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The use of the maxillary artery (MA) as a donor has increasingly become an alternative method for cerebral revascularization. Localization difficulties emerge due to rich infratemporal anatomical variations and the complicated relationships of the MA with neuromuscular structures. We propose an alternative localization method via the interforaminal route along the middle fossa floor. Five silicone-injected adult cadaver heads (10 sides) were dissected. Safe and effective localization of the MA was evaluated. The MA displayed anatomical variations in relation to the lateral pterygoid muscle (LPM) and the mandibular nerve branches. The proposed L-shaped perpendicular 2-step drilling technique revealed a long MA segment that allowed generous rotation to the intracranial area for an end-to-end anastomosis. The first step of drilling involved medial-to-lateral expansion of foramen ovale up to the lateral border of the superior head of the LPM. The second step of drilling extended at an angle approximately 90° to the initial path and reached anteriorly to the foramen rotundum. The MA was localized by gently retracting the upper head of the LPM medially in a posterior-to-anterior direction. Considering all anatomical variations, the L-shaped perpendicular 2-step drilling technique through the interforaminal space is an attainable method to release an adequate length of MA. The advantages of this technique include the early identification of precise landmarks for the areas to be drilled, preserving all mandibular nerve branches, the deep temporal arteries, and maintaining the continuity of the LPM. [ABSTRACT FROM AUTHOR]

We sought to assess the feasibility of endoscopic lateral and superior cerebellar keyhole approach for exposure of the anterior and middle incisural space and Meckel cave. The endoscopic lateral and superior cerebellar keyhole approach was performed in 6 cadaveric heads (12 sides) using 0- and 30-degree endoscopes, respectively. The anatomic structures for this approach to the anterior and middle incisural space and Meckel cave were observed. By grinding out the suprameatal tubercle and petrous apex and incising the tentorium, the anatomic structures in the anterior incisural space were visualized. The mean area exposed with a 0-degree endoscope in the anterior incisural space was 212.50 ± 6.04 mm2, significantly less than that exposed with a 30-degree endoscope (233.83 ± 8.72 mm2) (P < 0.05). The anatomic distance of the Meckel cave in the depth was the same between a 0-degree endoscope and a 30-degree endoscope; however, the distance in the width was 9.48 and 12.32 mm, respectively (P < 0.01). The area of petrous window grinded by a 30-degree endoscope was only increased by 5.83 mm2, compared with a 0-degree endoscope (P > 0.05). This approach provides access to the anterior and middle incisural space and Meckel cave, which is feasible to clearly expose the anatomic structures in those regions with minimal invasiveness. Additionally, better visualization and surgical space can be achieved under a 30-degree endoscope. [ABSTRACT FROM AUTHOR]

Background: The cavernous sinus (CS) is a highly vulnerable anatomical space, mainly due to the neurovascular structures that it contains; therefore, a detailed knowledge of its anatomy is mandatory for surgical unlocking. In this study, we compared the anatomy of this region from different endoscopic and microsurgical operative corridors, further focusing on the corresponding anatomic landmarks encountered along these routes. Furthermore, we tried to define the safe entry zones to this venous space from these three different operative corridors, and to provide indications regarding the optimal approach according to the lesion's location. Methods: Five embalmed and injected adult cadaveric specimens (10 sides) separately underwent dissection and exposure of the CS via superior eyelid endoscopic transorbital (SETOA), extended endoscopic endonasal transsphenoidal-transethmoidal (EEEA), and microsurgical transcranial fronto-temporo-orbito-zygomatic (FTOZ) approaches. The anatomical landmarks and the content of this venous space were described and compared from these surgical perspectives. Results: The oculomotor triangle can be clearly exposed only by the FTOZ approach. Unlike EEEA, for the exposure of the clinoid triangle content, the anterior clinoid process removal is required for FTOZ and SETOA. The supra- and infratrochlear as well as the anteromedial and anterolateral triangles can be exposed by all three corridors. The most recently introduced SETOA allowed for the exposure of the entire lateral wall of the CS without entering its neurovascular structures and part of the posterior wall; furthermore, thanks to its anteroposterior trajectory, it allowed for the disclosure of the posterior ascending segment of the cavernous ICA with the related sympathetic plexus through the Mullan's triangle, in a minimally invasive fashion. Through the anterolateral triangle, the transorbital corridor allowed us to expose the lateral 180 degrees of the Vidian nerve and artery in the homonymous canal, the anterolateral aspect of the lacerum segment of the ICA at the transition zone from the petrous horizontal to the ascending posterior cavernous segment, surrounded by the carotid sympathetic plexus, and the medial Meckel's cave. Conclusions: Different regions of the cavernous sinus are better exposed by different surgical corridors. The relationship of the tumor with cranial nerves in the lateral wall guides the selection of the approach to cavernous sinus lesions. The transorbital endoscopic approach can be considered to be a safe and minimally invasive complementary surgical corridor to the well-established transcranial and endoscopic endonasal routes for the exposure of selected lesions of the cavernous sinus. Nevertheless, peer knowledge of the anatomy and a surgical learning curve are required. [ABSTRACT FROM AUTHOR]

Purpose: The transpetrosal–transtentorial approach provides a practical and safe surgical corridor for the treatment of petroclival region lesions. Any inaccuracies while performing this surgical technique can result in catastrophic results; nevertheless, this can be prevented under the guidance of a detailed anatomical orientation. An "intertriangles line" was defined to preserve the internal auditory canal (IAC) and cochlea during extradural bone drilling. Methods: The anatomical study consisted of two groups: the cadaveric head and the skull group. A literature-based landmark and criteria list was created to examine the borders of the Kawase triangle/space and evaluate the anatomical structures that may be at risk during drilling for anterior petrosectomy. Results: A total of 20 cadaveric head sides and 30 dried skull sides were examined. The rhomboid area was divided into two triangles with a common the intertriangles line. In all dissections, the IAC was found to be localized posterior to the "intertriangle line". A minimum distance of 1 mm for the Internal Carotid artery and 2 mm for the IAC can serve as threshold values to be considered by the surgeon during drilling for petrosectomy. Conclusions: Kawase's area resembles a minefield, in which every step and manipulation should be considered. A minimal but effective resection of the cranial base is needed to increase safety and decrease morbidity during skull base surgery. Furthermore, this study investigated accessible and prominent landmarks to establish a feasible area of triangles and define the intertriangles line to guide the neurosurgeon under microscope and avoid IAC injury. [ABSTRACT FROM AUTHOR]

