Persistent Stapedial Artery in Adhesive Otitis Media: A Case Report.

A persistent stapedial artery (PSA) is a rare embryologic remnant that typically involutes at week 10 of embryogenesis. However, if it is persistent, it may lead to conductive hearing loss and pulsatile tinnitus. It is of utmost importance to identify such an anomaly, as it leads to serious complications intraoperatively if overlooked. Proper clinical and radiological assessment helps an otologist recognize the PSA. We describe the case of a 24-year-old female presenting with a chronically discharging ear in addition to pulsatile tinnitus and conductive hearing loss with an incidental finding of a PSA upon otoscopy.

Prominent Enlargement of the Facial Nerve Canal in a Case of a Persistent Stapedial Artery.

In this case report, we present a 23-year-old patient with complaints of a recurrent plop sound in the left ear. Non-contrast CT and MR imaging revealed an enlargement of the tympanic segment of the facial canal due to venous congestion. A persistent stapedial artery (PSA) and absent foramen spinosum were identified as concomitant factors. This unique combination of anomalies has not been previously reported and knowledge about this condition is essential to avoid unnecessary surgery. Teaching Point: A persistent stapedial artery may be associated with enlargement of the tympanic facial nerve canal due to venous congestion.

Morphometric and morphologic analysis of the foramen spinosum in the Slovenian population with clinical correlations.

Background: The foramen spinosum (FS) is a pivotal passage for neurovascular structures within the skull base. We performed a detailed morphometric and morphological analysis of the FS to emphasize its clinical relevance. Materials & Methods: The study was performed on dried skull specimens obtained from the anatomical collections of the Institute of Anatomy and Institute of Forensic Medicine of the University of Ljubljana. The morphometric and morphologic features of FS in 126 whole human skulls and 15 skull halves were analyzed, including dimensions, shape, and other anatomical variations, as well as relationships to surrounding structures. Measurements were done with a digital sliding caliper. Results: The mean length and width of the FS were 2.45 ± 0.65 mm and 2.03 ± 0.53 mm on the right side and 2.49 ± 0.61 mm and 2.08 ± 0.48 mm on the left side. The most frequently observed shape was round (56.7%), followed by oval (28.2%), irregular (8.7%) and drop shaped (6.3%). Several anatomical variations were also noted, including FS duplication, confluences with other foramina, and FS obstruction due to marginal bony outgrowths. Conclusion: The FS exhibits notable interindividual differences in anatomical characteristics which should be considered during neurosurgical procedures and radiological interventions in the skull base.

Topographic and Morphometric Study of the Foramen Spinosum of the Skull and Its Clinical Correlation.

Background and Objectives: The spinous foramen (FS) of the skull is an opening located in the greater wing of the sphenoid bone at the base of the skull, and it includes the middle meningeal vessels and the meningeal branch of the mandibular trigeminal nerve. The FS is commonly used as an anatomical landmark in neurosurgical procedures and neuroimaging of the middle cranial fossa because of its relationship with other cranial foramina and surrounding vascular and nervous structures. Thus, specific knowledge of its topography and possible anatomical variations is important regarding some surgical interventions and skull imaging. The aim of this study was to provide further details on the morphology of the FS of the skull by evaluating its topographic and morphometric relationships and correlating the findings with clinical practice. Materials and Methods: Thirty dried skulls of human skeletons from body donors from the collection of the Laboratory of Anatomical Microdissection at a medical school were used. The metric dimensions and variations of the FS and its relationship with adjacent bone structures were analyzed with an interface digital microscope. Results: The results showed the bilateral presence of the FS in all skulls; however, differences were observed in the shape, diameter, and topography in relation to the foramen ovale and the spine of the sphenoid. The FS was present in the greater wing of the sphenoid bone; however, in one skull, it was located in the lateral lamina of the pterygoid process. The FS was smaller than the foramen ovale. A round and oval FS shape was the most common (42.1% and 32.8% of the samples, respectively), followed by drop-shaped (12.5%) and irregular-shaped (12.5%) foramina. Conclusions: In conclusion, FS variations among individuals are common and must be considered by surgeons during skull base interventions in order to avoid accidents and postoperative complications.

