Lateral Opticocarotid Recess Research Articles

Endoscopic endonasal pituitary sacrifice for select tumors with retrochiasmatic and/or retrosellar extension: surgical anatomy, operative technique, and case series.

Tumors located in the retrochiasmatic region with extension to the third ventricle might be difficult to access when the pituitary-chiasmatic corridor is narrow. Similarly, tumor extension into the interpeduncular and retrosellar space poses a major surgical challenge. Pituitary transposition techniques have been developed to gain additional access. However, when preoperative pituitary function is already impaired or the risk of postoperative panhypopituitarism (PH) is considered to be particularly high, removal of the pituitary gland (PG) might be the preferred option to increase the working corridor. The aim of this study was to describe the relevant surgical anatomy, operative steps, and clinical experience with the endoscopic endonasal pituitary sacrifice (EEPS) and transsellar approach. This study comprised anatomical dissections to highlight the relevant surgical steps and a retrospective case series reporting clinical characteristics, indications, and outcomes of patients who underwent EEPS. The surgical technique is as follows: both lateral opticocarotid recesses are exposed laterally, the limbus sphenoidale superiorly, and the sellar floor inferiorly. After opening the dura, the PG is detached circumferentially and mobilized off the medial walls of the cavernous sinuses. The descending branches of the superior hypophyseal artery are coagulated, and the stalk is transected. After removal of the PG, drilling of the dorsum sellae and bilateral posterior clinoidectomies are performed to gain access to the hypothalamic region, interpeduncular, and prepontine cisterns. From 2018 to 2023, 11 patients underwent EEPS. The cohort comprised mostly tuberoinfundibular craniopharyngiomas (n = 8, 73%). Seven (64%) patients had partial or complete anterior PG dysfunction preoperatively, while 4 (36%) had preoperative diabetes insipidus. Because of the specific tumor configuration, the chance of preserving endocrine function was estimated to be very low in patients with intact function. The main reasons for pituitary sacrifice were impaired visibility and surgical accessibility to the retrochiasmatic and retrosellar spaces. Gross-total tumor resection was achieved in 10 (91%) patients and near-total resection in 1 (9%) patient. Two (18%) patients experienced a postoperative CSF leak, requiring surgical revision. When preoperative pituitary function is already impaired or the risk for postoperative PH is considered particularly high, the EEPS and transsellar approach appears to be a feasible surgical option to improve visibility and accessibility to the retrochiasmatic hypothalamic and retrosellar spaces, thus increasing tumor resectability.

Endoscopic transorbital decompression for traumatic superior orbital fissure syndrome: from cadaveric study to clinical application.

The endoscopic endonasal approach (EEA) is a minimally invasive and promising modality for treating traumatic superior orbital fissure (SOF) syndrome (tSOFS). Recently, the endoscopic transorbital approach (ETOA) has been considered an alternative method for reaching the anterolateral skull base. This study accessed the practicality of using the ETOA to treat SOF decompression using both cadaveric dissection and clinical application. Bilateral anatomic dissections were performed on four adult cadaveric heads using the ETOA and EEA to address SOF decompression. The ETOA procedure for SOF decompression is described, and the extent of SOF decompression was compared between the ETOA and EEA. The clinical feasibility of the ETOA for treating SOF decompression was performed in two patients diagnosed with tSOFS. ETOA allowed for decompression over the lateral aspect of the SOF, from the meningo-orbital band superolaterally to the maxillary strut inferomedially. By contrast, the EEA allowed for decompression over the medial aspect of the SOF, from the lateral opticocarotid recess superiorly to the maxillary strut inferiorly. In both patients treated using the ETOA and SOF decompression, the severity of ophthalmoplegia got obvious improvement. Based on the cadaveric findings, ETOA provided a feasible access pathway for SOF decompression with reliable outcomes, and our patients confirmed the clinical efficacy of the ETOA for managing tSOFS.

Defining the limits of the anterior wall of the cavernous sinus through an endoscopic view: Cadaveric anatomical study.