The middle fossa, cavernous sinus, and paraclival triangles consist of ten triangles. Their use in a surgical approach is vast; most are used as landmarks to access and identify other structures of surgical interest. Multiple labels, borders, and contents mentioned by different authors make understanding and reproduction challenging and confusing. This study aims to organize and clarify recent or most relevant publications and disclose our portrayal of the ten triangles using cadaveric dissection and simple and practical figures. Four middle fossa triangles, four cavernous sinus triangles, and two paraclival triangles were dissected and delineated in a cadaveric specimen. Drawings were simplified to eliminate confusion and evaluate the triangles effortlessly. Similarities and differences in triangle names, border limits, and contents are described in a precise form. The recognition of triangle landmarks allows for treating pathologies in a frequently distorted anatomy or challenging to access structure. That is why an accurate knowledge of the surgical anatomy should be mastered, and a safe approach should be accomplished. [ABSTRACT FROM AUTHOR]

The middle cranial fossa is one of the most complex regions in neurosurgery and otolaryngology—in fact, the practice of skull base surgery originated from the need to treat pathologies in this region. Additionally, great neurosurgeons of our present and past are remembered for their unique methods of treating diseases in the middle fossa. The following article reviews the surgical anatomy of the middle fossa. The review is divided into the anatomy of the bones, dura, vasculature, and nerves—in two parts. Emphasis is paid to their neurosurgical significance and applications in skull base surgery. Part I focuses on the bony and dural anatomy.

Surgical access to the middle fossa can be technically challenging. As neurosurgery evolves to minimally invasive approaches, the objective of this study is to demonstrate the extension of the Minipterional approach to access the middle fossa. We present a new surgical approach to the middle fossa for the treatment of secondary trigeminal neuralgia. Three cases are reported to illustrate the following techniques: a patient with petrotentorial meningioma and trigeminal neuralgia, a patient with an arachnoid cyst compressing the fifth nerve, and a patient with a middle cerebral artery aneurysm and a long history of TN (trigeminal neuralgia) refractory to medical and surgical treatments. All three experienced full symptom controls with no permanent neurological deficits. Therefore, the Minipterional technique might represent a feasible, effective, and safe option to treat refractory secondary TN. It also allows approaching these lesions when the posterior fossa approach is compromised by anatomical distortion and enables the simultaneous treatment of secondary trigeminal neuralgia and other lesions, such as aneurysms and meningiomas. [ABSTRACT FROM AUTHOR]

Background: The anatomy and surgical approach to the cavernous sinus and the middle fossa can constitute a considerable challenge, specially for young surgeons. Although their surgical explorations have gone through a popular phase in the past, to this date, they remain an uncomfortable subject for many neurosurgeons. The aim of this paper is to systematically review its anatomy and multiple corridors through a step-by-step dissection of the middle fossa triangles, providing a roadmap for surgeons. Methods: A step-by-step dissection of the cavernous sinus was performed in two fresh-frozen cadavers aiming to describe the anatomy of ten different middle fossa triangles, demonstrating the feasibility of the use of their spaces while surgically approaching this area. Results: The intradural opening of the roof of the cavernous sinus was obtained by dissection of clinoidal, carotid-oculomotor, supratrochlear, optic-carotideal, and oculomotor triangles, allowing an expanded superior view. On the counterpart, the extradural exploration of the lateral wall through the middle fossa floor peeling exposed the infratrochlear, anteromedial, and anterolateral triangles. The middle fossa floor itself was the door to approaching posterior fossa through anterior petrosectomy. The dissection of each individual triangle can be amplified exponentially with exploration of its adjacents, providing broader surgical corridors. Conclusion: The cavernous sinus still remains far from an "every man's land," but its systematic study based on direct approaches can ease the challenges of its surgical exploration, allowing surgeons to feel more comfortable with its navigation, with consequently benefit in the treatment of patients. [ABSTRACT FROM AUTHOR]

Background: The cavernous sinus (CS) is a highly vulnerable anatomical space, mainly due to the neurovascular structures that it contains; therefore, a detailed knowledge of its anatomy is mandatory for surgical unlocking. In this study, we compared the anatomy of this region from different endoscopic and microsurgical operative corridors, further focusing on the corresponding anatomic landmarks encountered along these routes. Furthermore, we tried to define the safe entry zones to this venous space from these three different operative corridors, and to provide indications regarding the optimal approach according to the lesion’s location. Methods: Five embalmed and injected adult cadaveric specimens (10 sides) separately underwent dissection and exposure of the CS via superior eyelid endoscopic transorbital (SETOA), extended endoscopic endonasal transsphenoidal-transethmoidal (EEEA), and microsurgical transcranial fronto-temporo-orbito-zygomatic (FTOZ) approaches. The anatomical landmarks and the content of this venous space were described and compared from these surgical perspectives. Results: The oculomotor triangle can be clearly exposed only by the FTOZ approach. Unlike EEEA, for the exposure of the clinoid triangle content, the anterior clinoid process removal is required for FTOZ and SETOA. The supra- and infratrochlear as well as the anteromedial and anterolateral triangles can be exposed by all three corridors. The most recently introduced SETOA allowed for the exposure of the entire lateral wall of the CS without entering its neurovascular structures and part of the posterior wall; furthermore, thanks to its anteroposterior trajectory, it allowed for the disclosure of the posterior ascending segment of the cavernous ICA with the related sympathetic plexus through the Mullan’s triangle, in a minimally invasive fashion. Through the anterolateral triangle, the transorbital corridor allowed us to expose the lateral 180 degrees of the Vidian nerve and artery in the homonymous canal, the anterolateral aspect of the lacerum segment of the ICA at the transition zone from the petrous horizontal to the ascending posterior cavernous segment, surrounded by the carotid sympathetic plexus, and the medial Meckel’s cave. Conclusions: Different regions of the cavernous sinus are better exposed by different surgical corridors. The relationship of the tumor with cranial nerves in the lateral wall guides the selection of the approach to cavernous sinus lesions. The transorbital endoscopic approach can be considered to be a safe and minimally invasive complementary surgical corridor to the well-established transcranial and endoscopic endonasal routes for the exposure of selected lesions of the cavernous sinus. Nevertheless, peer knowledge of the anatomy and a surgical learning curve are required.

