Wall Of Cavernous Sinus Research Articles

Recurrent Sphenocavernous Meningioma.

A case of a recurrent sphenocavernous meningioma is presented. The patient is a 42-year-old male who presented with an episode of transient right-sided numbness. A magnetic resonance imaging (MRI) revealed a large left sphenocavernous meningioma. The patient underwent a frontotemporal craniotomy for tumor resection. Near total resection was achieved with minimal residual in the left cavernous sinus (CS) and orbital apex. The pathology was consistent with meningioma, World Health Organization (WHO) grade I. A follow-up MRI was done 9 months after surgery and showed a growth of the residual tumor, which was treated with intensity modulated radiotherapy. Tumor growth was detected on serial imaging over a 4-year period. Surgical resection was offered. A left frontotemporal craniotomy with pretemporal transcavernous approach was performed. The bone flap was reopened and the dura was opened in a Y-shaped fashion. The roof of the optic canal was drilled off, and the falciform ligament was opened to decompress the optic nerve. The tumor was disconnected from the anterior clinoid region (the anterior clinoid process was eroded by the tumor) and reflected off the wall of the lateral CS. Tumor was adherent to the V2 fascicles (the lateral CS wall was resected in the first surgery) and was sharply dissected off. Gross total resection was achieved. The pathology was consistent with meningioma, WHO grade I. The patient had an unremarkable postoperative course without any new neurological deficits. The link to the video can be found at: https://youtu.be/KVBVw_86JqM .

Endoscopic-Assisted Microsurgical Resection of Right Recurrent Meckel's Cave Meningioma Extended to Cavernous Sinus.

Objective This study was aimed to present the complete removal of a large recurrent Meckel's cave meningioma. Design This study is a case report. Setting The study was conducted at Department of Neurosurgery and Skull Base Laboratory at Lariboisiére Hospital, Paris. Participant A 53-year-old male was presented with a severe V1, V2, and V3 hypoesthesia and pain. He was operated 7 years ago for a right Meckel's cave meningioma with postoperative V1–V2 hypoesthesia. Magnetic resonance imaging (MRI) showed a large tumor recurrence extending into the cavernous sinus (CS), posterior fossa (PF), sphenoid sinus (SS), pterygopalatine (PPF), and infratemporal fossa (ITF; Fig. 1 ). Main Outcome Measures Radiological results and postoperative course were assessed for this study. Results The previous right frontotemporal approach was used. The lateral wall of the orbit, the middle fossa floor and the anterior temporal base were drilled to expose the orbit, PPF, and ITF. Foramen ovale (FO), foramen rotondum (FR), and superior orbital fissure (SOF) were opened. The meningoorbital band was cut and the lateral wall of CS was elevated ( Fig. 2 ). The inferior orbital fissure was opened and tumor removed into the ITF, PPF, and orbit. After entering Meckel's cave from above, tumor was removed from PF. After microsurgical tumor removal, a 45-degree endoscope was used to remove tumor remnant and mucosa into SS. A watertight dural closure with pericranium was performed, reinforced with autologous fat and fibrin glue. Postoperative MRI showed complete tumor resection ( Fig. 1 ). The patient experienced a right-side keratitis that resolved within 10 days and a V3 hypoesthesia that improved at 2 months. Conclusion This surgical case shows how the anatomical knowledge is mandatory in skull base surgery and how the integration of microsurgical and endoscopic-assisted techniques allows to obtain optimal results. The link to the video can be found at: https://youtu.be/qxt_389AdWU .

Spheno-Orbital Meningioma with Cavernous Sinus Extension.

We present a case of a 37-year-old female, with progressive left eye proptosis and an extensive ipsilateral en plaque spheno-orbital meningioma, with diffuse involvement of the lateral wall of the cavernous sinus and the orbit.A cranio-orbital zygomatic approach was performed to reach all extension of the lesion. We made an extradural clinoidectomy and an extensive bone removal of the orbit, exposition of the superior and lateral walls of the cavernous sinus, unroofing of the optic canal, superior orbital fissure, foramen rotundum, and foramen ovale. We performed the peeling of the lateral wall of cavernous sinus with total removal and preservation of the cranial nerves anatomy and function.In this video, we illustrate the importance of the first time aggressive removal of such tumors. We also demonstrate the concept that secondary invasion of the cavernous sinus are suitable for removal with cranial nerve preservation. The link to the video can be found at https://youtu.be/GJmkqVa6jSs .

