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Intracranial chondrosarcomas located in the region of the posterior clinoid process have not been focused on. Here, we report the case of a 29-year-old woman with a skull base tumor in that region. Seven years after the diagnosis, the tumor had grown and showed calcification and tumor stain; chondrosarcoma, posterior clinoid meningioma, and chordoma were suspected. The patient underwent subtotal tumor resection, and the histopathological study revealed that the tumor was a low-grade chondrosarcoma. Chondrosarcomas can be located in the region of the posterior clinoid process, and not only chordomas but also posterior clinoid meningiomas should be considered as a differential diagnosis of tumors located in that region, especially when the tumor has calcification or receives a vascular supply.

Purpose. Sella turcica bridging (STB) refers to a rare anatomical variation formed by the ossification of the ligament between the anterior and posterior clinoid processes. The presence of the STB was significantly correlated with craniofacial skeleton classification and a higher prevalence rate in skeletal Class III. The current study is aimed at investigating the dimensions of sella turcica and the prevalence of STB in different sexes and on the three craniofacial skeletal patterns using cone beam computed tomography (CBCT). Materials and Methods. A total of 159 adults (66 males and 93 females), including 3 different craniofacial skeletal patterns (skeletal Classes I, II, and III), were included in the study. The sella turcica dimensions and the prevalence of STB were calculated. An independent t -test and generalized linear model were used to compare the differences in the sella turcica dimensions and the skeletal relations. The Spearman rank correlation coefficient was used to analyze the correlations between sella turcica dimensions and skeletal relation. Results. The sella length (SL) was 11.05 ± 1.80 mm for males and 10.77 ± 1.56 mm for females. The anterior clinoid distance (ACD) which was measured for the anterior width of sella turcica showed 25.83 ± 2.04 mm and 24.04 ± 2.28 mm for males and females, respectively ( p < 0.0001 ). The overall percentage of complete bridging and partial bridging was 6.6% and 56.9%, respectively. Complete bridges were more common in males (males: 9.1%, females: 4.8%), and partial bridges were more frequent in females (males: 49.2%, females: 62.4%). Both sexes differed with respect to sella turcica dimensions. Moreover, males had a significantly larger ACD, posterior clinoid distance (PCD), and diameter of sella turcica (DST), on both sides, relative to females. Conclusion. The prevalence rate of complete STB in the Taiwanese population was 6.6%. Significant differences between sexes were found in sella turcica dimensions. The prevalence rates of STB as well as the sella turcica dimensions did not significantly differ between different craniofacial skeletal patterns (skeletal Classes I, II, and III).

OBJECTIVEThe pretemporal transcavernous approach (PTA) and the endoscopic endonasal transcavernous approach (EETA) are both used to access the retroclival region. A direct quantitative comparison of both approaches has not been made. The authors compared the technical nuances of, and surgical exposure afforded by, each approach and identified the key elements of the approach selection process.METHODSFourteen cadaveric specimens underwent either PTA (group A) or EETA with unilateral (group B) followed by bilateral (group C) interdural pituitary gland transposition. The percentage of drilled clivus; length of exposed oculomotor nerve (cranial nerve [CN] III), posterior cerebral artery (PCA), and superior cerebellar artery (SCA); and surgical area of exposure of both cerebral peduncles and the pons for the 3 groups were measured and compared.RESULTSGroup A had a significantly lower percentage of drilled area than group B (mean [SD], 35.6% [11.2%] vs 91.3% [4.9%], p < 0.01). In group C, 100% of the upper third of the clivus was drilled in all specimens. Significantly longer segments of the ipsilateral PCA (p < 0.01) and SCA (p < 0.01) were exposed in group A than in group B. There was no significant difference in the length of the ipsilateral CN III exposed among the 3 groups. There was also no significant difference between group A and either group B or group C for the contralateral CN III or PCA exposure. However, longer segments of the contralateral SCA were exposed in group C than in group A (p = 0.02). Furthermore, longer segments of CN III (p < 0.01), PCA (p < 0.01), and SCA (p < 0.01) were exposed in group C than in group B. For brainstem exposure, there was greater exposure of the pons in group C than in group A (mean [SD], 211.4 [19.5] mm2 vs 157.7 [25.3] mm2, p < 0.01) and group B (211.4 [19.5] mm2 vs 153.9 [34.1] mm2, p < 0.01). However, significantly greater exposure of the ipsilateral peduncle was observed in group A (mean [SD], 125.6 [43.1] mm2) than in groups B and C (56.3 [6.0] mm2, p < 0.01). Group C had significantly greater exposure of the contralateral peduncle than group B (p = 0.02).CONCLUSIONSThis study is the first to quantitatively identify the advantages and limitations of the PTA and EETA from an anatomical perspective. Understanding these data may help the skull base surgeon design a maximally effective yet minimally invasive approach to individual lesions.

Background Determining if paraclinoid aneurysms are intradural or extradural is critical for surgical planning. Objective To create an easily reproducible diagnostic method based on bony anatomy that precisely locates the distal dural ring (DDR) to determine the position of paraclinoid aneurysms as intradural, transitional, or extradural. Methods Bilateral anatomic dissections of 10 cadaveric heads (20 sides) were performed to evaluate DDR anatomy. We observed a plane that reflects the position of the DDR passes through 4 bony landmarks: 1) The anterior clinoid-internal carotid artery intersection, 2) the optic strut, 3) the optico-carotid elevation, and 4) the base of the posterior clinoid process. This landmark-based plane can thus define the location of the DDR using 3-dimensional computed tomography angiography (CTA). This was confirmed in 27 surgical patients with intradural/transitional aneurysms and 7 patients with extradural aneurysms confirmed with magnetic resonance imaging (MRI). The DDR plane method easily classified aneurysm locations as intradural (above the DDR plane), extradural (below the DDR plane), or transitional (the DDR plane crosses the aneurysm). The aneurysm's location was subsequently confirmed intraoperatively or with MRI. Results The DDR plane method determined if paraclinoid aneurysms were intradural, transitional, or extradural in all 34 cases examined. The visibility of the anatomic features that define the DDR plane was also verified in 82% to 89% of CTA images from 100 patients. Conclusion The DDR plane method provides a useful diagnostic tool to evaluate the position of the DDR and determine the anatomic location of paraclinoid aneurysms.

We report a rare case of nonapoplectic pituitary adenoma that did not invade the cavernous sinus and was associated with isolated oculomotor nerve palsy. A 61-year-old male was admitted to our hospital due to diplopia that had gradually worsened from 6 months to presentation. He was diagnosed with right oculomotor nerve palsy, and brain magnetic resonance imaging (MRI) showed a mass lesion within the sella. The tumor was homogeneously enhanced on contrast-enhanced MRI. However, no findings suggestive of pituitary apoplexy were found. Brain computed tomography revealed the tumor to have eroded the right side of the posterior clinoid process by gradual expansion. Endoscopic transsphenoidal surgery was used for complete resection of the tumor. Intraoperative findings showed that the tumor did not invade the cavernous sinus. The histological diagnosis was pituitary adenoma, and symptom improvement was observed from the early postoperative stage onward. Surgical treatment is essential because oculomotor nerve palsy caused by the enlargement of pituitary adenoma is not expected to resolve if treated conservatively, unlike that caused by pituitary apoplexy.