The anterior petrosectomy, also known as the Kawase approach, and the retrosigmoid intradural suprameatal approach (RISA) have both been used to reduce the petrous apex and access the petroclival region. Our goal was to compare the volumes and 3-dimensional shapes of bony resection obtained through each approach while trying to resemble realistic surgical settings. Five cadaveric specimens totaling 10 sides were dissected and analyzed. In every specimen, 1 side was used for the Kawase approach while the opposite side was used for the RISA. Petrosectomy volumes were assessed by comparing preoperative and postoperative thin-sliced computed tomography scans. Petrosectomy volumes were significantly larger through the Kawase approach than through the RISA (0.82 ± 0.11 vs. 0.49 ± 0.07 cm3, P < 0.001). In addition, surgical maneuverability and freedom were greater in the Kawase operative variant. Lastly, the morphology of the bony window achieved through each approach was clearly different: trapezoid for the anterior petrosectomy versus elongated ellipsoid for the RISA. The Kawase approach invariably results in larger volumes of bony removal than the RISA operative variant, and the volume of petrosectomy that is spatially congruent is only partially identical. The Kawase corridor is best suited for middle fossa lesions that extend into the posterior fossa, while the RISA is suitable for pathologies mainly residing in the posterior fossa and extending into the Meckel cave. [ABSTRACT FROM AUTHOR]

Objectives  To analyze the relationship between preoperative and intraoperative auditory brain stem response (ABR) characteristics and hearing outcomes in patients with vestibular schwannomas (VS) undergoing hearing preservation (HP) surgery via a middle cranial fossa (MCF) approach. Design  Prospective study. Setting  Academic tertiary skull base referral center. Methods  Pre- and postoperative pure-tone average (PTA) and word recognition score (WRS) were examined. Intraoperative ABR wave III latency, wave V latency, and amplitude were recorded. HP was defined as postoperative WRS ≥50%. Participants  Adult patients with VS and WRS ≥50% who underwent MCF tumor resection between November 2017 and September 2019. Main Outcome Measures  Postoperative hearing outcomes. Results  Sixty patients were included. Mean tumor size was 9.2 mm (range, 3–17). HP rates were 56.7% for the cohort and 69.7% for tumors <10 mm. A complete loss of wave V was associated with an 82.9% increase in postoperative PTA (p  < 0.001) and 97.2% decrease in WRS (p  < 0.001), whereas a diminished wave V was correlated with 62.7% increase in PTA (p  < 0.001) and 55.7% decrease in WRS (p  = 0.006). A diminished or absent wave V, but not increased wave III/V latency or decreased wave V amplitude, was correlated with a decline in postoperative hearing class (r  = 0.735, p  < 0.001). Receiver-operating characteristic analysis demonstrated that a stable wave V has the highest accuracy in predicting HP (sensitivity of 82.6%, specificity of 84.8%). Conclusion  Of the examined preoperative and intraoperative ABR characteristics, a stable wave V intraoperatively was the strongest predictor of HP after MCF resection of VS. Level of Evidence  Level III. [ABSTRACT FROM AUTHOR]

Background: Facial nerve schwannomas can extend to the middle fossa or the cerebellopontine angle through the labyrinthine and cisternal segments of the facial nerve. The middle fossa approach (MFA) and its extensions provide a wide approach to deal with a large variety of lesions located in the middle and posterior cranial fossa junction. Methods: We describe the MFA along with its advantages and limitations to treat a facial nerve schwannoma involving the middle and posterior cranial fossa. Conclusions: The MFA is a well-established route to surgically deal with tumors located in and around the proximal four segments of the facial nerve. [ABSTRACT FROM AUTHOR]

Background: Arachnoid cysts are benign extra-cerebral congenital lesions that are thought to arise from the splitting of the arachnoid membrane. Although most arachnoid cysts remain static with advancing age, occasionally they can become symptomatic due to cyst enlargement or hemorrhage. Hemorrhage into the arachnoid cysts (intra-cystic hemorrhage) with or without associated subdural hematoma is of rare occurrence.Case Discussion: A 23-year-old male presented with a history of sudden onset severe headache while sleeping. The patient also noticed double vision, especially when looking towards the left side. Non-contrast computed tomography (NCCT) scan of the head showed left temporal pole hematoma with left Sylvian fissure bleed and bilateral fronto-temporoparietal (FTP) subacute SDH.Conclusion: Every patient with incidentally detected AC, especially in the middle cranial fossa, should be counseled regarding the risk of possible complications including hemorrhage and regular follow-up. [ABSTRACT FROM AUTHOR]

Introduction  As endovascular techniques evolve toward replacing open surgery, several clinical scenarios still require surgical revascularization. Characterizing this era are decreasing surgical volumes and lack of realistic training models. In an effort to develop lifelike simulation models, we developed a platform for surgical training on high-flow bypass in a fresh cadaver model. Our technique incorporated an extracorporeal circulating system that resembled clinical conditions and confirmed anastomosis efficacy by clinical parameters. Methods  On three fresh cadaveric heads, the subtemporal approach exposed the petrous internal carotid artery (ICA) (C2) as the donor vessel for an interposition radial artery graft. Using a continuous extracorporeal circulation system, the bypass model was tested in three fresh heads and verified using clinical technologies. Results  Successful C2 ICA to M2 anastomosis was completed in all three fresh heads, confirmed with qualitative and quantitative Doppler, and indocyanine green angiography. Antegrade distribution through graft and revascularized territory was documented on postoperative computed tomography (CT) scan with radiopaque silicone injected through the ipsilateral carotid. Conclusion  This study confirmed the feasibility of a totally intracranial high-flow bypass in a fresh cadaver model that achieved hemodynamic features aligned with those of normal middle cerebral artery flow in the clinical setting. [ABSTRACT FROM AUTHOR]

