Localization of Maxillary Artery for Cerebral Revascularization: L-Shaped Perpendicular Two-Step Drilling Technique Stretching from the Foramen Ovale to Rotundum.

BACKGROUND: The use of the maxillary artery (MA) as a donor has increasingly become an alternative method for cerebral revascularization. Localization difficulties emerge due to rich infratemporal anatomical variations and the complicated relationships of the MA with neuromuscular structures. We propose an alternative localization method via the interforaminal route along the middle fossa floor. METHODS: Five silicone-injected adult cadaver heads (10 sides) were dissected. Safe and effective localization of the MA was evaluated. RESULTS: The MA displayed anatomical variations in relation to the lateral pterygoid muscle (LPM) and the mandibular nerve branches. The proposed L-shaped perpendicular 2-step drilling technique revealed a long MA segment that allowed generous rotation to the intracranial area for an end-to-end anastomosis. The first step of drilling involved medial-to-lateral expansion of foramen ovale up to the lateral border of the superior head of the LPM. The second step of drilling extended at an angle approximately 90° to the initial path and reached anteriorly to the foramen rotundum. The MA was localized by gently retracting the upper head of the LPM medially in a posterior-to-anterior direction. CONCLUSIONS: Considering all anatomical variations, the L-shaped perpendicular 2-step drilling technique through the interforaminal space is an attainable method to release an adequate length of MA. The advantages of this technique include the early identification of precise landmarks for the areas to be drilled, preserving all mandibular nerve branches, the deep temporal arteries, and maintaining the continuity of the LPM.

Neuronavigation-Specific Parameters for Selective Access of Trigeminal Rootlets in Radiofrequency Lesioning: A Cadaveric Morphometric Study.

BACKGROUND AND OBJECTIVE: Radiofrequency lesioning (RFL) is a safe and effective treatment for medically refractory trigeminal neuralgia. Despite gaining mainstream neurosurgical acceptance in the 1970s, the technique has remained relatively unchanged, with the majority of series using lateral fluoroscopy over neuronavigation for cannula guidance. To date, there are no studies describing neuronavigation-specific parameters to help neurosurgeons selectively target individual trigeminal rootlets. In this cadaveric study, we sought to provide a neuronavigation-specific morphometric roadmap for selective targeting of individual trigeminal rootlets. METHODS: Embalmed cadaveric specimens were registered to cranial neuronavigation. Frontotemporal craniotomies were then performed to facilitate direct visualization of the Gasserian ganglion. A 19-gauge cannula was retrofit to a navigation probe, permitting real-time tracking. Using preplanned trajectories, the cannula was advanced through foramen ovale (FO) to the navigated posterior clival line (nPCL). A curved electrode was inserted to the nPCL and oriented inferolaterally for V3 and superomedially for V2. For V1, the cannula was advanced 5 mm distal to the nPCL and the curved electrode was reoriented inferomedially. A surgical microscope was used to determine successful contact. Morphometric data from the neuronavigation unit were recorded. RESULTS: Twenty RFL procedures were performed (10R, 10L). Successful contact with V3, V2, and V1 was made in 95%, 90%, and 85% of attempts, respectively. Mean distances from the entry point to FO and from FO to the clival line were 7.61 cm and 1.26 cm, respectively. CONCLUSION: In this proof-of-concept study, we found that reliable access to V1-3 could be obtained with the neuronavigation-specific algorithm described above. Neuronavigation for RFL warrants further investigation as a potential tool to improve anatomic selectivity, operative efficiency, and ultimately patient outcomes.

The pterygospinous foramen (Civinini) and the pterygoalar (crotaphitico-buccinatorius): laboratory findings / El foramen pterigoespinoso (Civinini) y el pterigoalar (crotafítico-buccinatorius): hallazgos de laboratorio

