeses y a la vez estimar su localización mediante el uso de un punto de referencia óseo. El conocimiento de la ubicación precisa del pterion es un hito impor- tante en el abordaje neuroquirúrgico.

Pterional variable topography and morphology. An anatomical study and its clinical significance.

BACKGROUND: Pterion is the junction of the frontal, parietal, greater wing of the sphenoid and the squamous part of the temporal bone. The sphenoparietal, frontotemporal, stellate and epipteric pteria were described. The current study determines pterion topography, morphology (variant types' frequency) and morphometry, as well as epipteric bones presence in dried skulls. Gender impact is underlined as well. MATERIALS AND METHODS: Ninety Greek adult dried skulls were observed. The distances in between pterion and the zygomatic arch midpoint and in between pterion and the frontozygomatic suture were measured. RESULTS: The sphenoparietal pterion was the commonest (58.3%), following by the stellate (25%), epipteric (15.5%) and by the frontotemporal pterion (1.1%). Twenty-eight (15.5%) skulls had epipteric bones, further categorised as quadrisutural (35.7%), trisutural (57.1%), bisutural and multiple (3.57%). The mean distances between pterion and the midpoint of zygomatic arch were 4.13 ± 0.45 cm on the right and 4.09 ± 0.47 cm on the left side and between pterion and the frontozygomatic suture were 3.47 ± 0.61 cm on the right and 3.52 ± 0.65 cm on the left side. Both distances were symmetrical. Male skulls showed slightly higher values on the left side for the distance (pterion-midpoint of zygomatic arch). CONCLUSIONS: Pterion is a commonly used neurosurgical landmark and thus in depth knowledge of the pteric area and its variants could be valuable. Recognition of the possible variability in pterion location, morphology and morphometry, as well as possible occurrence of epipteric bones may render pterional craniotomy safer among different population groups.

Frontotemporal dermoid cyst with incomplete dermal sinus tract in an adult: A case report.

BACKGROUND: Non-midline supratentorial dermoid cyst with dermal sinus tract has been rarely reported especially in adults. We recently experienced a noteworthy patient with frontotemporal dermoid cyst with incomplete dermal sinus tract. CASE DESCRIPTION: A 43-year-old female presented with recurrent subcutaneous mass in the left superolateral orbital region. She had a history of active bronchial asthma, which precluded her from contrast-enhanced imaging studies. Plain imaging studies showed a subcutaneous mass which was continuous with an intrasylvian fissure mass by a tract in the sphenoid ridge and the lesser wing of the sphenoid bone. Frontotemporal craniotomy was performed to reset the mass and the tract. Intraoperative finding showed no intradural tumor components. Extradural component was carefully removed focusing attention on the frontal branch of the facial nerve. The pathology was consistent with dermoid cyst and dermal sinus tract. Postoperatively, she had mild facial palsy of the corrugator supercilii (House and Brackmann Grade II). She was discharged home with modified Rankin scale 1. CONCLUSION: Dermoid cyst needs to be included in the differential diagnosis of adult-onset subcutaneous mass in the frontotemporal regions. After thorough imaging studies for the presence and extent of the sinus tract, the symptomatic lesion should be excised completely once and for all.

Morphometric localisation of pterion for lateral neurosurgical planning and approach.