Introduction  The middle fossa (MF) approaches encompass a group of versatile surgical accesses to pathologies in the MF, internal auditory canal (IAC), and superomedial aspect of the posterior fossa. Although many descriptions of the MF approaches have been published, a practical surgical guide that allows an easy understanding for Skull Base trainees is needed. Methods  Three formalin-fixed, colored-injected specimens were dissected under microscopic magnification (six sides). A MF craniotomy followed by IAC drilling was performed on three sides, and anterior petrosectomy (AP) was performed in the remaining three sides. The anatomical dissection was documented in stepwise three-dimensional photographic images. Following dissection, representative case applications were reviewed. Results  The MF approach provides direct access to the MF structures and IAC. The AP provides excellent access to the superomedial aspect of the posterior fossa. Key common steps include: positioning and skin incision; scalp and muscle flaps; burr holes; craniotomy flap elevation; dural dissection along the petrous ridge; division of the middle meningeal artery; and exposure of the greater superficial petrosal nerve, tegmen tympani, and V3. Then, to approach the IAC: superior IAC drilling, and longitudinal dura opening. The area drilled in the AP approach forms a pentagon limited by the petrous internal carotid artery, cochlea, IAC, petrous ridge, and lateral border of V3. Conclusion  The MF approaches are challenging. Operatively oriented skull base dissections provide a crucial foundation for learning these techniques. We describe comprehensive step-by-step approaches intended to develop familiarity in the cadaver laboratory and facilitate understanding of their potential for skull base disorders. Basic surgical principles are described to help in the operating room as well as illustrative cases. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the incidence of cochlear fibrosis after vestibular schwannoma (VS) resection via middle cranial fossa (MCF) approach. Design: A retrospective case review was conducted. Setting: The review was conducted in a tertiary care academic medical center. Participants: Patients who (1) underwent resection of VS via MCF approach between 2013 and 2018, (2) had complete pre- and post-audiometric testing, and (3) had clinical follow-up with magnetic resonance imaging (MRI) for at least 1 year after surgery were included. Main Outcome Measure(s): The main outcome of this study was cochlear fibrosis as assessed by MRI 1 year after surgery. Results: Fifty-one patients underwent VS resection via MCF technique during the study period. Of 31 patients with AAO-HNS class A or B preoperative hearing ability, 18 (58.0%) maintained class A, B, or C hearing postoperatively. Of 16 patients who lost hearing and had MRI 1 year after surgery, 11 (61.1%) had MRI evidence of fibrosis in at least some portion of the labyrinth and 4 (22.2%) showed evidence of cochlear fibrosis. Of 16 patients with preserved hearing and MRI 1 year after surgery, 4 (25%) had fibrosis in some portion of the labyrinth, with no fibrosis in the cochlea. Conclusions: In patients who lose hearing during VS resection with the MCF approach, there is usually MRI evidence of fibrosis in the labyrinth 1 year after surgery. However, there is also, but less commonly, fibrosis involving the cochlea. It is unclear if this will affect the ability to insert a cochlear implant electrode array. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate the correlation between arachnoid cysts and chronic subdural hematomas in young adults. Methods: This retrospective study evaluated ten patients having concomitant chronic subdural hematomas and arachnoid cysts. Patients were evaluated with the data of age and gender, location of hematoma and arachnoid cyst, trauma history, symptoms at admission, maximum hematoma diameter, contiguity between arachnoid cyst and hematoma, and treatment methods. Results: We treated 285 patients who were diagnosed with cSDH between January 2013 and December 2019. 22 patients were under the age of 40 years. Ten of them had both cSDH and arachnoid cysts. The mean age of patients was 24.8±3.9 years. Patients with only chronic subdural hematoma had higher mean age than the patients with arachnoid cyst-related chronic subdural hematoma. In four patients, the onset of chronic subdural hematoma was reported after arachnoid cyst diagnosis. Four of the patients did not have causative trauma history, and two patients suffered minor sports-related traumas. All patients had headache, and only two patients had hemiparesis. The location of arachnoid cysts were in the middle fossa in eight patients. All patients had chronic subdural hematomas on the ipsilateral side of arachnoid cyst. Four patients who had smaller than 10 mm maximal cSDH diameter underwent conservative management. They were followed by serial neuroimaging studies and it was noted that the hematoma disappered and the size of the arachnoid cysts decreased over time without any neurological complication. In six cases, craniotomy was required, and all recovered completely. cSDH did not recur during 5–60 months of follow-up period (median 12 months). Conclusions: It seems that presence of an arachnoid cyst in young adults is a predisposing factor for the formation of chronic subdural hematoma. Coincidentally diagnosed arachnoid cyst patients may be followed up with periodical clinical examinations and neuroimaging studies.

Objective: This study aimed to evaluate the correlation between arachnoid cysts and chronic subdural hematomas in young adults. Methods: This retrospective study evaluated ten patients having concomitant chronic subdural hematomas and arachnoid cysts. Patients were evaluated with the data of age and gender, location of hematoma and arachnoid cyst, trauma history, symptoms at admission, maximum hematoma diameter, contiguity between arachnoid cyst and hematoma, and treatment methods. Results: We treated 285 patients who were diagnosed with cSDH between January 2013 and December 2019. 22 patients were under the age of 40 years. Ten of them had both cSDH and arachnoid cysts. The mean age of patients was 24.8±3.9 years. Patients with only chronic subdural hematoma had higher mean age than the patients with arachnoid cyst-related chronic subdural hematoma. In four patients, the onset of chronic subdural hematoma was reported after arachnoid cyst diagnosis. Four of the patients did not have causative trauma history, and two patients suffered minor sports-related traumas. All patients had headache, and only two patients had hemiparesis. The location of arachnoid cysts were in the middle fossa in eight patients. All patients had chronic subdural hematomas on the ipsilateral side of arachnoid cyst. Four patients who had smaller than 10 mm maximal cSDH diameter underwent conservative management. They were followed by serial neuroimaging studies and it was noted that the hematoma disappered and the size of the arachnoid cysts decreased over time without any neurological complication. In six cases, craniotomy was required, and all recovered completely. cSDH did not recur during 5–60 months of follow-up period (median 12 months). Conclusions: It seems that presence of an arachnoid cyst in young adults is a predisposing factor for the formation of chronic subdural hematoma. Coincidentally diagnosed arachnoid cyst patients may be followed up with periodical clinical examinations and neuroimaging studies.