BackgroundSkull base chordomas (SBCs) are rare malignant bone tumors with dismal long-term local control. Endoscopic endonasal surgeries (EESs) are increasingly adopted to resect SBCs recently. Gross total resection (GTR) favors good outcomes. However, the SBCs often invade the skull base extensively and hide behind vital neurovascular structures; the tumors were challenging to remove entirely. To improve the GTR, we established a surgical strategy for EES according to the tumor growth directions.MethodsA total of 112 patients with SBCs from 2018 to 2019 were classified into the derivation group. We retrospectively analyzed their radiologic images and operation videos to find the accurate tumor locations. By doing so, we confirmed the tumor growth directions and established a surgical strategy. Fifty-five patients who were operated on in 2020 were regarded as the validation group, and we performed their operations following the surgical strategy to verify its value.ResultsIn the derivation group, 78.6% of SBCs invade the dorsum sellae and posterior clinoid process region. 62.5% and 69.6% of tumors extend to the left and right posterior spaces of cavernous ICA, respectively. 59.8% and 61.6% of tumors extend to the left and right posterior spaces of paraclival and lacerum ICA (pc-la ICA), respectively. 30.4% and 28.6% of tumors extended along the left and right petroclival fissures that extend toward the jugular foramen, respectively. 30.4% of tumors involved the foramen magnum and craniocervical junction region. The GTR was achieved in 60.8% of patients with primary SBCs in the derivation group. Based on the tumors’ growth pattern, pituitary transposition and posterior clinoidectomy techniques were adopted to resect tumors that hid behind cavernous ICA. Paraclival ICA transposition was used when the tumor invaded the posterior spaces of pc-la ICA. Lacerum fibrocartilage resection and eustachian tube transposition may be warranted to resect the tumors that extended to the jugular foramen. GTR was achieved in 75.0% of patients with primary SBCs in the validation group.ConclusionBesides the midline clival region, the SBCs frequently grow into the eight spaces mentioned above. The surgical strategy based on the growth pattern contributes to increasing the GTR rate.

Background Different surgical approaches have been developed to manage lesions of the anterior and middle skull base areas. Frontal, pterional, bifrontal, and fronto-orbito-zygomatic approaches are traditionally used to reach these regions. With advancements in the neurosurgical field, skull opening should be simple and as minimally invasive as possible, tailored on the surgical corridor to the target. The supraorbital approach and the “keyhole” concept have been introduced and popularized by Axel Perneczky starting from 1998 and are now considered a part of everyday practice. The extended possibilities of this surgical route, considering the reachable targets and surgical limits, are described and systematically analyzed, including a description of the salient surgical anatomy, presenting different illustrative cases. Methods and Results Different illustrative cases are presented and discussed to underline the potentials and limits of the minimally invasive subfrontal approach (MISFA) and the possibilities to tailoring the craniotomy on the basis of the targets: extra-axial lesions with different localizations (anterior roof of the orbit, olfactory groove, tuberculum sellae, medial third of the sphenoid wing, anterior and posterior clinoid process), deeper intra-axial lesions (gyrus rectus, medial temporal lobe-uncus-amygdala-anterior hippocampus), and vascular lesions (anterior communicating aneurysm). Each case has been preoperatively planned considering the anatomical and radiologic features and using virtual simulation software to tailor the best possible corridor to reach the surgical target. Conclusions The MISFA is a safe multicorridor approach that can be used efficiently to manage lesions of the anterior and middle skull base areas with extremely low approach-related morbidity.

The clivus was defined as “no man’s land” in the early 1990s, but since then, multiple approaches have been described to access it. This study is aimed at quantitatively comparing endoscopic transnasal and microsurgical transcranial approaches to the clivus in a preclinical setting, using a recently developed research method. Multiple approaches were performed in 5 head and neck specimens that underwent high-resolution computed tomography (CT): endoscopic transnasal (transclival, with hypophysiopexy and with far-medial extension), microsurgical anterolateral (supraorbital, mini-pterional, pterional, pterional transzygomatic, fronto-temporal-orbito-zygomatic), lateral (subtemporal and subtemporal transzygomatic), and posterolateral (retrosigmoid, far-lateral, retrolabyrinthine, translabyrinthine, and transcochlear). An optic neuronavigation system and dedicated software were used to quantify the working volume of each approach and calculate the exposure of different clival regions. Mixed linear models with random intersections were used for statistical analyses. Endoscopic transnasal approaches showed higher working volume and larger exposure compared with microsurgical transcranial approaches. Increased exposure of the upper clivus was achieved by the transnasal endoscopic transclival approach with intradural hypophysiopexy. Anterolateral microsurgical transcranial approaches provided a direct route to the anterior surface of the posterior clinoid process. The transnasal endoscopic approach with far-medial extension ensured a statistically larger exposure of jugular tubercles as compared with other approaches. Presigmoid approaches provided a relatively limited exposure of the ipsilateral clivus, which increased in proportion to their invasiveness. This is the first anatomical study that quantitatively compares in a holistic way exposure and working volumes offered by the most used modern approaches to the clivus.

Background Calcification between the anterior and posterior clinoid processes, also the so-called sella turcica bridging, has been associated in some studies with skeletal anomalies as well as with dental and eruption disturbances. It was hypothesized that sella turcica bridging was associated with an altered direction of dental eruption. The aim of the study was to assess whether there was a relationship between the degree of calcification and the presence or absence of an alteration in the tooth eruption direction. Material and methods A case-control multicenter study was conducted. The study population consisted of 150 subjects (age 10-50 years), 30 of which presented some type of alteration of the direction canine eruption (impactation or transposition) (cases) and 120 selected at random who did not present altered direction of dental eruption (controls). Cases and controls were matched by age, sex, and approximate date of starting orthodontic treatment. Lateral cephalometric radiographies were obtained and the extent of the sella turcica bridging was measured using a Vernier caliper and scored as no calcification, partially calcified, and completely calcified. Results The frequency of a partially or completely calcified sella turcica bridge was significantly higher among cases with altered direction of dental eruption as compared with controls. There was a trend towards a shorter length of sella turcica in subjects with two or more canine eruption alterations. Sella turcica bridging was unrelated to sex, but it was significantly influenced by age. Conclusions Sella turcica bridging is frequently detected in subjects with altered direction of dental eruption of canines. Key words:Dental eruption, sella turcica bridging, anterior clinoid process calcification, posterior clinoid process calcification, cephalometric radiographs.

The anatomy and definition of the petroclinoid ligament (PCL) and its relationship with the abducens nerve are variably described. The goal of this study was to clarify the anatomy of the PCL and better elucidate its relationship with the abducens nerve. Thirty-six sides from 18 fresh-frozen adult cadaveric heads were used in this study. Specimens were all Caucasian and derived from 10 males and 8 females. The mean age at death was 79 years. Dissection of the PCL and abducens nerve was performed using a surgical microscope. The anterior and posterior attachments of the PCL, and position of the abducens nerve were noted. Subsequently, the width, thickness, and length of the ligament, and diameter of the abducens nerve were measured. Thirty-one sides (86.1%) were found to have a PCL, on two sides (5.6%), the PCL was ossified, and on three sides (8.3%), the PCL was absent. The width, thickness, and length of the PCL ranged from 0.54 to 3.39, 0.07 to 0.49, and 3.27 to 17.85 mm, respectively. No PCL had an anterior attachment onto the posterior clinoid process but rather, the clivus. Therefore, based on our findings, the PCL would be better described as the petroclival ligament.

Objective Pituitary macroadenomas extend into the extrasellar space, such as the sphenoid sinus, cavernous sinuses, and suprasellar region. However, factors that regulate the direction of their extensions into the surrounding anatomical structures remain unknown. Methods This retrospective study included 162 patients who were treated for pituitary adenomas that had maximum diameters greater than 20 mm. According to the direction of adenoma extension, patients were divided into 4 groups: group A, inferior into the sphenoid sinus; group B, lateral into the cavernous sinus; group C, suprasellar region with enlarged sella turcica; and group D, supraellar region without enlarged sella turcica. Several anatomical structures surrounding the sella turcica were evaluated statistically, and multivariate logistic regression analysis was performed if the structures met the determining factors of adenomas extensions. Results The maximum diameter of adenomas was significantly larger in groups A and D. The maximum diameter of the diaphragmatic foramen was largest in group C (19.3 mm) and was significantly narrower in groups B (12.7 mm) and D (12.5 mm). Intrasphenoid septation, attached on the midline of the sella turcica, was observed most frequently in group D (78.6%) and was not detectable in group A (0%). Extension into the cavernous sinus, classified as dural discontinuity, was highly prevalent in group B (80.0%) and was uncommon in group C (12.3%). Erosion of the posterior clinoid process was most apparent in group B (92.0%). Conclusions The integrity of the sella dura and the intrasphenoid septation can regulate adenoma extension by encouraging their growth towards paths of least resistance.

