Anterior Clinoid Process Research Articles

Precise Localization of the Posterior Clinoid Process in the Fetal Skull Base.

To determine the precise position of the posterior clinoid process (PCP) in fetuses. Skull bases of 32 fetuses (11 males/21 females) aged 17 to 32 weeks in utero were included in the study. The distances of PCP to certain reference points were measured. The distances of PCP to the foramen ovale, foramen rotundum, superior orbital fissure, anterior clinoid process, foramen magnum, and crista galli were measured as 7.70±1.86mm, 6.99±1.65mm, 6.07±1.85mm, 3.85±1.10mm, 15.34±3.38mm, and 14.49±2.65mm, respectively. All parameters were similar for both sides (P>0.05). Apart from the distance of PCP to the foramen magnum, the remaining parameters were similar for both genders. This parameter was greater in males than females (P=0.001). All parameters were greater in the third-trimester fetuses than the second-trimester fetuses. All parameters increased with advancing gestational weeks (P<0.001). Linear functions were calculated for the distances of PCP to the crista galli (y = 1.311 + 0.551 × age), to the foramen magnum (y = 0.086 + 0.638 × age), to the anterior clinoid process (y = -0.303 + 0.174 × age), to the superior orbital fissure (y = - 2.013 + 0.338 × age), to the foramen rotundum (y = 1.803 + 0.217 × age), and to the foramen ovale (y = 0.760 + 0.290 × age). The measured distances increased with growth. The linear functions displaying the growth dynamics of PCP-related parameters may be used to estimate the distances.

Posterior clinoid process in children: morphometric analysis, pneumatization ratio, and surgical implications.

To describe pneumatization and topographic position of the posterior clinoid process (PCP) in healthy children when approaching the anterior and middle fossae. The study consisted of computed tomography images of 180 pediatric patients (90 males / 90 females), aged 1-18years. The presence or absence of PCP pneumatization was noted, and the distances of certain landmarks to PCP were measured. The distances of the foramen ovale, foramen rotundum, superior orbital fissure, anterior clinoid process (ACP), foramen magnum and crista galli to PCP were measured as 18.59 ± 3.36mm, 15.37 ± 3.45mm, 14.60 ± 3.05mm, 5.27 ± 3.24mm, 32.03 ± 3.27mm, and 30.45 ± 3.93mm, respectively. These parameters increased with growth (between 1-18years), but the distance between PCP and ACP decreased with an irregular pattern. In 11 sides (3.10%), a fusion between PCP and ACP was determined. PCP pneumatization was identified in 32 sides (8.9%). Its pneumatization correlated with pediatric ages (p < 0.001), but not gender (p = 0.459) or side (p = 0.711). Most of PCP pneumatization appeared after late childhood period (i.e., between 10-18years). Our study provides beneficial data for neurosurgeons to use PCP as a reference point for creating a skull base map in children, because of the incomparable position of PCP in the skull base center.

Morphology, pneumatization, septation, and protrusion of nearby structures into the sphenoid sinus: A retrospective radiological study

The morphology of the sphenoid sinus is critical in planning endoscopic sinus surgery, pituitary gland surgery, cerebrospinal fluid leak repair, the management of chronic sphenoid sinusitis, and the evaluation of skull base tumours. The objective of this study was to evaluate the morphology of the sphenoid sinus, with an emphasis on classification, septation, protrusion of structures, and dehiscence of the bony covering. In this retrospective radiological study, the morphology of the sphenoid sinus was analysed using 400 computed tomography scans. According to Hamberger’s classification, the sphenoid sinus was classified into postsellar and presellar varieties. Additionally, the extent of pneumatization of the pterygoid process, anterior clinoid process, and greater wing of the sphenoid was noted. The anteroposterior, transverse, and vertical diameters of the sphenoid sinus were also measured. The relative positions of the genu of the internal carotid artery, vidian canal, and intracanalicular optic nerve were also recorded. The mean anteroposterior length, transverse length, and vertical length of the sphenoid sinus were found to be 29.3 (±2.8), 31.9 (±2.7), and 22.8 (±1.9) mm, respectively. The sellar type was found in 90% of subjects, while the remaining 10% had the presellar type. Only two subjects had the concha type of sinus. A single septum was noted in 32% of cases.Pneumatization of the pterygoid process was found in 22.5%, the anterior clinoid process in 27%, and the greater wing of the sphenoid in 21.25%. Optic nerve protrusion occurred in 24.5% of cases, and 23% of optic canals were dehiscent. The findings of this study hold significant relevance for neurosurgery, particularly in procedures involving the skull base, such as transsphenoidal surgery and optic nerve decompression