Objective: This study aimed to evaluate the correlation between arachnoid cysts and chronic subdural hematomas in young adults. Methods: This retrospective study evaluated ten patients having concomitant chronic subdural hematomas and arachnoid cysts. Patients were evaluated with the data of age and gender, location of hematoma and arachnoid cyst, trauma history, symptoms at admission, maximum hematoma diameter, contiguity between arachnoid cyst and hematoma, and treatment methods. Results: We treated 285 patients who were diagnosed with cSDH between January 2013 and December 2019. 22 patients were under the age of 40 years. Ten of them had both cSDH and arachnoid cysts. The mean age of patients was 24.8±3.9 years. Patients with only chronic subdural hematoma had higher mean age than the patients with arachnoid cyst-related chronic subdural hematoma. In four patients, the onset of chronic subdural hematoma was reported after arachnoid cyst diagnosis. Four of the patients did not have causative trauma history, and two patients suffered minor sports-related traumas. All patients had headache, and only two patients had hemiparesis. The location of arachnoid cysts were in the middle fossa in eight patients. All patients had chronic subdural hematomas on the ipsilateral side of arachnoid cyst. Four patients who had smaller than 10 mm maximal cSDH diameter underwent conservative management. They were followed by serial neuroimaging studies and it was noted that the hematoma disappered and the size of the arachnoid cysts decreased over time without any neurological complication. In six cases, craniotomy was required, and all recovered completely. cSDH did not recur during 5–60 months of follow-up period (median 12 months). Conclusions: It seems that presence of an arachnoid cyst in young adults is a predisposing factor for the formation of chronic subdural hematoma. Coincidentally diagnosed arachnoid cyst patients may be followed up with periodical clinical examinations and neuroimaging studies.

Abstract Background The BONEBRIDGE (MED-EL, Innsbruck, Austria) is a bone-conduction implant used in the treatment of conductive and mixed hearing loss. The BONEBRIDGE consists of an external audio processor and a bone-conduction floating mass transducer that is surgically implanted into the skull in either the transmastoid, retrosigmoid or middle fossa regions. The manufacturer includes self-tapping screws to secure the transducer; however, self-drilling screws have also been used with success. In cases where the skull is not thick enough to house the transducer, lifts are available in a variety of sizes to elevate the transducer away from the skull. The objective of the present study was to investigate the effects of screw type, lift thickness, and implant location on the sound transmission of the BONEBRIDGE. Method Six cadaveric temporal bones were embalmed and dried for use in this study. In each sample, a hole was drilled in each of the three implant locations to house the implant transducer. At the middle fossa, six pairs of screw holes were pre-drilled; four pairs to be used with self-tapping screws and lifts (1, 2, 3, and 4 mm thick lifts, respectively), one pair with self-tapping screws and no lifts, and one pair with self-drilling screws and no lifts. At the transmastoid and retrosigmoid locations, one pair of screw holes were pre-drilled in each for the use of the self-tapping screws. The vibration of transmitted sound to the cochlea was measured using a laser Doppler vibrometry technique. The measurements were performed on the cochlear promontory at eight discrete frequencies (0.5, 0.75, 1, 1.5, 2, 3, 4 and 6 kHz). Vibration velocity of the cochlear wall was measured in all samples. Measurements were analyzed using a single-factor ANOVA to investigate the effect of each modification. Results No significant differences were found related to either screw type, lift thickness, or implant location. Conclusions This is the first known study to evaluate the effect of screw type, lift thickness, and implant location on the sound transmission produced by the BONEBRIDGE bone-conduction implant. Further studies may benefit from analysis using fresh cadaveric samples or in-vivo measurements.

Objective: This study aimed to evaluate the correlation between arachnoid cysts and chronic subdural hematomas in young adults. Methods: This retrospective study evaluated ten patients having concomitant chronic subdural hematomas and arachnoid cysts. Patients were evaluated with the data of age and gender, location of hematoma and arachnoid cyst, trauma history, symptoms at admission, maximum hematoma diameter, contiguity between arachnoid cyst and hematoma, and treatment methods. Results: We treated 285 patients who were diagnosed with cSDH between January 2013 and December 2019. 22 patients were under the age of 40 years. Ten of them had both cSDH and arachnoid cysts. The mean age of patients was 24.8±3.9 years. Patients with only chronic subdural hematoma had higher mean age than the patients with arachnoid cyst-related chronic subdural hematoma. In four patients, the onset of chronic subdural hematoma was reported after arachnoid cyst diagnosis. Four of the patients did not have causative trauma history, and two patients suffered minor sports-related traumas. All patients had headache, and only two patients had hemiparesis. The location of arachnoid cysts were in the middle fossa in eight patients. All patients had chronic subdural hematomas on the ipsilateral side of arachnoid cyst. Four patients who had smaller than 10 mm maximal cSDH diameter underwent conservative management. They were followed by serial neuroimaging studies and it was noted that the hematoma disappered and the size of the arachnoid cysts decreased over time without any neurological complication. In six cases, craniotomy was required, and all recovered completely. cSDH did not recur during 5–60 months of follow-up period (median 12 months). Conclusions: It seems that presence of an arachnoid cyst in young adults is a predisposing factor for the formation of chronic subdural hematoma. Coincidentally diagnosed arachnoid cyst patients may be followed up with periodical clinical examinations and neuroimaging studies.

Background: Petrous apicitis (PA) is a serious infection involving the apical portion of the petrous temporal bone. The classic triad of purulent otorrhea, ipsilateral abducens nerve palsy and retroorbital pain is rarely seen due to early detection and widespread use of antibiotics. Medical management is the primary treatment modality with surgery reserved for cases of recalcitrant petrous apex abscess. Methods and Results: We presented a case of PA with previously untreated otitis media. After multidisciplinary evaluation, the patient was initially treated with intravenous antibiotics followed by drainage of the abscess using a combined transmastoid and middle cranial fossa (MCF) approach. The patient recovered well with no recurrence of the infection based on imaging and symptoms. Discussion: While a variety of different surgical approaches can be used in treatment of PA, we recommend the MCF approach in cases where access to the anterior petrous apex may be challenging via transcanal or transmastoid approach. [ABSTRACT FROM AUTHOR]

Background  Skull base chordomas are a major therapeutic challenge. The surgical management involves selecting an approach that will offer the patient the best chance of largest/complete removal while minimizing morbidity and mortality. Methods  Medical records and imaging review of two skull base chordomas involving the middle fossa and posterior fossa that were successfully treated with an endoscope-assisted middle fossa approach. Results  The use of angled endoscopes provided better identification of anatomical landmarks and improved tumor resection when compared with the microscopic surgical exposure. The approach selection, anatomical landmarks, and technical aspects of the intraoperative setting of the endoscope-assisted approach are discussed. Conclusion  Endoscopic assistance in the middle fossa approach is a safe and valuable tool for maximizing the reach of the surgical corridor when treating skull base chordomas. [ABSTRACT FROM AUTHOR]

