Middle Clinoid Process Research Articles

The Prevalence of the Middle Clinoid Process: A Cross-Sectional Comparative Study in Patients with and without Pathology of the Sella Turcica.

Background The middle clinoid process (MCP), particularly caroticoclinoid ring (CCR) type of the MCP, is an important part of the sphenoid bone for skull base surgery. Previous studies have shown a wide range of MCP prevalence affected by various factors. However, no study has investigated the association between the MCP and the presence of sellar lesions. Objectives The main aim of this study was to evaluate the prevalence of the MCP in the Thai population and factors associated with its presence. Materials and Methods We conducted a cross-sectional study on 400 sides from 200 patients (100 with and 100 without sellar lesions) using cranial computerized tomography scans. Demographic data and MCP characteristics were collected. The association between individual variables and the presence of the MCP was determined by univariate and multivariate analysis. Results The MCP was identified in 168 of 400 sides (42%). Patients with sellar lesions had a significantly lower prevalence of the MCP compared with normal controls (29.5% versus 54.5%, p < 0.001). Of all MCP only 6% were the CCR type. Univariate and multivariate analysis showed that the absence of the sellar lesion was the only factor significantly associated with presence of the MCP (odds ratio: 2.86; 95% confidence interval: 1.90-4.32; p < 0.001). Conclusion The prevalence of the MCP was relatively high in the Thai population, while the prevalence of the CCR was relatively low compared with previous studies. The absence of sellar lesions was the only factor associated with the presence of the MCP.

O papel do forame clinocarotídeo na cirurgia de aneurismas da artéria oftálmica

Introduction: The anterior clinoid process may present anatomical variations between individuals, even with changes in the same individual (between sides), mainly related to the formation of a bone bridge between it and the middle clinoid process and the clinoid process later. Recognition of the clinocarotid foramen is important in the treatment of aneurysms of the ophthalmic segment of the internal carotid artery, since the need to perform anterior clinoidectomy may result in inadvertent injury to the vascular structures. Objective: To review the incidence of clinocarotid foramen and interclinoid bone bridge in current literature. Method: Integrative review collecting existing information on virtual platforms using the descriptors “brain aneurysm, skull base, internal carotid artery, sphenoid bone” with AND or OR search. Result: Twenty-five articles were found who met the objective, being read and summarized for this review. Conclusion: The presence of aneurysms in the paraclinoid region/ ophthalmic segment of the internal carotid artery has a higher incidence in both the clinocarotid foramen and the interclinoid bone bridge.

Incidence of Ossification of Caroticoclinoid Ligament in Dry Adult Human Skulls with its Surgical Implications: A Cross-sectional Study from Telangana Region, India

Introduction: The caroticoclinoid ligament extends from the Anterior Clinoid Process (ACP) to the Middle Clinoid Process (MCP). Occasionally, it gets ossified and forms the caroticoclinoid foramen. Anterior clinoidectomy is a common surgical procedure to treat internal carotid artery aneurysms or pituitary tumours. Abnormal ossification of the caroticoclinoid ligament may lead to intraoperative or postoperative complications as it is not normally present. Aim: To find out the incidence of ossification of the caroticoclinoid ligament in adult human skulls. Materials and Methods: This was an observational crosssectional study that included 100 dry adult human skulls collected from the Department of Anatomy, Gandhi Medical College, Secunderabad; Osmania Medical College, Hyderabad; Bhaskar Medical College, Moinabad, Telangana, India, from January 2021 to February 2023. Adult human skulls with open vault were included. All the skulls were observed and skulls damaged in the clinoid regions were excluded from the study. The skulls were observed for the presence of any ossifications of the caroticoclinoid ligaments and the observations were noted. The qualitative data was presented as number and percentage was calculated. The data was recorded in MS excel version 2021. Results: The incidence of ossification of caroticoclinoid ligament was 8 (8%). The incidence was higher on right-side when compared to the left-side. Bilateral complete ossification of the caroticoclinoid ligament was observed in 2 (2%) skulls; bilateral incomplete ossification was observed in 3 (3%) skulls, unilateral complete ossification was observed in 2 (2%) skulls on the right-side. In one skull 1 (1%), complete ossification was observed on the right-side and incomplete ossification was observed on the left-side. Conclusion: Knowledge of the ossification of the caroticoclinoid ligament is important for neurosurgeons while performing anterior clinoidectomies or skull base surgeries. Radiological confirmation of the ossification of the caroticoclinoid ligament is essential to avoid complications.