Exploring optimal microscopic keyhole access to the skull base: an anatomical evaluation of transciliary supraorbital and transpalpebral orbitofrontal craniotomy approaches

Purpose: The past two decades have witnessed the rise of keyhole microscopic minimally invasive surgeries, including the transciliary supraorbital approach (TCA) and transpalpebral approach (TPA), commonly known as the transorbital approach. This study aims to elucidate the nuances, specific indications, and advantages of each approach. Methods: A series of dissections were conducted on five formalin-fixed, alcohol-preserved cadaver heads. The TCA was performed on one side, and the TPA on the other. Virtual measurements of working angles for both approaches were recorded. Additionally, three clinical cases were presented to illustrate the practical application of the techniques. Results: For TCA, the craniotomy dimensions were 1.7 cm x 2.5 cm (Cranial-Caudal (CC) x Lateral-Lateral (LL)), while for TPA, they measured 2.1 cm x 2.9 cm (CC x LL). The measurements of anterior clinoid processes (ACP) were obtained and compared between approaches. In the TCA, the mean ipsilateral ACP measurement was 62 mm (Range: 61 –63 mm), and the mean contralateral ACP measurement was 71.2 mm (Range: 70 –72 mm). In TPA, these measurements were 47.8 mm (Range: 47 –49 mm) and 62.8 mm (Range: 62 –64 mm), respectively. TCA exhibited an average cranial-caudal angle of 14.9°, while TPA demonstrated an average of 8.3°. Conclusion: The anterior cranial fossa was better exposed by a TCA, which also featured shorter operative times, enhanced midline visualization, and a quicker learning curve. Conversely, the middle fossa was better exposed by a TPA, making it an excellent option for middle fossa pathologies, including those in the anterior temporal lobe. After sphenoid bone wing drilling, the TPA offers superior visualization from the lateral to the medial aspect and enhances the CC angle. Additionally, the TPA reduces the risk of postoperative frontalis palsy based on anatomic landmarks. However, the TPA requires a greater cranial osteotomy, and due to unfamiliarity with eyelid anatomy, the learning curve for most neurosurgeons is lengthier for this procedure.

The Endoscopic Transorbital Approach for Vascular Surgery: An Anterior Circulation Anatomic Study, 2-Dimensional Operative Video.

Minimally invasive endoscopic approaches in cranial base surgery have been developing in the past decades. The transorbital (TO) route is one promising alternative, yet its adequacy for intracranial vascular lesions remains unclear. The present anatomic work aimed to test the feasibility and to provide a qualitative description of the endoscopic TO approach for the anterior circulation, namely the internal carotid artery and the middle cerebral artery. Seven embalmed adult cadaveric specimens (12 sides) were used in the study. Each side was approached in 3 successive steps: (1) Superior-eyelid TO approach, with great and lesser sphenoid wing removal. (2) Removal of anterior clinoid process (ACP). (3) Removal of the lateral orbital rim. All the procedures were performed under endoscopic view. The TO approach without removing the ACP allowed to dissect the sphenoidal and lateral segments of the Sylvian fissure with an adequate identification of the middle cerebral artery bifurcation in all specimens. The removal of the ACP allowed further dissection toward the opticocarotid cistern, with the identification of the ophthalmic, posterior communicating, and the anterior choroidal arteries. The internal carotid artery bifurcation and A1 segment were also readily identified. Finally, removal of the lateral orbital rim provided a wider and more comfortable access to the above-mentioned vascular structures. According to our anatomic data, the TO approach can be used to reach the main vascular components of the anterior circulation. This opens the field for exploring its application in the treatment of vascular pathology, particularly aneurysms.

Morphology of the Sella Turcica in Individuals With Different Skeletal Malocclusions in Upper Egypt Assessed Using Lateral Cephalometric Radiographs.