Eyebrow incision with a crescent-shaped orbital rim craniotomy for microscopic and endoscopic transorbital approach to the anterior and middle cranial fossa: A cadaveric study and case presentation.

•The transorbital approach combining eyebrow incision and crescent-shaped craniotomy increases the surgical freedom to access the anterior and middle skull-base.•The technic allows the use of both endoscope and microscope.•The concept is at the crossroad between the supraorbital keyhole and endoscopic trans-orbital approach.

Variant Bilateral Foramina of the Middle Cranial Fossa.

Variations of the foramina located at the skull base can have direct clinical implications. For example, transcutaneous approaches to the trigeminal nerve using long spinal needles for treatment of trigeminal neuralgia can inadvertently enter such variant foramina and potentially result in hemorrhage. Therefore, knowledge of such variant foramina is important to the clinician treating or diagnosing patients based on imaging of this region. We report an adult male skull found to have unusual foramina located at the skull base. The foramina were located approximately 3.1 cm lateral to the plane of the foramen rotundum and foramen ovale. The left foramen had a diameter of 0.82 mm and the right foramen had a diameter of 0.77 mm. Both foramina opened up just medial to the sphenotemporal suture into the roof of the infratemporal fossa. Additionally, each foramen was the most lateral of a larger collection of foramina found to exit the skull base but confluent with the diploic space of the greater wind of the sphenoid and not with the floor of the middle cranial fossa. This group of openings, including the most lateral which communicated with the middle cranial fossa, were lateral to the lateral plate of the pterygoid process. Knowledge of variant foramina of the skull base is important to clinicians treating patients with pathology of this region. To our knowledge, foramina as described herein have not been previously reported in the extant medical literature.

Anatomical localization of horizontal segment of the petrous internal carotid artery in transnasal endoscopic skull base surgery.

OBJECTIVE: To discuss the localization of horizontal segment of petrous internal carotid artery in transnasal endoscopic skull base surgery, and to provide anatomical data for clinical surgery. METHODS: The horizontal segment of the petrous internal carotid artery of 5 adult cadaveric heads were exposed by endoscopic transnasal and microscopic open approaches respectively, and the relevant data and images were measured and collected. RESULTS: The medial wall of the foramen spinosum is the lateral wall of the isthmus of the eustachian tube, and the thickness of the bone is 0.5 ± 0.2 mm. The medial wall of the isthmus of the eustachian tube is the lateral wall of the posterior genu of the carotid canal and the thickness of the bone is 0.2 ± 0.1 mm. The vidian nerve originates from the anterior genu of the petrous internal carotid artery. The distance from the base of vidian nerve to the isthmus of eustachian tube is 19.2 ± 2.8 mm. CONCLUSION: The foramen spinosum is the landmark of isthmus of the Eustachian tube. The isthmus of the Eustachian tube is the landmark of the posterior genu of the internal carotid artery. The line between the base of the vidian nerve and the isthmus of the Eustachian tube ioks the landmark of horizontal segment of the petrous internal carotid artery.

Key anatomical landmarks for middle fossa surgery: a surgical anatomy study.

