Removal Of Anterior Clinoid Process Research Articles

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.

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.

Anatomical Justification of Extradural Resection of the Anterior Clinoid Process.

Objective The study aimed to provide neuroanatomical justification of the extradural resection of the anterior clinoid process (ACP). Material and Method Using a cross-sectional study design, 47 cranial computed tomography (CT) scans were examined. There were 31 (65.96%) females aged 28 to 79 years. The measured dimensions were ACP length and width, and optic strut (OS) width. Index (i acp ) was measured as the ratio of ACP width to ACP length. The ACP volume and working operating field (WOF) volume were measured using Syngo.via Siemens program. The percentage expansion of WOF after removal of the ACP was estimated on 5 fixed human cadaver heads with the exoscope VITOM 3D. The possibilities of the combined approach were demonstrated in a clinical case. Results The mean ACP lengths were 11.31 ± 2.76 and 11.54 ± 2.86 mm, on the right and left, respectively. The mean ACP widths were 7.70 ± 1.66 and 7.64 ± 1.67 mm, on the right and left, respectively. Average i acp was 0.67 (minimum 0.45; maximum 0.90). The width of the OS varied in the range from 1.37 to 4.75 mm. The average volume of right ACP was 0.71 ± 0.16 cm 3 , right WOF was 3.26 ± 0.74 cm 3 , left ACP was 0.71 ± 0.15 cm 3 , left and WOF was 3.20 ± 0.76 cm 3 . Removal of the right ACP expanded the right WOF by 22.21 ± 3.88%, and left ACP by 22.78 ± 5.50%. There was an approximately 25% increase in the WOF from the cadaveric dissections. Taking into account the variability of the ACP and OS, we proposed our own surgical classification of complicated (i acp ≥ 0.67; medium OS 2.5 mm ≤ 4.0 mm; wide OS ≥ 4.0 mm; ACP with pneumatization) and uncomplicated ACP (i acp 0.45 ≤ 0.67 mm; i acp ≤ 0.45; narrow OS ≤ 2.5 mm; ACP without pneumatization). Using this classification, we developed an algorithm for ACP dissection and removal. This was piloted in a clinical case of microsurgical clipping of a left internal carotid artery-posterior communicating artery aneurysm via the left minipterional approach. Conclusion Extradural removal of ACP expands the WOF by approximately 25%, it helps neurosurgeons to improve proximal vascular control and avoid complications, and expands the range of indications for neurosurgical interventions in the skull base area.

Extensive and Advanced Craniofacial Dysplasia

A 35-year-old Syrian patient presented to our department complaining of 7-year history of asymptomatic hard swelling in right side of the frontotemporal and naso-orbito-ethmoidal region, reaching the contralateral side (Panels A and B). Patient stated that from 1 year back his visual acuity has been decreased compared with the previous 6 years. Computed tomography (CT) with contrast (Panels C–F) showed diffuse bony expansion involving the frontal bones bilaterally. Bone expansion was more on the right side extending into the vertical plates as well as the horizontal plates forming the roof extending to involve the cribriform plates and into the crista galli extending posteriorly to involve the sphenoid bone including the body, greater and lesser wings of the sphenoid bone as well as the clinoid processes ends extending to the roots of the pterygoid plates. Multidisciplinary decision team meeting was done, with neurosurgery, anesthesiology, and maxillofacial surgery to decide the treatment. Under the general anesthesia the patient underwent remodeling and recontouring of the facial and cranial bones through bilateral occipital approach. Using the unilateral fronto-temporal extradural approach and retracting the dura and reaching the base of the skull the anterior clinoidectomy for optic nerve decompression was performed. Right clinoid process surgery reshaped the base of the skull releasing the bone which compressed the right orbital nerve. Affected bone which involved the frontotemporal area was removed and reconstruction was performed with cranioplasty fixed with osteosynthesis to the adjacent and healthy bony structures. The resected bone was submitted to Hamad general hospital histopathology laboratory which reported following fixation and decalcification irregular shaped trabeculae of immature woven bone scattered in a loosely hypercellular stroma histopathological diagnosed as fibrous dysplasia (Panels G and H: H&E staining). After 5 days of medical management as inpatient, the patient was discharge with close follow up. Patient was followed up in a weekly basis with a normal postoperative status. 5 months after the surgery (Panel I, photography on postoperative day 120 showed remanent dystopia but generalized acceptable craniofacial projection), patient stated to have improvement in his visual acuity compared to his base line as well as craniofacial projection with a remanent vertical dystopia. Panels J and K compare preoperative CT (Panel J) where anterior clinoid process involved with the pathology is noted and postoperative CT (Panel K) which reveals removal of anterior clinoid process for orbital nerve decompression.