To evaluate the morphology of sella turcica (ST) in individuals with different skeletal malocclusions in upper Egypt. 300 lateral cephalometric radiographs of adult patients of both sexes, varying ages from 18 to 30 years, were selected and divided into three equal groups, group (1): skeletal class I (control group), group (2): skeletal class II, and group (3): skeletal class III. Pre-treatment lateral cephalograms were taken from the archives of the Department of Orthodontics, Faculty of Dentistry, Minia University. The tuberculum and dorsum sella, the floor of ST, and posterior and anterior clinoid processes (ACPs) were drawn. The direct measurements such asdiameter (APD), depth (D), and length(L) of sella were measured using Silverman and Kisling methods. A significant difference was found in depth (D) between class I and class II, with class II having a greater depth.Also, the largest diameter (APD) was found in the class III group.A significant difference was found in diameter (APD) between the two age groups (from 18 to 24 years and from 25 to 30 years) Conclusion: The larger diameter values were seen in the skeletal class III subjects, while the larger depth values were observed in the class II subjects. The older age group (25-30 years) has a greater diameter than the younger one. Highly significant differences were found in length and depth between the sexes.

The classical supraorbital minicraniotomy to approach the areas of origin of anterior skull base meningiomas: Anatomical nuances influencing accessibility, operability, and frontal lobe retraction.

The classical supraorbital minicraniotomy (cSOM) constitutes a minimally invasive alternative for the resection of anterior skull base meningiomas (ASBM). Surgical success depends strongly on optimal patient selection and surgery planning, for which a careful assessment of tumor characteristics, approach trajectory, and bony anterior skull base anatomy is required. Still, morphometrical studies searching for relevant anatomical factors with surgical relevance when intending a cSOM for ASBM resection are lacking. Bilateral cSOM was done in five formaldehyde-fixed heads toward the areas of origin of ASBM. Morphometrical data with potential relevant surgical implications were analyzed. The more tangential position of the cSOM with respect to the olfactory groove (OG) led to a reduction in surgical freedom (SF) in this area compared to others (P < 0.0001). Frontal lobe retraction (FLR) was also higher when approaching the OG (P < 0.05). Olfactory nerve mobilization was higher when accessing the planum sphenoidale (PS), tuberculum sellae (TS), and anterior clinoid process (ACP) (P < 0.0001). OG depth and the slope of the sphenoid bone between the PS and TS predicted lower SF and higher frontal retraction requirements along the OG and TS, respectively (P < 0.05). In contrast, longer distances to the ACP tip predicted lower SF over this structure (P < 0.01). Although clinical validation is still needed, the present anatomical data suggest that assessing minicraniotomy's position/extension, OG depth, the sphenoid's slope, and distance to ACP-tip might be of particular relevance to predict FLR, maneuverability, and accessibility when considering the cSOM for ASBM resection, thus helping surgeons optimize patient selection and surgical strategy.

Morphometric Analysis of the Sella Turcica on Cone-Beam Computed Tomography Images.

Sella turcica is an important anatomic formation that contains the pituitary gland and is in a close neighborhood with many vital structures. It is important to know the morphometry of the sella turcica, as it is a transition point during surgical interventions such as the endoscopic endonasal transsphenoidal approach to the region. The findings obtained are thought to be useful in the examination of sella turcica and surrounding structures and will contribute to the literature by knowing the morphometry of the region for the surgical method. In this study, cone-beam computed tomography images of 400 individuals, 200 females and 200 males, aged between 18 and 65 years, who did not have craniofacial pathology, who applied to Gaziantep University, Faculty of Dentistry between 2015 and 2020 for any reason, were evaluated retrospectively. In the sagittal section, 8 parameters were examined, 6 of which were transverse. The length () of the sella turcica in the sagittal plane is 10.19±1.77mm, the diameter of the sella turcica is 11.6±1.69mm, the anterior height of the sella turcica is 7.88±1.56mm, the median height of the sella turcica 8.18±1.42mm, posterior height of sella turcica 6.98±1.31mm, width of sella turcica 11.10±1.6mm. The distance between anterior clinoid processes in the transverse plane was 24.93±2.57mm, and the distance between posterior clinoid processes was 14.92±2.46mm. It was determined that there was an increase in many parameters with age, and length of the sella turcica and anterior clinoid processes were statistically significantly higher in males.