OBJECTIVEMiddle fossa surgery is challenging, and reliable surgical landmarks are essential to perform accurate and safe surgery. Although many descriptions of the middle fossa components have been published, a clinically practical description of this very complex anatomical region is lacking. Small structure arrangements in this area are often not well visualized or accurately demarcated with neuronavigation systems. The objective is to describe a "roadmap" of key surgical reference points and landmarks during middle fossa surgery to help the surgeon predict where critical structures will be located.METHODSThe authors studied 40 dry skulls (80 sides) obtained from the anatomical board at their institution. Measurements of anatomical structures in the middle fossa were made with a digital caliper and a protractor, taking as reference the middle point of the external auditory canal (MEAC). The results were statistically analyzed.RESULTSThe petrous part of the temporal bone was found at a mean of 16 mm anterior and 24 mm posterior to the MEAC. In 87% and 99% of the sides, the foramen ovale and foramen spinosum, respectively, were encountered deep to the zygomatic root. The posterior aspect of the greater superficial petrosal nerve (GSPN) groove was a mean of 6 mm anterior and 25 mm medial to the MEAC, nearly parallel to the petrous ridge. The main axis of the IAC projected to the root of the zygoma in all cases. The internal auditory canal (IAC) porus was found 5.5 mm lateral and 4.5 mm deep to the lateral aspect of the trigeminal impression along the petrous ridge (mean measurement values). A projection from this point to the middle aspect of the root of the zygoma, being posterior to the GSPN groove, could estimate the orientation of the IAC.CONCLUSIONSIn middle fossa approaches, the external acoustic canal is a reliable reference before skin incision, whereas the zygomatic root becomes important after the skin incision. Deep structures can be related to these 2 anatomical structures. An easy method to predict the location of the IAC in surgery is described. Careful study of the preoperative imaging is essential to adapt this knowledge to the individual anatomy of the patient.

Intraspinosum Middle Meningeal Artery Ligation: A Simple Technique to Control Bleeding in the Middle Fossa During the Anterior Transpetrosal Approach.

BACKGROUND: Although the greater superficial petrosal nerve (GSPN) is an important landmark of the anterior transpetrosal approach (ATPA), bleeding from the interdural space around the foramen spinosum (FS), the GSPN, and the foramen ovale impedes the identification of the GSPN, during epidural dissection in the ATPA. OBJECTIVE: To describe the technique of intraspinosum middle meningeal artery (MMA) ligation, which enables us to control bleeding from the interdural space. METHODS: During epidural dissection, we identified the FS and partially drilled the lateral side of the FS. Next, we cut the convergence site of the neurovascular structures such as the MMA, middle meningeal vein, and the meningeal branch of the mandibular nerve with the periosteal dura within the FS and continued dural detachment epidurally to expose the petrous apex. Bleeding control around the FS and postoperative facial nerve paresis were assessed for 96 patients treated with the ATPA. Additionally, histological study was performed around the FS using Masson's trichrome stain. RESULTS: In all cases, in which this technique was used, bleeding from the interdural space was well controlled and no persistent facial nerve paresis was identified. In the histological study, we confirmed that the MMA, the middle meningeal vein, and the meningeal branch of the mandibular nerve converged into the FS and many venous channels existed in the interdural space around the FS and the foramen ovale. CONCLUSION: Intra-FS MMA ligation is an effective method for control of bleeding from the interdural space of the middle fossa during the ATPA.

Hearing Preservation During Anterior Petrosectomy: The "Cochlear Safety Line".

BACKGROUND: Identification and protection of the cochlea during anterior petrosectomy is key to prevent hearing loss. Currently, there is no optimal method to infer the position of the cochlea in relation to the Kawase quadrangle; therefore, damage to the cochlea during anterior petrosectomy remains a substantial risk. OBJECTIVES: To identify and define landmarks available during anterior petrosectomy to locate the cochlea and prevent its damage. METHODS: The Kawase approach was simulated in 11 cadaveric specimens. After a subtemporal craniotomy, foramen spinosum and ovale were identified. Anterior petrosectomy was performed, and the upper dural transitional fold (UDTF) was identified. Two virtual lines, from foramen spinosum (line A), and the lateral rim of the foramen ovale (line B), were projected to intersect the UDTF perpendicularly. The cochlea was exposed, and the distances between lines A and B and the closest point of the outer rim and membranous part of the cochlea were measured. RESULTS: The average distance between line A to the bony and membranous edges of the anteromedial cochlea was -0.62 ± 1.38 mm and 0.38 ± 1.63 mm, respectively. The average distance between line B to the bony and membranous edges of the cochlea was 1.82 ± 0.99 mm and 2.78 ± 1.29 mm, respectively. Line B (cochlear safety line) never intersected the cochlea. CONCLUSIONS: The cochlear safety line is a reliable landmark to avoid the cochlea during the Kawase approach. When expanding the anterior petrosectomy posteriorly, the cochlear safety line can be used as a reliable landmark to prevent exposure of the cochlea, thus preventing hearing loss.