Surgical Management of Tumors Involving Meckel's Cave and Cavernous Sinus: Role of an Extended Middle Fossa and Lateral Sphenoidectomy Approach.

To study the indications and outcomes of lateral sphenoidectomy as part of a combined skull base approach in the treatment of tumors involving Meckel's cave (MC) and cavernous sinus (CS). Retrospective patient series. Tertiary referral center. Twenty-two consecutive patients (mean age: 45 yr, range: 16-76) who underwent transzygomatic, extended middle fossa approaches for tumors involving MC and CS. Surgical access to MC and CS was achieved via extended middle fossa, trans-clinoid approach. Lateral sphenoidectomy was defined as drill-out of the greater sphenoid wing lateral to foramen rotundum and ovale, decompression of superior orbital fissure, and removal of anterior clinoid process. Reconstruction was achieved using combination of autologous and synthetic materials. Eleven patients (50%) received adjuvant radiation. Tumor pathologies included meningioma (16 patients), epidermoid cyst (2), trigeminal schwannoma (2), invasive pituitary adenoma (1), and chondrosarcoma (1). Mean (range) preoperative tumor size was 4.0 cm (1.3-9). Mean (range) length of follow-up was 4 years (range 0.1-10). Overall tumor control and gross total resection were achieved in 95 and 23% of patients, respectively. Lateral sphenoidectomy was performed in 16 patients (73%) for enhanced surgical access and/or tumor extension to the infratemporal fossa (6 patients). Postoperatively, cranial nerve deficits occurred in 12 (55%) patients (V-9 patients; III, IV, or VI-4; VII-2; VIII-2). Cerebrospinal fluid leak and hydrocephalus occurred in two and four patients, respectively. In combination with middle fossa-based approaches to tumors involving MC and CS, lateral sphenoidectomy may play a viable role in tumor access and control.

Study of ossified clinoid ligaments in sphenoid bone of north Indian skulls

IntroductionThe 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. MethodsThis 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. ResultsThe 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. DiscussionThe 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.

Prevention of Visual Function in the Operation of Paraclinoid Aneurysms

Objective: Paraclinoid aneurysms are aneurysms of the internal carotid artery (ICA) around the anterior clinoid process (ACP), including carotid cave and IC-ophthalmic aneurysms. To treat those aneurysms by direct clipping, it would need the removal of ACP and opening of the external dural ring, which might harm the optic nerves and their function. Then, the endovascular surgery is sometimes recommended especially in the case with carotid cave aneurysm. However, the recent paper reported that the complication and recurrence rates of endovascular surgery are relatively high. This direct surgery is useful, but difficult for the young and middle surgeon because those aneurysms are rare and dangerous lesion. We reviewed our recent cases and assessed the pitfall for prevention of visual function. Method: A total of eight cases with paraclinoid aneurysms treated in our hospital since December 2012 are assessed. Result: One case was treated by endovascular and seven were treated by direct surgery. Five cases were completely clipped with the removal of ACP, however, one of five showed visual impairment after surgery. In this case with right carotid cave aneurysm, ICG-VA during the surgery had shown disappearance of aneurysm and patency of ICA and perforators, however, her right vision gradually worsened 2days after surgery. Right ophthalmic artery was patent on her MRI/MRA and 3D-CTA, and her right optic disc was normal. Operative video was assessed, and showed that her right optic was contracted to ICA during the dissection of aneurysm and ophthalmic artery because of incomplete cutting of falcifalm fold, suggesting that this physiological compression to the optic nerve might cause the visual function. Conclusion: For prevention of visual function in the surgery of paraclinoid aneurysms, the complete opening of dural ring, the removal of optic strut, and the appropriate cutting of falcifalm fold are important as well as the removal of ACP. We emphasize that those techniques are essential as well as the removal of ACP to mobilize the optic nerve and perform the safe surgery.