Navigating a Carotico-Clinoid Foramen and an Interclinoidal Bridge in the Endonasal Endoscopic Approach: An Anatomical and Technical Note.

Objective The carotico-clinoid foramen and interclinoid bridge are two anatomical variants of the sellar region. If these anatomical variants go unrecognized and are not managed safely by the surgeon during expanded endoscopic endonasal surgery for a posterior clinoidectomy, a carotid artery injury may occur. We summarize a method to safely navigate in the presence of the carotico-clinoid foramen and interclinoid bridge in an endoscopic endonasal approach. Study Design The study involves cadaveric dissection and management of the anatomical variants. Setting The study took place in a cadaveric dissection laboratory. Participants The object of study is one cadaveric head. Main Outcome Measures After discovering the two variants in both cavernous sinuses of a cadaveric head, we established a stepwise coping strategy to avoid carotid artery injury while performing an endoscopic endonasal bilateral interdural pituitary transposition, and we report the final view after endoscopic management. Results Debulking of the middle clinoid process can decrease the obstacle effect, and the pituitary transposition can be performed medial to the ossified carotico-clinoid ligament. Disconnection of the interclinoid bridge is the prerequisite to an effective posterior clinoidectomy, and distinguishing the transition between the sellar diaphragm and the interclinoid bridge is essential. Conclusion In the presence of both the carotico-clinoid foramen and the interclinoid bridge, a bilateral interdural pituitary transposition can still be performed, although preoperative strategic preparation, full inspection, and stepwise disconnections are of paramount importance in such a scenario to avoid cavernous carotid artery injury.

Ossification around intercavernous sinus: An osteological finding that can complicate trans – sphenoidal surgery

The aim of the study was to document an anatomical variation around the sella turcica which was unique and lacked any reference in the literature. A low lying osseous bar connecting the right middle clinoid process to the midpoint of the right lateral border of the dorsum sella was observed in a human skull specimen. The osseous bar was forming a foramen close to the floor of the sella, and the structure in association with this part of sella is the inferior intercavernous sinus. Measurements of the sella turcica bridge (STB), carotico-clinoid foramen (CCF), interclinoid foramen (ICF) on both sides and that of the ossified bar and foramen formed by itself were taken with the help of ImageJ software. The values observed for the measurements of different parameters of STB and its components, for CCF and ICF were bilaterally different. While the values for the osseous bar and foramen formed by it cannot be compared because of its unilateral occurrence. The presence of foramen around the inferior intercavernous sinus may lead to difficulty in performing procedures like transsphenoidal surgery (TSS) or extended TSS (eTSS) while extracting intradural lesions, thus increasing the chances of haemorrhage.

The caroticoclinoid foramen in fetal and infantile orbitosphenoid, presphenoid, and sphenoid bones: developmental and neurosurgical considerations.

OBJECTIVEThe presence of a caroticoclinoid foramen may increase the likelihood of adverse neurosurgical events. Despite the clinical importance of the caroticoclinoid foramen, its study has been mostly limited to adult populations. Therefore, the object of this study was to describe the prevalence, morphology, and development of the caroticoclinoid foramen among varied sexes and races in early life.METHODSThe study analyzed caroticoclinoid foramina in dry orbitosphenoid, presphenoid, and sphenoid bones from a population of 101 fetal and infantile crania of varied sex and race.RESULTSA caroticoclinoid foramen, whether complete, near complete, or partial, was found in 36 of 199 sides (18.1%). Of the 98 crania with bilaterally intact sides, 21 (21.4%) had the presence of at least one caroticoclinoid foramen. Caroticoclinoid foramina were found unilaterally and bilaterally, in both female and male crania (9/41, 22.0%; 12/57, 21.1%, respectively) and, likewise, in crania of both black and white races (9/54, 16.7%; 12/44, 27.3%, respectively). Caroticoclinoid foramina were formed from cornuate bony projections from the anterior clinoid process, middle clinoid process, or both anterior and middle clinoid processes. Caroticoclinoid foramina were also found in isolated orbitosphenoid bones from individuals as young as 4 months' fetal age.CONCLUSIONSThe caroticoclinoid foramen occurs in approximately one of every 5 sides and in one in every 5 individuals of perinatal age and should, therefore, be considered a common finding in both fetuses and infants. It is common in both females and males as well as in both black and white races, alike. Furthermore, the caroticoclinoid foramen can be found in individuals as young as 4 months of fetal age. Failure to anticipate the presence of a caroticoclinoid foramen will place important neurovascular structures, including the internal carotid artery, at risk of injury. Neurosurgeons should, therefore, anticipate the caroticoclinoid foramen even in their youngest patients.