Despite the advances in microsurgery and neuroanatomy, surgery of the central skull base still represents a challenge. Fronto-temporal approach has represented the mainstay of surgical approaches to this region. With advances in skull base surgery, orbital and zygomatic extensions were added to fronto-temporal approach to improve exposure minimizing brain retraction.The authors compared fronto-temporal and fronto-orbitozygomatic approaches to the central skull base by using the previously described operability score, to three different anatomical targets: the ipsilateral anterior clinoid process, the contralateral anterior clinoid process, and the ipsilateral posterior clinoid process.Based on the measurements taken, fronto-orbitozygomatic approache showed higher values at all 3 targets. The reported values were critically discussed.The operability score has been reported as an effective method to compare surgical approaches. The present study demonstrated the maximal possibility of exposure of the two approaches. Based on the strong variability of this anatomical region, especially because of the different pathologies, the authors suggest considering the operability score as a further tool to better define the best surgical approach to this anatomical region.

The inferomedial triangle is one of the two surgical triangles in the paraclival subregion of the skull base. It is delineated by the posterior clinoid process, the dural entrance of the trochlear nerve and the dural entrance of the abducens nerve. The aim of the present article is to describe the anatomical variations within the inferomedial triangle. Measurements of the triangle’s borders and area were supplemented by detailed observations of the topographical anatomy and various arrangements of its contents. Nine adult cadaveric heads (18 sides) and 28 sagittal head sections were studied. The mean area of the inferomedial triangle was estimated to be 60.7 mm2. The mean lengths of its medial, lateral and superior borders were 16.1 mm, 11.9 mm and 10.4 mm, respectively. The dorsal meningeal artery was identified within the inferomedial triangle in 37 out of 46 sides (80.4%). A well-developed petrosphenoidal ligament of Grüber was identified within the triangle on 36 sides (78.3%). Although some structures were variable, the constant contents of the inferomedial triangle were the posterior petroclinoid dural fold, the upper end of the petroclival suture, the gulfar segment of the abducens nerve and the posterior genu of the intracavernous internal carotid artery.

Benign, small, and asymptomatic World Health Organization grade I meningiomas are usually managed expectantly with surveillance imaging with the assumption that they are predictably slowing growing. In this paper, we report the case of an incidentally discovered small, right-sided posterior clinoid meningioma in a 53-year-old female. The tumor was managed conservatively but an annual surveillance magnetic resonance imaging demonstrated that the meningioma had an unexpected significant growth impinging on the brainstem, requiring surgical resection and radiosurgery for residual tumor. Despite histopathological confirmation of a grade I meningioma, the tumor recurred significantly and incurred substantial neurological deficits, requiring further surgery and radiotherapy. This report illustrates the potential pitfall for expectant management of small meningiomas in anatomically precarious locations and draws attention to the need for detailed informed discussions with patients regarding the management of these tumors.

Objective The retroinfundibular and upper clival regions are challenging to access using the endoscopic endonasal approach because these regions are obstructed by the dorsum sellae and posterior clinoid processes. We evaluated the safety and clinical efficacy of endoscopic dorsum sellar resection (DSR) and identified the optimal indications for endoscopic DSR in patients with craniopharyngioma. Methods A retrospective study was conducted of patients who had undergone treatment with an endoscopic endonasal approach from January 2014 to January 2019. We identified a total of 50 patients who had undergone DSR. The indications for DSR included the following: 1) a tumor involving the upper clivus; 2) a tumor located behind the dorsum sellae; and 3) a tumor involving the interpeduncular or prepontine cistern. We evaluated the clinical outcomes, postoperative endocrinological status, and surgical morbidities. Results Of the 50 patients, 16 had been treated for craniopharyngioma, 30 for chordoma, 2 for pituitary adenoma, 1 for schwannoma, and 1 for chondrosarcoma. An extradural approach for DSR with posterior clinoidectomy was performed in 33 patients (66.0%) and an interdural transcavernous approach in 17 patients (34.0%). The overall gross total tumor resection rate was 92.0% (46 of 50 patients). Postoperatively, 28 of 33 patients (84.8%) with normal pituitary function preoperatively showed preservation of hormonal function postoperatively. Conclusions DSR with or without posterior clinoidectomy is a challenging procedure that requires considerable effort and advanced surgical techniques. However, it can be safely performed with accumulating experience and a thorough knowledge of the surrounding anatomical structures.

Background: There is a great variance between the extent of pneumatisation of the sphenoid sinuses that can reach beyond the body of the sphenoid bone. The purpose of this study was to find the frequency prevalence of the recesses of the sphenoid sinuses in Polish adult population. Materials and methods: 296 computed tomography (CT) scans of patients who did not present any pathology in the sphenoid sinuses were evaluated in this retrospective analysis. Spiral CT scanner — Siemens Somatom Sensation 16 — was used to glean the medical images. Standard procedure applied in the option Siemens CARE Dose 4D. No contrast medium was administered. Results: In the majority of the patients — 93.92%, the pneumatisation of the sphenoid sinuses expanded beyond the body of the sphenoid bone, hence there were recesses of the sinuses present. The most common variant was the prevalence of two recesses — 12.84% of the cases. The frequency prevalence of all the 17 recesses was only 0.34%. Amongst the uneven recesses present, the sphenoidal rostrum’s recess (61.15% of the patients) and the inferior clinoid recess (56.42%) were the most common. Amongst the even recesses present, the lateral recess was prevalent in the majority (65.88%), whereas the posterior clinoid process’ recess was the least common (9.8%). Conclusions: Presence of the recesses might facilitate access to the cranial fossae, hence comprehensive evaluation of the sphenoid sinuses is of immense importance in order to avoid unnecessary drills through the hard bone, that could potentially damage the nearby neurovascular structures.

Long-term sequelae are major limitations of radiation therapy use, especially for childhood brain tumour. Circle of Willis irradiation strongly increases the long-term risk of stroke, but to establish dose-response relationship, anticipating long-term effects of new techniques, requires to perform accurate and reproducible dosimetric estimations in large cohorts of patients having received radiotherapy decades ago. For the accuracy of retrospective dose reconstruction, the topographic variability of the Circle of Willis arteries is crucial. In order to improve retrospective dosimetric studies and dose-volume estimates to the typical Circle of Willis arteries, we aim to study the inter-individual topographic variability of these structures. Thirty-eight time of flight MRI sequences of children aged 2–17 years in both genders were investigated. A region growth algorithm was used for the segmentation of the cerebral arteries. A rigid registration in a common skull was performed following the anatomy of skull base foramina. The Posterior clinoid processes of the sella turcica were used as reference landmark (R0), and 5 key landmarks were chosen in each segmented Circle of Willis, then distances between the 5 landmarks and R0 were calculated for each of the 38 subjects. The distance between R0 and each landmark of the Circle of Willis followed a normal distribution, the average values ranging from 13.6 to 17.0 mm, and the standard deviations ranged from 2.6 to 3.0 mm, i.e. less than a fifth of the average value. The perimeter of the Circle of Willis was longer in older subjects, this increase being isotropic. Our study shows a remarkably low topographic variability of the typical Circle of Willis. An important result, allowing reliable anthropomorphic phantoms-based retrospective estimations of the radiation doses delivered to these arterial structures during radiotherapy treatment., Zrafi et al. report inter-individual topographic variability in the Circle of Willis structure in a paediatric population. Their work shows a remarkably low variability of the typical Circle of Willis and provide data that have potential benefit for retrospective dosimetric studies in children developing cerebrovascular diseases after radiotherapy., Graphical Abstract Graphical Abstract

Basilar tip aneurysm clipping is technically challenging because of the depth of operative corridor, rarity in presentation, and important perforators supplying deep, critical structures. Two major approaches to basilar tip aneurysms include (1) a frontotemporal (transorbital) trans-sylvian approach for most aneurysms and (2) a modified subtemporal approach for aneurysms with low-lying necks. A 53-yr-old woman presented to our institution with a large unruptured basilar tip aneurysm notable for a low, broad neck (6.4 mm). After discussion of risks and benefits of endovascular vs surgical options, the patient consented to operative intervention. She underwent a right frontotemporal craniotomy with zygomatic osteotomy, intradural petrous apicectomy, elective sectioning of the fourth cranial nerve (CN IV), and intracavernous removal of the dorsum sellae and posterior clinoid process to provide more space for aneurysm dissection. After temporary clipping of the basilar artery, the perforating arteries were dissected free from the aneurysm and the aneurysm occluded with 2 fenestrated clips. Important technical nuances of the approach include (1) achieving ample working room for temporary occlusion aneurysm dissection, (2) careful dissection of the perforators and contralateral P1, and (3) utilization of 2 fenestrated clips to accommodate and preserve the ipsilateral P1 segment. Postoperative angiogram showed complete aneur-ysmal occlusion. Postoperatively, the patient demonstrated mild cognitive impairment and a right CN IV palsy. At 6-wk follow-up, cognition recovered to normalcy. More recently, at 12-mo follow-up, the patient noted intermittent diplopia. Formal neuro-ophthalmologic assessment confirmed persistence of a CN IV palsy treated with prism lenses but no other neurological deficits.