Morphology and Morphometry of the Anterior Clinoid Process in a Select South African Population

Background: Clinoid space is revealed when the anterior clinoid process (ACP) is removed, and it makes anterior vertical segment of the internal carotid artery (ICA) visible. Also, the presence of Carotico-clinoid foramen (CCF) makes the ICA from the cavernous sinus emerges through it and endangers the artery during anterior clinoidectomy which necessitates understanding the variable dimensions of ACP. Aim and Objectives: This study intended to investigate the morphology and morphometry of the ACP and to document the prevalence of the CCF in a select group of the South African population. Materials and Methods: The study was carried out on a total of 32 open crania (n=64 ACP) obtained from the University of KwaZulu-Natal, Nelson Mandela School of Medicine, Discipline of Clinical Anatomy using digital vernier caliper to measure the dimensions of the ACP. Results: The mean length, basal width, and thickness of the ACP on the right were10.18±1.34mm, 10.27±0.73mm, and 5.81±0.80mm and the left side was 10.89±0.94mm, 11.63±0.90mm, and 4.78±0.64mm respectively. The left ACP was significantly longer, wider, and thinner than the right ACP. Type I (short and broad) ACP was the most prevalent type, occurring in 53.13% of the studied population. Out of the 32 skulls studied, the CCF was observed in 6 (18.75%) cases. Five out of the six skulls (83.33%) had a bilateral complete CCF, and 1 (16.67%) had a unilaterally incomplete CCF. Conclusion: The ACP in our setting differs from other populations in terms of type, dimensions, and prevalence of the CCF and these should be considered when interpreting skull base radiographs and planning anterior clinoidectomy.

Open-door extended endoscopic transorbital technique to the paramedian anterior and middle cranial fossae: technical notes, anatomomorphometric quantitative analysis, and illustrative case.

The superior eyelid endoscopic transorbital approach (SETOA) provides a direct and short minimally invasive route to the anterior and middle skull base. Nevertheless, it uses a narrow corridor that limits its angles of attack. The aim of this study was to evaluate the feasibility and potential benefits of an "extended" conservative variant of the "standard" endoscopic transorbital approach-termed "open-door"-to enhance the exposure of lesions affecting the paramedian aspect of the anterior and middle cranial fossae. First, the authors described the technical nuances of the open-door extended transorbital approach (ODETA). Next, they documented its morphometric advantages over standard SETOA. Finally, they provided a clinical-anatomical application to demonstrate enhanced exposure and better angles of attack to treat lesions occupying the paramedian anterior and middle cranial fossae. Five adult cadaveric specimens (10 sides) initially underwent standard SETOA and then extended open-door SETOA (ODETA to the paramedian anterior and middle fossae). The adjunct of hinge-orbitotomy, through three surgical steps and straddling the frontozygomatic suture, converted conventional SETOA to its extended open-door variant. CT scans were performed before dissection and uploaded to the neuronavigation system for quantitative analysis. The angles of attack on the axial plane that addressed four key landmarks, namely the tip of the anterior clinoid process (ACP), foramen rotundum (FR), foramen ovale (FO), and trigeminal impression (TI), were calculated for both operative techniques and compared. Hinge-orbitotomy of the extended open-door SETOA resulted in several surgical, functional, and esthetic advantages: it provided wider axial angles of attack for each of the target points, with a gain angle of 26.68° ± 1.31° for addressing the ACP (p < 0.001), 29.50° ± 2.46° for addressing the FR (p < 0.001), 19.86° ± 1.98° for addressing the FO (p < 0.001), and 17.44° ± 2.21° for addressing the lateral aspect of the TI (p < 0.001), while hiding the skin scar, avoiding temporalis muscle dissection, preserving flap vascularization, and decreasing the rate of bone infection and degree of orbital content retraction. The extended open-door technique may be specifically suited for selected patients affected by paramedian anterior and middle fossae lesions, with prevalent anteromedial extension toward the anterior clinoid, the foremost compartment of the cavernous sinus and FR and not completely controlled with the pure endoscopic transorbital approach.

