Anterolateral surgical triangle of the cavernous sinus: a cadaveric study of neurosurgical importance.

BACKGROUND: The anterolateral triangle around the cavernous sinus is a surgical skull base triangle used as a neurosurgical landmark essential to skull-based surgeries. There are few reports of its measurements with little attention paid to anatomical variations. METHODOLOGY: A total of 15 adult human cadaveric skulls were dissected to expose the anterolateral triangle on both sides. The triangle was defined and measurements of the three borders were taken precisely and the area of each triangle was calculated using Heron's formula. RESULTS: On an average, the length of the anteromedial border is 11.4 (+ 2.2 mm); the length of the posteromedial border is 8.7 (+ 2.6 mm); the length of the lateral border is 13.06 (+ 2.6 mm) and the area of the anterolateral triangle is 48.05 (+ 17.5 mm2). CONCLUSION: Concise understanding of anterolateral triangle is essential to skull-based surgeries; comprehending its anatomy helps with better surgical planning and provides insight into local pathology.

The learning curve for cavernous sinus surgery illustrated by symptomatic intracavernous aneurysm clipping through a pretemporal transcavernous approach.

OBJECTIVE: The anatomy of the cavernous sinus (CS) has been well studied in the laboratory for decades; however, performing surgery in and around the CS is still a challenge. To reveal the learning curve for CS surgery via the pretemporal transcavernous approach (PTTC), surgical procedures were examined. The authors proposed 4 levels of surgical difficulty in opening the walls of the CS through this approach. Details of the approach were illustrated by surgical videos of symptomatic intracavernous aneurysm clipping. METHODS: Four levels of surgical difficulty were proposed. The higher the level, the more the CS walls were opened. Pathologies corresponding to each level of difficulty in and around the CS were categorized in each level together with explanations. From 2015 to 2021, 5 patients with symptomatic intracavernous aneurysms (diplopia due to compressive cranial neuropathy) underwent the PTTC at the authors' institute and served as representative cases in opening the walls of the CS. All CS cases from 2009 to 2021 were reviewed and categorized to demonstrate the learning curve. RESULTS: Four levels of surgical difficulty are as follows: level 1, a basic Dolenc extradural approach, which involves opening the anterior third of the superior and lateral walls of the CS; level 2, mobilizing the internal carotid artery (ICA) and opening the proximal dural ring to enter the roof of the CS and treat lesions around the clinoid and upper cavernous ICA; level 3, opening the entire aspect of the superior and lateral walls of the CS, which involves opening the oculomotor triangle and peeling the lateral wall of the CS to the tentorial incisura; and level 4, mobilizing cranial nerves III, IV, and V1 to gain access to the supra-/infratrochlear triangles to have proximal ICA control and opening the posterior wall as the last step to enter the posterior fossa. Surgical steps were described and illustrated with surgical videos of symptomatic intracavernous aneurysm clipping. CONCLUSIONS: The learning curve for CS surgery is long. The authors use 4 levels of surgical difficulty to describe applications of the PTTC in CS surgery. This approach serves as an effective workhorse in treating CS pathologies with low morbidity and high success rates when performed by experienced neurosurgeons.

Seno cavernoso: anatomía, histología y terminología.

BACKGROUND: Although the cavernous sinus (CS) has been studied since 1695, its anatomy and name are still under discussion. METHOD: Anatomy and histology of 40 CS from human cadavers were studied, included both from a newborn specimen. RESULTS: Two walls limit the CS, an inferior medial one composed only of the dura's outer layer and a superior lateral one consisting of both dura's layers. Sinusoidal veins pass through the lateral wall of the CS as a transition between venous tributaries and the CS. An endothelial layer covers the inner surface of the CS and the outer surface of the internal carotid artery. The space within the CS shows trabeculae, which are rarer in adults compared to the newborn. The loss of trabeculae in the CS may be a natural process along with life. CONCLUSIONS: In conclusion, the CS is a real sinus, and the term "cavernous sinus" is appropriately applied.