Sella turcica bridging occurs with fusion or calcification of the anterior and posterior clinoid processes in the middle cranial region. This study aimed to compare the cephalometric parameters among normal shape, partial bridge, and total bridge of the sella turcica in adolescent and young adult subjects.This retrospective study was performed on the lateral cephalometric radiographs of 410 Turkish adolescent and young adult subjects. The subjects were divided into three groups: normal sella turcica shape (128 females, 32 males; mean age: 17.7 ± 1.54 years), partial sella turcica bridge (129 females, 32 males; mean age: 17.8 ± 2.15 years), and total sella turcica bridge (66 females, 23 males; mean age: 18.2 ± 1.82 years). Thirteen angular and eight linear cephalometric measurements were performed using a cephalometric software program. The data were analyzed by one-way analysis of variance, and the Kruskal-Wallis test with the Bonferroni correction.Significant differences were found for Nperp-A distance, Nperp-Pg distance, and palatal plane-to-anterior cranial base angle among the groups (p 0.016). There were no significant differences in the cephalometric parameters between the partial and total sella turcica bridging groups (p 0.05).This study evaluated a large amount of data for cephalometric measurements focusing on the degree of calcification of the sella turcica in adolescent and young adult subjects. The maxilla and mandible were located in a sagittally retrusive position in the partial and total sella turcica bridge subjects compared with the normal sella turcica shape subjects.

Objective Neck clipping remains a valuable treatment option for basilar apex aneurysms, especially in those with complex morphology, such as incorporation of branching vessels or large size, and young patient age. Several approaches have proved to give effective exposure for various types of lesion morphologies. Our historic literature review from 1976 to the present systematically compares the outcomes and complications of the key surgical approaches in the treatment of basilar apex aneurysms. Methods We searched PubMed for articles with at least 5 patients, data on neurologic outcome, and procedure-associated complications for the following approaches: pterional or orbitozygomatic transsylvian, subtemporal (with or without zygomatic osteotomy), pretemporal (with or without transcavernous extension), and transpetrous. n-Weighted averages for clinical outcome, aneurysm occlusion rates, morbidity, mortality, and aneurysm morphology were compared. Results Of 35 articles selected, 2041 patients with 722 ruptured aneurysms underwent microsurgery, including 1131 transsylvian, 241 pretemporal, 375 subtemporal, and 17 transpetrous approaches. Comparing these 4 approaches in n-weighted averages, respectively, we noted good neurologic outcomes (81%, 85%, 81%, and 58%), surgical morbidity (14%, 10%, 34%, and 53%), surgical mortality (4%, 1%, 0, and 1%), and complete occlusion rates (95%, 94%, 86%, and 75%). Conclusions Transsylvian, pretemporal, and subtemporal approaches showed favorable neurologic outcomes at similar rates and were applied for aneurysms located between −1mm and +7mm in relation to the posterior clinoid process. The pretemporal approach was preferably applied to large and giant aneurysms with good outcome; the transsylvian approach was most frequently used for ruptured aneurysms.

Aims: The posterior clinoid process (PCP) is a paired anatomic structure located in the middle cranial fossa on the superior surface of the sphenoid bone where it forms a bony eminence that is the lateral boundary of the dorsum sellae (DS). The aim of the study was to analyze PCP and DS morphometry in computed tomography (CT) . Materials and methodology: The study was based on 100 CT investigations of 54 women and 46 men aged 18–88 (mean age 52.49 years). The PCP and DS morphometry was studied in coronal and sagittal planes. Data were analyzed statistically in relation to patients ’ gender and age (group 1: up to 45 years, group 2: over 45 years). Results: The average width of the right and left PCP was 10.2 mm and 9.85 mm, respectively, while the average height of the right and left PCP was 2.32 mm and 2.04 mm, respectively. The thickness of the DS superior edge was 3.29 mm, and of the right and left PCP: 4.28 mm and 4.31 mm, respectively. Statistical calculations lead to the conclusion that the right PCP is wider and thicker in men. Moreover, the DS superior edge is also thicker in men, and the left PCP is wider and higher in people over 45 years of age. Conclusions: The PCP and DS are characterized by considerable individual variability. CT is a useful modality for PCP and DS morphometry assessment. PCP and DS are different in men and women. Age affects skull base morphometry.

Despite technological advances in endovascular therapy, surgical clipping of paraclinoid aneurysms remains an indispensable treatment option and has an acceptable profile risk. Intraoperative monitoring of motor and somatosensory evoked potentials has proven to be an effective tool in predicting and preventing postoperative motor deficits during aneurysm clipping.1,2 We describe the case of a 61-yr-old Japanese woman with a history of hypertension and smoking. During follow-up for bilateral aneurysms of ophthalmic segment of the internal carotid artery (ICA), left-sided aneurysm growth was detected. A standard pterional approach with extradural clinoidectomy was used to approach the aneurysm. After clipping, a significant intraprocedural change in motor evoked potential (MEP) amplitude was observed despite native vessel patency was confirmed through micro-Doppler and indocyanine green video angiography.3-5 After extensive dissection of the sylvian fissure and exposure of the communicating segment of ICA, the anterior choroidal artery was found to be compressed and occluded by the posterior clinoid because of an inadvertent shift of the ICA after clip application and removal of brain retractors. Posterior clinoidectomy was performed intradurally with microrongeur and MEP amplitude returned readily to baseline values. Computed tomography (CT) angiogram demonstrated complete exclusion of the aneurysm, and magnetic resonance imaging (MRI) was negative for postoperative ischemic lesions on diffusion weighted images. The patient tolerated the procedure well and was discharged home on postoperative day 3 with modified Rankin Scale (mRS) 0. The patient signed the Institutional Consent Form to undergo the surgical procedure and to allow the use of her images and videos for any type of medical publications.

Objective The presigmoid approach can be used to treat vertebrobasilar artery aneurysms when circumstances require more operative exposure. High morbidity and mortality in these cases have been reported. In this study, we describe our modified presigmoid approach for vertebrobasilar artery aneurysms and our clinical results. Methods This series includes patients with vertebrobasilar aneurysms clipped via the modified presigmoid approach at the Department of Neurosurgery at Helsinki University Hospital from 1998 to 2014. Data were collected from the operating record books, patients' medical records, and a radiologic database server. Results Thirty-three presigmoid procedures of 31 patients were performed to treat 34 aneurysms (14 ruptured, 20 unruptured). The aneurysms had a mean distance from the posterior clinoid process to the aneurysm neck of 12.2 mm (range, 0–26.6 mm). A favorable outcome was achieved in 21 patients (64%). A favorable outcome was achieved in 74% of unruptured and good-grade patients, whereas favorable outcome was achieved in only 36% of poor-grade patients. Complete or near-complete occlusion was achieved in 79%. Larger aneurysms, fusiform morphology, and anterior dome projection had lower occlusion rates. Conclusions We have described our experiences of using the presigmoid approach to treat vertebrobasilar aneurysms. The clinical and radiographic results are acceptable given the complex location and configuration of the treated aneurysms. Unfavorable outcomes are related to the poor admission Hunt and Hess grade, aneurysm morphology, and aneurysm size.