Observações anatômicas sobre o canal carótido-clinóideo do osso esfenóide humano

O conhecimento da complexa anatomia e da possível variação anatômica do processo clinóideo anterior e médio do osso esfenóide é importante na abordagem cirúrgica dessa região. Dentre essas variações, está a presença do canal carótido-clinóideo, o qual é formado pela união dos processos clinóideos anterior e médio. O objetivo deste trabalho foi avaliar a freqüência de ocorrência do canal carótido-clinóideo em brasileiros. Utilizaram-se 49 crânios secos de cadáveres adultos masculinos, acima de 30 anos de idade. O processo clinóideo anterior apresentou-se sob a forma de pirâmide de base anterior; o ápice, na maioria dos casos, é projetado medialmente. O canal carótido-clinóideo do tipo completo ocorreu em 10,2% dos crânios , e do tipo incompleto apareceu em 24,48%. A ocorrência bilateral do tipo completo esteve presente em 8,16% dos casos. Considerando o canal carótido-clinóideo dos tipos completos e incompletos, a freqüência foi de 32,64%, aproximando-se do valor relatado para americanos (34,84%). Estudos em vivos, através de imagem, poderia ser uma abordagem interessante para se esclarecer o processo de formação do canal carótido-clinóideo, bem como permitir possíveis correlações entre a sua presença e outros aspectos do estado de saúde do indivíduo.

A morphometric survey of the parasellar region in more than 2700 skulls: emphasis on the middle clinoid process variants and implications in endoscopic and microsurgical approaches.

OBJECTIVE The middle clinoid process (MCP) is a bony projection that extends from the sphenoid bone near the lateral margin of the sella turcica. The varied prevalence and morphological features of the MCP in populations stratified by age, race, and sex are unknown; however, the knowledge of its anatomy and preoperative recognition on CT scans can aid greatly in complication avoidance and management. The aim of this study was to further illustrate the surgical anatomy of the parasellar region and to quantify the incidence of MCP and caroticoclinoid rings (CCRs) in dried preserved human anatomical specimens. METHODS The presence, dimensions, morphological classification (incomplete, contact, and CCR), and intracranial relations of the MCP were measured in 2726 dried skull specimens at the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History. Specific morphometric data points were recorded from each of these hemiskulls, and categorized based on age, sex, and ethnicity. Linear and logistic regressions were used to determine associations between explanatory variables and MCP morphology. Computed tomography scans of the skull specimens were obtained to explore radiological landmarks for different types of MCPs. Illustrative intraoperative videos were also analyzed in the light of these crucial surgical landmarks. RESULTS The sample included 2250 specimens from males and 476 from females. Specimens were classified as either "white" (60.5%) or "black" (39.2%). An MCP was found in 42% of specimens, with 60% of those specimens presenting bilaterally. Fully ossified CCR comprised 27% of all MCPs, and contact (defined as contact without ossification between MCP and anterior clinoid process) comprised 4% of all MCPs. White race (relative to black race) and increasing age were significant predictors of MCP presence (p < 0.001). White race was significantly associated with greater average MCP height (p < 0.001). Among skulls with CCR, both male sex and older age (> 70 years relative to < 50 years) were associated with increased CCR diameter (p < 0.001). No other significant predictors or associations were observed. The CT scans of skulls replicated and validated the authors' morphometric observations on incomplete, contact, and CCR patterns adequately. The surgical strategies of clinoid bone removal are validated, with appropriate video illustrations. CONCLUSIONS Variations in the patterns of bony MCPs can pose a significant risk for injury to the internal carotid artery during parasellar procedures, especially those involving clinoidectomy and optic strut drilling. Understanding parasellar anatomy, especially on skull-base CT imaging, may be integral to surgical planning and preoperative risk counseling in both transcranial and extended endonasal procedures, as well as to preparing for complications management perioperatively.