OBJECTIVE: To localise pterion, as a safe landmark, on dry skulls, for performing various neurosurgical procedures. To analyse the variation in the type and location of pterion among Pakistani male population. METHODS: This cross sectional study was conducted form August 2018 to May 2019 on 50 dry skulls obtained from The anatomy departments of different medical colleges of Rawalpindi and Islamabad. Shape of the pterion was noted and different measurements of the pterion from the two reference points, frontozygomatic suture and superior border of zygomatic arch, were recorded. Mean differences between the right and left sides were compared using SPSS version 23. RESULTS: The pattern of pterion suture was sphenoparietal in 47 skulls, 2 skulls had epipteric type and 1 skull had a stellate type of pterion. The mean distance of pterion, on the right side, from posterolateral aspect of frontozygomatic suture was 2.490±0.596cm, 1.485±0.497cm, 2.922±0.697cm measured as horizontal, vertical and direct respectively. The mean horizontal, vertical and direct frontozygomatic measurements on the left side were 2.265±0.574cm, 1.395±0.548cm, 2.717±0.665cm respectively. The mean frontozygomatic horizontal and direct measurements were significantly greater on the right side as compared to the left side (p value 0.001). The mean distance from superior border of zygomatic arch to the centre of pterion on the right and left sides were 3.744±0.444cm and 3.644±9.473 respectively. CONCLUSIONS: The findings of the study provided important information regarding the probability of type and location of pterion in Pakistani males for lateral skull neurosurgical planning, especially when CT scan facility is not available.

Morphology of the pterion in Serbian population / Morfología del pterion en población serbia

The pterion is a topographic point on the lateral aspect of the skull where frontal, sphenoid, parietal and temporal bones form the H or K shaped suture. This is an important surgical point for the lesions in anterior and middle cranial fossa. This study was performed on 50 dry skulls from Serbian adult individuals from Department of Anatomy, Faculty of Medicine in Novi Sad. The type of the pterion on both sides of each skull was determined and they are calcified in four types (sphenoparietal, frontotemporal, stellate and epipteric). The distance between the center of the pterion and defined anthropological landmarks were measured using the ImageJ software. Sphenoparietal type is predominant with 86 % in right side and 88 % in left side. In male skulls, the distance from the right pterion to the frontozygomatic suture is 39.89±3.85 mm and 39.67±4.61 mm from the left pterion to the frontozygomatic suture. In female skulls the distance is 37.38±6.38 mm on the right and 35.94±6.46 mm on the left. The shape and the localization of the pterion are important because it is an anatomical landmark and should be used in neurosurgery, traumatology and ophthalmology.

El pterion es un punto topográfico en la cara lateral del cráneo donde los huesos frontales, esfenoides, parietales y temporales forman la sutura en forma de H o K. Este es un punto quirúrgico importante para las lesiones en la fosa craneal anterior y media. Este estudio se realizó en 50 cráneos secos de adultos serbios del Departamento de Anatomía de la Facultad de Medicina de Novi Sad. Se determinó el tipo de pterión en ambos lados de cada cráneo y se calcifican en cuatro tipos (esfenoparietal, frontotemporal, estrellado y epipterico). La distancia entre el centro del pterion y los puntos de referencia antropológicos definidos se midió utilizando el software ImageJ. El tipo esfenoparietal es predominante con 86 % en el lado derecho y 88 % en el lado izquierdo. En los cráneos masculinos, la distancia desde el pterion derecho hasta la sutura frontocigomática es 39,89 ± 3,85 mm y 39,67 ± 4,61 mm desde el pterion izquierdo hasta la sutura frontocigomática. En los cráneos femeninos, la distancia es 37,38 ± 6,38 mm a la derecha y 35,94 ± 6,46 mm a la izquierda. La forma y la localización del pterion son importantes debido a que es un indicador anatómico y debe usarse en neurocirugía, traumatología y oftalmología.

Cranial CT scan evaluation of morphological variations and location of pterion in Pakistani male population for lateral neurosurgical approach.