ANTECEDENTES: Si bien el seno cavernoso (SC) ha sido estudiado desde 1695, su anatomía y nombre aún están bajo discusión. MÉTODOS: Se estudiaron la anatomía y la histología de 40 SC de cadáveres humanos, incluyendo los dos de un recién nacido. RESULTADOS: El SC está limitado por dos paredes, una inferomedial compuesta solo por la capa más externa de la duramadre y otra superolateral compuesta por ambas capas de la duramadre. Hay venas sinusoidales que atraviesan la pared lateral del SC formando una transición entre venas tributarias y el SC. Una capa endotelial recubre la superficie interna del SC y la superficie externa de la arteria carótida interna. El espacio dentro del SC presenta trabéculas, las cuales son escasas en el adulto en comparación con el recién nacido. La pérdida de trabéculas en el SC puede ser un proceso natural a lo largo de la vida. CONCLUSIONES: En conclusión, el SC es un verdadero seno, por lo que el término «seno cavernoso¼ se aplica de forma correcta.

Microsurgical and illustrative anatomy of the cavernous sinus, middle fossa, and paraclival triangles: a straightforward, comprehensive review.

The middle fossa, cavernous sinus, and paraclival triangles consist of ten triangles. Their use in a surgical approach is vast; most are used as landmarks to access and identify other structures of surgical interest. Multiple labels, borders, and contents mentioned by different authors make understanding and reproduction challenging and confusing. This study aims to organize and clarify recent or most relevant publications and disclose our portrayal of the ten triangles using cadaveric dissection and simple and practical figures. Four middle fossa triangles, four cavernous sinus triangles, and two paraclival triangles were dissected and delineated in a cadaveric specimen. Drawings were simplified to eliminate confusion and evaluate the triangles effortlessly. Similarities and differences in triangle names, border limits, and contents are described in a precise form. The recognition of triangle landmarks allows for treating pathologies in a frequently distorted anatomy or challenging to access structure. That is why an accurate knowledge of the surgical anatomy should be mastered, and a safe approach should be accomplished.

Microsurgical anatomy of the cavernous sinus and limitations of surgical approaches: a cadaveric study.

BACKGROUND: The endoscopic endonasal approach is common in the treatment of pathologies in and around the cavernous sinus. This cadaveric study aims to examine the anatomy of the cavernous sinus to guide endoscopic studies and determine points to consider during surgical approaches. MATERIALS AND METHODS: For this study, a total of 7 cadavers, 4 male and 3 female, were injected with coloured silicone and dissections were performed under the microscope. The characteristics of the surgical corridors encountered during the transsphenoidal, transsellar and transcavernous approaches were examined and their images were recorded. RESULTS: The stages and limitations of surgical approaches to the cavernous sinus in cadavers are presented. The anatomical features of the triangles defined in the cavernous sinus and the structures they contain are explained. It was determined that the surgical field formed by clinoidal and anteromedial triangles could be used effectively to reach cavernous sinus pathologies during endoscopic endonasal interventions. It was also observed that supratrochlear and infratrochlear triangles are dangerous for such surgical interventions. CONCLUSIONS: The detailed anatomical features related to the cavernous sinus, revealed in our cadaveric study, are valuable in terms of preventing complications that may occur during surgical interventions.

Expanded endoscopic endonasal transsphenoidal approach to determine morphological characteristics and clinical considerations of the cavernous sinus venous spaces.

The study aimed at investigating the morphological characteristics and interconnected regularities of the cavernous sinus (CS) venous spaces using an expanded endoscopic endonasal transsphenoidal approach. Surgical dissections were performed for 15-colored silicon-injected human head specimens. The CS venous spaces were examined for their morphological and clinical characteristics using an expanded endoscopic endonasal transsphenoidal approach. The intracavernous course of the internal carotid artery (ICA) divided the CS venous spaces into four interconnected virtual compartments: medial, anteroinferior, posterosuperior, and lateral. The CS venous spaces had peculiar morphological characteristics; the medial compartment was C-shaped while the anteroinferior compartment resembled a boat's bow. The mean distances from the medial border of the inferior horizontal segment of cavernous ICA to the mid-line of the pituitary gland (PG) were 6.07 ± 1.61 mm (left) and 5.97 ± 1.89 mm (right); the mean distances from the medial border of the subarachnoid segment of cavernous ICA to the mid-line of the PG were 5.77 ± 1.16 mm (left) and 5.63 ± 1.17 mm (right); the mean distances from the medial border of the anterior vertical segment of cavernous ICA to the mid-line of the PG were 10.27 ± 1.74 mm (left) and 10.47 ± 1.90 mm (right). Morphological characteristics and the knowledge of the interconnected regularities of the CS venous spaces may help surgeons accurately locate the neurovascular structure, and thus may contribute to the effective prediction of tumor invasion and extension during endoscopic CS surgery.