Familiarity with the shape and dimensions of sella turcica is important to recognize and manage pathological conditions of pituitary gland as well as for orthodontic treatment planning. The present study aims to describe the morphology and dimensions of sella turcica from Indian population, using lateral cephalograms to set a reference data for comparison among different races. The study used 36 lateral skull radiographs of both sexes between age group of 13 to 18 years. Shape of sella turcica was noted by visual inspection. Length, height anterior, height median, height posterior, distance between frontonasal suture and mental spine to midpoint of posterior clinoid process, and tuberculum sella were measured using digital vernier caliper with reference to Frankfort line. The results of the study revealed that mean length, height anterior, height median, height posterior were larger in females than in males. The morphological types identified include pointed posterior clinoid process with rounded hypophyseal fossa, hooked posterior clinoid process with rounded hypophyseal fossa, hooked posterior clinoid process with flask-shaped hypophyseal fossa. These observations would be beneficial for the clinicians and orthodontists to design treatment planning in pathology of pituitary gland and in correcting dentofacial anomalies.

Carotid-cavernous fistulas (CCFs) are an abnormal vascular shunt between the carotid artery and the cavernous sinus, and were traditionally classified into four subtypes based on the detailed fistulas anatomy and arterial supply. CCFs are frequently encountered in patients with traumatic skull base fractures. In this report, we present one such case caused by two head traumas. Computed tomography and digital subtraction angiography confirmed that this CCF arose from posterior communicating artery of the internal carotid artery, which is not included in the traditional Barrow et al’s categorization. The possible mechanisms include laceration of dural mater of posterior clinoid process and laceration or pseudoaneurysm formation of posterior communicating artery. This case was successfully treated with endovascular coil embolization.

Objectives Currently in Sri Lanka otorhinolaryngologists are vastly involved in functional endoscopic sinus surgery (FESS), while transsphenoidal approach to sellar lesions is becoming popular among neurosurgeons. There is a possibility of endoscopic supra sellar, lateral skull base and clival surgery to take off in near future although no sufficient database is available about the anatomical variations of the sphenoid sinuses of Sri Lankans. This research is aimed at filling this deficit. Design and Methods A cross sectional retrospective study of 200 CT scans of 0.5mm intervals of the ‘nose, paranasal sinus and brain” of Sri Lankans who were seen at district general hospital Trincomalee were analyzed. Details were collected regarding pneumatization, sellar budge, protrusion and dehiscence of the walls of maxillary nerve (MN), optic nerve (ON), vidian nerve (VN) and internal carotid artery (ICA) and the different types and attachment of the sphenoid sinus septum. Results We found no conchal pneumatization but 100% of the study population to have presellar area of the sphenoid body pneumatization, 87% to have sellar and 39.5% to have post sellar area of the sphenoid bone pneumatization. Superior extension of pneumatization into anterior clinoid process (ACP) was found among 13.5% and extension in to posterior clinoid process (PCP) in 4.5%. Lateral extension in to opticocarotid recess was found in 60% and pneumatization in to greater wing of sphenoid (GWS) was found in 42% while 13.5% had pneumatization of lesser wing of sphenoid (LWS). Anterior pneumatization extended in to vomer and ethmoid bones and was 25%and 19% respectively. Posterior extension in to clivus was 34.5% while pneumatization extended inferiorly in to pterygoid process in 54.5 %. The sellar bulge was well defined in 75.5% and not so in 24.5%. The Intersinus septum was absent in 0.5% while single Intersinus septum was present in 86.5% and 8% had a transverse septum. 29.5% had multiple Intrasinus septum while 64.5 % had accessory septa. Occurrence of protrusion and dehiscence in optic nerve, maxillary nerve, vidian nerve and internal carotid artery were, 54%, 8.5%, 24.5% and 79% and, 23%, 7%, 14% and 57.5% respectively. Conclusions The sinus anatomy has a racial difference and regional anatomy varies randomly. Posterior, inferior and lateral extensions of pneumatization could make orientation and relative positioning of vital structures confusing. Septal attachments to vessels and nerves are much higher than appreciated previously. Individual study with greater attention to detail in CT scans is recommended prior to surgery to minimize complications.

Maffucci syndrome is an extremely rare disorder characterized by benign enchondromas, skeletal deformities, and cutaneous lesions composed of abnormal blood vessels. Enchondromas rarely arise in the cranial bones. Interdural pituitary transposition is an effective way to gain access to the posterior clinoid, without affecting the function of the pituitary gland. Here, the authors present a case of a posterior clinoid process enchondroma in a patient with Maffucci syndrome. The tumor was resected via an interdural pituitary transposition fashion. Four months postoperatively, the patient’s oculomotor function had recovered to normal and the function of the pituitary gland was preserved intact.The video can be found here: https://youtu.be/EYgVwVZuC4g.

The transcavernous approach (TcA) is an extension of the pterional approach that widens access to the central and lateral skull base regions. Through working between the nerves and vascular structures within the cavernous sinus, the TcA enables enhanced exposure of areas and structures including but not limited to the retrosellar area, Meckel's cave, and the basilar trunk. When the basilar apex and retrosellar regions are targeted, the TcA offers a valuable solution to the problem of the restricted space between the neurovascular structures of the central skull base through opening and widening the 2 major triangles of the cavernous sinus roof: the clinoidal and oculomotor triangles. Mastery of this approach requires careful review of the anatomy and much time spent in the cadaver lab. Although many quantitative studies and illustrative papers exist on the technical nuances of the TcA to the basilar apex region, the TcA is still difficult to understand, learn, and undertake. This cadaveric surgical simulation attempts to facilitate this objective. Of note, we have demonstrated and discussed the specific variant of the TcA that aims to reach the basilar apex area, and this video does not include the full TcA that also involves complete exposure of the lateral aspect of the cavernous sinus and the Meckel's cave.

Purpose Cone-beam computed tomography (CBCT) is widely used for 3-dimensional assessments of cranio-maxillofacial relationships, especially in patients undergoing orthognathic surgery. We have introduced, for reference in CBCT cephalometry, an anatomical mid-sagittal plane (MSP) identified by the nasion, the midpoint between the posterior clinoid processes of the sella turcica, and the basion. The MSP is an updated version of the median plane previously used at our institution for 2D posterior-anterior cephalometry. This study was conducted to test the accuracy of the CBCT measures compared to those obtained using standard posterior-anterior cephalometry. Materials and methods Two operators measured the inter-zygomatic distance on 15 CBCT scans using the MSP as a reference plane, and the CBCT measurements were compared with measurements made on patients' posterior-anterior cephalograms. The statistical analysis evaluated the absolute and percentage differences between the 3D and 2D measurements. Results As demonstrated by the absolute mean difference (roughly 1 mm) and the percentage difference (less than 3%), the MSP showed good accuracy on CBCT compared to the 2D plane, especially for measurements of the left side. However, the CBCT measurements showed a high standard deviation, indicating major variability and low precision. Conclusion The anatomical MSP can be used as a reliable reference plane for transverse measurements in 3D cephalometry in cases of symmetrical or asymmetrical malocclusion. In patients who suffer from distortions of the skull base, the identification of landmarks might be difficult and the MSP could be unreliable. Becoming familiar with the relevant software could reduce errors and improve reliability.

