Osteological Study of the Parietal Foramen in the Adult Human Skull Bones and its Clinical and Surgical Correlations / Estudio Osteológico del Foramen Parietal en los Huesos del Cráneo Humano Adulto y sus Correlaciones Clínicas y Quirúrgicas

SUMMARY: Parietal emissary foramina (PEF) are small holes, which are localized between the middle and posterior thirds of the parietal bone posterior surface close to the sagittal suture. PEF are important structures that protect the parietal emissary vein, which passes through it. During neurosurgery procedures, parietal foramina (PF) knowledge is crucial. This work aimed to evaluate presence and location of the PF in the skull of an adult human. Moreover, measure the distance amidst PF and the sagittal suture's midline to ascertain its clinical repercussions. 74 adult human skulls, without gross pathology, were observed for the PF's existence. The PF's and sagittal suture's midline distance were measured. According to the PF patterns of presence, five groups were distributed. Finally, specimens were photographed and subjected to statistical analysis. The PF was absent in 7 skulls (9.5 %). There were 9 skulls (12.2 %) exhibited central parietal foramen where the parietal foramen lies on the sagittal suture. 17 skulls (23 %) showed right unilateral parietal foramen, whereas 15 skulls (20.3 %) demonstrated left unilateral parietal foramen. The final 26 skulls (35.1 %) exhibited bilateral parietal foramen. This descriptive study supplies valuable information of PF variations, which is crucial for neurosurgeons in modifying surgical techniques and procedures to alleviate injury to PF-emerging structures such as emissary veins.

Los forámenes emisarios parietales (FEP) son pequeños orificios que se localizan entre los tercios medio y posterior de la superficie posterior del hueso parietal, cerca de la sutura sagital. Los FEP son estructuras importantes que protegen la vena emisaria parietal, que lo atraviesa. Durante los procedimientos de neurocirugía, el conocimiento de los forámenes parietales (FP) es crucial. Este trabajo tuvo como objetivo evaluar la presencia y ubicación del FP en el cráneo de hombres adultos, además, medir la distancia entre el FP y la línea mediana de la sutura sagital para conocer su repercusión clínica. Se examinaron 74 cráneos humanos adultos, sin patología grave, para determinar la existencia del FP. Se midió la distancia de la línea mediana de la sutura sagital y del FP. De acuerdo con los patrones de presencia del FP, se distribuyeron en cinco grupos. Finalmente, los especímenes fueron fotografiados y sometidos a análisis estadístico. El PF estaba ausente en 7 cráneos (9,5 %). Hubo 9 cráneos (12,2 %) que presentaban un PF central localizándose en la sutura sagital. 17 cráneos (23 %) presentaban un FP unilateral derecho, mientras que 15 cráneos (20,3 %) se observó un FP unilateral izquierdo. Los 26 cráneos restantes (35,1 %) exhibieron FP bilaterales. Este estudio descriptivo proporciona información valiosa sobre las variaciones del FP, que es fundamental para los neurocirujanos en el momento de modificar las técnicas y los procedimientos quirúrgicos para aliviar las lesiones de las estructuras emergentes del FP, como las venas emisarias.

Prevalence, morphology, morphometry and associated clinical implications of mastoid emissary veins: narrative review / Prevalência, morfologia, morfometria e implicações clínicas das veias emissárias mastóideas: uma revisão narrativa

Abstract The mastoid emissary vein connects the posterior auricular vein to the sigmoid sinus and varies in size, number, location, and course, resulting in clinical complications. This study was conducted in response to the vast clinical implications associated with this vein. The aim of this review is to highlight and describe the prevalence, varied morphology, and morphometry of the mastoid emissary vein, how these varied parameters cause clinical complications, and how these can be rectified and avoided. A literature survey was conducted using various databases and different terms related to mastoid emissary vein were used to search the literature. Pitfalls related to surgery in the vicinity of this vein and their remedies were elucidated. The literature search revealed that the prevalence, morphology, and morphometry of mastoid emissary veins vary immensely and are responsible for morbidity and mortality. Pre-operative identification of mastoid veins is thus essential and so multidetector computed tomography of the temporal bone should be scheduled before planning surgery.