The Abducens Nerve: Anatomy and Pathology.

The abducens, or the sixth cranial nerve, is purely motor and runs a long course from the brainstem to the lateral rectus. Travels with the inferior petrosal sinus through the Dorello's canal before entering the cavernous sinus. Based on the location of an abnormality, other neurologic structures may be involved with the disturbs related to this nerve. This article aims to review the abducens nerve anatomy and demonstrates the imaging aspect of the diseases that most commonly affect it.

Intracranial Breakthrough Through Cavernous Sinus Compartments: Anatomic Study and Implications for Pituitary Adenoma Surgery.

BACKGROUND: Pituitary adenomas (PAs) with cavernous sinus (CS) invasion can extend into the intradural space by breaking through the CS walls. OBJECTIVE: To elaborate on the potential breakthrough route through CS compartments for invasive PAs and describe relevant surgical anatomy and technical nuances, with an aim to improve resection rates. METHODS: Twelve colored silicon-injected human head specimens were used for endonasal and transcranial dissection of the CS walls; ligaments, dural folds, and cranial nerves on each compartment were inspected. Two illustrative cases of invasive PA are also presented. RESULTS: The potential breakthrough routes through the CS compartments had unique anatomic features. The superior compartment breakthrough was delimited by the anterior petroclinoidal ligament laterally, posterior petroclinoidal ligament posteriorly, and interclinoidal ligament medially; tumor extended into the parapeduncular space with an intimate spatial relationship with the oculomotor nerve and posterior communicating artery. The lateral compartment breakthrough was limited by the anterior petroclinoidal ligament superiorly and ophthalmic nerve inferiorly; tumor extended into the middle fossa, displacing the trochlear nerve and inferolateral trunk to reach the medial temporal lobe. The posterior compartment breakthrough delineated by the Gruber ligament, petrosal process of the sphenoid bone, and petrous apex inferiorly, posterior petroclinoidal ligament superiorly, and dorsum sellae medially; tumor displaced or encased the abducens nerve and inferior hypophyseal artery and compressed the cerebral peduncle. CONCLUSION: The superior lateral and posterior components of the CS are potential routes for invasion by PAs. Better identification of CS breakthrough patterns is crucial for achieving higher gross total resection and remission rates.

Anatomical study of the internal carotid venous plexus: new findings with application to skull base surgery.

OBJECTIVE: The venous plexus (internal carotid venous plexus) surrounding the petrous part of the internal carotid artery (ICAp) is said to be one drainage pathway of the cavernous sinus. These veins have many potential clinical implications including iatrogenic hemorrhage during surgical approaches to the skull base and carotid-cavernous fistulas. Because there are few morphological data about this venous plexus at the skull base, this descriptive/quantitative study was performed to elucidate its anatomy. METHODS: Six latex-injected cadaveric heads (twelve sides) were dissected via a superior craniotomy approach in which the ICAp was exposed by drilling away the overlying bone. A venous plexus surrounding parts of the ICAp in all sides was documented along with the positions of its major tributaries and their connections. RESULTS: The veins were most concentrated near the junction of the ICAp and the cavernous part of the internal carotid artery, and usually along the medial and lateral sides of the ICAp. Tributaries included branches joining the basilar venous plexus posteriorly and branches joining the veins surrounding the foramen ovale anteriorly. CONCLUSION: Detailed knowledge of the anatomy of this venous plexus surrounding the ICAp is useful for interpreting imaging of the skull base and valuable for surgeons operating in this part of the cranium.

Hakuba's triangle: a cadaveric study detailing its anatomy and neurovascular contents with vascular and skull base implications.

Hakuba's triangle is a superior cavernous sinus triangle that allows for wide and relatively safe exposure of vascular and neoplastic lesions. This study provides cadaveric measurements of the borders of Hakuba's triangle and describes its neurovascular contents in order to enrich the available literature. The anatomical borders of the Hakuba's triangle (lateral, medial, and posterior borders) were defined based on Hakuba's description and identified. Then the triangle was dissected to reveal its morphology and relationship with adjacent neurovascular structures in Embalmed Caucasian cadaveric specimens. The oculomotor nerve occupied roughly one-third of the area of the triangle and the nerve was more or less parallel to its medial border. The mean lengths of the lateral border, posterior border, and medial border were 17 mm ± 0.5 mm, 12.2 mm ± 0.4 mm, and 10.6 mm ± 0.4 mm, respectively. The mean area of Hakuba's triangle was 63.9 mm2 ± 4.4 mm2. In this study, we provided cadaveric measurements of the borders of Hakuba's triangle along with descriptions of its neurovascular contents.