Introduction  Tumors of the lateral skull base often require collaboration between neurosurgeons and neurotologists for the surgical approach. The three main transosseous surgical approaches are retrosigmoid (RS), translabyrinthine (TL), and middle fossa (MF). The literature reflects a relative paucity regarding the various closure techniques for these approaches and the postoperative complications. We have performed a systematic review comparing closure techniques from each approach. Methods  A systematic review was performed using Ovid MEDLINE (1990–2016) on closure technique and postoperative complications for patients undergoing lateral skull base surgery via the TL, RS, or MF approach. Studies were included if they contained at least 10 patients, described their closure technique, and provided data on postoperative complications. Results  A total of 1,403 studies were reviewed. Of these, 53 studies met inclusion criteria yielding a total of 10,466 subjects in this analysis. The average rate of cerebrospinal fluid leak was 5.3% in the TL approach, 9% in the RS approach, and 6.2% in the MF approach. There was no significant effect of various closure techniques on postoperative wound complications in the MF approach. Multiple factors were identified which affected postoperative wound complication in the RS and TL approaches. Conclusion  There are a plethora of closure techniques for lateral skull base surgery. Several techniques were identified in this review that may affect the postoperative wound complication rates in lateral skull base surgery. [ABSTRACT FROM AUTHOR]

Introduction: Since the early use of the endoscopic view for treating simple intrasellar pituitary adenomas, the skull base surgery has experienced an unprecedented revolution elevating the treatment of skull base lesions to the next level in proficiency and excellence of care. Methods: We have reviewed the preclinical and clinical evidence supporting the use of the endoscope in the treatment of skull base lesions. In this article, we aim to discuss and provide a wide view of the current indications and future perspectives of the endoscopic endonasal approaches (EEA) and of the endoscopic transcranial approaches. Results: As in the development of any other technique, EEA have gone through a transformation process from theoretical anatomic models to a pragmatic clinical use. Along the way, EEA have required several modifications, as well as pushbacks in the application of this technique in some indications. This process has resulted in the provision of an additional tool to the current surgical armamentarium that allows the skull base surgeon to face most challenging lesions along the skull base. Conclusions: The judicious combination of transcranial and endoscopic-transnasal approaches warrants highest chances of achieving satisfactory tumors resection with a reduced risk of complications. [ABSTRACT FROM AUTHOR]

Facial nerve hemangiomas are a rare entity of skull base lesions that arise within the temporal bone and affect the seventh cranial nerve. 1 They are vascular malformations arising from the vascular plexuses surrounding the nerve. Although slow growing and overall benign in nature, they can cause significant facial nerve dysfunction even at small sizes. 2 Facial nerve hemangiomas can arise within different segments of the facial nerve within the temporal bone, but most commonly arise near the geniculate ganglion. 3 We describe the case of a 34-year-old female who presented with progressive right facial palsy (House-Brackmann 4) and a calcified lesion arising from the petrous temporal bone. Resection of the lesion was performed with a posterior to anterior middle fossa approach, with identification of the greater superficial petrosal nerve and geniculate ganglion, sectioning of the middle meningeal artery, and identification of V2 and V3 segments of the trigeminal nerve (Video 1). The bony mass was peeled off the petrous temporal bone and the geniculate ganglion without sacrifice of the facial nerve. Postoperative imaging showed gross total resection, and the patient's facial palsy improved to House-Brackmann 1. A comprehensive literature review on surgical approaches and outcomes for the resection of hemangiomas involving the geniculate ganglion or the facial nerve is also provided. 2,4-18 The case presentation, surgical anatomy, operative nuances with technical considerations, and postoperative course with imaging are reviewed. The patient and family provided informed consent for the procedure and publication of patient images. [ABSTRACT FROM AUTHOR]

Objective: The lateral retrocanthal transorbital endoscopic approach (LRCTEA) facilitates trajectory to the middle fossa, preserving the lateral canthal tendon and thus avoiding postoperative complications such as eyelid malposition. Here, the authors sought to define the surgical anatomy and technique of LRCTEA using a stepwise approach in cadaveric heads and offer an in-depth examination of existing quantitative data from cadaveric studies., Methods: The authors performed LRCTEA to the middle cranial fossa under neuronavigation in 7 cadaveric head specimens that underwent high-resolution (1-mm) CT scans preceding the dissections., Results: The LRCTEA provided access to middle fossa regions including the cavernous sinus, Meckel's cave, and medial temporal lobe. The trajectories and endpoints of the approach were confirmed using electromagnetic neuronavigation. A stepwise approach was delineated and recorded., Conclusions: The authors' cadaveric study delineates the surgical anatomy and technique of the LRCTEA, providing a stepwise approach for its implementation. As these approaches continue to evolve, their development and refinement will play an important role in expanding the surgical options available to neurosurgeons, ultimately improving outcomes for patients with complex skull base pathologies. The LRCTEA presents a promising advancement in skull base surgery, particularly for accessing challenging middle fossa regions. However, surgeons must remain vigilant to potential complications, including transient diplopia, orbital hematoma, or damage to the optic apparatus.

The internal maxillary artery (IMAX) is currently considered one of the main donor vessels in extracranial-to-intracranial bypass surgeries. Four main techniques for harvesting the IMAX have been described: via the anterior medial infratemporal fossa (AMITF), the middle infratemporal fossa (MITF), the anterior lateral middle fossa (ALMF), and the lateral middle fossa (LMF). The advantages and limitations of these techniques have not yet been systematically evaluated and compared. Twenty-five cadaver specimens were used to evaluate the harvesting technique. The length and the caliber of the targeted IMAX segments, as well as the depth from the operating plane to the IMAX, surgical time, and surgical area of exposure, were analyzed. The MITF technique provided the greatest operating area of exposure (mean, 3.88 ± 0.97 cm2). The LMF and MITF techniques provided the largest IMAX caliber (mean, 3.1 ± 0.4 mm and 3.0 ± 0.3 mm, respectively). The ALMF technique provided the shallowest operative depth as well as the least time of exposure (21.8 minutes). The MITF technique exposed the longest IMAX segment (mean, 18.8 ± 3.5 mm). Advantages of the AMITF and MITF techniques include anatomic simplicity, absence of skull base drilling, and greater discretion in muscle dissection. These properties can simplify the anastomosis procedure compared with the ALMF and LMF techniques. Identification of the IMAX pattern is important before selecting the approach for this bypass operation. [ABSTRACT FROM AUTHOR]