The anterior wall of the cavernous sinus (CS) represents an important landmark for endoscopic surgery that although mentioned before, no precise anatomical boundaries have been described. We describe the anatomical landmarks that delimit the anterior wall of the CS, emphasizing its importance as a reference for accessing the CS through endoscopic approaches. Six adult cadaveric heads fixed with formaldehyde and injected with colored silicone were studied. In all the heads, an endonasal endoscopic approach to the sellar and parasellar regions was performed and the anatomy of the anterior wall of the CS was studied. Four consistent anatomical landmarks that mark the limits of the anterior wall of the CS were found in all the specimens: anterosuperiorly, the lateral opticocarotid recess; posterosuperiorly, the medial opticocarotid recess; anteroinferiorly, the inferior part of the maxillary strut; and posteroinferiorly, the superolateral angle of the clival recess. It is of paramount importance to recognize the anatomical landmarks that define the limits of the anterior wall of the CS to achieve a safe access to this so complex region.

Endoscopic Orientation of Juxta-pituitary Carotid in Transsphenoidal Approaches: Critical Considerations for Clinical Applications.

Introduction In sphenoid sinuses with ill-defined carotid bony landmarks, accidental injury of the internal carotid artery (ICA) remains one of the most challenging complications, which is particularly reported in the endoscopic endonasal transsphenoidal approaches (EETAs). Objectives To describe an anatomical model for the endoscopic orientation of the juxta-pituitary segment of the ICA in relation to the lateral opticocarotid recess (OCR) as a nearby bony landmark. Methods Dissection was performed progressively, simulating the EETA, in twenty fresh adult cadavers. After reducing the posterior and lateral walls of the sphenoid sinuses, various measurements were taken from both lateral OCRs to "contact points" on the juxta-pituitary segment of the ICA and lateral margins of the pituitary gland. Results The current results have enabled us to divide the region between the lateral OCRs into 3 compartments: 2 lateral parasellar compartments contain juxta-pituitary segments of the ICA with a mean width of 8 mm and a narrow range from 7 mm to 10 mm; and a central intercarotid sellar compartment represents the safe region for bone drilling, showing widely variable widths ranging from 9 mm to 20mm. In all specimens, the variation in the width of the intercarotid compartment correlated with the distance between both lateral OCRs. Conclusion The present study improves surgeon awareness of the variations in the course of the ICA through the EETA along sphenoid sinuses with ill-defined bony landmarks. An appreciation of the measurements taken in the present study can help in operative training, and can also provide a base for future studies to confirm ICA courses associated with a higher risk of injury.

Normal Anatomy of the Pituitary Gland

This study describes the anatomy of the pituitary gland during endoscopic endonasal surgery. Before surgery, the extent of pneumatization of the sphenoid sinus and bony septations in the sphenoid sinus should be evaluated using computed tomography. After wide sphenoidotomy, several important surgical landmarks, including the medial and lateral opticocarotid recesses and carotid protuberances, can be observed in the sphenoid sinus. The pituitary gland is composed of two components: the adenohypophysis and neurohypophysis. Two small vessels, the superior and inferior hypophyseal arteries, supply the pituitary gland. Several vital structures exist inside the cavernous sinus, including the internal carotid artery and cranial nerves. Understanding the surgical anatomy is mandatory for treating lesions around the pituitary fossa via the endoscopic endonasal approach.

Comparison of the Endoscopic Endonasal Approach with the Endoscopic Supraorbital Keyhole Approach to the Tuberculum Sellae Region: A Quantitatively Cadaveric Study.

The endoscopic endonasal approach (EEA) and the endoscopic supraorbital keyhole approach (eSKA) provide minimally invasive access to tuberculum sellae (TS) tumors. Evaluation of the operating maneuverability is helpful for approach selection. Herein, we compared the two approaches and aimed to provide quantitative anatomic data for surgical decision-making in the management of TS lesions. Fifteen dissections were performed on five silicone-injected cadaveric heads. The EEA and eSKA (both right and left) were performed on each head. Surgical freedom and working angles in the axial and sagittal planes were calculated using the stereotactic navigation system in the selected six targets: the midpoint of the leading edge of the sphenoid sinus (leSS), the midpoint of the edge of the dorsum sellae (eDS), the ipsilateral medial opticocarotid recess (imOCR), the contralateral medial opticocarotid recess (cmOCR), the ipsilateral lateral opticocarotid recess (ilOCR), and the contralateral lateral opticocarotid recess (clOCR). The surgical freedom at the ilOCR and the axial working angles at the leSS, ilOCR, and imOCR (imOCR with excessive manipulation of the optic apparatus) were greater in the eSKA. The EEA provided greater surgical freedom and/or working angles at most targets than eSKA (the surgical freedom at the imOCR, cmOCR, clOCR, and eDS; the axial working angles at the cmOCR and clOCR; and the sagittal working angles at the leSS, imOCR, cmOCR, clOCR, and eDS). The EEA provides greater surgical freedom and working angles for paramedian lesions, whereas the eSKA provides better surgical maneuverability for lesions with lateral extension.