From Above and Below: The Microsurgical Anatomy of Endoscopic Endonasal and Transcranial Microsurgical Approaches to the Parasellar Region.

INTRODUCTION: The parasellar region is one of the most complex of the skull base. In this study, we review the anatomy and approaches to this region through a 360° perspective, correlating microsurgical and endoscopic anatomic nuances of this area. METHODS: An endoscopic endonasal approach (EEA) and microsurgical dissections were performed. The parasellar anatomy is reviewed and common areas of tumor extensions are assessed. Surgical approaches are discussed based on the anatomic nuances of those regions. RESULTS: The cavernous sinus (CS) can be divided into 2 spaces: posterosuperior, above and behind the internal carotid artery (ICA); and anterior, in front of the cavernous ICA. Those spaces can be approached through the CS walls: anterior and/or medial wall via EEA; or superior and/or lateral wall via transcranial approaches. The relationship of the Meckel cave, adjacent to the lateral and posterior wall of the CS, is relevant for surgical planning. Areas often affected by tumor extension can be divided into 6 regions: superior (cisternal), superolateral (parapeduncular), posterolateral (Meckel cave and petrous bone), medial (sella), anterior (superior orbital fissure), and anterior inferior (pterygopalatine fossa). Anatomic and technical nuances of each of those regions should be taken into consideration when dealing with tumors in the parasellar space. CONCLUSIONS: A transcranial approach and EEA provide effective access to the parasellar region. Management of cavernous sinus and Meckel cave tumors requires familiarity with those approaches. Understanding of the surgical anatomy of the parasellar region, from above and below, is therefore necessary for adequate surgical planning and execution.

A comparative study of the morphology of suboccipital cavernous sinus using magnetic resonance imaging and cast specimens / Un estudio comparativo de la morfología del seno cavernoso suboccipital utilizando imágenes de resonancia magnética y muestras de yeso

SUMMARY: A comparative study of the morphology of suboccipital cavernous sinus (SCS) using MRI and cast specimens was performed. The present retrospective study analysed the craniocervical magnetic resonance venography (MRV) imaging data of 61 patients. Three-dimensional reconstruction was performed using Mimics 19.0. The SCS left-right diameter(d1), distance from the midline (d2), supero-inferior diameter(d3), anteroposterior diameter (d4), distance from posterior diameter to skin (d5), and diameter of the SCS at different parts (d6-d8) were measured. Comparison between MRV images and cast specimens, the SCS, marginal sinus, anterior condylar vein, and vertebral artery venous plexus were symmetrical and could be bilaterally displayed, whereas the presence of extra condylar vein and posterior condylar vein exhibited different types. The adjacency between the SCS and its communicating vessels and changes in its communicating vessels corresponded well with the MRV images and cast specimens. Many types of the presence of left and right lateral condylar and posterior condylar veins were found in the cast specimens, which could be divided into the bilateral presence of posterior condylar and lateral condylar veins, unilateral presence of posterior condylar veins, and unilateral presence of lateral condylar vein. A total of 61 cases analysed using MRV images revealed the bilateral presence of posterior condylar and lateral condylar veins (77.1 %), the unilateral presence of posterior condylar vein (18.0 %), and the unilateral presence of lateral condylar vein (9.8 %), of which the bilateral presence of posterior condylar and lateral condylar veins accounted for the largest proportion. MRV images and cast specimens of the SCS showed its normal morphological structure and adjacency, thus providing accurate and complete Three-dimensional imaging anatomical data of the SCS and its communicating vascular structures. This study enriches the Chinese SCS imaging anatomy data and may be valuable in clinical practice.