SUMMARY: The Pterygospinous foramen and pterygoalar foramen (crotaphitico-buccinatorius) are variant and atavic formations of the skull base and arise respectively from complete or incomplete idiopathic ossifications of the pterygospinous and pterygoalar ligaments. By proximity with areas of relevance for diagnosis and surgery, such as access pathways to the parapharyngeal and retropharyngeal spaces, it is necessary to be aware of these conditions due to the difficulties generated in surgical maneuvers and the promotion of compressive syndromes of mandibular nerve branches. This study was conducted on 45 samples of dry skulls and disarticulated sphenoid bones belonging to the collection of the Federal University of Juiz de Fora, Governador Valadares campus, Minas Gerais, Brazil. Our results indicated a total incidence of complete and incomplete pterygospinous and pterygoalar foramen (crotaphitico- buccinatorius) in 15, 5 % (7 skulls), with a higher incidence for the incomplete form of pterygospinous foramen (Civinini foramen) in 4 skulls (8.8 %), with 3 presenting unilaterally and 3 presenting bilaterally. The pterygoalar foramen (crotaphitico-buccinatorius or Hyrtl) was noted bilaterally in 1 of the skulls (2.2 %). The pterygospinous foramen and pterygoalar foramen are important findings, sometimes incidental, of an area of great anatomical expressiveness and pathological occurrences, besides the indispensable and unclear studies of phylogenetic order.

RESUMEN: El foramen pterigoespinoso y el foramen pterigoalar (crotafítico-buccinatorius) son formaciones variantes y atávicas de la base del cráneo y surgen respectivamente de osificaciones idiopáticas completas o incompletas, de los ligamentos pterigoespinoso y pterigoalar. Debido a la proximidad con áreas de relevancia para el diagnóstico y la cirugía, como las vías de acceso a los espacios parafaríngeo y retrofaríngeo, es necesario conocer estas condiciones por las dificultades que se generan en las maniobras quirúrgicas. Este estudio se realizó en 45 muestras de cráneos secos y huesos esfenoides desarticulados pertenecientes a la colección de la Universidad Federal de Juiz de Fora, campus Governador Valadares, Minas Gerais, Brasil. Nuestros resultados indicaron una incidencia total de foramen pterigoespinoso y pterigoalar completo e incompleto (crotafítico-buccinatorius) en el 15,5 % (7 cráneos), con una mayor incidencia de la forma incompleta de foramen pterigoespinoso (agujero de Civinini) en 4 cráneos (8,8 %), con 3 de presentación unilateral y 3 de presentación bilateral. El foramen pterigoalar (crotaphitico-buccinatorius o Hyrtl) se observó bilateralmente en 1 de los cráneos (2,2 %). El foramen pterigoespinoso y pterigoalar son hallazgos importantes, a veces incidentales, de un área de gran expresividad anatómica y ocurrencias patológicas, además de los estudios indispensables y poco claros de orden filogenético.

The three fetal shunts: A story of wrong eponyms.

The fetal circulatory system bypasses the lungs and liver with three shunts. The foramen ovale allows the transfer of the blood from the right to the left atrium, and the ductus arteriosus permits the transfer of the blood from the pulmonary artery to the aorta. The ductus venosus is the continuation of the umbilical vein, allowing a large part of the oxygenated blood from the placenta to join the supradiaphragmatic inferior vena cava, bypassing the fetal liver and directly connecting the right atrium. These structures are named after the physicians who are thought to have discovered them. The foramen ovale and the ductus arteriosus are called the "foramen Botalli" and the "ductus Botalli," after Leonardo Botallo (1530-c. 1587). The ductus venosus is styled "ductus Arantii" after Giulio Cesare Arantius (1530-1589). However, these eponyms have been incorrectly applied as these structures were, in fact, discovered by others earlier. Indeed, the foramen ovale and the ductus arteriosus were described by Galen of Pergamon centuries earlier (c. 129-210 AD). He understood that these structures were peculiar to the fetal heart and that they undergo closure after birth. The ductus venosus was first described by Andreas Vesalius (1514-1564) 3 years before Arantius. Therefore, the current anatomical nomenclature of the fetal cardiac shunts is historically inappropriate.

An Anatomical Study of the Foramen Ovale for Neuromodulation of Trigeminal Neuropathic Pain.