Resumo A veia emissária mastóidea que conecta a veia auricular posterior ao seio sigmoide pode variar em tamanho, número, localização e curso, resultando em complicações clínicas. O objetivo desta revisão é destacar e descrever a prevalência, variação morfológica e morfometria da veia emissária mastóidea, além de como esses parâmetros causam complicações clínicas e como corrigi-las e reduzi-las. Foram conduzidas buscas em diversas bases de dados utilizando diferentes termos relacionados à veia emissária mastóidea. As armadilhas relacionadas a procedimentos cirúrgicos realizados nas proximidades dessa veia e as respectivas soluções foram descritas. A pesquisa na literatura revelou que a prevalência, a morfologia e a morfometria da veia emissária mastóidea variam imensamente, sendo responsáveis ​​por alta morbidade e mortalidade. Portanto, a identificação da veia mastóidea deve ser realizada no pré-operatório através de tomografia computadorizada multidetectores do osso temporal, antes do planejamento cirúrgico.

Study Of Incidence, Laterality, And Patency Of Posterior Condylar Foramina In 60 Dry Human Skulls In North Gujarat

Introduction: Posterior Condylar foramina present just behind the occipital condyles, which transmits emissaryvein connecting sub occipital venous plexus with intracranial sinuses.Materials and Methods: Study conducted on 60 dry human skulls. Each skull is observed for incidence, lateralityand patency of posterior condylar foramina. Here patency of foramina is observed by probe.Result: We observed that 77% skulls have presence of condylar foramina and 23% have absence of foramina.50%skulls have bilateral foramina,20% skulls have left sided and 7% have right sided foramina.70% skulls havepatent foramina and 30% skulls have absent patency.Conclusion: There is variation in incidence, laterality and patency of condylar foramina so knowledge of variationin condylar foramina is important for neurosurgeon and ENT surgeon in skull base surgery and also for radiologist.

Study of Incidence, Laterality and Patency of the Posterior Condylar Canal In 100 Dry Human Skulls.

Background: The posterior condylar foramina are the largest of the emissary foramina’s present in the human skull. The posterior condylar canal transmits the posterior condylar emissary vein and it acts as a route for venous circulation between extracranial venous system and intracranial venous sinuses. It also acts as a channel for spread of infection. Due to its varied clinical implications and to get a better knowledge about the canal this study was taken up. Objectives: To determine the variations in the occurrence of posterior condylar canalwith respect to incidence, laterality, patency and if patent whether intrasinus or retrosinus. Materials and methods: An observational study was carried out on 100 dry human skulls obtained from the department of anatomy, Kempegowda Institute Of Medical Sciences, Bangalore, India. The posterior condylar canal was observed and noted. The patency was ascertained by passing a probe and care was taken to note whether the canal opened intrasinus or retrosinus. Result: The posterior condylar canal was found to be present in 90% of the skulls. The incidence of bilateral presence was more than the unilateral presence. 82.22% of the canals were patent with the intrasinus type being themost prevalent. Conclusion: The knowledge of the posterior condylar canal and its variations is important for the radiologist, neurosurgeons, ENT surgeons operating in this area.