RESUMEN: Se realizó un estudio comparativo de la morfología del seno cavernoso suboccipital (SCS) mediante resonancia magnética y muestras de yeso. El presente estudio retrospectivo analizó los datos de imágenes de venografía por resonancia magnética (RNM) craneocervical de 61 pacientes. La reconstrucción tridimensional se realizó con Mimics 19.0. Se midió: el diámetro izquierdo-derecho del SCS (d1), la distancia desde la línea mediana (d2), el diámetro superoinferior (d3), el diámetro anteroposterior (d4), la distancia desde el diámetro posterior hasta la piel (d5) y el diámetro del SCS en diferentes partes (d6-d8). En la comparación entre las imágenes RNM y las muestras de yeso, el SCS, el seno marginal, la vena condilar anterior y el plexo venoso de la arteria vertebral eran simétricos y se observaron bilateralmente, mientras que la presencia de la vena extracondilar y la vena condilar posterior presentaba tipos diferentes. La proximidad del SCS y sus vasos comunicantes y los cambios en sus vasos comunicantes se correspondieron bien con las imágenes de RNM y los especímenes moldeados. Se encontraron muchos tipos de venas condilares laterales y condilares posteriores izquierda y derecha en las muestras de yeso, que podrían dividirse en presencia bilateral de venas condilares posteriores y condilares laterales, presencia unilateral de venas condilares posteriores y presencia unilateral de venas condilares laterales. Un total de 61 casos analizados mediante imágenes MRV revelaron la presencia bilateral de venas condilares posteriores y condilares laterales (77,1 %), la presencia unilateral de venas condilares posteriores (18,0 %) y la presencia unilateral de venas condilares laterales (9,8 %) de los cuales la presencia bilateral de las venas condilar posterior y condilar lateral representó la mayor proporción. Las imágenes de RNM y las muestras de yeso del SCS mostraron su estructura morfológica y adyacencia normales, lo que proporcionó datos anatómicos de imágenes tridimensionales precisos y completos del SCS y sus estructuras vasculares comunicantes. Este estudio enriquece los datos de anatomía de imágenes de SCS chino y puede ser valioso en la práctica clínica.

Approach to the Superior Ophthalmic Vein for Endovascular Treatment of Cavernous Dural Fistula.

The cavernous sinus area is the second most common location for intracranial dural fistulas. Although these spontaneous dural cavernous fistulas are self-limited, a sizeable number of patients will develop progressive vision loss, diplopia, or intractable glaucoma, which warrant interventional therapy.1,2 We present the case of a 54-year-old male with hypertension and type 2 diabetes, who presented with a red right eye associated with progressive exophthalmos, ophthalmoparesis, and deterioration of visual acuity. The angiotomography showed the exophthalmos with an ingurgitated superior ophthalmic vein, with early filling in the arterial phase. A digital angiography was made, and a diagnosis of dural cavernous fistula, Barrow type D was made.3 Considering several transvenous approaches, alternatives included inferior petrosal sinus, access through the superior ophthalmic vein, and an open approach.4 In this particular case the inferior petrosal sinus was not present, so we tried to catheterize through the facial vein and also puncture the ophthalmic vein. Both procedures were unsuccessful. We decided to perform, then, an open approach with the oculoplastic surgery team (Video 1). Through an eyelid dissection, we localized the superior ophthalmic vein and then canalized it by direct visualization.5 With this approach, we were able to perform the cavernous sinus packing with coils and achieved a complete occlusion of the fistula. We reproduced the direct approach to the superior ophthalmic vein in a cadaveric specimen and schematized it step by step with 3-dimensional photographs.6.

The Inferolateral Surgical Triangle of the Cavernous Sinus: A Cadaveric and MRI Study with Neurosurgical Significance.

BACKGROUND: The inferolateral triangle is a surgical skull base triangle used as a neurosurgical landmark. There are few reports of its measurements with little attention paid to anatomic variations. METHODS: The inferolateral triangle was measured in 10 adult human cadaveric heads via dissection then direct measurement and 5 participants undergoing neuroimaging using tracing features. RESULTS: In the cadavers, mean lengths (mm) of the superior, anterior, and posterior borders were 17.0 (±5.5), 12.9 (±1.7), and 17.8 (±3.3), respectively, with mean area of 97.85 (±28.17) mm2. In the participants, mean lengths (mm) of the superior, anterior, and posterior borders were 17.35 (±4.01), 14.36 (±1.36), and 18.01 (±2.43), respectively, with mean area of 113.6 (±25.46) mm2. No statistical difference in triangle areas between groups was found. CONCLUSIONS: Intimate understanding of the inferolateral triangle is essential to skull-based surgery; knowing its anatomy and variations aids in surgical planning and understanding of regional pathology.