Importance of Epidural Microsurgical Working in Surgery for Medial Sphenoid Wing Meningiomas

Objective: Epidural microsurgical working (EMW) technique including the removal of anterior clinoid process, opening the optic canal, and coagulation of the fine feeding arteries could decompress the optic nerve and decrease subdural hemorrhage before the tumor manipulation. It seems to be the good technique for medial sphenoid wing meningiomas (SWM), which are usually fed by internal carotid artery (ICA), recurrent meningeal artery, middle meningeal artery, and inferolateral trunk. Here, we have explored whether EMW influence the functional recovery of the optic nerve and tumor radicality in patients with medial SWM, by comparing the surgical results between groups with and without EMW. Methods: Total 65 patients with medial SWM affected optic nerve were analyzed. The consecutive series of patients were divided into two groups; without EMW in 14 and with EMW in 51 patients. Prognostic factors were statistically assessed using univariate analysis between two groups. Results: In the group without EMW, 9 of 14 patients (64.3%) had visual disturbance preoperatively and only 1 (of 9, 11.1%) improved. On the other hand, 30 of 51 (58.8%) had visual disturbance preoperatively and 25 of 31 (83.3%) postoperatively showed improvement in the group with EMW (p < 0.01). Epidural ACP resection increased the tumor radicality by exposing the tumor base around the optic canal and ICA. Conclusions: Introduction of EMW dramatically improved the patient's visual function and tumor radicality.

Importance of Epidural Microsurgical Working in Surgery for Medial Sphenoid Wing Meningiomas

Objective: Epidural microsurgical working (EMW), including removal of anterior clinoid process (ACP), opening the optic canal, and coagulation of the fine feeders from carotid and recurrent meningeal arteries, could decompress the optic nerve and decrease subdural hemorrhage before the tumor manipulation. A purpose of this study is to analyze the functional recovery of the optic nerve and tumor radicality, compared in two groups with or without EMW to verify the effectiveness of EMW on the surgical results in medial sphenoid wing meningiomas.

Measurement of Critical Structures around Paraclinoidal Area : A Cadaveric Morphometric Study.

ObjectiveAlthough removal of the anterior clinoid process (ACP) is essential surgical technique, studies about quantitative measurements of the space broadening by the anterior clinoidectomy are rare. The purposes of this study are to investigate the dimension of the ACP, to quantify the improved exposure of the parasellar space after extradural anterior clinoidectomy and to measure the correlation of each structure around the paraclinoidal area.MethodsEleven formalin-fixed Korean adult cadaveric heads were used and frontotemporal craniotomies were done bilaterally. The length of C6 segment of the internal carotid artery on its lateral and medial side and optic nerve length were checked before and after anterior clinoidectomy. The basal width and height of the ACP were measured. The relationships among the paraclinoidal structures were assessed. The origin and projection of the ophthalmic artery (OA) were investigated.ResultsThe mean values of intradural basal width and height of the ACP were 10.82 mm and 7.61 mm respectively. The mean length of the C6 lateral and medial side increased 49%. The mean length of optic nerve increased 97%. At the parasellar area, the lengths from the optic strut to the falciform liament, distal dural ring, origin of OA were 6.69 mm, 9.36 mm and 5.99 mm, respectively. The distance between CN III and IV was 11.06 mm.ConclusionWith the removal of ACP, exposure of the C6 segments and optic nerve can expand 49% and 97%, respectively. This technique should be among a surgeon's essential skills for treating lesions around the parasellar area.