Background In this video abstract, we present a one burr-hole craniotomy for a modified presigmoid approach developed in Helsinki Neurosurgery to access the space extended to both middle and posterior fossa. Thus, indications for this approach are lesions that extend to both middle and posterior fossa, petroclival tumors, basilar tip aneurysms located extremely low below the posterior clinoid process, trunk basilar aneurysms, and bypass procedures from the P2 segment of the posterior cerebral artery. The procedure is composed by three stages: a temporal and presigmoid craniotomy, a partial petromastoidectomy, and the dura opening with section of the superior petrosal sinus (SPS) and the tentorium. Even though some risks related to the opening of the mastoid cells or cut of the SPS may exist, benefits of this optimized craniotomy are higher compared with the complications. Case description The patient with a giant petroclival meningioma is placed in park bench position and spinal drainage is inserted. Skin incision starts in front of the ear curve going to 1 inch behind the mastoid line. Strong retraction with hooks keeps a clean space for the craniotomy. Hemostatic Raney clips are placed at the superior border of the skin flap. A burr-hole is made at the most cranial part of the temporal bone. After the detachment of the dura with long flexible blunt dissectors, the craniotomy is performed to expose the sigmoid sinus, the SPS and the dura of the inferior temporal lobe, and the floor of the middle fossa. Aiming to access the posterior fossa by a presigmoid route, a partial petromastoidectomy is performed preserving the semicircular canals. Few drill holes are made for tack-up sutures. Once we properly reach the dura of the middle and posterior fossa, dura of the temporal lobe and later, the presigmoid dura are opened joining at the level of the SPS. The SPS, which is running over the petrous bone between the posterior and the middle fossa, is coagulated, ligated, and cut. After SPS is sectioned, the tentorium is cut anterior to the drainage of vein of Labbe and posterior to the deep tentorial insertion of the fourth nerve. Finally, special care should be taken to seal the opened mastoid cells with muscle and glue, and for the hermetic dura closure using pericranium or temporal muscle aponeurosis. Conclusion The described one burr-hole craniotomy may represent the more efficient approach for the management of the deep and hardly accessible lesions extended to both middle and posterior fossa. Videolink http://surgicalneurologyint.com/videogallery/presigmoid-approach-craniotomy-lt.

Purpose: Assessment of sphenoid sinus (SS), posterior clinoid process (PCP), and dorsum sellae (DS) pneumatisation is significant when planning surgical approaches both to intra- and extrasellar pathologies. The authors analysed pneumatisation of the SS, with particular attention paid to pneumatisation of the PCP and DS. Material and methods: The study was based on 100 computed tomography angiography examinations. SS, PCP, and DS pneumatisation grades were assessed using the classification system proposed by Hardy. The analyses were conducted in sagittal planes: midline plane (MP), sagittal posterior clinoid plane right (SPCP-R), and sagittal posterior clinoid plane left (SPCP-L). The occurrence of the highest pneumatisation grade (IVB according to Hardy), which encompasses DS and PCP, prompted the authors to conduct a further analysis in the coronal plane. In this way, seven DS and PCP pneumatisation symmetry types were identified. Results: In the MP and SPCP-R, the most frequent pneumatisation grade was grade III (41% and 38%, respectively). In the SPCP-L, grade IVA prevailed (41%). Grade IVB was found in 12% of the SPCP-R images, 10% of the SPCP-L images, and in 12% of the MP images. Consistent pneumatisation grades in all analysed planes were found for 64% of cases. This was usually grade III noted in 28% of cases. Conclusions: SS pneumatisation is characterised by considerable individual variability. There are a number of SS pneumatisation classification systems, but the system proposed by Hardy is the most useful for assessment of DS and PCP pneumatisation. Grade III of SS pneumatisation is the most common. Pneumatisation encompassing DS and PCP was found in 10-12% of cases.

Objective To explore the techniques of microsurgical treatment for posterior cerebral circulation aneurysms via keyhole approaches and assess its feasibility. Methods A total of 27 patients with 28 posterior cerebral circulation aneurysms were treated surgically by keyhole approaches; 24 patients presented with subarachnoid hemorrhage and 3 with headache. Of these 27 patients, 15 patients were treated via the supraorbital keyhole approach, 6 via the retrosigmoid keyhole approach, 3 via the subtemporal keyhole approach, 2 via median suboccipital approach, and 1 via the pterional keyhole approach. Results Of the 28 posterior cerebral circulation aneurysms, 24 aneurysms were clipped and 4 trapped; 23 aneurysms clipped completely, and 1 had residual aneurysm. Glasgow Outcome Scores at discharge revealed 25 patients had a good recovery; 1 patient was slightly disabled, and 1 patient was severely disabled. Of 15 patients treated via the supraorbital keyhole approach, to make a wider operative space, drilling of anterior clinoid process (2 patients) and posterior clinoid process (3 patients) was performed; posterior communicating artery was cut off (1 patient). For 3 patients with multiple aneurysms, complete occlusion was achieved via the same approach at one-stage. Conclusions Individualized keyhole approaches for posterior cerebral circulation artery aneurysms are safe and effective. The anterior clinoid process or posterior clinoid process could be drilled to offer a wide operative space for clipping. The use of multiple working windows is very helpful for controlling the parent artery and clipping the aneurysm.

Background: An extremely rare occurrence of the pituitary gland duplication inspired us to examine in detail the accompanying craniovertebral congenital anomalies in a patient involved. Materials and methods: T1-wighted magnetic resonance imaging (MRI) was performed, as well as the multislice computerised tomography (MSCT) and MSCT angiography in our patient, as well as in a control group of 10 healthy subjects. Results: In a 20-year-old male a double pituitary gland was identified, as well as hypothalamic enlargement, tuberomamillary fusion and hamartoma. In addition, the patient also showed a duplicated hypophyseal fossa and posterior clinoid processes, notch of the upper sphenoid, prominent inner relief of the skull, inverse shape of the foramen magnum, third occipital condyle, partial aplasia of the anterior and posterior arches of the atlas with a left arcuate foramen, duplication of the odontoid process and the C2 body, and fusion of the C2–C4 and T12–L1 vertebrae. The MSCT angiography presented a segmental dilatation of both vertebral arteries and the A2 segment of the anterior cerebral artery, as well as a duplication of the basilar artery. Conclusions: This patient is unique due to complex craniovertebral congenital anomalies associated with a duplication of the pituitary gland.

Introduction The sphenoid bone lies in the base of the skull between the frontal, temporal and occipital bones. Certain parts of the sphenoid bone are connected to each other by ligaments, such as caroticoclinoid ligament and interclinoid ligament which occasionally ossify and result in the formation of foramen. Methods This study was performed on 40 specimens i.e. 30 dried skulls and 10 sphenoid bones, obtained from the Department of Anatomy, SRMS IMS, Bareilly. In all skulls and sphenoids the anterior, middle and posterior clinoid processes were examined to reveal their relationship and the incidence of clinoid foramina and ossification of ligaments around pituitary fossa were noted. Results The incidence of anterior clinoid foramen is more as compared to posterior clinoid foramen. The ossification of caroticoclinoid ligament is more common than interclinoid ligament. The incidence of presence of anterior clinoid foramen on right and left side is same. Posterior clinoid foramen is present in one sphenoid bone only out of 40 bones. Discussion The knowledge of anatomy of ossified interclinoid ligament and caroticoclinoid ligament in sphenoid bone around pituitary fossa is important from diagnostic, surgical (especially surgeries involving removal of anterior clinoid process) and clinical point of view and should be evaluated by neurosurgeons before proceeding to skull based surgery. The presence of an ossified CCL ligament is likely to cause compression and straightening of the internal carotid artery thus giving rise to vascular complications.

Background: The sixth cranial nerve (CN VI) — or the abducens nerve — in humans supplies only the lateral rectus muscle. Due to its topographic conditions, including angulations and fixation points along its course from the brainstem to the lateral rectus muscle, the CN VI is vulnerable to injury. Every case of CN VI palsy requires precise diagnostics, which is facilitated by an understanding of the anatomy. The present article’s aims include a detailed study of the intracranial course of the CN VI, determination of occurrence of its particular anatomical variations, as well as presentation of some essential anatomical conditions which may conduce to CN VI palsy. Special emphasis was put on the correlation between craniometric measurements and a particular variation of the CN VI, which complements the data that can be found in literature. Materials and methods: Twenty randomly selected specimens of cadaveric heads fixed in a 10% formalin solution were studied. The study used 40 specimens of the CN VI in order to examine its course variations within the section between the pontomedullary sulcus and the superior orbital fissure. Results: Detailed analysis of the CN VI topography and anatomy in its intracranial course revealed 3 anatomical variations of the nerve in the studied specimens. Variation I, found in 70% of cases, covers those cases in which the CN VI was found to be a single trunk. Those cases in which there was a branching of the CN VI exclusively inside the cavernous sinus were classified as variation II, occurring in 20% of cases. Cases of duplication of the CN VI were classified as variation III, found in 10% of the specimens. In 75% of cases of CN VI duplication one of the nerve trunks ran upwards from the petrosphenoidal ligament, outside Dorello’s canal. Conclusions: The CN VI throughout its intracranial course usually runs as a single trunk, however, common variations include also branching of the nerve in the cavernous sinus or duplication. Topographic relations of the CN VI with adjacent structures account for the risk of injuries which may be caused to the nerve as a result of a disease or surgical procedures.