Endoscopic endonasal optic nerve sheath decompression (EONSD) for idiopathic intracranial hypertension: Technical details and meta-analysis

BackgroundThe neurosurgical management of idiopathic intracranial hypertension (IIH) remains controversial. Although shunting and newer endovascular stenting techniques are part of the neurosurgical armamentarium to treat medically refractory IIH symptoms, optic nerve sheath fenestration has traditionally been performed by ophthalmologists. ObjectiveWe present a detailed cadaveric dissection that simulates the endoscopic endonasal optic nerve sheath decompression (EONSD) technique along with the literature review. MethodsEONSD was performed in four freshly injected cadaveric specimens. Additionally, a systematic review from different electronic databases has been done. ResultsBilateral EONSD was performed in all specimens without significant technical difficulties. Based on our experience, there is no need to expose the periorbita or orbital apex. The primary anatomic landmarks were the optic canal, the lateral opticocarotid recess, the tuberculum, the limbus, and the clinoid segment of the internal carotid artery. Based on the systematic review, 68 patients (77.9% female) underwent EONSD, with a mean age of 33.4 ± 6.9 years in adult patients. Follow-up ranged from 3 to 58 months across different studies. The pooled meta-analysis showed headache, papilledema, and visual disturbance improvement in 78% [95%CI 0.65–0.90], 72% [95%CI 0.61–0.83], and 88% [95%CI 0.80–0.96] of cases who underwent EONSD, respectively. The subgroup analysis showed there was no statistically significant difference between unilateral and bilateral EONSD in terms of different measured outcomes. ConclusionEONSD is a feasible surgical procedure that may obviate the need for shunting in patients with IIH. Although clinical studies showed that EONSD is a safe and effective technique, further studies are required to establish the preferences of either unilateral or bilateral approaches.

The Anatomical Landmarks in Endonasal Endoscopic Optic Nerve Decompression Surgery: An Anatomical Study

Aim
 Optic nerve decompression can be applied for many pathologies that affect the optic canal and the optic nerve. Optic nerve decompression via endonasal endoscopic method is very popular in nowadays with the developments in endoscopic surgery. 
 Material and Methods
 In this study, the lateral opticocarotid recess (LOCR) and the medial opticocarotid recess (MOCR) which are important anatomical landmarks used during transsphenoidal approach to the opticocarotid region were evaluated. The relations of these anatomical landmarks with each other and with important surrounding landmarks such as optic nerve were examined.
 Results
 MOCR were observed in all cadavers on the right side and in 4 of 5 cadavers on the left side. The superior border of the LOCR was measured as 4.85±1.94 mm in average on the right side and 3.93±1.11 mm in average on the left side. The inferior border of the LOCR was measured as 4.72±2.11 mm in average on the right side and 3.98±1.67 mm in average on the left side. The linear distance between the LOCR and the MOCR was measured as 3.11±1.41 mm in average on the right side and 2.46±1.36 mm in average on the left side.
 Conclusion
 It is necessary for a safe surgery to reveal the anatomical landmarks and to know the detailed anatomy of this region during optic nerve decompression.

Lateral optico-carotid recess as an anatomical landmark for optimal endoscopic optic nerve decompression

Lateral optico-carotid recess as an anatomical landmark for optimal endoscopic optic nerve decompression

Endoscopic Orientation of Juxta-Pituitary Carotid in Transsphenoidal Approaches: Critical Considerations for Clinical Applications.

Accidental injury of the internal carotid artery (ICA) remains one of the most challenging complications reported in the endoscopic endonasal transsphenoidal approaches (EETA) particularly, in sphenoid sinuses with ill-defined carotid bony landmarks. The purpose of this study was to describe an anatomical model for the endoscopic orientation of juxta-pituitary segment of ICA in relation to the lateral optico-carotid recess (OCR) as a nearby bony landmark. Cadaveric dissection was conducted progressively in twenty fresh adult cadavers simulating the EETA. After reducing posterior and lateral walls of sphenoid sinuses, various measurements were taken from both lateral OCRs to "contact points" of the juxta-pituitary segment of ICA and lateral margins of the pituitary gland. Current results have enabled us to divide the region between lateral OCRs into three compartments. Two lateral parasellar compartments contain juxta-pituitary segments of ICA showing a mean width of 8mm; with a narrow range of 7-10mm; and a central inter-carotid sellar compartment represents the safe region for bone drilling showing widely variable widths ranging between 9 to 20mm. In all specimens; variation in the width of the inter-carotid compartment correlated with the distance between both lateral OCRs. This study improves surgeons' awareness of the ICA course variations in the EETA through sphenoid sinuses with ill-defined bony landmarks. An appreciation of the measurements gathered from this study can help in operative training, and can also provide a base for future studies to confirm ICA courses associated with higher risk of injury.