Endoscopic Transorbital Approach to the Cavernous Sinus Lateral Compartment (Anatomical Cadaver Study).

To determine whether the endoscopic transorbital (ETO) approach could be an alternative and a safer route to access the cavernous sinus (CS) lateral compartment. ETO technique was studied on 3 cadavers and 6 CSes of these cadavers. Endoscopic dissection was visualized with a 0-degree angle endoscope and recorded with fiberoptic cable, light source and camera system and digital video recording system. Superior orbital fissure (SOF), optic canal (OC), anterior ethmoidal artery (AEA) and posterior ethmoidal artery (PEA) foramens were visualized with periorbital dissection. Anterior wall of CS was reached after drilling the optic strut (OS). When the wall was opened, CS lateral and anteroinferior compartments were visualized. Internal carotid artery (ICA) were visualized from proximal ring to the last 2 cm of paraclival carotid artery. Cranial nerves (CNs) within the CS and the course of the interclinoid ligament were revealed. The transorbital endoscopic method is an alternative approach to other techniques for accessing the lateral and anteroinferior compartments of CS. The advantages, disadvantages and limitations of the technique have been determined.

Anatomy of the cavernous sinus walls: an anatomical study of the dural layers

Anatomy of the cavernous sinus walls: an anatomical study of the dural layers

Superficial middle temporal vein as a pivotal route to embolize dural carotid–cavernous fistulas

Dural carotid–cavernous fistulas (DCCF) are located in the cavernous sinus wall involving the arterial feeders from the external and internal carotid arteries. The venous route usually passes through the internal jugular vein and inferior petrosal sinus (IPS) up to the pathologic shunts of the cavernous sinus. In cases of a thrombosed IPS, catheterization is not always possible because of the obstruction. Here, we report eight cases of DCCF treated with endovascular transvenous embolization via the superficial middle temporal vein (SMTV). A retrospective study involving eight patients with DCCF treated with transvenous embolization via SMTV was performed. In six patients, IPS was thrombosed. In one patient, IPS was patent, but we could not catheterize the internal jugular vein. In the other patient, because of the compartmentalization of the cavernous sinus, we could not access the anterior part of the cavernous sinus via IPS. Therefore, we performed the embolization via SMTV to occlude the shunts of the anterior part of the cavernous sinus.In all eight cases, navigating through the tortuous junction of the angular vein and superior ophthalmic vein (SOV) was possible. After transvenous catheterization of the cavernous sinus via SMTV, placement of coils resulted in complete occlusion of DCCF with clinical improvement in all eight patients. In the endovascular treatment of DCCF, the transfemoral approach via SMTV provides a pivotal route alternative to other transvenous routes. In patients with dilated SOV, catheterization of the cavernous sinus via SMTV is usually successful.

Neuroimaging of aggressive pituitary tumors.

Aggresssive pituitary tumors are defined as radiologically invasive, exhibiting a rapid growth and a poor response to the medical and surgical treatment options. The role of magnetic resonance imaging (MRI) is fundamental to assess tumor aggressiveness before surgical exploration. Distinction between cavernous sinus invasion and cavernous sinus compression is often challenging and cannot be solved always by using the Knosp criteria. Ideally, T2W images demonstrating the ruptured internal dural wall of cavernous sinus is the ultimate proof of cavernous sinus invasion. Subtle tumor volume increase in a short time can be shown when sequential MR images are rigorously replicable. A microcystic pattern observed on T2W images frequently reflects a potentially aggressive tumor as observed in silent corticotroph pituitary adenomas.

Scrub Typhus with Partial Superior Orbital Fissure Syndrome

We report a case of a 33 year old woman suffering from scrub typhus who presented with binocular horizontal diplopia. Magnatic Resonance Imaging of Brain showed thickening and enhancement of the lateral wall of cavernous sinus, extending to involve orbital apex. She improved after treatment with doxycycline. Various ophthalmological manifestations of scrub typhus have also been reviewed.

Resection of Pituitary Tumor with Lateral Extension to the Temporal Fossa: The Toothpaste Extrusion Technique.