OBJECTIVE: Neuromodulation for trigeminal pain syndromes such as trigeminal neuropathic pain (TNP) necessitates accurate localization of foramen ovale (FO). The Härtel-type approach is very well-established and safe, ideal for temporary cannulation of the FO for ablative procedures such as balloon microcompression. A key shortcoming of the Hartel approach for placement of neuromodulation leads is the limited opportunity for secure anchoring. The aim of this study is to introduce a novel surgical approach for the treatment of TNP by investigating key osseous landmarks and their spatial relationships to the FO. MATERIALS AND METHODS: Sixteen sides of cadaver heads were dissected to investigate a surgical route of the FO via transoral gingival buccal approach. Alveolar arch of the maxilla and zygomaticomaxillary suture were selected to serve as an osseous landmark for the surgical guidance to the FO. Through the intraoral route, a needle simulating electrode was traversed to aim the FO from the inferior lateral to the superior medial direction to target specific fibers of the aimed division of the nerve. RESULTS: Visual identification and access to the trigeminal nerve at the external opening of FO was successful in all 16 hemifacial cadavers. A needle successfully targeted different regions of the trigeminal nerve by changing the angle of the trajectory allowing the needle to reach a specific division of the trigeminal nerve. CONCLUSIONS: This study provides a novel means of approaching the FO via transoral gingival buccal access.

The pterygospinous and pterygoalar ligaments and their relationship to the mandibular nerve: Application to a better understanding of various forms of trigeminal neuralgia.

INTRODUCTION: Ossification of the pterygospinous and pterygoalar ligaments has been well documented forming pterygospinous and pterygoalar bars. However, the actual ligaments have been rarely shown in the existing literature. Therefore, this study aimed to reveal the anatomy of the pterygoalar ligament/bar and pterygospinous ligament/bar, and its relationship with the branches of the mandibular nerve. METHODS: Thirty sides from fifteen Caucasian fresh frozen cadaveric heads were used in this study. The branches of the mandibular nerve and any ligaments or bony bridges between the lateral plate of the pterygoid process and spine of the sphenoid were observed. RESULTS: A pterygospinous ligament/bar and pterygoalar ligament/bar were defined based on the relationship with the branches of the mandibular nerve. The pterygoalar ligament/bar was further classified into two types. Twenty-seven sides (90%) had at least one pterygoalar ligament/bar or pterygospinous ligament/bar. A pterygospinous ligament/bar was found on 15 sides (50.0%). A pterygoalar ligament/bar was found on 16 sides (53.3%), and a type I on 11 sides and type II on 5 sides. CONCLUSIONS: This finding and classification are simple to understand and easy to apply for future studies, and have important implications regarding the clinical anatomy of trigeminal neuralgia and facial pain.

Patent Foramen Ovale: Pivotal Role of Transesophageal Echocardiography in the Indications for Closure, Assessment of Varying Anatomies and Post-procedure Follow-up.

Patent foramen ovale (PFO) is present in 15%-30% of the general population and has been associated with various pathologic states, including cryptogenic stroke, platypnea-orthodeoxia syndrome, decompression sickness and migraine with auras. Transesophageal echocardiography (TEE) has a major role in the diagnostic evaluation of PFO, as well as in the post-procedural assessment after transcatheter closure. The goals of this article were to synthesize the echocardiographic transesophageal techniques required for accurate PFO diagnosis and careful anatomic assessment of its anatomic variants, to focus TEE indications for device closure as complementary to clinical indications and to assess the role of TEE in the post-procedure follow-up.

Topographic and microscopic anatomical description of the emissary sinus of foramen ovale in adult humans.

OBJECTIVE: Although the Emissary Sinus of Foramen Ovale (ESFO) was first described by Trolard in 1868, its definition remains confused and neglected in the medical literature. This structure represents a vein, two veins, a venous plexus, or a dural sinus? Does it really exist? To understand this topic, this work aimed to describe the anatomy, topography, and microscopic features of the ESFO, precisely characterizing its structure, routes and anatomical correlations. PATIENTS AND METHODS: ESFO from the skull's base of adults were dissected into fifty anatomical blocks and evaluated using Hematoxylin and Eosin, Picro-sirius red and Weigert staining, and by Scanning Electron Microscopy (SEM). RESULTS: ESFO was always present between cavernous sinus and pterygoid plexus on both antimeres, its inferior route passing through the foramen ovale and/or sphenoidal emissary foramen (foramen of Vesalius), anterior to the mandibular branch of trigeminal nerve. Its microscopic arrangement resembled what was found on transverse sinus, that is composed by layers of collagen fibers oriented on transversal and longitudinal planes. It wasn't possible to identify the media and adventitial tunica, features seen in veins, and the elastic layer was very thin near its lumen. SEM analysis showed that, like the transverse sinus, the ESFO was composed by parallel cells that presented a rhombus shape containing central rounded nuclei. CONCLUSION: In summary, the venous channel passing through the foramen ovale and/or sphenoidal emissary foramen (foramen of Vesalius) is a dural venous sinus constituted by dura mater layers and should be considered during surgical approaches near the foramen ovale in the middle cranial fossa.