Morphometric Analysis of the Middle Clinoid Process Using Maxillofacial Computed Tomography Scans.

The interest in detailed anatomy of the sella and parasellar regions has resurged recently due to the wide clinical applications of the expanded endoscopic approaches to the skull base. The middle clinoid process (MCP) is a bony structure that can affect wide endoscopic exposure of the sella and parasellar region. To study and analyze the anatomic variations of the MCP in the general population using computed tomography scans. A total of 150 maxillofacial computed tomography scans were reviewed to characterize the MCP. Only adult patients without intracranial or nasal pathology were included. Measurements were made in the axial and sagittal planes to determine the maximum diameter, length, angulation, and location of the MCP. The prevalence of the MCP was 30.7% in male and 42.7% in female patients. Of the MCPs, 41.8% were ring forming, whereas 76.4% were pneumatized. Quantitatively, the average axial base diameter was 4.6 ± 1.4mm, the average sagittal base diameter was 5.0 ± 1.8mm, the average length was 4.7 ± 1.7mm, the average midline distance was 5.9 ± 2.3mm, the average distance from the sellar-clival junction was 10.6 ± 3.3mm, the average sagittal angle was 91.0 ± 21.1°, and the average axial angle was 45.2 ± 15.5°. A significant increase was found in the prevalence of MCPs in white patients compared with black patients, and a significantly greater midline distance and axial angle were found in male compared with female patients. A clear understanding of the sellar and parasellar anatomy is crucial for successful and safe expanded endoscopic approaches. This study provides a quantitative anatomic characterization of the MCP in the U.S. population with demographic data analysis.

A Survey of the Variable Anatomy of the Parasellar Region with Specific Emphasis on the Middle Clinoid Process

A Survey of the Variable Anatomy of the Parasellar Region with Specific Emphasis on the Middle Clinoid Process

Bilateral “Carotico-clinoid Foramen” With “Sella Turcica Bridge”- A Case Report

Introduction: The Carotico-clinoid foramen is the result of ossification of carotico-clinoid ligament between anterior and middle clinoid process. Whereas bony bridge between anterior and posterior clinoid processes formed by ossified dural extension connecting these two processes, is called Sella Turcica Bridge. They can be developed unilaterally or bilaterally and vary in frequency. Both these foramina may cause different presentations, i.e. compression, tightness or stretching of internal carotid artery as well as endocrinological problems affecting hypothalamus or hypophysis cerebri or neurological problems through Oculomotor or optic nerve, pituitary gland, which manifest as headache, behavioral changes, hormonal, visual, epileptic, craniofacial deviation and tooth anomalies, etc. That’s why thorough anatomical knowledge is a great clinical help for neurosurgeons, neurophysicians, endocrinologists, radiologists, anatomists and biological anthropologists. Case report: Recently during teaching medical students one dry skull having bilateral ossified interclinoid ligaments (carotico-clinoid foramen and sella Turcica Bridge) is found which is relatively very rare as per literatures. The morphologic analysis has been done.

The Recesses of the Sellar Wall of the Sphenoid Sinus and Their Intracranial Relationships

The sellar wall of the sphenoid sinus and its recesses have been previously studied, but their intracranial relationships to the diaphragma sellae, tuberculum, clinoid segment of the internal carotid artery, chiasmatic sulcus, and middle clinoid process need further definition. To describe these intra- and extracranial relationships of the recesses in the anterior sellar wall. The middle clinoid was studied in 132 parasellar areas of dry crania. Thirty-eight parasellar areas of formalin-fixed/silicone-colored specimens were dissected. After transsphenoidal endoscopic exposure, the optic, carotid, and sellar prominences; lateral opticocarotid and tuberculum recesses; and caroticosellar and medial opticocarotid points were identified. High-speed drills opened 1-mm perforations at these points to allow study of intracranial relationships. Two recesses and 2 junction points can be recognized in the sphenoid sinus: lateral opticocarotid and tuberculum recesses and medial opticocarotid and caroticosellar points. The lateral opticocarotid recess corresponds to the optic strut base, and the clinoid segment of the internal carotid artery is located medially. The diaphragma sellae attachment is at the level of the tuberculum recess, which in 50% of cases corresponds to the tuberculum. A middle clinoid in base or height greater than 1.5 mm is present in 21.1% and a caroticoclinoid ring in 3%. The middle clinoid is 1 mm inferior and lateral to the caroticosellar point and 4.7 mm inferior to the medial opticocarotid point. An understanding of the intra- and extracranial relationships of the recesses of the sphenoid sinus will aid in accurately directing transsphenoidal approaches.