1234 The Transposition Technique of Internal Carotid Artery in Endonasal Endoscopic Surgery: Beyond the Lateral Boundary of Middle Line Approach

INTRODUCTION: There was no report regarding the transposition technique of ICA in endonasal endoscopic surgery (EES) METHODS: Six cadaveric heads (3 arterial and venous injected, 1 embalmed artery injected, 1 fresh artery injected) were prepared for dissection. The trabecular fiber (parasellar ligaments) in cavernous sinus(CS), small branches of ICA, dura, bony structures along ICA were meticulously dissected and photographed. The endoscopic dissections were performed using 0° (4-mm-diameter, 18-cm-long) rod lens endoscopes (Karl Storz). 36 cases (Jan 2014 to June 2022) underwent EES ICA transposition were reviewed. RESULTS: The trabecular fiber and small branches of ICA formed four sets of limiting structures around ICA: the medial, lateral, anterior, and posterior group. The medial group consisted of carotid clinoid ligaments (12/12), inferior hypophyseal artery (11/12), inferior parasellar ligament (6/12). The lateral groupcomprised inferolateral trunk (12/12), the sympathetic nerve plexus (12/12), the trabecular fibers between ICA and CN3 (6/12),CN4 (5/12), CN6 (12/12). The anterior group consisted of trabecular fibers between the proximal dural ring and the ICA (7/12). The posterior group was made of trabecual fibers (8/12) around the post genu and posterior wall of CS. Proximal and distal dura ring was the main dura structures impeding mobilizing ICA. The anterior clinoid and lingual process obstructed ICA lateral transposition. Grade 1 (inner CS limiting structures), Grade 2 (inner CS + dura ring open), Grade 3 (inner CS + dura ring + bony remove) transposition were used in 24 (66.7%), 9 (25%), 3 (8.3%) cases respectively. CSF leakage (2.7%), ICA injury (2.7%), new transient CN palsy (8.3%), permanent CN palsy (5.4%) were developed postoperatively. CONCLUSIONS: The EES ICA transposition technique is technically feasible and could be graded according to extent of freeing the limiting structures. It is a novel technique worth exploring in suitable cases to enlarge the working zone and surgical freedom in middle line approaches.

Tomographical study of optic strut location and its significance

To determine the attachment of optic strut relative to anterior clinoid process. To categorize optic strut into the sulcal, pre-sulcal, post-sulcal. To determine the association between laterality and optic strut attachment pattern. The study was conducted on 100 normal CT scans of Head and Para nasal sinus. Optic strut was classified as pre-sulcal, sulcal, post-sulcal, and asymmetric in relation to the prechiasmatic sulcus. Optic strut location was determined as anterior, middle and posterior with respect to anterior clinoid process. The optic strut was found to be anterior in 28% specimen, middle in 57% specimen and posterior in 15% specimen. The optic strut was pre-sulcal in 31% specimens, sulcal in 50%, post-sulcal in 16%. The above were observed bilaterally, and 3% were unilateral. Anatomical variations in the optic strut are significant in planning for anterior clinoidectomy and optic-canal decompression.

Bone anatomic variations of the parasellar region and its technical implications in para clinoid and posterior communicating segment aneurysms microsurgical clipping - Technical note.

Microsurgical treatment of paraclinoid aneurysms is a complex task that generally requires anterior clinoid process (ACP) removal to obtain adequate surgical exposure. This procedure poses a considerable technical difficulty due to the association of the ACP to critical neurovascular structures. Furthermore, anatomical variations in the parasellar region, such as the caroticoclinoid foramen (CCF) or an interclinoid bridge (ICB), may impose additional challenges and increase surgical complications. The present study aims to briefly review some anatomic variations in the parasellar region and describe a step-by-step surgical technique for a hybrid anterior clinoidectomy based on the senior author's experience. We present two cases with bone variations on the parasellar region in patients with a paraclinoid aneurysm and another with a posterior communicating segment aneurysm treated by microsurgical clipping at our hospital. We focused on safely dealing with these variations during surgery, without further complications, and with good postoperative results. Patients were discharged with no significant deficit. Postoperative control, computed tomography angiography showed complete exclusion of aneurysms. Although anatomical variations in the parasellar region can complicate surgical clipping of these aneurysms, it is essential to ensure the best possible surgical outcome to conduct thorough preoperative and radiological evaluations.