An osteometric evaluation of the foramen spinosum and venosum / Una evaluación osteométrica de los forámenes espinoso y venoso

The foramen spinosum (FS) and foramen venosum (of Vesalius) (FV) are alisphenoid apertures situated within the hub of the middle cranial fossa in close proximity to foramen ovale (FO). The FS and FV provide a passage to important neurovascular structures. An accurate knowledge of the morphometric details of the FS and FV including their shape, incidence, relation to other foramina and/or presence of any anomalies may represent a reliable anatomical landmark during surgical explorative maneuvers. Therefore, the aim of this study was to investigate the morphologic and morphometric features of the FS and FV. The study was conducted on 100 dry human skulls (n= 200) obtained from the osteological bank at the University of KwaZulu-Natal, to produce a database which may serve as a useful guideline to surgeons and anesthetists. Although single (95%), duplicate (2.5%) and triplicate (0.5%) FS were identified; only single (5%) and duplicate (0.5%) FV were found. Oval (FS: 43.5%; FV: 4.5%) and round (FS: 58%; FV: 0.5%) foramina were observed. In addition, the relationship of the FS and FV to FO was recorded: postero-lateral (FS: 93%; FV: 0%); posterior (FS: 1.9%; FV: 0%); postero-medial (FS: 0.5%; FV: 0%); anterior (FS: 0%; FV: 0.5%); antero-medial (FS: 0%; FV: 4.5%). The mean morphometric parameters of the FS and FV included the internal diameter (FS: 2.53±0.76 mm; FV: 1.93±0.46 mm), external diameter (FS: 2.50±0.74 mm; FV: 2.81±1.53 mm) and distance to the FO (FS: 3.45± 1.29 mm; FV: 2.63±1.24 mm). In light of the morphometric and morphological variations of skull-based foramina, the evaluation of the FS and FV in our study may provide a reliable osteometric reference in clinical practice which may be beneficial during interpretation of imaging and surgical intervention.

El foramen espinoso (FE) y foramen venoso (FV) son aberturas situadas en el centro de la fosa craneal media en las proximidades de un foramen oval permeable (FO). El FE y FV proporcionan el acceso a importantes estructuras neurovasculares. Un conocimiento preciso de los datos morfométricos del FE y FV, incluyendo su forma, incidencia, relación con otros forámenes o presencia de cualquier anomalía puede representar un punto de referencia anatómica fiable durante las maniobras exploratorias quirúrgicas. El objetivo de este estudio fue investigar las características morfológicas y morfométricas del FE y FV. El estudio se realizó sobre 100 cráneos humanos secos (n= 200) obtenidos del banco osteológico de la Universidad de KwaZulu-Natal, para producir una base de datos que pueda servir como guía útil para los cirujanos y anestesistas. Se identificaron FE únicos (95%), dobles (2,5%) y triples (0,5%); junto a FV únicos (5%) y dobles (0,5%). Según forma, se encontraron forámenes de tipo oval (FE: 43,5%; FV: 4,5%) y circular (FE: 58%; FV: 0,5%). Además, se registró la relación entre FE, FV y FO: postero-lateral (FE: 93%; FV: 0%); posterior (FE: 1,9%; FV: 0%); postero-medial (FE: 0,5%; FV: 0%); anterior (FE: 0%; FV: 0,5%) y antero-medial (FE: 0%; FV: 4,5%). Los parámetros morfométricos medios de los FE y FV incluyeron el diámetro interno (FE: 2, 53±0,76 mm; FV: 1,93±0,46 mm), diámetro externo (FS: 2,50±0,74 mm; FV: 2,81±1,53 mm) y distancia al FO (FS: 3,45±1,29 mm; FV: 2,63±1,24 mm). Considerando la morfometría y las variaciones morfológicas de los forámenes en la base del cráneo, la evaluación del FE y FV puede proporcionar una referencia osteométrica fiable en la práctica clínica, que puede ser beneficiosa durante la interpretación imagenológica y la intervención quirúrgica.