The Recesses of the Sellar Wall of the Sphenoid Sinus and Their Intracranial Relationships

Introduction: The sellar wall of the sphenoid sinus and its recesses have been previously studied, but their intracranial relationships to the clinoid segment of the internal carotid artery, chiasmatic sulcus, tuberculum, diaphragma sellae, and middle clinoid process need further definition.

The Medial Opticocarotid Recess

The medial opticocarotid recess (MOCR) has become an important landmark for endoscopic approaches to the cranial base. To examine the anatomy of the MOCR and outline its role as a "key landmark" for approaches to the sellar and suprasellar regions. Ten silicone-injected cadaveric specimens and 96 dry crania were examined. Dissections were done endoscopically and microscopically. The lateral tubercular recess is an osseous depression located at the lateral edge of the tuberculum when viewed from the sphenoid sinus. Intracranially, it corresponds to the lateral tubercular crest (LTC), a ridge situated at the superomedial aspect of the carotid sulcus. The MOCR is a teardrop-shaped osseous indentation formed at the medial junction of the paraclinoid carotid canal and the optic canal. Dorsally, it is represented by a teardrop-shaped area with vertices at the inferior aspect of the LTC, the medial aspect of the junction of the superior and posterior surfaces of the optic strut, and the superolateral aspect of the tuberculum. The middle clinoid process is situated inferior to the LTC. The distal osseous arch of the carotid sulcus connects the lateral opticocarotid recess to the lateral tubercular recess and is a landmark for the paraclinoid internal carotid artery. Only 44% of the specimens had middle clinoid processes. The MOCR and middle clinoid process are distinct structures. Because of its location at the confluence of the optic canal, the carotid canal, the sella, and the anterior cranial base, the MOCR is a key landmark for endoscopic approaches.

Incidence Of Ossified Interclinoid Bars In Dry Human Skulls Of Gujarat State

A group of intrinsic ligaments of the sphenoid bone which connect the anterior, middle and posterior clinoid processes occasionally get ossified and give rise to various types of ossified interclinoid bars. In present study the incidence of various types of ossified interclinoid bars were observed in 200 dry human skulls of unknown age and sex belonging to department of Anatomy of various Medical Colleges of Gujarat region. The interclinoid bars are classified on the basis of two classifications, proposed by Rani Archana et al and Keyers. Rani Archana et al, classified interclinoid bars into four types : Type I (caroticoclinoid foramen) bridge present between anterior and middle clinoid process, Type II bridge between anterior, middle and posterior clinoid process, Type III bridge between anterior and posterior clinoid process and Type IV bridge between the middle and posterior clinoid process. Each interclinoid bar was classified into contact, incomplete, complete types based on the classification of Keyers. In present study total incidence of interclinoid bars was 18%. Type I were present in 10.5%, out of which 8% were complete and 2.5% were incomplete. Types II in 3.5%, amongst them 2% were complete and 1.5% was mixed. Type III in 4%, out of which 2% were complete and 2% were incomplete. Total incidence of caroticoclinoid foramens was 14.5%, out of which 11.5% were complete and 3% were incomplete. Total incidence of sellar bridge was 7.5%, out of which 4.5% were complete and 3% were incomplete. Presence of osseous interclinoid bars may cause compression of surrounding structures like the cavernous sinus and its content, sphenoid sinus and pituitary gland. Therefore, detailed anatomical knowledge of various types of interclinoid bars can increase the success of diagnostic evaluation and surgical approaches to the region.