OBJECTIVE: To determine the morphological variations and location of pterion in Pakistani male population. METHODS: This retrospective observational study was carried out in the Department of Radiology, Shifa International Hospital from December 2018 to June 2019. The sample size was calculated by Open Epi web-based calculator. Fifty-three cranial CT scans with slice thickness of 0.5mm; consecutive scans of males were randomly selected. The patients with no craniofacial fracture and ages from 25 to 45 years were included. The dataset was obtained from Toshiba Aquilion One, 360-slice MDCT. The images were imported into the imaging software PACS (WFM), and analyzed in maximum intensity projection mode with three dimensional multiplanar reconstruction viewers. Measurements were taken in lateral projections of skull in Frankfurt plane, as horizontal and vertical distance from the posterolateral margin of frontozygomatic suture to center of pterion. Vertical distance from the superior border of zygomaticotemporal arch to the center of pterion. The morphological types were also recognized. RESULTS: The type of pterion on right side was 94.3% sphenoparietal 5.6% epipteric whereas left side was (90.5%) sphenoparietal (3.7%) epipteric, (3.7%) stellate type, (1.8%) frontotemporal type. The mean horizontal and vertical frontozygomatic measurements on right side were 2.23 ± 0.22cm and 1.25±0.219 cm respectively. The same measurements on the left side were 2.27-±0.25 cm and 1.226-±0.22 cm respectively. The mean zygomaticotemporal measurements on the right and left sides were 3.45 ±0.29cm and 3.44 ±0.25 cm respectively. The mean distance on right and left side of skull was statistically insignificant. CONCLUSION: The study provides useful data for position and location of pterion for safe neurosurgical procedures via pterion. Moreover, the knowledge about different morphological types of pterion help the radiologist to differentiate between a fracture line and normal morphological variety.

Anatomic Analysis of the Internal and External Aspects of the Pterion.

OBJECTIVE: The pterion is an H-shaped suture complex. This study's goal was to determine the location of its external and internal surfaces and extension and emphasize and discuss its surgical importance. METHODS: Fifty dried adult human skulls were obtained from the Department of Anatomy. A 2-mm drill bit was placed externally over the pterion, and the pterion was drilled through the bone perpendicular to the skull's surface. RESULTS: The midpoint of the H shape in the pterion area was not at the same level on the skull's external and internal pterion surfaces. According to these measurements, the external pterion lay above the internal pterion when the skull was viewed externally. Furthermore, the internal pterion was on average longer than the external pterion. The internal and external pterions were schematized such that the skull was viewed from the outside. These areas were divided into 4 quadrants (anterior-superior, anterior-inferior, posterior-superior, and posterior-inferior) by a vertical and horizontal line. In 30 cases (60%), sulci of the middle meningeal artery's parietal branches entered the posterior-superior quadrant on the bone, whereas the artery's frontal branches were located in the anterior-superior and anterior-inferior quadrants, and the Sylvian fissure's origin was in the posterior-inferior quadrant. CONCLUSIONS: By using a subdivision into 4 quadrants, and considering our anatomic findings, we determined the way surgical procedures can be performed more easily and reliably. Even with modern localization technologies, anatomic landmarks can be useful to the neurosurgeon.

Reappraising the neurosurgical significance of the pterion location, morphology, and its relationship to optic canal and sphenoid ridge and neurosurgical implications.

Frontolateral craniotomy procedures have advanced from conventional craniotomy to mini-craniotomy, and to contemporary keyhole surgery. In this context, it is important for the neurosurgeon to precisely locate the pterion. The distance of the pterion center from midpoint of zygomatic arch and posterolateral margin of frontozygomatic suture was studied bilaterally in 50 whole adult skulls in Indian ethnic group. The depth of optic canal and sphenoid ridge from the pterion was recorded bilaterally in fifty cut adult skulls and fifteen three-dimensional computed tomography scans. The suture length, thickness, and morphology were studied. The data were analyzed using SPSS software, two-tailed Student's t test, binary logistic regression and receiver operating characteristic curve for sexual dimorphism. The pterion center was located at a mean distance of 37.02 mm above the midpoint of zygomatic arch, 28.20 mm behind the posterolateral margin of frontozygomatic suture, 42.73 mm lateral to the optic canal and 10.59 mm from the sphenoid ridge. The location did not exhibit sexual dimorphism. In 20% cases the pterion center was 40 mm or more above the midpoint of the zygomatic arch and in 5% cases 35 mm or more posterior to the posterolateral margin of frontozygomatic suture. The mean suture length was 10±3 mm. The mean thickness at the center of the pterion was 3.52±1.45 mm. The commonest variety was sphenoparietal followed by frontotemporal, epipteric, and stellate types. A thorough knowledge of these dimensions has innumerable neurosurgical implications in resection of sellar, parasellar, and paraclinoid tumors and circulatory aneurysms.