Prevalencia y características morfométricas del foramen mastoideo y vena emisaria mastoidea en población mexicana / Prevalence and morphometric characteristics of mastoid foramen and mastoid emmisary vein in the Mexican population

Las descripciones anatómicas del foramen mastoideo (FM) y la vena emisaria mastoidea (VEM) son escasas en la literatura. Dicho conocimiento es fundamental para realizar un abordaje quirúrgico de la fosa craneal posterior o región mastoidea. El objetivo del estudio fue determinar la prevalencia, variantes y características morfométricas del FM y VEM en población mexicana. Se evaluaron 176 hemicráneos por dos observadores independientes cegados el uno del otro, se determinaron la prevalencia, número y características morfométricas. La prevalencia del FM entre los dos lados fue de 75% con una mayor frecuencia de forámenes del lado izquierdo comparado con el lado derecho; respecto al número de forámenes se encontraron 108 hemicráneos con un foramen único, 22 con doble foramen y 2 con triple foramen. La prevalencia del FM y VEM fue de 75%, siendo la variante única la más frecuente.

The anatomic descriptions of mastoid foramen (MF) and mastoid emissary vein (MEV) are lacking in the literature. This knowledge is fundamental for the surgeon who is about to perform surgery of the posterior fossa or mastoid region. This study aims to determine the prevalence of MF and MEV in Mexican population, determine the morphometric characteristics of MF and describe possible variations in the number, size, location and asymmetry. In this study 88 craniums were evaluated (176 hemicranium) by two independent observers who did not have access to information of each other´s results. The prevalence, number and the morphometric characteristics were determined. MF prevalence of the two sides of the skull was 75 % with a higher frequency of the left foramina compared to the right side; in reference to the number of foramina we found 108 hemicranium with a single MF, 22 double and 2 triple foramen. In conclusion, the prevalence of MF and MEV in this study is 75%, this single variant noted as being the most frequent.

Morphological characteristics of foramen of Vesaliusand its relationship with clinical implications

The aim of this study was to evaluate the incidence as well morphometry of the foramen of Vesalius in humanskulls and analyzing their clinical importance. Dry human skulls (n = 80) and with gender distinction wereused (40 male and 40 female). The results demonstrates an total incidence of 40%, 13.75% skulls with thebilateral presence of the foramen, 26.25% skulls with the unilateral presence of the foramen, 31.25% skullswith foramen only of the right side, 22.50% skulls with foramen only of the left side, 25% masculine skulls withat least 1 foramen and 52.25% skulls with at least 1 foramen. The morphometry showed an average diameterof 1.457 ± 1.043 mm on the right and 1592 ± 0938 mm to the left. The average distance to the foramenovale was 1.853 ± 0.303 mm on the right side and 2.464 ± 0.311 mm on the left. It can be concluded that adeepened anatomical study of the foramen of Vesalius collaborates not only for anatomical knowledge of thisstructure, but also in clinical situations involving this foramen.

Para-condylar Foraminal Approach in Microvascular Decompression for Hemifacial Spasm

The ideal approach in microvascular decompression(MVD) for hemifacial spasm(HFS) should provide the shortest and perpendicular route to the facial nerve root exit zone(FNREZ) with minimal cerebellar retraction and early cerebrospinal fluid drainage to avoid surgical morbidity. Small basal craniectomy anterior, posterior and superior to the condylar foramen would be the ideal approach for HFS, because it is maximal basal route to FNREZ. We performed this approach in 15 patients with HFS. Slightly curved skin incision 5cm in length was placed from inferior nuchal line 2cm posterior to the mastoid notch toward the angle of the mandible and the neck muscles were splitted. Posterior condylar emissary vein was elevated from condylar fossa. Small basal craniectomy extending from the inferior nuchal line to the condylar foramen was made. Jugular process was drilled out along the superior margin of the occipital condyle to expose distal sigmoid sinus and the junction of sigmoid sinus and jugular bulb. Lateral margin of foramen magnum posteroinferior to the condylar foramen was removed for early drainage of CSF from lateral medullary cistern. Dura was opened in T-shaped manner. With minimal elevation of cerebellum, arachnoid around lower cranial nerves can be dissected and FNREZ can be identified easily and safely. In conclusion, para-condylar foraminal approach can be considered to be minimally invasive and maximally safe in MVD for HFS.