Anatomy of the clinoidal region with special emphasis on the caroticoclinoid foramen and interclinoid osseous bridge in a recent Turkish population.

In this study we present the incidence of caroticoclinoid foramen and interclinoid osseous bridge and some topographic aspects regarding the clinoidal internal carotid artery (ICA) in a recent Turkish population to provide a guide for neurosurgeons in any surgical approach, especially to the cavernous sinus. One hundred nineteen adult dry skulls and 52 adult cadaveric heads were used for this purpose. Caroticoclinoid foramen and the interclinoid osseous bridge were divided into three types based on the classification of Keyers [13]. Caroticoclinoid foramen was observed in 35.67% of the specimens, unilaterally in 23.98%, and bilaterally in 11.69%. The complete-type caroticoclinoid foramen was observed in 4.09% of the specimens, the contact type in 4.68%, and the incomplete type in 14.91%. Transverse diameter of the foramen was 5.32+/-0.52 mm for the incomplete type. The incidence of interclinoid osseous bridge was 8.18%. The middle clinoid process was prominent in 15.12% of cases and rudimental in 13.23%. The mean distance between the proximal and distal dural rings of the clinoidal ICA was 4.51+/-0.44 mm, and mean diameter of the distal ring was 5.25+/-0.59 mm. Right-left differences were assessed for each parameter, and populational differences are discussed.

Internal carotid artery: correlative anatomy as a guide to surgery

The course of the internal carotid artery (ICA), particularly the C4–C6 segments, cavernous, clinoid, and ophthalmic, respectively, as described by Bouthillier et al. traverses a relatively compact region of complex anatomical relationships. The bony, dural, connective tissue, and neurovascular elements of this region frequently deter access or “block” surgical entry. The key to unlocking this region is a detailed understanding of its surgical anatomy. The treatment of aneurysms in proximity to the distal dural ring (DDR), e.g. clinoid, superior hypophyseal, or carotid ophthalmic aneurysms, presents considerable challenges to the neurosurgeon. The anterior clinoid process (ACP) and its associated anatomical variations, including a prominent middle clinoid process (MCP) and aerated optic strut, must be considered and anticipated when performing an anterior clinoidectomy. Aneurysms of the C4–C6 segments can transgress either the proximal or distal dural rings or both; this transgression (so-called transitional aneurysms) can occur in either direction making an extradural aneurysm and also intradural or vice versa. The existence of a carotid cave as originally described by Kobayashi et al. must be taken into consideration in the analysis of aneurysms of the ICA in proximity to the DDR. Again, determination of the relationship of the aneurysm to the DDR is critical to the decision making process; extradural aneurysms have a considerably different prognosis and treatment than intradural aneurysms. The correlation of cadaveric anatomy to surgical anatomy will serve as a guide to improve surgical techniques, strategies, and outcome.

Medial Wall of the Cavernous Sinus

The medial wall (MW) of the cavernous sinus (CS) was studied to define its structure, position and relations with the other CS structures. The study was performed on twenty-five fresh cadaver specimens featuring the sellar and both parasellar regions and parts of the anterior, middle and posterior cranial fossa. Fifteen specimens were injected with auto-polymerizing two component colored substance while ten were left non injected. The uppermost membranous part of the MW of the CS was found dividing the pituitary gland from the CS on each side. This membrane represented the most lateral part of the dural capsule surrounding the pituitary gland and invariably showed its completeness. The position and shape of the MW of the CS was found to be determined by ligaments anchoring it to the nearby bone and dural formations: anteriorly it was anchored to the middle clinoid process (MCP), posteriorly to the dorsum sellae and posterior clinoid process (PCP), superiorly to the diaphragm sellae and the posterior interclinoid ligament and inferiorly to the lateral surface of the sphenoid body. The position of the MW of the CS and the shape of its points of anchorage were found to be the most important factors determining the presence, configuration and size of the entry points of the intercavernous venous communications through the sella. The knowledge of the MW of the CS could have implications both on neuroradiological interpretation and on surgical planning and treatment of lesions involving these regions.