We report a case of an osteochondroma in the posterior clinoid process that occurred in a 43-year-old man with trochlear nerve palsy. Although the potential preoperative diagnoses based on computed tomography and magnetic resonance imaging included other intracranial tumors such as calcified meningioma, thallium-201 single-photon emission computed tomography effectively differentiated osteochondroma from those possibilities. Via an orbitozygomatic approach, a subtotal resection was achieved with a good relief of symptoms. Twenty-two cases of solitary osteochondromas in the skull base have been reported that have demonstrated little risk of recurrence or malignant transformation. However, surgery for skull base osteochondromas does carry a significant risk with a reported mortality > 10%. Although some previous reports advocate complete resection as the only curative method for skull base osteochondromas, the risks of total resection should be weighed against the chance for recurrence; our review of the literature demonstrated a relatively high mortality and an extremely low incidence of recurrence.

BACKGROUND The management of basilar apex (BX) aneurysms remains problematic. OBJECTIVE We quantified the surgical exposure of the BX through the opticocarotid window (OCW) and the carotid-oculomotor window (COW), before and after mobilization of the internal carotid artery and division of the posterior communicating artery (PCoA). METHODS Eleven silicone-injected cadaveric heads were dissected bilaterally. The surgical dissection was divided into 4 major steps: (1) supraorbital modified orbitozygomatic craniotomy, (2) mobilization of the internal carotid artery after drilling out the anterior clinoid process intradurally and cutting the distal dural ring, (3) drilling out the posterior clinoid process and dorsum sellae, and (4) dividing the PCoA from the posterior third portion of the vessel. A frameless navigation system was used to quantify the surgical exposure area of the BX through the OCW and COW. RESULTS The total surgical area increased significantly from steps 1 to 4 (P < .001) in both OCW and COW groups. Overall, there was a larger total surgical area obtained in the COW compared with the OCW (P = .010). ICA mobilization increased the surgical area for temporary (P < .001) and permanent (P < .003) clip application in both windows. The division of PCoA significantly increased the overall surgical area for permanent clip application (P < .003). Compared with the OCW, the COW had a significantly increased change in the area for permanent clip application in the low-lying group (P = .03). CONCLUSION When approaching the BX via the pterion route, the appropriate surgical step and window should be selected according to characteristics of the PCoA and height of the BX.

Purpose The aim of this study is to provide a new and comprehensive anatomic study of the posterior clinoid process (PCP) as well as data for PCP location to guide the surgeons in endoscopic surgery. Materials and methods Computed tomography angiography images of 120 PCPs and structures around them in adults were reviewed. The measurement was on coronal, sagittal, and axial planes after multiplanar reconstruction. The length, width, and thickness were accessed for the best understanding of the feature of PCP. The distance from the base of the PCP and the middle lowest point of the sellar floor was measured to find the position of the PCP during the transphenoid approach. Result PCP varies in width and thickness in different portions of it and is closely related to the internal carotid artery and posterior communicating artery, which makes it an important landmark during surgery. Conclusion The shape of PCP is various, and the analysis of its relationship to the important structures around it is of great value. In addition, the preoperative radiological evaluation plays a major role in patients considered for endoscopic sinus surgery. Detailed preoperative analysis of the anatomy of the sphenoid sinus and its boundaries is crucial in facilitating entry to the pituitary fossa and reducing intraoperative complications.

We describe a new and freely available 3D interactive model of the intracranial internal carotid artery (ICA) and the skull base that also allows to display and compare its main segment classifications. High-resolution 3D human angiography (isometric voxel’s size 0.36 mm) and Computed Tomography angiography images were exported to Virtual Reality Modeling Language (VRML) format for processing in a 3D software platform and embedding in a 3D Portable Document Format (PDF) document that can be freely downloaded at http://diposit.ub.edu/dspace/handle/2445/112442 and runs under Acrobat Reader on Mac and Windows computers and Windows 10 tablets. The 3D–PDF allows for visualisation and interaction through JavaScript-based functions (including zoom, rotation, selective visualization and transparentation of structures or a predefined sequence view of the main segment classifications if desired). The ICA and its main branches and loops, the Gasserian ganglion, the petrolingual ligament and the proximal and distal dural rings within the skull base environment (anterior and posterior clinoid processes, silla turcica, ethmoid and sphenoid bones, orbital fossae) may be visualized from different perspectives. This interactive 3D–PDF provides virtual views of the ICA and becomes an innovative tool to improve the understanding of the neuroanatomy of the ICA and surrounding structures.

Purpose The current study investigated the incidence, morphology and morphometry of the ossified ligaments expanding between petrous bone and posterior clinoid processes and in between the anterior, middle and posterior clinoid processes. Side symmetry, gender dimorphism and age influence were also studied. Materials and Methods A total of 123 adult Greek dry skulls were observed. Results A caroticoclinoid bar (CCB) was found in 60.2%. Partial CCBs appeared more commonly (36.6%) than complete (23.6%). The caroticoclinoid foramen (CCF) was symmetrical on both sides and genders. An anterior interclinoid, a posterior petroclinoid and a partial posterior interclinoid bar appeared in 19.5%, 6.5% and 2.4%, respectively. Osseous spurs posterolateral to the posterior clinoid process were present in 5.7%. Conclusion The study highlights important morphometric details about osseous bars of the sella region and the related CCF in Greek skulls. Notable differences in the incidence of these bars in Greek individuals compared with findings from other populations highlight the growing awareness of ethnic differences in skull base landmarks. Variations and surgically oriented measurements provided by this study may benefit clinicians involved in the treatment of the middle cranial fossa pathology, enriching understanding of the complicated regional anatomy. Preoperative sellar area mapping is essential, by using computed tomography images, since modification of the surgical approach may be required in cases of severe ossification.

The transsphenoidal approach has been utilized in intrasellar craniopharyngioma surgeries. However, the advent of endoscopic extended transsphenoidal approach (EETSA) has expanded its indication to suprasellar craniopharyngiomas. We compared the indication and limitations of EETSA to those of unilateral basal interhemispheric approach (UBIHA), which presents similar indications for surgery. We analyzed 30 patients with tumors located below the foramen of Monro and the lateral boundary extending slightly beyond the internal carotid artery (UBIHA: N = 18; EETSA: N = 12). Postoperative magnetic resonance imaging (MRI) revealed gross total resection in 10 patients in the EETSA group (83.3%) and 12 in the UBIHA group (66.7%). Postoperative MRI in the EETSA group revealed residual tumor at the cavernous sinus in one patient, at the prepontine in one; in the UBIHA group, residual tumors were located in the retrochiasmatic area in two patients, infundibulum-hypothalamus in one, on the stalk in one, and in the intrasellar region in two. No intergroup differences were observed in the preservation of pituitary function and postoperative improvement of visual function. The extent of resection was better with EETSA than with UBIHA. EETSA is considered the first-line therapy because the distance between the optic chiasm and the superior border of the pituitary is large; the lateral extension does not go beyond the internal carotid artery; and the tumor does not extend inferiorly beyond the posterior clinoid process. However, in patients showing poorly developed sphenoid sinuses or pituitary stalks anterior to the tumor, surgery is difficult regardless of the selection criteria., Neurologia medico-chirurgica, 54(12), pp.974-982; 2014

An understanding of the microsurgical anatomy of posterior clinoid process (PCP) is extremely important to where the removal of PCP is required to access the interpeduncular and prepontine cisterns and upper basilar artery region to manage the aneurysms located in this region. In the present article, we describe our experience with a technique that is safe and provides ample space to look into these regions. The key to safe drilling is that the drilling of the posterior clinoid needs to be performed in a “touch and back” manner (rather than clockwise or counterclockwise motion) to break the cortex.