Anatomical examination of the foramens of the middle cranial fossa / Examinación anatómica de los forámenes de la fosa craneal media

Three foramina can be identified in the greater wing of the sphenoid bone: The foramen rotundum (FR), foramen ovale (FO) and foramen spinosum (FS). In addition, there may be another foramen called foramen ovale accessorium or foramen vesalius (FV) which connects the middle cranial fossa to the fossa pterygoidea (pterygoid fossa). It is described as an opening with smooth walls in front and medial to foramen ovale which leads to an oblique channel directed towards the fossa pterygoidea. FV was present between FO and FR in 14 (31.8%) of 44 dry and 6 (33.3%) of 18 cadaver skullbase sides (total 20 (32.3%) of 62). The diameter values of foramens on both the right and the left side were observed to be almost symmetrical. FR's distance from the midline on the left side was greater than the right side. Also, the distance between FO and the petrous apex and the distance between FS and the petrous apex were greater on the left side. On the right side the distance between FO and FR, and the distance between FO and FS were greater. Also, the distance between FR and the petrous apex was greater on the right side. Anatomical variations in appearance size and distance of FR, FO, FS and FV are of great surgical importance. In conclusion, we can infer that the information provided with this study can help the neurosurgeon and anatomist to increase the knowledge about anatomy of middle cranial fossa.

Tres forámenes pueden ser identificados en el ala mayor del esfenoides: El foramen redondo (FR), foramen oval (FO) y el foramen espinoso (FS). Puede además existir otro foramen llamado foramen oval accesorio o foramen de Vesalio (FV), que conecta la fosa craneal media a la fosa pterigoidea. Se describe como una abertura con paredes lisas por anterior y medial al foramen oval, que conduce a un canal oblicuo dirigido hacia la fosa pterigoidea. FV estuvo presente entre FO y FR en 14 (31,8%) de 44 cráneos secos y 6 (33,3%), en 18 lados en la base de cráneos de cadáveres (total 20 (32,3%) de 62). El diámetro de los forámenes en los lados derecho e izquierdo se observó casi simétricos. Las distancias de FR desde la línea mediana en el lado izquierdo fue mayor que en el lado derecho. Además, la distancia entre FO y el vértice de la porción petrosa y la distancia entre el FS y el vértice porción petrosa fueron mayores en el lado izquierdo. En el lado derecho la distancia entre A y FR, así como la distancia entre A y FS fueron mayores. Por otra parte, la distancia entre los FR y el vértice del porción petrosa fue mayor en el lado derecho. Las variaciones anatómicas en el tamaño de la apariencia y la distancia de FR, DE, FS y FV son de gran importancia quirúrgica. Podemos inferir que la información proporcionada en este estudio puede ayudar al neurocirujano y anatomista para aumentar el conocimiento sobre la anatomía de la fosa craneal media.

Abnormality of the Foramen Spinosum due to a Variation in the Trajectory of the Middle Meningeal Artery: A Case Report in Human.

Originating from the maxillary artery, the middle meningeal artery (MMA) is predominantly periosteal irrigating the bone and dura mater. It enters the floor of the middle cranial fossa through the foramen spinosum, travels laterally through a middle fossa bony ridge, and curves over the previous upper-greater wing of the sphenoid, where it in a variable point is divided into frontal and parietal branches. The complex sequence of the MMA development gives many opportunities for variant anatomy. In a Caucasian cadaver skull of an approximately 35-year-old individual belonging to the didactical collection of the Laboratory of Human Anatomy at the University of Santa Cruz do Sul, Brazil, it was noted that the right foramen spinosum has an abnormal shape. In this report, we discuss an abnormality of the foramen spinosum due to a variation in the trajectory of the MMA. Thus, the present study shall be important for health sciences and those who have some interest in pathologies associated with the MMA.

An anatomical study on the foramen ovale and the foramen spinosum.