Transsphenoidal resection of the sellar and suprasellar lesions, whether microscopic or endoscopic, has been traditionally limited by tumors extending laterally to the carotid artery and cavernous sinus. Extended endoscopic or transmaxillary approaches may be warranted depending on these tumor extensions. We describe the use of an intraoperative Valsalva maneuver as a surgical adjunct to the transsphenoidal approach to improve the extent of resection for a favorable outcome. The patient was a 65-year-old woman who underwent resection of a giant pituitary tumor that extended laterally to the cavernous sinus to occupy a volume within the middle fossa. It was the senior author's impression that the lateral cavernous wall was intact at the time of surgery although this is difficult to determine definitively. After a transsphenoidal intrasellar resection of the intrasellar tumor, side-angled endoscopic visualization enabled identification of the breach in the medial cavernous wall where the tumor had invaded the cavernous sinus and ultimately grown into the middle fossa. A Valsalva maneuver was then applied, and the tumor was extruded from the cavernous sinus lateral to the carotid. The significant tumor was removed under direct visualization of the abducens nerve, which was well preserved. Postoperative imaging showed a sufficient extent of resection, and there were no postoperative complications. An intraoperative Valsalva maneuver can be a potentially useful technique for extending tumor resection in cases with a soft tumor and visualization of the opening within the cavernous sinus wall.

Endoscopic Transsphenoidal Surgery of Microprolactinomas: A Reappraisal of Cure Rate Based on Radiological Criteria.

Current standard treatment of microprolactinomas is dopamine agonist therapy. As this drug treatment is lifelong in up to 80% of cases, many patients consult pituitary surgeons regarding a surgical alternative. To identify prognostic criteria for surgical remission, we reviewed outcomes of our series of microprolactinomas treated with endoscopic transsphenoidal surgery, with a special emphasis on magnetic resonance adenoma delineation and position. Our study cohort comprises a single center series of 60 patients operated for histopathologically verified magnetic resonance imaging unequivocally identifiable endosellar microprolactinoma between 2003 and 2017. In 31 patients the adenoma was enclosed by pituitary gland (group ENC), in 29 patients the adenoma was located lateral to the gland adherent to the medial cavernous sinus wall (group LAT). After a mean follow-up of 37 mo (range 4-143 mo), remission rate was significantly higher in adenomas enclosed by pituitary gland (group ENC) than adenomas located lateral to the gland (group LAT), with 87% vs 45%, P=.01. Intraoperatively, 4 patients showed signs of invasiveness. Preoperative prolactin levels did not differ between the groups (mean 155 and 187 ng/ml in group ENC and LAT, respectively).A binary logistic regression model revealed that only the radiological criteria applied showed a significant correlation (P=.003) with endocrine remission. According to our results, remission rate is significantly higher in microprolactinomas enclosed by the pituitary gland. However, the decision for surgery should take into account surgeons experience and possibility of complications.

Endoscopic transorbital approach to anterolateral skull base through inferior orbital fissure: a cadaveric study

Endoscopic transorbital approach (eTOA) has been announced as an alternative minimally invasive surgery to skull base. Owing to the inferior orbital fissure (IOF) connecting the orbit with surrounding pterygopalatine fossa (PPF), infratemporal fossa (ITF), and temporal fossa, the idea of eTOA to anterolateral skull base through IOF is postulated. The aim of this study is to access its practical feasibility. Anatomical dissections were performed in five human cadaveric heads (10 sides) using 0-degree and 30-degree endoscopes. A stepwise description of eTOA to anterolateral skull base through IOF was documented. The anterosuperior corner of the maxillary sinus in the horizontal plane of the upper edge of zygomatic arch was defined as reference point (RP). The distances between the RP to the foramen rotundum (FR), foramen ovale (FO), and Gasserian ganglion (GG) were measured. The exposed area of anterolateral skull base in the coronal plane of the posterior wall of the maxillary sinus was quantified. The surgical procedure consisted of six steps: (1) lateral canthotomy with cantholysis and preseptal lower eyelid approach with periorbita dissection; (2) drilling of the ocular surface of greater sphenoid wing and lateral orbital rim osteotomy; (3) entry into the maxillary sinus and exposure of PPF and ITF; (4) mobilization of infraorbital nerve with drilling of the infratemporal surface of the greater sphenoid wing and pterygoid process; (5) exposure of middle cranial fossa, Meckel's cave, and lateral wall of cavernous sinus; and (6) reconstruction of orbital floor and lateral orbital rim. The distances measured were as follows: RP-FR = 45.0 ± 1.9mm, RP-FO = 55.7 ± 0.5mm, and RP-GG = 61.0 ± 1.6mm. In comparison with the horizontal portion of greater sphenoid wing, the superior and inferior axes of the exposed area were 22.3 ± 2.1mm and 20.5 ± 1.8mm, respectively. With reference to the FR, the medial and lateral axes of the exposed area were 11.6 ± 1.1mm and 15.8 ± 1.6mm, respectively. The eTOA through IOF can be used as a minimally invasive surgery to access whole anterolateral skull base. It provides a possible resolution to target lesion involving multiple compartments of anterolateral skull base.