Foramen Venosum in macerated skulls from the North-East of Brazil: morphometric study

The foramen venosum (FV) is a small, inconstant orifice in the middle cranial fossa, located anterior and medial to the foramen ovale (FO). The object of the present study was to analyse the frequency of the FV, its side of appearance, diameter and distance from the FO, in macerated skulls of adult Brazilians from the north-eastern region of Brazil. 194 macerated skulls were analysed. The diameter of the FV and its distance from the FO (FV-FO) were measured with a digital calliper. The FV was present in 18.5% of the skulls. Unilateral presence (12.4%) was more frequent than bilateral (6.1%). When unilateral, the FV was more frequent on the left side (9.3%) than the right (3.1%). We observed asymmetry in the size of the FV, which was larger on the left side (p=0.043). No statistically significant difference was observed between sides for FV-FO, however this distance was significantly greater in women than in men (p=0.006). The FV is an important anatomical variation, and may occur bilaterally or unilaterally. It is asymmetrical, with larger diameter found on the left side. The findings of this study provide important information for surgeons and morphologists on the anatomy of the middle cranial fossa

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Morphological study of fossa ovalis and its clinical relevance.

AIMS: Patent foramen ovale (PFO) has been implicated in the etiology of a number of different pathologies, including cryptogenic stroke, decompression sickness in divers, etc. It can act as a channel for paradoxical embolism. PFO is not an uncommon condition, with a probe-patency in 15-35% population. The fossa ovalis (FOv) varies in size and shape from heart to heart; the prominence of annulus FOv also varies. The entire FOv may be redundant and aneurysmal. The anatomico-functional characterization of interatrial septum seems to be of paramount importance for both atrial septal defect (ASD) and PFO, not only for the device selection, but also for the evaluation of the outcome of this procedure. METHOD: This study was conducted in 50 apparently normal hearts available in Department of Anatomy. After opening the right atrium, the shape of FOv was observed. The size was measured with the digital vernier caliper; the prominence and extent of limbus, and the redundancy or otherwise of FOv were noted; probe patency was confirmed. RESULTS: In the majority, FOv was oval (82%); average transverse diameter was 14.53mm and vertical 12.60mm. In 90%, the rim of the annulus was raised; in 20%, a recess was found deep to the margin of the annulus; and 18% showed probe patency. CONCLUSION: As no study of this nature has been carried out in the Indian population, this provides pertinent information on the morphology of FOv, which may be useful for device selection in treating ASD and PFO.

Surgical landmarks of the nasopharyngeal internal carotid using the maxillary swing approach: A cadaveric study.

OBJECTIVES/HYPOTHESIS: Surgery of the paranasopharyngeal space is very hazardous due to the position of the internal carotid artery, which is surrounded by soft tissue with few anatomical landmarks. STUDY DESIGN: Fresh cadaveric study. METHODS: In this study, we used the maxillary swing procedure to have a broad view of the internal carotid artery using an anterior approach. We sought to establish surgical landmarks, make measurements, and compare them to other imagery and cadaveric studies in the literature. RESULTS: We performed the maxillary swing procedure in 10 subjects (six female and four male, mean deceased age 81 years). The internal carotid artery was found to be in the same sagittal plane as the lateral pterygoid plate, the foramen ovale, and the eustachian tube isthmus. It was always located behind the stylopharyngeal fascia and immediately lateral to the longus capitis muscle. The artery was measured on average 10.7 mm from the pharyngeal recess, 7.3 mm from the eustachian tube isthmus, and 22.8 mm from the torus tubarius. CONCLUSIONS: The eustachian tube isthmus, the longus capitis muscle, and the stylopharyngeal fascia are the main surgical landmarks of the internal carotid artery. The artery can also be found in an oblique sagittal plane including the eustachian tube isthmus, the foramen ovale, and the lateral pterygoid plate. The pharyngeal recess remains a very dangerous area, only millimeters away from the carotid artery. LEVEL OF EVIDENCE: NA Laryngoscope, 126:1562-1566, 2016.