Anatomical assessment of the endoscopic endonasal approach for the treatment of paraclinoid aneurysms.

Endoscopic endonasal approaches (EEAs) are increasingly being incorporated into the neurosurgeon's armamentarium for treatment of various pathologies, including paraclinoid aneurysms. However, few anatomical assessments have been performed on the use of EEA for this purpose. The aim of the present study was to provide a comprehensive anatomical assessment of the EEA for the treatment of paraclinoid aneurysms. Five cadaveric heads underwent an endonasal transplanum-transtuberculum approach to expose the paraclinoid area. The feasibility of obtaining proximal and distal internal carotid artery (ICA) control as well as the topographic location of the origin of the ophthalmic artery (OphA) relative to dural landmarks were assessed. Limitations of the EEA in exposing the supraclinoid ICA were also recorded to identify favorable paraclinoid ICA aneurysm projections for EEA. The extracavernous paraclival and clinoidal ICAs were favorable segments for establishing proximal control. Clipping the extracavernous ICA risked injury to the trigeminal and abducens nerves, whereas clipping the clinoidal segment put the oculomotor nerve at risk. The OphA origin was found within 4 mm of the medial opticocarotid point on a line connecting the midtubercular recess point to the medial vertex of the lateral opticocarotid recess. An average 7.2-mm length of the supraclinoid ICA could be safely clipped for distal control. Assessments showed that small superiorly or medially projecting aneurysms were favorable candidates for clipping via EEA. When used for paraclinoid aneurysms, the EEA carries certain risks to adjacent neurovascular structures during proximal control, dural opening, and distal control. While some authors have promoted this approach as feasible, this work demonstrates that it has significant limitations and may only be appropriate in highly selected cases that are not amenable to coiling or clipping. Further clinical experience with this approach helps to delineate its risks and benefits.

Reaching the sellar region endonasally — One or both nostrils? A pilot study in body donors

IntroductionThe purpose of this study was to evaluate the effect of posterior septectomy size on surgical exposure and surgical freedom during the endoscopic transsphenoidal approach to the sellar and parasellar region. MethodsA mononostril and binostril approach to the sellar region was performed on 4 formalin-fixed cadaveric heads. Predefined anatomical structures were identified. Additionally, a millimeter gauge was introduced into the surgical site and the extent of dorsal septectomy was analyzed for both approaches. Surgical freedom was defined as the distance between the ipsilateral and contralateral limit of opening of the sphenoid sinus. ResultsThe mean extent of dorsal septectomy was 15.7±5.7mm using a binostril approach to achieve adequate visualization of all relevant anatomical structures.Superior results were obtained via binostril technique with respect to the ability to identify the contralateral internal carotid artery or opticocarotid recessus. No such advantage was found for all other landmarks. Surgical freedom between the ipsilateral and contralateral limit of exposure of the sphenoid sinus was measured with 15±0.8mm in the mononostril and 19.2±0.9mm in the binostril group. ConclusionsThe surgical exposure increased significantly with progressively larger posterior septectomy in binostril approaches until a 20-mm posterior septectomy. Bilateral lateral opticocarotid recesses were accessible with a mean of 15mm for posterior septectomy. In the mononostril group no dorsal septectomy was necessary. Thus, the nasal mucosa is more preserved by this technique. However, the lateral exposure is partially limited and the use of angled endoscopes is recommended when adopting a mononostril approach to the sellar region.

How to Expose the Entire Sella Floor With Minimal Manipulation During an Endoscopic Endonasal Transsphenoidal Approach.