Microsurgical anatomy of the inferior intercavernous sinus.

PURPOSE: Intercavernous sinuses (ICSs) are physiological communications between the cavernous sinuses. The ICSs run between the endosteal and meningeal layers of the dura mater of the sella turcica. Whereas the anterior and posterior ICSs have been frequently described, the inferior ICS (iICS) has been less well studied in the literature; however, poor awareness of the ICS's anatomy can lead to serious problems during transsphenoidal, transsellar surgery. The objective of the present anatomical study was to describe the iICS in detail. METHODS: The study was carried out over a 6-month period in a university hospital's anatomy laboratory, using brains extracted from human cadavers. The brains were injected with colored neoprene latex and dissected to study the iICS (presence or absence, shape, diameter, length, distance between inferior and anterior ICSs, distance between inferior and posterior ICSs, relationships, and boundaries). RESULTS: Seventeen cadaveric specimens were studied, and an iICS was found in all cases (100%). The shape was variously plexiform (47.1%), filiform (35.3%), or punctiform (17.6%). The mean ± standard deviation diameter and length of the iICS were 3.75 ± 2.90 mm and 11.92 ± 2.96 mm, respectively. The mean iICS-anterior ICS and iICS-posterior ICS distances were 5.36 ± 1.99 mm and 7.03 ± 2.28 mm, respectively. CONCLUSION: The iICS has been poorly described in the literature. However, damage to the iICS during transsphenoidal, transsellar surgery could lead to serious vascular complications. A precise radiological assessment appears to be essential for a safe surgical approach.

The inferior intercavernous sinus: An anatomical study with application to trans-sphenoidal approaches to the pituitary gland.

OBJECTIVES: The inferior intercavernous sinus is located below the pituitary gland in the sella turcica. Its presence has been controversial among anatomists because it is not always found on radiological imaging or during cadaveric dissections; however, it is becoming a better-known structure in the neurosurgical and radiological fields, specifically with respect to transsphenoidal surgery. Therefore, the present study was performed to better elucidate this structure at the skull base. PATIENTS AND METHODS: Fifty adult, latex injected cadavers underwent dissection. The presence or absence of the inferior cavernous sinus was evaluated and when present, measurements of its width and length were made. Its connections with other intradural venous sinuses were also documented. RESULTS: An inferior intercavernous sinus was identified in 26 % of specimens. In all specimens, it communicated with the left and right cavernous sinus. The average width and length were 3 mm and 9.5 mm, respectively. In the sagittal plane, the inferior intercavernous sinus was positioned anteriorly in 31 %, at the nadir of the sella turcica in 38 %, and slightly posterior to the nadir of the sella turcica in 31 %. In two specimens (15.4 %), the sinus was plexiform in its shape. In one specimen a diploic vein connected the basilar venous plexus to the inferior intercavernous sinus on its deep surface. CONCLUSION: An improved understanding of the variable anatomy of the inferior intercavernous sinus is important in pathological, surgical, and radiological cases.

Microsurgical and Endoscopic Anatomy of the Cavernous Sinus

Objective To describe the endoscopic and microsurgical anatomy of the cavernous sinus (CS) with focus on the surgical landmarks in microsurgical anatomy. Materials and methods Ten formalin-fixed central skull base specimens (20 CSs) with silicone-injected carotid arteries were examined through an extended endoscopic transsphenoidal approach. Fifteen formalin-fixed heads were dissected to simulate the surgical position in CS approaches. Results Endoscopic access enables identification of the anterior and posterior surgical corridors. Structures within the CS and on its lateral wall could be visualized and studied, but none of the triangular areas relevant to the transcranial microsurgical anatomy were fully visible through the endoscopic approach. Conclusion The endoscopic approach to the CS is an important surgical technique for the treatment of pathological conditions that affect this region. Correlating endoscopic findings with the conventional (transcranial)microsurgical anatomy is a useful way of applying the established knowledge into a more recent operative technique. Endoscope can provide access to the CS and to the structures it harbors.

Surgical anatomy of the internal carotid plexus branches to the abducens nerve in the cavernous sinus.