Clinical value of a self-designed training model for pinpointing and puncturing trigeminal ganglion.

OBJECTIVES. A training model was designed for learners and young physicians to polish their skills in clinical practices of pinpointing and puncturing trigeminal ganglion. METHODS. A head model, on both cheeks of which the deep soft tissue was replaced by stuffed organosilicone and sponge while the superficial soft tissue, skin and the trigeminal ganglion were made of organic silicon rubber for an appearance of real human being, was made from a dried skull specimen and epoxy resin. Two physicians who had experiences in puncturing foramen ovale and trigeminal ganglion were selected to test the model, mainly for its appearance, X-ray permeability, handling of the puncture, and closure of the puncture sites. Four inexperienced physicians were selected afterwards to be trained combining Hartel's anterior facial approach with the new method of real-time observation on foramen ovale studied by us. RESULTS. Both appearance and texture of the model were extremely close to those of a real human. The fact that the skin, superficial soft tissue, deep muscles of the cheeks, and the trigeminal ganglion made of organic silicon rubber all had great elasticity resulted in quick closure and sealing of the puncture sites. The head model made of epoxy resin had similar X-ray permeability to a human skull specimen under fluoroscopy. The soft tissue was made of radiolucent material so that the training can be conducted with X-ray guidance. After repeated training, all the four young physicians were able to smoothly and successfully accomplish the puncture. CONCLUSION. This self-made model can substitute for cadaver specimen in training learners and young physicians on foramen ovale and trigeminal ganglion puncture. It is very helpful for fast learning and mastering this interventional operation skill, and the puncture accuracy can be improved significantly with our new method of real-time observation on foramen ovale.

Transcranial segment of the trigeminal nerve: macro-/microscopic anatomical study using sheet plastination.

BACKGROUND: Trigeminal neuralgia (TN) may be caused by the mechanical compression of the trigeminal nerve. In the studies on the location of mechanical irritation and entrapment of the nerve, attention has been paid mostly to vascular structures in the subarachnoid space. Few studies have explored the relationship between the trigeminal nerve and its surrounding structures along its course in the skull base. The aim of this study was to examine and trace the root, ganglion and three divisions of the trigeminal nerve and their relationships with surrounding soft and bony structures in the skull base, and to identify the likely mechanical compression points. METHODS: A total of 26 adult cadavers (ten females, 16 males; age range, 45-81 years) were examined in this study, eight for dissection and 16 for sheet plastination study. RESULTS: Anatomical structures that may make the trigeminal nerve susceptible to entrapment in the skull base were located at (1) the inferolateral edge of the mouth of Meckel's cave, (2) the middle cranial fossa dura and the lateral wall of the anterior intracavernous portion of the internal carotid artery, (3) the ridge of the medial wall of the foramen rotundum, and (4) the twisted periosteum and venous plexus of the foramen ovale. CONCLUSION: This study identified four likely mechanical compression points along the course of the trigeminal nerve in the skull base. Knowledge of these TN-susceptible sites may be useful to both skull base surgeon and TN-animal model researcher, particularly when they study TN without vascular compression.

Endonasal, transmaxillary, transpterygoid approach to the foramen ovale: radio-anatomical study of surgical feasibility.

OBJECTIVE: This study aimed to examine the feasibility of an endonasal, transmaxillary, transpterygoid approach to the foramen ovale by examining key anatomical, radiological and surgical landmarks. METHOD: Measurements were taken from 183 patients' computed tomography scans using BrainLAB iPlan 1.1 Cranial software. Endoscopic dissection was then carried out on a cadaver to assess surgical viability. RESULTS: We found that the distances from the posterior maxillary wall to the foramen ovale and from the anterior nasal spine to the foramen ovale were statistically significantly larger in men than women. The distance from the base of the lateral pterygoid plate to the foramen ovale, and the angle between the foramen ovale, the anterior nasal spine and the sphenoid rostrum, were constant between the sexes. The importance of the lateral pterygoid plate in locating the foramen ovale was demonstrated. CONCLUSION: With the increasing popularity of image guidance and assisted navigation in endoscopic surgery, these findings increase anatomico-radiological understanding of the surgical approach investigated.