A method of opening the posterior ethmoid air cells with minimal manipulation is important for adequate exposure of the sella floor and minimal nasal morbidity. Between February 2009 and August 2016, 373 patients with skull-base tumors underwent surgery via endoscopic endonasal transsphenoidal approach with the 2-nostrils/4-hands technique using this technique. A linear incision was made laterally toward one-third of the superior turbinate along the superior border of the sphenoid sinus ostium. Then, the superior turbinate mucosa was fully elevated to expose the superior turbinate bone. This allowed us to expose the entire sella floor and adjacent vital structures, such as the optic and carotid protuberances, medial and lateral opticocarotid recesses, planum sphenoidale, and clivus, leaving the superior turbinate and surrounding nasal mucosa intact. This technique could improve the manipulability of surgical instruments and increase the accessibility of the parasellar region. This approach better conserves the nasal mucosa, posterior ethmoid, and superior and supreme turbinates and more efficiently exposes skull-base tumors than traditional methods with pathology of the anterior cranial fossa and parasellar region. This technique also prevents the drilling procedure from damaging the surrounding nasal mucosa, including the exfoliated and laterally preserved posterior sphenoid mucosa.

An Automated Methodology for Assessing Anatomy-Specific Instrument Motion during Endoscopic Endonasal Skull Base Surgery.

Objectives Describe instrument motion during live endoscopic skull base surgery (ESBS) and evaluate kinematics within anatomic regions. Design Case series. Setting Tertiary academic center. Participants A single skull base surgeon performed six anterior skull base approaches to the pituitary. Main Outcomes and Measures Time-stamped instrument coordinates were recorded using an optical tracking system. Kinematics (i.e., mean cumulative instrument travel, velocity, acceleration, and angular velocity) was calculated by anatomic region including nasal vestibule, anterior and posterior ethmoid, sphenoid, and lateral opticocarotid recess (lOCR) regions. Results We observed mean (standard deviation, SD) velocities of 6.14 cm/s (1.55) in the nasal vestibule versus 1.65 cm/s (0.34) near the lOCR. Mean (SD) acceleration was 7,480 cm/s 2 (5790) in the vestibule versus 928 cm/s 2 (662) near the lOCR. Mean (SD) angular velocity was 17.2 degrees/s (8.31) in the vestibule and 5.37 degrees/s (1.09) near the lOCR. We observed a decreasing trend in the geometric mean velocity, acceleration, and angular velocity when approaching the pituitary ( p < 0.001). Conclusion Using a novel method for analyzing instrument motion during live ESBS, we observed a decreasing trend in kinematics with proximity to the pituitary. Additional characterization of surgical instrument motion is paramount for optimizing patient safety and training.

Minimizing Septectomy for Endoscopic Transsphenoidal Approaches to the Sellar and Suprasellar Regions: A Cadaveric Morphometric Study.

The purpose of this study was to evaluate the effect of posterior septectomy size on surgical exposure and surgical freedom during the endoscopic transsphenoidal approach to the sella and parasellar region. Dissections were performed on 10 embalmed cadaver heads. Dissections started with wide bilateral sphenoidotomies, lateralization of middle turbinates, and a 5-mm posterior septectomy. The posterior septectomy was increased in 5-mm increments to a maximum of 35 mm, followed by bilateral middle turbinectomies. Surgical exposure was defined as the distance between the ipsilateral and contralateral limit of exposure as allowed by the posterior septum along a midsphenoid horizontal meridian. Surgical freedom was defined as the angle between the ipsilateral and contralateral limit. The mean baseline width of the posterior sphenoid sinus was 29.4 ± 3.7 mm. With a 5-mm septectomy, the mean width of surgical exposure was 21.1 ± 2.8 mm. The surgical exposure increased significantly with progressively larger posterior septectomy until a 20-mm posterior septectomy, after which no further increase in surgical exposure or freedom was obtained. Bilateral lateral opticocarotid recesses were accessible with a 15-mm posterior septectomy. The addition of bilateral middle turbinectomies did not significantly increase lateral exposure within the sphenoid sinus compared with middle turbinate lateralization.