Review of Surgical Anatomy of the Tumors Involving Cavernous Sinus.

The lesions involving cavernous sinus (CS) and lateral sellar region includes tumors, vascular lesions, infection, inflammation, and trauma. Tumors associated with CS cause significant distortion of the microanatomy posing an additional surgical challenge to the neurosurgeons. The surgical approach and microsurgical anatomy with respect to the origin and growth of the tumor within the CS region have not been comprehensively described in recent years. We conducted a review of literature concerning CS and associated tumors, complied through MEDLINE/OVID and using cross-references of articles on PubMed with the keywords cavernous sinus, CS tumors, pituitary adenoma, meningioma, schwannoma, chordoma, CS hemangiomas, extradural, interdural, intradural, skull base, gamma knife radiosurgery, endoscopic endonasal approach. Based on the tumor origin and growth pattern, the tumors associated with CS can be classified into three categories: Type-I: tumor originating from CS, Type-II: originating from lateral wall of CS, and Type-III: extraneous origin and occupying CS. The review focuses on approach to a tumor within each type of tumor in the CS region. The emphasis is that the tumor growth pattern and significant distortion of the CS anatomy caused by the tumor growth should be considered while planning the optimal surgical approach for tumors in this region to ensure complete tumor resection with minimal neurovascular morbidity.

Microsurgical management of benign lesions interior to the cavernous sinus: A case series.

Background:Benign lesion interior to the cavernous sinus (CS) is very rare.Objective:In this series we found nonneoplastic lymphatic aggregation and osteoclastoma inside the CS which is very rare and probably not reported in literature. One interesting postoperative complaint of feeling of tickling down of warm water under the skin forehead was found in the patient of inflammatory disease of CS which is not reported in literature. Here we also describe our experiences of microsurgical management of series of benign lesions inside the CS.Materials and Methods:Benign mass originated from the content of CS or inner side of walls of CS, confirmed peroperatively were included in this series. Prospectively recorded data of microsurgical management was retrogradely studied.Results:Total number of patient was 12. Patient's age range was 30–60 years. Follow-up range was 60 months to 19 months. Three was nonneoplastic lesion (tuberculosis, inflammatory and nonneoplastic lymphoid infiltration). Among the 9 neoplastic lesions, two hemangiomas, two meningiomas, three 6th nerve schwannomas, one osteoclastoma and one epidermoid tumor. Middle cranial fossa-subtemporal extradural approach was used in 9 cases and in two cases extended middle fossa zygomatic approach. New postoperative 3rd nerve palsy developed in 5 cases all recovered completely except one. In seven patients 6th nerve palsy developed after operation; only one recovered. Postoperatively simultaneous 3rd, 4th and 6th nerve palsy developed in four cases. One interesting postoperative complaint of feeling of tickling down of warm water under the skin of left sided forehead was found in the patient of inflammatory disease of CS. Mortality was nil. Total resection was done in 9 cases. There was no recurrence till last follow-up.Conclusion:Though decision for microsurgical removal of such lesions is not straight forward. Probably microsurgery is the best option in treating such benign lesions though it may associate with some permanent cranial nerve palsy.