Reappraising the neurosurgical significance of the pterion location, morphology, and its relationship to optic canal and sphenoid ridge and neurosurgical implications / 대한해부학회지

Cranial shape variation in adult howler monkeys (Alouatta seniculus).

Howler monkeys (genus Alouatta) display a distinctive cranial architecture characterized by airorhynchy (or retroflexion of the facial skeleton on the cranial base), a small braincase, and a posteriorly oriented foramen magnum. This configuration has been associated with distinct factors including a high folivory diet, locomotion, and the presence of a specialized vocal tract characterized by large hyoid bone. However, the morphological relationships between the facial and neurocranial blocks in Alouatta have been scarcely investigated. In this study we quantitatively analyzed the cranial shape variation in Alouatta seniculus, to evaluate possible influences and constraints in face and braincase associated with airorhynchy. We also considered the structural role of the pteric area within the cranial functional matrix. We applied landmark-based analysis and multivariate statistics to 31 adult crania, computing shape analyses based on 3D coordinates registration as well as the analysis of the Euclidean distance matrix to investigate patterns of intraspecific morphological variability. Our results suggest that allometry is the main source of variation involved in shaping cranial morphology in howlers, influencing the degree of facial proportions and braincase flattening, and generating the main sexual differences. Larger individuals are characterized by a higher degree of airorhynchy, neurocranial flattening, and expansion of the zygomatic arch. Allometric variations influence the skull as a whole, without distinct patterns for face and braincase, which behave as an integrated morphological unit. A preliminary survey on the pteric pattern suggests that the morphology of this area may be the result of variations in the vertical growth rates between face and braincase. Future studies should be dedicated to the ontogenetic series and focus on airorhynchy in terms of differential growth among distinct cranial districts.

Microsurgical treatment of large parasellar meningiomas by pterional craniotomy: A clinical experience with 34 cases / 第二军医大学学报

Objective To introduce the microsurgery treatment method for large parasellar meningiomas by pterional craniotomy and its curative effect. Methods The clinical data of 34 patients with large parasellar meningiomas, who underwent microsurgery via pterional or extensive pterional craniotomy in Seventh People’s Hospital of Shanghai University of Traditional Chinese Medicine Jul. 2006 to Aug. 2016, were retrospectively analyzed. The patients included 13 men and 21 women with ages ranging from 21 to 72 (average, 49±13) years old. The course of disease ranged from 1 to 55 (average, 13±10) months. Maximum diameter of tumors ranged from 3.3 to 5.2 (average, [4.3±0.6]) cm. Results No surgical death occurred in this study. Postoperatively, the cranial imaging examination showed that 24 of 34 cases were totally removed, 5 cases were subtotally removed, and 5 cases were partially removed. The postoperative follow-up time was 24-48 (average, 36±13) months. Twenty-eight cases had good prognoses with Karnofsky score being 80 to 100, and six cases had fair prognoses with Karnofsky score being 60 to 79. Five cases had postoperative oculomotor paralysis, which was improved with nutritional nerve treatment. Conclusion The microsurgical treatment via pterional or extensive pterional craniotomy can improve the total resection rate of the large parasellar meningiomas. Palliative operations combined with postoperative radiotherapy may be employed for the tumors that can only be subtotally and partially removed.