• The cavernous sinus and anterior clinoid process are challenging structures. • The meningo-orbital band tethers the fronto-temporal dura. • The detachment of the meningo-orbital band is a key step to expose these structures. • We proposed a method for the safe and effective detachment of the meningo-orbital band. The meningo-orbital band (MOB) is the most superficial dural band that tethers the fronto-temporal dura to the periorbita. It is usually encountered when performing a pterional or fronto-temporo-sphenoidal approach, and it disrupts surgical access to deeper regions. Our objective was to perform a detailed anatomy study and a stepwise method to successfully detach the MOB using cadaveric specimens. We used six formalin‐fixed, silicone‐injected cadaveric heads. On each side, we performed a pterional approach plus mini‐peeling of the anterior third of the middle fossa and/or extradural anterior clinoidectomy. We also applied this technique in three clinical cases to prove its safety and efficacy. The detachment of the MOB consists in four steps, 1) detachment of the temporal and frontal dura, 2) cutting of the MOB, 3) exposure and drilling of the anterior clinoid process, and 4) pealing of the lateral wall of the cavernous sinus. Using clinical cases, we explain how to adapt the technique depending on the localization of the lesion. The detachment of the MOB is the key to safely expose the cavernous sinus and the anterior clinoid process. The authors proposed a step-by-step method for the safe and effective detachment of the MOB. It is recommended, particularly to less experienced neurosurgeons that are starting with skull base surgery, and also to experts that want to expand their knowledge. [ABSTRACT FROM AUTHOR]

Background: The BONEBRIDGE (MED-EL, Innsbruck, Austria) is a bone-conduction implant used in the treatment of conductive and mixed hearing loss. The BONEBRIDGE consists of an external audio processor and a bone-conduction floating mass transducer that is surgically implanted into the skull in either the transmastoid, retrosigmoid or middle fossa regions. The manufacturer includes self-tapping screws to secure the transducer; however, self-drilling screws have also been used with success. In cases where the skull is not thick enough to house the transducer, lifts are available in a variety of sizes to elevate the transducer away from the skull. The objective of the present study was to investigate the effects of screw type, lift thickness, and implant location on the sound transmission of the BONEBRIDGE. Method: Six cadaveric temporal bones were embalmed and dried for use in this study. In each sample, a hole was drilled in each of the three implant locations to house the implant transducer. At the middle fossa, six pairs of screw holes were pre-drilled; four pairs to be used with self-tapping screws and lifts (1, 2, 3, and 4 mm thick lifts, respectively), one pair with self-tapping screws and no lifts, and one pair with self-drilling screws and no lifts. At the transmastoid and retrosigmoid locations, one pair of screw holes were pre-drilled in each for the use of the self-tapping screws. The vibration of transmitted sound to the cochlea was measured using a laser Doppler vibrometry technique. The measurements were performed on the cochlear promontory at eight discrete frequencies (0.5, 0.75, 1, 1.5, 2, 3, 4 and 6 kHz). Vibration velocity of the cochlear wall was measured in all samples. Measurements were analyzed using a single-factor ANOVA to investigate the effect of each modification. Results: No significant differences were found related to either screw type, lift thickness, or implant location. Conclusions: This is the first known study to evaluate the effect of screw type, lift thickness, and implant location on the sound transmission produced by the BONEBRIDGE bone-conduction implant. Further studies may benefit from analysis using fresh cadaveric samples or in-vivo measurements. [ABSTRACT FROM AUTHOR]

Petroclival tumors and ventrolateral lesions of the pons present unique surgical challenges. This cadaveric study provides qualitative and quantitative anatomic comparison for an anterior petrous apicectomy through the transcranial middle fossa (TMF) and expanded endoscopic transsphenoidal-transclival approaches. In 10 silicone-injected heads, the petrous apex and clivus were drilled extradurally using middle fossa and endonasal approaches. With in situ and frameless stereotactic navigation, we defined consistent points to compare working areas, bone removal volumes, approach angles, and surgical freedom. Mean exposed TMF area (21.03 ± 3.46 cm2) achieved a 44.71 ± 4.13° working angle to the brainstem between cranial nerves V and VI. Kawase's rhomboid area measured 1.76 ± 0.34 cm2, and bone removal averaged 1.20 ± 0.12 cm3 at the petrous apex. Surgical freedom on the lateral brainstem was higher halfway between cranial nerves V and VI at the center of the rhomboid compared with midline at the basilar sulcus (P < 0.01). After clivectomy and petrous apicectomy, mean exposed expanded endoscopic transsphenoidal-transclival area was 5.29 ± 0.66 cm2. Approach from either nostril showed no statistically significant differences in surgical freedom at the foramen lacerum and midpoint basilar sulcus. At the petrous apex, bone volume removed and area exposed were significantly larger for the TMF approach (P < 0.001). Expanded transclival anterior petrosectomy through the TMF approach provides an adequate corridor to lesions in the upper ventrolateral pons. The expanded endoscopic transsphenoidal-transclival approach better fits midline lesions not extending laterally beyond cranial nerve VI and C3 carotid when evaluating normal anatomic parameters. [ABSTRACT FROM AUTHOR]

Background: The eyebrow incision supraorbital approach is limited by the lack of exposure of the sylvian fissure exposure. By extending the skin incision 15 mm posteriorly and the supraorbital craniotomy beneath the superior temporal line, proximal sylvian dissection is achievable, and the surgical exposure is drastically improved. Methods: Throughout a cadaveric stepwise dissection and a pertinent anatomical analysis, we describe in detail the surgical technique of the extended eyebrow approach (xEBA). We additionally highlight main anatomical elements involved in this approach and provide technical nuances to avoid complications. Conclusion: xEBA is a versatile technique that uses the pretemporal, transylvian, and subfrontal corridor to enhance surgical exposure around the anterior cranial fossa. [ABSTRACT FROM AUTHOR]