Optimizing the Endoscopic Transorbital Approach: MacCarty Keyhole for Enhanced Surgical Exposure in the Opticocarotid Region

Background and ObjectiveIn recent years, the endoscopic transorbital approach has gained increasing interest for the treatment of middle cranial fossa lesions. We propose a technical refinement to the conventional superior-eyelid transorbital approach, which improves the surgical exposure and augments the working angles when targeting the opticocarotid region. MethodsFour embalmed adult cadaveric specimens (eight sides) were dissected at the Laboratory of Surgical Neuroanatomy of our institution. A transorbital approach was performed, with removal of the anterior clinoid process (ACP) and the lateral orbital rim. Subsequently, the MacCarty's keyhole was drilled in the superolateral orbital wall. Given that the lesser sphenoid wing was already drilled in the conventional transorbital craniectomy, the opening of the keyhole was essentially a lateral extension of the craniectomy. ResultsThe procedure was successfully conducted in all four orbits. Clinoidectomy was performed either before or after extending the craniectomy to the MacCarty´s point. Extending the craniectomy made anterior clinoidectomy easier, by increasing the surgical exposure, and allowing a more lateral entrance for the endoscope. The extension also facilitated frontal lobe retraction, and it facilitated the optic nerve and carotid artery manipulation. Postoperative CT scans showed a minimal 10 mm craniectomy extension, which remained covered by the temporal muscle after reconstruction. ConclusionThe modified endoscopic transorbital approach with the extension of the craniectomy to MacCarty´s point improves surgical access and visualization of the opticocarotid region. This facilitates anterior clinoidectomy and optic nerve decompression. Although it implies judicious instrument manipulation and a larger incision size, further studies can define its potential benefits.

Accessory optic canals and a caroticoclinoid foramen in an infant: considerations for anterior clinoidectomy in the pediatric population

Abstract: Anterior clinoidectomy is a routine neurosurgical procedure for the management of paraclinoid aneurysms and tumors in adults; however, it has been performed less extensively in children. The anterior clinoid process of the sphenoid bone is closely related to vital neurovascular structures including the optic nerve, internal carotid artery, and the ophthalmic artery. Therefore, sphenoidal variants, such as the accessory optic canal and caroticoclinoid foramen, pose serious complications in anterior clinoidectomy including potential blindness and death. Case report: This report presents a novel case of concomitant bilateral accessory optic canals and a right-sided caroticoclinoid foramen found within an infantile sphenoid of a 12-month-old black male. The case report documents two co-occurring, clinically relevant variants known to complicate anterior clinoidectomy in an individual from a population that has been underrepresented in the literature. Conclusion: Caroticoclinoid foramina and accessory optic canals can be mistaken for each other on preoperative imaging, and accessory optic canals can additionally be mistaken for pneumatization of the anterior clinoid process, lesser sphenoidal wing, or optic strut. A high index of suspicion for these anatomic variants on preoperative imaging could enable the prevention of adverse outcomes, including hemorrhaging of the internal carotid artery and/or ophthalmic artery and subsequent blindness or death.

Topographic Anatomy and Pneumatization of the Posterior Clinoid Process in Chiari Type I Malformation

ObjectiveThis study aimed to examine pneumatization and topographic location of the posterior clinoid process (PCP) in Chiari type I malformation (CIM) for skull base approaches. MethodsComputed tomography images of 52 (23 males / 29 females) CIM subjects aged 23.87±16.09 years, and 71 (26 males / 45 females) healthy subjects aged 42.48±21.48 years constituted the study universe. ResultsThe distances of PCP to the foramen magnum (p=0.037), superior orbital fissure (p<0.001), foramen rotundum (p<0.001), and foramen ovale (p<0.001) were smaller, but the distance of PCP to the crista galli (p=0.038) was greater in CIM patients, compared to normal subjects. In CIM, the fusion between PCP and the anterior clinoid process was observed in nine sides (8.70%), while in controls, in 12 sides (8.50%). PCP pneumatization was observed in 40 sides (38.50%) in CIM patients, while in 28 sides (19.70%) in normal subjects. This data displayed that PCP pneumatization was affected by CIM (p<0.001). ConclusionThe distances of PCP to the crista galli and foramen magnum indicate the anterior fossa length and the posterior fossa depth, respectively; thus, CIM patients have longer anterior fossa and shallow posterior fossa. In addition, the distances of PCP to superior orbital fissure, foramen rotundum and foramen ovale indicate the middle fossa width; thence, CIM patients have less middle fossa width than normal individuals. CIM patients have approximately 50% higher PCP pneumatization rate, and this may increase the risk of complications such as cerebrospinal fluid fistula during the application of posterior clinoidectomy.

Evaluation of variations of optic nerve course in relation to posterior paranasal sinuses in MDCT in a tertiary care center of Nepal: a retrospective cross-section study.