Object This study was designed to determine if the “keyhole concept,” proposed by Perneczky's group, can be verified quantitatively. Methods Fourteen (3 bilateral and 8 unilateral) sides of embalmed latex-injected cadaveric heads were dissected via 3 sequential craniotomy approaches: supraorbital keyhole, frontotemporal pterional, and supraorbital. Three-dimensional cartesian coordinates were recorded using a stereotactic localizer. The orthocenter of the ipsilateral anterior clinoid process, the posterior clinoid process, and the contralateral anterior clinoid process are expressed as a center point (the apex). Seven vectors project from the apex to their corresponding target points in a radiating manner on the parasellar skull base. Each 2 neighboring vectors border what could be considered a triangle, and the total area of the 7 triangles sharing the same apex was geometrically expressed as the area of exposure in the parasellar region. Results Values are expressed as the mean ± SD (mm2). The total area of exposure was as follows: supraorbital keyhole 1733.1 ± 336.0, pterional 1699.3 ± 361.9, and supraorbital 1691.4 ± 342.4. The area of exposure on the contralateral side was as follows: supraorbital keyhole 602.2 ± 194.7, pterional 595.2 ± 228.0, and supraorbital 553.3 ± 227.2. The supraorbital keyhole skull flap was 2.0 cm2, and the skull flap size ratio was 1:5:6.5 (supraorbital keyhole/pterional/supraorbital). Conclusions The area of exposure of the parasellar region through the smaller supraorbital keyhole approach is as adequate as the larger pterional and supraorbital approaches. The keyhole concept can be verified quantitatively as follows: 1) a wide area of exposure on the skull base can be obtained through a small keyhole skull opening, and 2) the side opposite the opening can also be visualized.

WOS: 000403546200006 PubMed: 27766486 In the present study, we investigated the types and ratio of posterior clinoid process (PCP) pneumatization in paranasal sinus multidetector computed tomography (MDCT). Paranasal MDCT images of 541 subjects (227 males, 314 females), between 15 and 65 years old, were included into the study. Pneumatization of anterior clinoid process and pneumatization types (I, II, or III) were evaluated in the males and females. PCP pneumatization was detected in 20.7 % of the males and 11.5 % of the females. Right, left, and bilateral PCP pneumatizations were detected in 7.9, 5.7, and 7.0 % of the males and 2.9, 3.2, and 4.5 % of the females, respectively. PCP pneumatization of the males is significantly higher than the females. The most detected type of pneumatization was type I (61.2 %) for all groups. In right, left, and bilateral pneumatizations separately, type I pneumatization was the most detected pneumatization type with the ratio of the 70.4, 65.2, and 50.0 %, respectively. In males, type I (61.7 %), and similarly in females, type I (60.6 %) pneumatization were detected more. Type II and type III pneumatizations were detected in decreasing order in both groups. In younger subjects, pneumatization of posterior clinoid process was found as higher, and in older subjects, PCP pneumatization was found as lower. Sclerosis process related to the aging may be responsible for the lower pneumatization ratios in older subjects. Structure of the surrounding regions of PCP is important for surgical procedures related to cavernous sinus, basilar apex aneurysms, and mass lesions. Preoperative radiological examinations are useful for operative planning. Any anomalies to PCP can cause unnecessary injury to the neurovascular complex structure around the cavernous sinus or postclinoidectomy CSF fistulas. Posterior clinoidectomies should be avoided in patients with type III PCP pneumatization to prevent CSF fistulas.

Clinical and radiological features or characteristics of posterior clinoid process (PCP) meningiomas have rarely been described because of their extreme scarcity and terminological confusion. Therefore, the strategies in the surgical intervention for PCP meningiomas have not been well established. Moreover, the presence of deep and critical neuroanatomical structures and relatively high morbidity, which can be difficult to predict preoperatively, make their surgical excision more challenging. We report two surgical cases of PCP meningioma and discuss the appropriate assessment of preoperative features and surgical strategies with review of the literature. Our study suggests that PCP meningioma may be characterized by the anterior displacement of internal carotid artery, and infero-laterally shifted posterior communicating arteries, and homonymous hemianopsia, a distinctive clinical feature. One of the key issues in PCP meningioma surgery is preservation of the optic nerve. Unlocking the optic nerve by anterior clinoidectomy and dissection, the falciform ligament is the important step to preserve vision for larger tumors. Complication with the perforators is also hazardous of these challenging surgeries than anterior clinoid meningiomas for their specific neuroanatomical structures and might not be feasible to avoid even with additional techniques and critical monitoring. A combination and multi-staged-surgical approach can be options of tailor-made surgical strategy in cases with tumor adhesion to the perforators.

The purpose of this study is to investigate and evaluate the exposure and maneuverability of this areas provided by an endoscope-assisted supraorbital approach and to compare that to a microscopic supraorbital approach. We exposed microscopically the optico-carotid and the infrachiasmatic windows after a supraorbital craniotomy executed using an eyebrow incision. We then proceeded to explore the retroinfundibular area using these two windows either using the microscope alone or using the endoscope–microscope combination where the microscope was used to (1) guide instrument and endoscope insertion into the surgical field, and (2) explore (with microscopic 3-d vision) subsegments of the endoscopic field of view. We compared the exposure and surgical maneuverability of the approach utilizing the microscopic mode alone with the endoscope-assisted mode. We evaluated the exposure and the surgical maneuverability of key anatomical structures of the retroinfundibular area. The structures evaluated included the diaphragma sellae, the dorsum sellae, the posterior clinoid process, the pituitary stalk, the mammillary bodies, the tuber cinereum, the oculomotor nerves, the basal pons, the upper trunk of the basilar artery, the superior cerebellar arteries, the posterior cerebral arteries, the posterior communicating arteries and the basilar bifurcation. The exposure and the surgical maneuverability were significantly higher in the endoscope-assisted mode (P < 0.0001). Based on our study, the endoscope-assisted supraorbital retroinfundibular approach is associated with larger exposure and maneuverability than the pure microscopic approach. Further clinical information is required to verify the results of this study.

Isolated oculomotor nerve palsy occasionally occurs in patients with cavernous sinus invasion with or without pituitary apoplexy. We describe two cases of pituitary apoplexy without cavernous sinus invasion presenting with isolated oculomotor palsy. In both cases, computed tomography (CT) showed erosion of the right posterior clinoid process. Magnetic resonance imaging (MRI) depicted pituitary adenoma with apoplexy protruding latero-posteriorly to the right cavernous sinus. The medio-posterior wall of the cavernous sinus was markedly displaced latero-posteriorly by the tumor, and there was no evidence of cavernous sinus invasion. Oculomotor palsy may be caused first by unilateral erosion of the posterior clinoid process, resulting in latero-posterior protrusion of the adenoma. Hemorrhage may result in sudden kinking of the oculomotor nerve at the entrance of the oculomotor trigone.

Interclinoid ligaments which connect the anterior and posterior clinoid processes comprise a group of intrinsic ligaments of sphenoid bone. The complete sella turcica bridge corresponds to the complete ossification of the interclinoid ligaments. 112 dry human adult skull bones were studied for presence of ossified interclinoid ligaments. Nine skulls (8.04%) showed sella turcica bridges, out of which six were unilateral and three bilateral. The average length of the bridge was 11.67mm. The average width and thickness at the anterior clinoid process was 6.33mm and 4.33mm ; atthe middle of the bridge 3.08mm and 2.66mm; and atthe posterior clinoid process, 4.91 mm and 3.66mm, respectively. Anomalies of sellar region are not very rare and may pose difficulties in interpretation of Magnetic Resonance Imaging or Computed Tomographyforthe radiologist. Thesefindings would also guide the neurosurgeons in planning neurosurgical procedures involving the sellar region.