Endoscopic Endonasal Approach to the Optic Canal

Increasing use of endoscopic endonasal surgery for suprasellar lesions with extension into the optic canal (OC) has necessitated a better endonasal description of the OC. To identify the osseous OC transcranially and then investigate its anatomic relationship to the key endonasal intrasphenoidal landmarks. We also aimed to determine and describe the technical nuances for safely opening the falciform ligament and intracanalicular dura (surrounding the optic nerve [ON]) endonasally. Ten fresh human head silicon-injected specimens underwent an endoscopic transtuberculum/transplanum approach followed by 2-piece orbitozygomatic craniotomy to allow identification of 20 OCs. After completing up to 270° of endonasal bony decompression of the OC, a dural incision started at the sella and continued superiorly across the superior intercavernous sinus. Subsequently the dural opening was extended anterolaterally across the dura of the prechiasmatic sulcus, limbus sphenoidale, and planum. Endonasally, the length of the osseous OC was approximately 6 mm and equivalent to the length of the lateral opticocarotid recess, as measured anteroposteriorly. The ophthalmic artery arose from the supraclinoidal carotid artery at approximately 2.5 mm from the medial osseous OC entrance. Transcranial correlation of the endonasal dural incision confirmed medial detachment of the falciform ligament and exposure of the preforaminal ON. The lateral opticocarotid recess allows distinction of the preforaminal ON, roofed by the falciform ligament from the intracanalicular segment in the osseous OC. This facilitates the preoperative surgical strategy regarding the extent of OC decompression and dural opening. Extensive endonasal decompression of the OC and division of the falciform ligament is feasible.

Endoscopic endonasal cranial base surgery simulation using an artificial cranial base model created by selective laser sintering.

Mastery of the expanded endoscopic endonasal approach (EEA) requires anatomical knowledge and surgical skills; the learning curve for this technique is steep. To a great degree, these skills can be gained by cadaveric dissections; however, ethical, religious, and legal considerations may interfere with this paradigm in different regions of the world. We assessed an artificial cranial base model for the surgical simulation of EEA and compared its usefulness with that of cadaveric specimens. The model is made of both polyamide nylon and glass beads using a selective laser sintering (SLS) technique to reflect CT-DICOM data of the patient's head. It features several artificial cranial base structures such as the dura mater, venous sinuses, cavernous sinuses, internal carotid arteries, and cranial nerves. Under endoscopic view, the model was dissected through the nostrils using a high-speed drill and other endonasal surgical instruments. Anatomical structures around and inside the sphenoid sinus were accurately reconstructed in the model, and several important surgical landmarks, including the medial and lateral optico-carotid recesses and vidian canals, were observed. The bone was removed with a high-speed drill until it was eggshell thin and the dura mater was preserved, a technique very similar to that applied in patients during endonasal cranial base approaches. The model allowed simulation of almost all sagittal and coronal plane EEA modules. SLS modeling is a useful tool for acquiring the anatomical knowledge and surgical expertise for performing EEA while avoiding the ethical, religious, and infection-related problems inherent with use of cadaveric specimens.

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

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

The Medial Opticocarotid Recess

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

Endoscopic endonasal approach for a tuberculum sellae meningioma.

The authors present the technical and anatomical nuances needed to perform an endoscopic endonasal removal of a tuberculum sellae meningioma. The patient is a 47-year-old female with headaches and an incidental finding of a small tuberculum sellae meningioma with no vascular encasement, no optic canal invasion, but mild inferior to superior compression of the cisternal segment of the left optic nerve. Neuroophthalmology assessment revealed no visual defects. Treatment options included clinical observation with imaging follow-up studies, radiosurgery, and resection. The patient elected to undergo surgical removal and an endonasal endoscopic approach was the preferred surgical option. Preoperative radiological studies showed the presence of an osseous ring between the left middle and anterior clinoids, the so-called carotico-clinoidal ring. The surgical implications of this finding and its management are illustrated. The surgical anatomy of the suprasellar region is reviewed, including concepts such as the chiasmatic sulcus and limbus sphenoidale, medial and lateral optico-carotid recesses, and the paraclinoidal and supraclinoidal segments of the internal carotid artery. Emphasis is made in the importance of exposing the distal dural ring of the internal carotid artery and the precanalicular segment of the optic nerve for adequate intradural dissection. The endonasal route allows for early coagulation of the tumor meningeal supply and extensive resection of dural attachments, and importantly, provides an inferior to superior access to the infrachiasmatic region that facilitates complete tumor removal without any manipulation of the optic nerve. The lateral limit of dural removal is formed by the distal dural ring, which is gently coagulated after the tumor is resected. A 45° scope is used to inspect for any residual tumor, in particular at the entrance of the optic nerve into the optic canal and at the most anterior margin of the exposure (limbus sphenoidale). The steps for reconstruction are detailed and include intradural placement of dural substitute and extradural placement of the nasoseptal flap. The nuances for proper harvesting, positioning, and reinforcement of the flap are described. No lumbar drain was used. The patient had an uneventful recovery with no CSF leak or any other complications. Imaging follow-up at 6 months showed complete removal of the tumor. The patient had no sinonasal or neurological symptoms, and olfaction was fully preserved. The video can be found here: http://youtu.be/kkuV-yyEHMg .