Microsurgical Landmarks for Safe Removal of Anterior Clinoid Process

The microsurgical and radiological anatomy of the clinoid process were studied to give surgeons more details about the anterior clinoid process and its relations to the vascular and nervous neighbourhood during intradural and extradural clinoidectomy, thus making the operative procedures safer. Seven formalin-fixed (14 sides) and two fresh cadavers (four sides) were studied to reveal the surgical anatomy of the anterior clinoid process and related landmarks during intradural and extradural drilling techniques of clinoid process. Furthermore, aeration of the anterior clinoid process was investigated in 100 paranasal tomography (200 sides) scans. Careful drilling of the anterior clinoid process is mandatory to avoid damage to the extremely important adjacent structures. The anterior clinoid process must not be removed in one piece. Clinoid folds and the frontotemporal fold should be exposed adequately. The falciform ligament must be cut to visualize the optic nerve and ophthalmic artery clearly. Preoperative radiological assessment of clinoid process variations should be done. In computerized tomography scans, pneumatization of the right anterior clinoid process was found in 12%, of the left anterior clinoid process in 7% and bilaterally pneumatization was present in 9%. Removal of the ACP is one of the most critical procedures to the successful and safe management of ophthalmic segment aneurysms and tumors located in the paraclinoid region and cavernous sinus. Special attention should be paid to the anatomic landmarks indicating the relationship between the anterior clinoid process and adjacent structures. Beside that, pneumatization of the anterior clinoid process should be evaluated preoperatively with computed tomography to avoid complications such as rhinorrhea and pneumocephalus.

Removal of anterior clinoid process for basilar tip aneurysm: Clinical and cadaveric analysis

The difculty in the operation for basilar tip aneurysm is the restrictionin surgical working space. To resolve this problem, aggressive skull base surgery has been reported, but these techniques are not prevalent. Pterional and subtemporal approaches are commonly used for basilar tip aneurysms. In an attempt to increase the surgical working space during the pterional approach, the anterior clinoid process and the roof of the optic nerve were removed extradurally to increase the mobilization of the intracranial internal carotid artery and optic nerve. The effects of removing the anterior clinoid process and microanatomy in the perioptic area were analyzed by cadaveric procedures in 10 cases (20 sides). With this procedure, the internal carotid artery can be retractedmedially with a spatula 6.1±0.8mm (mean±SD). The length and the area of dural fold in the bone defect region in the optic canal roof are 2.1mm and 13.6mm2 . In 10 clinical cases, this procedure allowed enough space to approach the basilar tip aneurysm without disturbing the internal carotid artery blood flow. The clinical outcome was satisfactory.

Factors influencing surgical outcome of the basilar bifurcation aneurysms.

To contribute to a better understanding of the clipping operation of the basilar bifurcation aneurysm, factors influencing the surgical outcome were analyzed in 80 patients. The age range of the patients was 34-74 years, with a mean age of 58.4 years, and there were 61 females and 19 males. Fifty-eight patients had been admitted because of subarachnoid hemorrhage and a basilar bifurcation aneurysm ruptured in 49 patients. The size of the aneurysms ranged between 2 and 19 mm with a mean of 7.9 +/- 3.9 mm. The height of the aneurysm neck was between -10 and 17 mm measured above a biclinoid line with a mean of 4.8 +/- 5.2 mm. Pterional approach was utilized in 72 patients and subtemporal in eight. Optic unroofing or removal of anterior clinoid process were performed in five patients, zygomatic osteotomy in 10, posterior clinoid removal in seven, and anterior petrosectomy in one. A bridging vein of the temporal lobe was divided in 16 patients. A short and/or hypoplastic posterior communicating artery was divided in 11 patients. Temporary occlusion of the basilar trunk was performed in 39 patients. Surgical outcome (Glasgow Outcome Scale) at 3 months after the operation was good recovery in 42 (53%), moderately disabled in 23 (29%), severely disabled in five (6%), vegetative survival in two (3%), and dead in eight (10%). The aneurysm size proved to be a single preoperative factor which significantly correlated with the surgical outcome (Spearman's rank correlation test, p < 0.0001). Division of the posterior communicating artery significantly contributed to the surgical outcome as an intraoperative factor (Mann-Whitney's U test, p = 0.01). The larger the aneurysm size was, the more often the posterior communicating artery was sectioned. Extreme care should be taken to obliterate a large aneurysm with a clip graft especially when division of the posterior communicating artery is required.