The proximity of optic nerves to the posterior paranasal sinuses (PNS) is a critical consideration in preventing optic nerve injuries during functional endoscopic sinus surgery. A retrospective cross-sectional study was conducted on 367 patients aged 13 years and above. Four radiologists, each with 2-6 years of experience, evaluated computed tomography scans of the PNS and the head of these patients. The optic nerves were classified into four types based on DeLano's classification, and their respective prevalence rates were determined. Additionally, the prevalence of optic nerve dehiscence and pneumatization of the anterior clinoid process was assessed. A total of 734 optic nerves were evaluated and categorized into four groups as per DeLano's classification. The most common type was classified as type 1 optic nerve, representing 65.4% of all optic nerves. Types 2, 3, and 4 optic nerves accounted for 16.9, 8.6, and 9.1%, respectively. The prevalence rates of type 1, type 2, type 3, and type 4 optic nerves were 76.6, 24.5, 12.3, and 14.4%, respectively. Optic nerve dehiscence was observed in 14.3% of cases, with a prevalence of 21.2% in the study. Type 3 optic nerves were most commonly associated with dehiscence, with 49.2% of them showing dehiscence in their course through the ethmoid or sphenoid sinus. The prevalence of pneumatization of the anterior clinoid process in the study population was 28.3%, with type 3 optic nerves being the most frequently associated. An understanding of the relationship between optic nerves and posterior PNS, as well as awareness of optic nerve dehiscence, is essential in preventing injuries during sinus surgeries. Type 1 optic nerve predominates among Nepalese patients visiting our hospital.

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.

Anatomical Dimensions and Types of the Anterior Clinoid Process in Libyan population by Using Computed Tomography: A cross Sectional Study

The anterior clinoid process (ACP) has a complex anatomical feature and surrounded by important structures which may complicate the surgical procedures during the anterior clinoidectomy. Our objective was to measure dimensions of anterior clinoid process, and to determine variations of its types. Forty-nine of cranial computed tomography scans were performed from adult Libyan patients on routine examination of paranasal sinus at Benghazi Medical Center between February 1, 2023, and April 14, 2023. The right and left ACP length and the base width were measured on the axial CT images. Data analysis was done using SPSS version 23. The means and standard deviations were calculated. The paired Student’s t test was used to determine the statistically significant differences in means between the right and left ACP. (P ≤ 0.05) was considered statistically significant at (95%) confidence interval. The length of the right and left ACPs were 11.2 ± 2.2 mm and 11.6 ± 2.4mm, respectively. The width of the right and left ACPs were 5.37± 1.22 mm and 5.42 ± 1.24mm, respectively. Type 2 anterior clinoid process was the commonest (75.5 %) while type 1 was the least common (4.1 %). There was no statistically significant difference between right and left sided measurements. Our study outcomes may be helpful for pre-operative planning. Presence of any variations may result in unnecessary injury to the complicated surgical procedures that involve removal of ACPs. Further research studies required with large sample size of population will give well understanding about the parameter of ACPs.

Unravelling the Complex Relationship Between Frontal Sinus Pneumatization and Paranasal Sinus Anatomical Variants: Insights from CT Imaging.

The aim of this study was to analyse the relationship between frontal sinus pneumatization and its effect on various variations of paranasal sinuses on paranasal sinus CT scan. A total number of 100 patients (51 males, 49 females) were included in this study. Patients were divided into three groups on the basis of their frontal sinus pneumatization extent on paranasal sinus CT as Type 1 pneumatization (aplasia and hypoplasia), Type 2 pneumatization (medium) and Type 3 pneumatization (hyperplasia). The prevalence of various variations like pneumatization of upper and middle turbinate, presence of agger nasi, Haller and Onodi cell, maxillary sinus hypoplasia, extent of sphenoid sinus pneumatization, pneumatization of anterior clinoid process, pterygoid process and greater wing of sphenoid sinus, dehiscence and protrusion of internal carotid artery and optic nerve types were ascertained and compared within each group. The prevalence of Onodi cell, anterior clinoid process and greater wing of sphenoid pneumatization and optic nerves type 3 and 4 were higher in Type 3 frontal sinus pneumatization group as compared with other groups. Excessive pneumatization of frontal sinus has various effects on paranasal sinus variations. Surgeons dealing with endoscopic sinus surgery, maxillofacial and skull base surgery must be vigilant of association between these variations preoperatively for avoiding complications.