INTRODUCTION: An anatomical study was undertaken to note the shape of the foramen ovale(FO), foramen spinosum (FS) & presence or absence of canalis innominatus. FO is present in the posterior part of the greater wing of sphenoid. FS is located posterolareral to foramen ovale. Aims & Objective: We attempted this study to find out the variations in shape, bony growth & divisions of FO & FS in available dry human skulls. MATERIAL & METHODS: We studied 100 human skulls available in the Department of Anatomy MVPS Medical College, Nashik. This study of FO & FS was done in both male & female skulls. OBSERVATION & RESULTS: We found oval, round, almond, triangular shaped FO. Variations in the shape of FO showed the maximum as oval shaped followed by almond, round & slit like. CONCLUSION: FO is of great surgical & diagnostic importance in procedures like percutaneous trigeminal rizotomy in trigeminal neuralgia, transfacial fine needle aspiration technique etc. Considering such clinical importance of FO & FS, this study was worthwhile as far as neurosurgeons are concerned.

Anatomic variants of foramen ovale and spinosum in human skulls / Variantes anatómicas de los forámenes oval y espinoso en cráneos humanos

Foramen ovale and spinosum are important foramina of the greater wing of the sphenoid. Normal variations in their shapes and sizes are quite common and widely studied. In the present study, conducted in the Department of Anatomy of School of Medical Sciences, Universiti Sains Malaysia, 25 dried human skulls were examined for anatomic variations of the foramina of the greater wing of the sphenoid. During the study, we noticed anatomic variations of the foramen ovale and spinosum. In one skull, there was an abnormally large and irregular foramen ovale which was confluent with the foramen spinosum. In the second skull, the foramen spinosum was absent on the left side and in the 3rd skull it was duplicated on the right side. These variations are very rare and may be of clinical and anatomical significance to neurosurgeons and physicians particularly in cases of trigeminal neuralgia, diagnostic detection of vascular tumors and aneurysm.

Los forámenes oval y espinoso son forámenes importantes del ala mayor del esfenoides. Variaciones normales en sus formas y tamaños son muy comunes y ampliamente estudiados. En el presente repórter, llevado a cabo en el Departamento de Anatomía de la Facultad de Ciencias Médicas, Universiti Sains Malaysia, fueron examinados en 25 cráneos humanos secos las variaciones anatómicas de los forámenes del ala mayor del esfenoides. Durante el estudio, se observaron algunas variaciones anatómicas de los forámenes oval y espinoso. En un cráneo, se observó un foramen oval anormalmente grande e irregular, que era confluente con el foramen espinoso. En el segundo cráneo, el foramen espinoso estaba ausente en el lado izquierdo y en el tercer cráneo se duplicó en el lado derecho. Estas variaciones son muy raras y pueden ser de importancia clínica y anatómica para neurocirujanos y médicos, en particular en casos de neuralgia del trigémino, detección diagnóstica de tumores vasculares y aneurismas.

A novel method of identifying the internal acoustic canal in the middle fossa approach in a cadaveric study-the rule of 2s.

Objective Multiple landmarks and anatomic relationships exist to identify internal acoustic canal (IAC) in middle fossa approach for removing intracanalicular schwannomas. We attempted to identify a reproducible, practical method to quickly identify the IAC that would be applicable when an expanded middle fossa approach is required. Design Middle fossa approach was performed on 10 cadavers (21 dissections). In the first head, temporal and suboccipital craniotomies were performed to identify landmarks and formulate a hypothesis. Porous acusticus (PA) was identified and IAC was circumferentially skeletonized into middle fossa. Orientation of IAC in the middle fossa was evaluated in relation to foramen spinosum (FS), foramen ovale (FO), petrous ridge, and petrous apex. Consistency of this relationship was tested in the remaining heads. Results The opening of PA (point A) was consistently found at a mean of 2.38 cm posterolateral to the petrous apex along the petrous ridge (range 2.1 to 2.8). A line was drawn from the FO to FS and extrapolated posteriorly. The IAC (point B) was found a mean distance of 2.39 cm from FS along the FS-FO line (range 2.1 to 2.8). The course of IAC was consistently found by connecting point A to point B. Conclusion A novel, practical, and reproducible method is described to identify the IAC via the expanded middle fossa approach.