Classification and incidence of pterion patterns of Thai skulls / Clasificación e incidencia de los patrones de pterion en cráneos de Tailandia

SUMMARY: The pterion, a landmark for neurosurgery, is the weakest part of the skull owing to relatively thin bone. Variant patterns of pterion can confuse the clinicians during diagnosis of the lateral skull fractures in emergency situations. Thedifferent pterion types of many races have been reported but not of Thais. In this study; therefore, we investigated the incidence of sutural pterion patterns on of Thai skulls. The infratemporal fossa of 110 sides from 55 dried skulls identified as Thais were observed and classified for individual pterion types. The results showed that the pterion patterns can be classified into 4 types; spheno-parietal (87.27 %), fronto-temporal (4.55 %), uni-epipteric (6.36 %), and multi-epipteric (1.82 %) types. It was found that the spheno-parietal type was dominant in males (61.81 %) than in females (25.45 %). The majority of the skulls showed bilateral symmetry (85.45 %) in all types and the unilateral ones were far less (14.55 %). In bilateral pterion incidence, the spheno-parietal type was approximately 93.61 % while the uni-epipteric type was not found. Moreover, the bilateral multi-epipteric type was found only in one female skull (2.13 %). These findings will be useful for the radiologists and the neurosurgeons concerning lateral skull fractures in emergency diagnosis.

RESUMEN: El pterion es un punto de referencia para la neurocirugía, y es la parte más débil del cráneo debido a estar conformado por hueso relativamente delgado. Los diversos patrones de pterion pueden confundir a los clínicos durante el diagnóstico de fracturas laterales de cráneo en situaciones de emergencia. Con excepción de los tailandeses, diferentes tipos de pterion se han reportado en muchas razas. hemos investigado la incidencia de diversos patrones de pterion en cráneos de Tailandia. Analizamos 110 fosas infratemporales, correspondientes a 55 cráneos secos del Noreste de Tailandia y se clasificaron de acuerdo al tipo de pterion. Los resultados mostraron que el pterion puede clasificarse en 4 tipos: esfeno-parietal (87,27 %), fronto-temporal (4,55 %), epiptérico (3,63 %) y multi-epiptérico (1,81 %). Se encontró que el tipo esfeno-parietal tuvo mayor incidencia en hombres (61,81 %) que en mujeres (25,45 %). Además, la incidencia de simetría bilateral (85,45 %) fue mayor que la unilateral (14,55 %). A nivel bilateral, el tipo esfeno-parietal fue de 93,61 %, mientras que el tipo epiptérico no se observó. Por otra parte, el tipo multiepiptérico fue encontrado bilateralmente en un solo cráneo femenino (2,13 %). Esta incidencia puede ser utilizada como un conocimiento básico para los radiólogos tailandeses sobre las fracturas laterales del cráneo en un diagnóstico de emergencia.

Superficial Temporal Artery-Sparing Mini-Pterional Approach for Cerebral Aneurysm Surgery.

OBJECTIVE: The purposes of this study were to introduce a superficial temporal artery (STA)-sparing mini-pterional approach for the treatment of cerebral aneurysms and review the surgical results of this approach. METHODS: Between June 2010 and December 2015, we performed the STA-sparing mini-pterional approach for 117 patients with 141 unruptured intracranial aneurysms. We analyzed demographic, radiologic, and clinical variables including age, sex, craniotomy size, aneurysm location, height of STA bifurcation, and postoperative complications. RESULTS: The mean age of patients was 58.4 years. The height of STA bifurcation from the superior border of the zygomatic arch was 20.5 mm±10.0 (standard deviation [SD]). The craniotomy size was 1051.6 mm2±206.5 (SD). Aneurysm neck clipping was possible in all cases. Intradural anterior clinoidectomy was performed in four cases. Contralateral approaches to aneurysms were adopted for four cases. Surgery-related complications occurred in two cases. Permanent morbidity occurred in one case. CONCLUSION: Our STA-sparing mini-pterional approach for surgical treatment of cerebral aneurysms is easy to learn and has the advantages of small incision, STA sparing, and a relatively wide surgical field. It may be a good alternative to the conventional pterional approach for treating cerebral aneurysms.