巨大内頸-眼動脈瘤治療の問題点

Direct clipping was performed in two cases of giant ophthalmic (30mm in diameter, subopticochiasmal global type) aneurysms in the right side who presented with visual disturbances in both eyes. Case 2 showed a second small aneurysm in the left IC-ophthalmic region. Preoperatively collateral circulation and tolerance to ischemia were studied by the Allcock and Matas tests. Both cases were operated on by right frontotemporal craniotomy. The neck carotid arteries were prepared for temporary occlusion during which time the brain function was monitored by scalp EEG. An STA-MCA anastomosis was performed before aneurysm surgery in Case 2.The optic canal was opened and the anterior clinoid processes, which were well developed and pneumatized in both cases, were meticulously removed subdurally with an air drill. The anterior clinoid process in Case 1 continued to the middle clinoid process forming a bony canal around C3, which made the situation even more difficult. The cavernous sinus had to be opened around C3 in both cases in order to obtain space for the clip blade in the proximal neck of the aneurysm. Further dissection of the aneurysm from the surrounding structures such as the contralateral IC, optic nerve and chiasm could only proceed after the aneurysm had been decompressed by puncture, after which fenestrated clips could be applied without difficulty. Only one fenestrated and angled clip was applied in Case 1. Three fenestrated clips were needed in tandem manner in order to close the neck in Case 2. Here a fourth straight clip was necessary in order to stop continuous oozing, probably from the space between the tandem clips.Postoperatively Case 1 returned to her normal household activities. Case 2 was blinded in her right eye and showed dense left hemiparesis, for which she is receiving rehabilitation at four months after the surgery. CT showed an infarction in the territory of the right anterior choroidal artery.Discussions are presented about 1) choice of treatment, direct or IC occlusion with bypass surgery; 2) ischemia monitors and brain protection during temporary occlusion of the IC; 3) importance of opening the cavernous sinus in order to obtain the proximal neck of the aneurysm; 4) importance of protection of the posterior communicating, anterior choroidal and perforating arteries, especially when fenestrated and angled clips are applied.

Radiography of the Sella Turcica

The present interest in endocrine disorders and the apparent increasing frequency with which the roentgenologist is called upon to assist in the diagnosis of these conditions have caused the roentgen demonstration and interpretation of changes in the sella turcica to become of considerable importance. The value, however, of the roentgen interpretation in these cases is dependent on a knowledge of the normal structure as revealed not only by roentgenologic studies on normal individuals, but on actual anatomic specimens as well. Unfortunately, the latter prerequisite was underestimated by early workers and as a result there have arisen certain conclusions which cannot be substantiated by anatomic facts. I refer particularly to the so-called “bridged sella,” which has been cited from time to time as a cause for diabetes insipidus, epilepsy, and migraine. This anatomic variation, which consists of a bony union between the anterior and posterior clinoid processes with occasional inclusion of the middle clinoid process, occurs in about 5 per cent of necropsy specimens. When the relation of the anterior clinoid processes to the pituitary fossa is considered and especially the fact that they always pass lateral to this fossa and never over it, the theory of a union between the anterior and posterior clinoid processes producing pressure on the hypophysis, infundibulum or associated blood vessels, seems quite improbable. Roentgenograms of this anatomic variation are quite misleading, as the shadow of the bony union which is in reality just lateral to the pituitary fossa is cast over the outlet of the sella and seems to enclose it and diminish its size. Aside from existing as an anatomic possibility, the appearance of a bridged sella may be produced on the roentgenogram by the superimposition of the shadows of the anterior and posterior clinoid processes. This may occur when the sagittal plane of the head is not placed parallel with the film, or when the tube is incorrectly centered. An incorrect lateral position not only distorts the images of the clinoid processes but the contour of the sella as well, and under such conditions the pituitary fossa may appear unusually small or shallow. These are not uncommon faults of roentgenograms of this region and many of the so-called bridged sellæ are not true anatomic variations but artifacts due to technical errors. The intimate relation of the sella turcica to the pituitary gland is no doubt responsible for the erroneous idea that all changes in its contour are the result of pituitary disease. It is true, with certain exceptions, that pituitary tumors produce changes in the contour rather characteristic in type, but there are so many other causes of sellar deformities that failure to bear them in mind may result in an erroneous diagnosis with subsequent disappointment for the surgeon and perhaps disaster for the patient.