A feasibility study on pinpointing the branches of trigeminal nerve in radiofrequency ablation.

OBJECTIVE: To propose a pinpointing method and to obtain technique parameters for puncture of the branches of the trigeminal nerve through anatomical radiological study. DESIGN: Trigeminal ganglions and intracranial branches of 25 pieces (50 sides) of adult skull wet-specimens were dissected and coated with contrast agent. X-ray images of the skull in lateral cranial position were collected with the tube inclining towards head at 15°, 20° and 25°. 'Porus-Clinoid Line' and 'FO-PC axis' were delineated on the images. The latter set as the base line, Point A, B and C were settled separately as the upper rim of the trigeminal ganglion, the axis of Brach V2 and the junction of the extended border lines of Branch V2 and V3 all intersected with it. The collected data was processed afterwards. RESULTS: In the cases of 50 sides, the maximum value of the 'FO-PC Distance' was 17.8 mm; Distance A, 6.6 mm; Distance B, 10.1 mm; and Distance C, 6.6 mm, while the minimum of each was 9.4 mm, 0.3 mm, 4.4 mm and 6.6 mm respectively. Ratios of the 'FO-PC Distance' to Distance B were respectively 2.00 ± 0.15 mm, 1.98 ± 0.15 mm and 1.95 ± 0.16 mm when tube inclined towards head at angles of 15°, 20° and 25°; to Distance C were 3.06 ± 0.53 mm, 3.36 ± 0.60 mm and 3.75 ± 0.96 mm and to Distance A were 10.65 ± 9.17 mm, 7.33 ± 5.28 mm, 5.16 ± 2.30 mm under the same condition. CONCLUSION: The results showed that Distances from each branch of trigeminal nerve to the medial rim of foramen ovale vary on different individuals while the proportional relationship between each branch and 'FO-PC Distance' has regularity.

High-resolution computed tomography analysis of the medial infratemporal fossa: a pilot study.

BACKGROUND: The medial aspect of the infratemporal fossa (ITF) can be accessed endoscopically. Two important landmarks to help guide dissection in this area have previously been identified: the anterior border of the foramen ovale (AFO) and the "bony bridge" (BB), a consistent bridge of bone between the foramen ovale and spinosum. We conducted a pilot study using high-resolution computed tomography (HRCT) to measure the distances to these structures. METHODS: Thirty measurements were acquired from 15 adult patients undergoing HRCT scans of the sinuses. The position of the anterior nasal spine (ANS), AFO, and BB on the 3 orthogonal planes were identified by 3 observers. Euclidian distances between each of these structures were calculated. A cadaveric dissection was performed and images were acquired to provide an endoscopic view. RESULTS: Fifteen HRCT scans of the sinuses (8 females) were analyzed. The mean distances from the ANS to the AFO and BB were 78.5 ± 5.9 mm and 83.2 ± 6.0 mm, respectively. For males alone, these distances were 80.3 ± 4.3 mm and 85.3 ± 4.8 mm, respectively, and in females 77.0 ± 6.5 mm and 81.4 ± 6.7 mm, respectively. CONCLUSION: Average distance from the ANS to the AFO and BB was 78.5 mm and 83.2 mm, respectively. These measurements can be used by endoscopic skull base surgeons to guide dissection in the ITF.

Progressive anatomical closure of foramen ovale in normal neonatal mouse hearts.

In the prenatal heart, right-to-left atrial shunting of blood through the foramen ovale is essential for proper circulation. After birth, as the pulmonary circulation is established, the foramen ovale functionally closes as a result of changes in the relative pressure of the two atrial chambers, ensuring the separation of oxygen depleted venous blood in the right atrium from the oxygenated blood entering the left atrium. Little is known regarding the process of anatomical closure of the foramen ovale in the postnatal heart. Genetically engineered mouse models are powerful tools to study heart development and to reveal mechanisms underlying cardiac anomalies, including defects in atrioventricular septation. Using three-dimensional reconstructions of serial sectioned hearts at early postnatal Days 2-7, we show a progressive reduction in the size of the interatrial communication throughout this period and complete closure by postnatal Day 7. Furthermore we demonstrate that fusion of the septum primum and septum secundum occurs between 4 weeks and 3 months of age. This study provides a standard timeline for morphological closure of the right-left atrial communication and fusion between the atrial septa in normal mouse hearts.