Morphological aspect of the superior wall of the cavernous sinus

The lateral wall of cavernous sinus (CS) is made of two distinct layers of dura: meningeal dura (the external one) and endosteal dura (internal one). On the other hand, some debates about the histomorphological aspects of the superior and medial wall of CS are present in literature (1-2). In this study we aimed to demonstrate the histomorphological features of the superior wall of CS during cadaver dissection studies. We considered only the sellar area, bounded anteriorly by the posterior margin of planum sphenoidale, antero-inferiorly by the antero-superior surface of sphenoid sinus, inferiorly by the superior surface of sphenoid sinus, posteriorly by dorsum sellae, laterally by the interclinoid ligament (preserving the medial wall of CS) and superiorly by diaphragma sellae. The samples were collected, decalcified, paraffin embedded and serial sections were finally processed for standard histomorphological staining. Sections of each sample were analyzed using optical light microscope equipped with a digital camera. Our results showed that the two layers separated themselves at the superior wall of CS: the meningeal layer continued as diaphragma sellae and the endosteal layer continued downward between the venous compartment and pituitary capsule. In addition, between these two layers it was possible to define an interdural pathway. These data should be considered in the evaluation of the rare, though possible, extension of pituitary adenomas in the interdural space, rather than into the cavernous sinus.

A Massive Congenital Intracranial-orbital Immature Teratoma Tracing Trigeminal Nerve Pathway in One Monozygotic Twin: Report of a Case and Review of the Literature

Background: Congenital intracranial teratomas are extremely rare tumors, which may extend through the extracranial structures, namely orbit, and pose difficulties in determining of original site and also in the surgical procedures. Methods and materials: In this paper, we presented two newborn male monozygotic twins in which only one twin had a proptosis of the right eye. The magnetic resonance imag¬ing (MRI) revealed a huge tumor along a trigeminal nerve that involved orbit, wall of cavernous sinus, infratemporal fossa, and brain stem. Because of the large involvement of this tumor, the patient underwent a subtotal resection of the middle cranial fossa and debulking of intra orbital portion. The histopathological findings demonstrated a congenital immature teratoma. Result: To date, the patient is treated with adjuvant chemotherapy, and the other twin remains healthy, with normal brain CT scan. Conclusion: To our knowledge, given the low incidence of congenital teratomas, there is no certain treatment for these tumors, and perhaps this report is the first case of congenital immature teratoma presented in intracranial or orbital structures in only one monozygotic twin.

Which Strategy for Petroclival Tumors?

Access to the petroclival region has always been challenging owing to the surrounding neurovascular structures. The ideal approach to the region depends not only on the specific tumor characteristics, but also on surgeon preference. In this video article, we have highlighted the use of the modified Dolenc-Kawase approach to expand the standard anterior petrosectomy corridor for challenging tumors that need additional exposure.1, 2, 3, 4, 5 A 60-year-old woman presented with facial sensory loss and occasional diplopia. On radiological investigation, a densely calcified petroclival lesion was identified (Video 1). A temporal craniotomy with zygomatic osteotomy was performed followed by deroofing of the superior orbital fissure, saucerization of the foramen spinosum, and coagulation and division of the middle meningeal artery. The temporal dura propria was then dissected off the lateral wall of cavernous sinus using a combination of sharp and blunt dissection to expose the modified Dolenc-Kawase rhomboid. A T-shaped dural incision was made along with tentorial sectioning and division of the superior petrosal sinus. Owing to dense calcification in the tumor, a bone Cavitron ultrasonic aspirator (CUSA; Integra LifeSciences, Princeton, New Jersey, USA) was used for debulking of the tumor. Tumor was removed piecemeal alternately using the bone CUSA and scissors. Tumor was dissected from above and below the trigeminal nerve that forms the center of the corridor followed by dissection off the sixth cranial nerve as it enters the Dorello canal. An endoscope may be used at the end to ensure complete removal of the tumor.

Improved subtemporal approach and frontotemporal-zygomatic arch subtemporal approach in resection of cavernous sinus tumors: a clinical comparative study

Objective To compare the efficacy of the improved subtemporal approach and traditional frontotemporal-zygomatic arch subtemporal approach in resection of cavernous sinus tumors. Methods The clinical data of two groups of patients were analyzed retrospectively. There were 26 patients in an improved subtemporal approach (that is preauricular straight incision preserving zygomatic arch) group (group A). There were 14 females and 12 males, and 9 patients had meningioma, and 17 had trigeminal neurinoma. There were 22 patients in a traditional frontotemporal-zygomatic arch subtemporal approach group (group B). There were 13 females and 9 males, 8 patients had meningioma and 14 had trigeminal neurinoma. The incidence of total resection rate, cranial nerve complications of postoperative lateral wall of cavernous sinus in the patients of both groups were compared, and they were followed up regularly after procedure. Results There was no significant difference in the complete resection rate and the incidence of complications of the cranial nerves between the two groups; however, preserving the zygomatic arch subtemporal approach, the time of craniotomy was shortened significantly. The incidences of postoperative temporal branch injury of facial nerve and temporal muscle atrophy were reduced significantly. Conclusions Preauricular straight incision subtemporal approach can fully expose the cavernous sinus and preserve zygomatic arch. The surgery trauma and complications are less. It is a good choice for the removal of tumors in cavernous sinus areas. Key words: Cavernous sinus; Brain neoplasms; Subtemporal approach