OBJECTIVE: Sympathetic branches to the abducens nerve derived from the internal carotid artery sympathetic plexus, while in the cavernous sinus, have been scantly described in the extant literature. Therefore, the present cadaveric study was performed to better elucidate this anatomy. PATIENTS AND METHODS: Eighteen cadaveric sides underwent dissection. RESULTS: The number of branches derived from the sympathetic plexus traveling with the internal carotid artery in the cavernous sinus was one on 11.1 %, two in 11.1 %, and three in 72.2 %. One side was found to have no branches (5.6 %). The mean diameter of the distance from the posterior border of the internal carotid artery, length, and diameter of the branches was 7.0 ±â€¯4.1 mm, 2.9 ±â€¯1.3 mm, and 0.4 ±â€¯0.1 mm, respectively. Of 44 of 45 sympathetic branches, 97.8 % originated from the lateral wall of the cavernous part of the internal carotid artery with only one from the medial wall. CONCLUSION: Based on our cadaveric findings, sympathetic connections between the internal carotid artery and the abducens nerve are common. Therefore, surgeons who operate in or near the cavernous sinus should be aware of such connections in order not to place unwanted tension on the cavernous part of the internal carotid artery or abducens nerve during dissection.

Variations of the 6th cranial nerve (nervus abducens) in the petroclival region: A microsurgical study.

The aim of this study is to present the variations of nervus abducens in localization and number as it pierces the clival dura mater. The calvaria of 16 cadaveric heads were removed by making horizontal incisions from Glabella to Inion in both sides of the head. The dura mater was dissected. Cerebrum and cerebellum were taken out by obtuse dissection. Dissections of cavernous sinus were made under the stereomicroscope and the findings were photographed. Out of 16 specimens, one of them was excluded. Fifteen heads were bilaterally analyzed. Analysis of these nerves presented four different variations. Variation types a classified CN VI as a single trunk and entering a single dural pore with 77% occurrence. Variation type b classified CN VI with two branches running in the petroclival region and entering a single dural pore with 10% occurrence. Variation type c classified CN VI as 2 trunks and entering 2 separate but close dural pores with 10% occurrence. Variation type d classified CN VI with 2 distinct trunks and 2 branches entering 2 separate but close dural pores with 3% occurrence. CN VI plays a major role in the clinic of the eye. Due to its intracranial and extracranial course, injuries to the head and to the nerve may result in malfunctioning of the lateral muscles of the eye. Therefore, the variations of branching, relations and its course were analyzed.

Anatomical characterization of the inferior petrosal sinus and adjacent cerebellopontine angle cistern for development of an endovascular transdural cerebrospinal fluid shunt.

BACKGROUND AND PURPOSE: We evaluated the inferior petrosal sinus (IPS) and adjacent cerebellopontine angle (CPA) cistern as a potential implantation site for a novel venous endovascular transdural CSF shunt concept to treat communicating hydrocephalus. We analyzed the dimensions of the IPS, CPA cistern, and distances to adjacent neurovascular structures. MATERIALS AND METHODS: Gadolinium enhanced T1 weighted brain MRI datasets of 36 randomly selected patients, aged 20-80 years, were analyzed with three-dimensional multiplanar reconstruction to measure IPS diameter and length, CPA cistern depth, and IPS proximity to the vertebrobasilar arteries and brainstem. Statistical analysis was used to assess gender, sidedness, and age dependence. RESULTS: Mean IPS diameter ranged from 2.27 mm to 3.31 mm at three axial levels, with >90% larger than 1.46 mm. CPA cistern adjacent to the IPS exhibited a mean depth of 3.86 mm to 7.39 mm between the dura and brainstem at corresponding axial levels. There was no side dependence except for a longer distance from the IPS to the basilar artery on the left compared with the right (9.72 vs 7.28, P<0.019). Linear regression analysis showed that the distance from the IPS to the brainstem was statistically significantly increased with age (P<0.0002) and was greater in men, with little side variation (P=0.524). CONCLUSION: Our results demonstrate sufficient CSF CPA cisternal space adjacent to the IPS and support the feasibility of an endovascular catheter delivered transdural implantable shunt. Such a device could serve to mimic the function of the arachnoid granulation by establishing a regulated path for CSF flow from the intracranial subarachnoid space to the venous system and provide a treatment for communicating hydrocephalus.