The anatomic relationship around the horizontal segment of petrous internal carotid artery: a study based on reconstructed computed tomography angiography.

PURPOSE: The anatomic relationship around the horizontal segment of petrous internal carotid artery (ICA) is complicated. Relative researches on human patients using radiographic technique are scarce. It is essential to get adequate anatomic knowledge about this region for performing some bypass procedures. METHODS: Using the independent software Mimics, we prospectively studied the 0.45-mm-thick computed tomography angiography (CTA) images of 29 patients (58 sides). All patients' middle cranial fossa and related critical anatomic structures were reconstructed in 3D. Some measurements were established on the multiplanar reconstructed images, including the distance from foramen ovale and foramen spinosum to the petrous ICA; the distance from the lumen of cochlea to the edge of trigeminal impression and petrous ICA; and the length of the horizontal segment of petrous ICA. RESULTS: The horizontal segment of petrous ICA was surrounded by the trigeminal impression, the cochlea and the auditory tube spatially. On the multiplanar reconstructed CTA images, the average distances from foramen ovale and foramen spinosum to the petrous ICA were 4.1 mm and 5.8 mm, respectively; the average distance from the lumen of cochlea to the edge of trigeminal impression and petrous ICA were 8.2 mm and 2.0 mm, respectively; and the mean length of the horizontal segment of petrous ICA was 15.8 mm. CONCLUSIONS: Our results indicate adequate and reliable anatomic information can be obtained using reconstructed CTA on an individualized basis.

Original landmarks for intraoperative localization of the foramen ovale: a radio-anatomical study.

PURPOSE: Radiofrequency lesioning is one of the frequently used modalities for the treatment of trigeminal neuralgia. Easily identifiable radiological landmarks are necessary for correct intra-operative localization of foramen ovale. METHODS: One hundred and seventy sides of dry skulls were studied for the following measurements. D-1: the transverse distance between the apex of the petrous temporal and the centre of the foramen ovale. D-2: the transverse distance from the midline to the centre of the foramen ovale. The distances between the centre of the foramen ovale and, D-3: the anterior margin of mandibular fossa, D-4: centre of the mandibular fossa and D-5: point at the junction of posterior margin and floor of the sella. D-6: the vertical distance between the centre of the foramen ovale and point at the junction of posterior margin and floor of the sella. RESULTS: The mean values measured were D-1: 13.9 mm, D-2: 24.5 mm, D-3: 3.1 mm, D-4: 11.4 mm, D-5: 0.75 and D-6: 12.42 mm. In majority of cases the centre of foramen was around 25 mm from midline. Additionally the centre of the foramen was at the level of the junction of the posterior wall and floor of the sella or within 2 mm of this point in the antero-posterior direction. In most (81%) cases the vertical displacement of the foramen was 1-1.5 cm inferior to this point. CONCLUSION: During intra-operative imaging, the midline of the skull and the junction of the posterior wall and floor of the sella can be used as reliable landmarks for the identification of foramen ovale.

A morphometric study of foramen ovale.

AIM: To note the morphological variations and morphometric details of foramina ovale in dry adult skulls of Indian origin. MATERIAL AND METHODS: 82 dry adult human skulls of unknown sex and of Indian origin were obtained and variations in appearance and number of foramen ovale were noted. The length and width of the foramina ovale of both sides were determined using digital Vernier calipers and area (A) was also calculated and analyzed. RESULTS: Out of 82 adult skulls, the values for the right side was 7.64 ± 1.194 mm, 5.128 ± 0.827 mm and 30.808 ± 7.545 mm2 and for the left side the values was 7.561 ± 1.123 mm, 5.244 ± 0.950 mm and 31.310 ± 8.262 mm2 respectively, for the mean length, width and area of the foramen ovale. The shape of foramen was typically ovale in most of the skulls (56.70%) with some bony variations such as spine, tubercles etc. CONCLUSION: There was no statistically significant difference between the two sides in length, width and area of foramen ovale and there was a positive correlation between lengths and areas of both sides.