Factors associated with recurrence after endoscopic transphenoidal surgery for Cushing’s disease

Introduction: Surgical removal is the standard treatment for Cushing’s disease. Although endoscopic transsphenoidal surgical (ETS) approach has grown in popularity, its efficacy has not yet been established. Furthermore, achieving long-term remission remains challenging. Methods: We conducted a retrospective chart review of 39 consecutive patients who underwent ETS for Cushing’s disease at our institution between 2005 and 2014. Univariate analysis using Pearson’s χ2 test was carried out on variables of patient demographics, radiology, pathology, biochemical markers versus recurrence. Results: The mean age was 40, with 82% females. Average length of follow-up was 44.8 months. Based on serum cortisol level, 28 patients (71%) achieved mid to long-term remission after ETS. Of them, 25 experienced an immediate remission, and 3 achieved a delayed remission as long as 4 months postoperatively. MRI findings of (1) microadenomas or no detectable abnormality, (2) adjacency to the cavernous sinus wall were associated with significantly higher recurrence rate (p<0.05). Histologically, MIB-1 >5% was not a significant variable (p=0.55). Conclusion: We found ETS resection to be an effective and safe procedure for majority of the ACTH-secreting adenomas, with remission rates >70%. Additionally, patients with microadenomas, negative preoperative MR, and cavernous sinus adjacency were less likely to achieve remission.

Six Walls of the Cavernous Sinus Identified by Sectioned Images and Three-Dimensional Models: Anatomic Report

For the diagnosis and surgical treatment of diseases around the cavernous sinus (CS), radiologists should achieve complete mastery of the sectional anatomy of the CS, and neurosurgeons need to understand the stereoscopic orientation of the CS and circumjacent structures. However, despite the complicated structure of the CS, the current educational resources for its sectional and stereoscopic anatomy are insufficient. Another problem is that the definition of CS walls varies for each researcher. The purpose of this study is to redefine the walls of the CS and to provide related educational materials. Previous studies on the shape of the CS were analyzed. Sectioned images of a cadaver were prepared at 0.1-mm intervals to be made into three-dimensional (3D) models of the CS and neighboring structures. Based on other studies, the shape of the CS was redefined as a hexahedron, consisting of 6 walls, and was illustrated as a schematic figure. Scientific exactitude of the hexahedron was proven through matching the points with the actual structures on the sectioned images and 3D models that were made in this study. The combination of the hexahedron theory, the sectioned images, and the 3D models in this study will enhance the efficiency of studying CS anatomy. The educational resources of this study can be obtained free of charge by medical students, radiologists, and neurosurgeons requiring knowledge of CS anatomy.

Histological structure of the medial and lateral walls of cavernous sinus in human fetuses.

The aim of this study is to elucidate the architecture of these fine structures in human fetuses. The histological examination of medial wall (MW) and lateral wall (LW) was performed in 15 normal human fetuses. Eleven fetuses were female and four were male. The gestational age ranged between 14 and 35weeks. The weight ranged between 180 and 1750g. The wall samples (two MW and two LW from each fetus) were obtained by microsurgical technique and underwent histological examination. Each wall was examined for the structure and composition of collagen and elastic fibers, ganglions, peripheral nerves, and vessels. A total of 60 wall samples (30 MW and 30 LW) were examined in 15 fetuses. Loose connective tissue composed of type III collagen was observed in both of the walls. Elastic fibers were observed only in three wall samples (two MW and one LW). Ganglion was detected in 11 samples (nine in LW and two in MW), and peripheral nerve was found in 28 walls (18 LW and 10 MW). Vessels were observed in 51 samples (26 LW and 25 MW). None of the walls was stained with type I collagen. The structure of LW and MW of the cavernous sinus (CS) in fetuses is mainly composed of collagen tissue while some elastic fibers are supported by this tissue. Type III collagen is the main component of fetal CS walls. Because of the weak histological structure, CS may be more prone to tumor invasion in infants.