Objective  This study was aimed to better characterize the surgical anatomy of the floor of the middle cranial fossa using three dimensional Euclidean relationships between the arcuate eminence (AE), the superior semicircular canal (SSC), and the geniculate ganglion (GG). Study Design  Submillimeter distances were recorded from computed tomography (CT) scans of 50 patients (100 sides). The AE, apex of the SSC, and the GG were identified and three dimensional distances measured. Setting  The study was conducted at a tertiary academic teaching hospital. Main Outcome Measures  In this study, Euclidean distance was obtained from AE to SSC by using a fixed anatomical landmark (GG) as the origin. Results  On average, the AE is 2.1 ± 0.3 mm lateral, 2.5 ± 0.1 mm superior, and 2.1 ± 0.3 posterior to the SSC. Thirty percent (30/100) of patients had an AE that was less than 2 mm superior to SSC. The AE was medial to the SCC in 13% samples and anterior to the SSC in 18% samples. The results also show that there was no difference in mean distance between sides (1.08 mm; 95% confidence interval [CI] =  − 2.67–0.52; p -value = 0.29) or gender (0.56 mm; 95% CI =  − 1.34, 2.45; p -value = 0.86). Conclusions  This study represents a comprehensive analysis of the relational anatomy of the floor of the middle fossa to date. In quantifying relationships between the AE, SSC, and GG, and by understanding the variability of these relationships in some planes, the middle fossa surgeon can feel more comfortable with this most challenging approach. [ABSTRACT FROM AUTHOR]

Objectives: To determine the relationship, if any, between body mass index (BMI) and attenuation of the arcuate eminence (AE).Study Design: Case series with chart review.Setting: Tertiary neurotologic referral center.Subjects and Methods: Submillimeter distances were recorded from high-resolution temporal bone computed tomography (CT) scans of 50 patients (100 sides). The AE (defined as the superiormost location of the petrous bone over the otic capsule), the bony apex of the superior semicircular canal (SSC), and the geniculate ganglion (GG) were identified and 3-dimensional distances measured. The height of the AE relative to the bony apex of the superior semicircular canal was determined using Euclidean geometry using the fixed anatomical landmark of the GG as the origin. Correlations between AE and BMI were calculated using Pearson's, linear mixed effects, and sensitivity analysis models.Results: The mean (SD) BMI was 30 (8.1) kg/m2, with 16 (30%) patients falling in the underweight/normal category (BMI <25 kg/m2), 10 (20%) overweight patients (25 kg/m2≤ BMI ≤ 30 kg/m2), and 24 (48%) patients considered obese (BMI >30 kg/m2). The mean (SD) AE heights for the left and right ears were 2.5 (1.11) and 2.6 (1.09), respectively. The results of the linear mixed-effects models indicated little evidence that BMI is associated with AE height when including all patients (partial R2 = 0.040) and when using BMI categories (partial R2 = 0.025).Conclusion: Contrary to other structures within the lateral skull base, the relative prominence of the arcuate eminence does not correlate with BMI or any other demographic variables. [ABSTRACT FROM AUTHOR]

Introduction: Meningiomas are the most common primary tumors, although most are benign, their location in the central nervous system can cause severe morbidity and mortality. Around the world this type of neoplasia has an incidence of 7.7 per 100,000 inhabitants and presenting a variable incidence in each region, being 3.8% in the middle fossa, 10% in the posterior fossa and in general 36% of all intracranial tumors. Their development will depend on several risk factors that are associated with both genetic to environmental causes. Interpretation: Meningiomas are the most common primary intracranial tumors and both its size and location differs, causing symptoms by mass effect therefore, in the middle fossa, the affectation is visual, while in posterior fossa vestibular symptoms, and even though the histological benign nature of this tumors, patients suffer from neurological symptoms and will require treatment; Being the surgery the primary treatment in all the cases which are accessible, on the other hand, radiation can be used as a primary treatment or, therefore, for recurrent or inaccessible lesions. [ABSTRACT FROM AUTHOR]

Purpose: There has not been a study documenting the distribution of cerebrospinal fluid (CSF) pathways in the anterolateral base of the middle fossa (ALB) and diploe of the pterional region (Pt). The present study aimed to delineate these pathways using magnetic resonance imaging. Methods: Thin-sliced, axial, and coronal T2-weighted sequences were performed for a total of 358 outpatients, including 20 pediatric patients. Results: Adult population: CSF-filled channels were identified on axial images in the ALB in 57% and in the diploe of the Pt in 65% of 338 patients. These pathways showed variable morphology and number bilaterally. CSF-filled channels were identified on coronal images in the ALB in 14% and in the diploe of the Pt in 100% of 59 patients. These were delineated as linear structures of variable number and thickness. Eleven percent of the pathways identified in the ALB was connected with extracranial channels. Pediatric population: CSF-filled channels were identified on axial images in the ALB in 75% and in the diploe of the Pt in 80% of 20 patients. Conclusions: The ALB and diploe of the Pt may function as CSF pathways in children and adults. The pathways in the ALB can be a CSF-drainage route connecting to the extracranial sites. [ABSTRACT FROM AUTHOR]

Petrous apex cholesterol granulomas (PACG) are rare disorders that can lead to patient morbidity and must, occasionally, be drained by either endoscopic endonasal (EN) or open procedures (OP). The objective of our study was to complete a review of the literature to compare the EN and OP approaches on multiple levels, notably on safety and effectiveness. Ovid MEDLINE and Embase were used to perform a thorough literature review of all cases of PACG treated by either EN or OP dating from January 1948 to August 2017. In total, 49 articles were selected including 23 for EN (n=76) and 26 for OP (n=210). Differences were found in the incidence of preoperative hearing loss (HL) (EN 18.4%, OP 57.3%; p<0.001), headache (EN 48.7%, OP 31.2%; p=0.007), and disequilibrium (EN: 14.5%, OP 26.1%; p=0.04). Differences in lesion proximity to the sphenoid sinus (EN 23.6%, OP: 1.0%; p<0.001), clivus (EN 11.8%, OP 4.7%; p=0.03), otic capsule (EN 0.0%, OP 5.2%; p=0.03), internal auditory canal (EN 2.6%, OP 10.9%; p=0.01), and internal carotid artery (ICA) (EN 9.2%, OP 2.8%; p=0.02) were found on preoperative imaging. The EN procedure had better hearing improvement rates (EN 85.7%, OP 23.4%; p<0.001), lower complication rates (EN 7.9%, OP 17.6%; p=0.04), shorter median follow-up (EN:13.5 months, OP:37.2 months; p<0.001), and shorter time to recurrence (EN 3 months, OP 22.6 months; p=0.002) than the known OP. No differences were found in age, preoperative size, recurrence rate, operative time, stent placement, or improvement of other symptoms. Endoscopic nasal approaches, when feasible, should be favored to open procedures for PACG drainage given their better hearing improvement and less complication rates. [ABSTRACT FROM AUTHOR]