Multicenter comparison of Chiari malformation type I presentation in children versus adults.

OBJECTIVE: Treatment for Chiari malformation type I (CM-I) often includes surgical intervention in both pediatric and adult patients. The authors sought to investigate fundamental differences between these populations by analyzing data from pediatric and adult patients who required CM-I decompression. METHODS: To better understand the presentation and surgical outcomes of both groups of patients, retrospective data from 170 adults and 153 pediatric patients (2000-2019) at six institutions were analyzed. RESULTS: The adult CM-I patient population requiring surgical intervention had a greater proportion of female patients than the pediatric population (p < 0.0001). Radiographic findings at initial clinical presentation showed a significantly greater incidence of syringomyelia (p < 0.0001) and scoliosis (p < 0.0001) in pediatric patients compared with adult patients with CM-I. However, presenting signs and symptoms such as headaches (p < 0.0001), ocular findings (p = 0.0147), and bulbar symptoms (p = 0.0057) were more common in the adult group. After suboccipital decompression procedures, 94.4% of pediatric patients reported symptomatic relief compared with 75% of adults with CM-I (p < 0.0001). CONCLUSIONS: Here, the authors present the first retrospective evaluation comparing adult and pediatric patients who underwent CM-I decompression. Their analysis reveals that pediatric and adult patients significantly differ in terms of demographics, radiographic findings, presentation of symptoms, surgical indications, and outcomes. These findings may indicate different clinical conditions or a distinct progression of the natural history of this complex disease process within each population, which will require prospective studies to better elucidate.

Transcortical endoportal subchoroidal endoscope-assisted approach to the third ventricle: from virtual reality to anatomical laboratory.

BACKGROUND: Surgical approaches to the third ventricle (TV) have always represented a technical challenge in neurosurgery. Virtual reality (VR) is attaining increasing relevance in training programs and preoperative planning. The aim of this study is to demonstrate the worthwhile mutual contribution of VR simulations and specimen dissections to develop a new surgical approach to the TV. METHODS: The transcortical endoportal subchoroidal endoscope assisted (TEPSEA) approach was planned and simulated thanks to VR (Surgical Theater©, LLC, Cleveland, OH, USA), and then implemented on cadaver specimens by using the VBAS portal system (Viewsite™ Brain Access System TC Model, Vycor Medical™ Inc., Boca Raton, FL, USA). We assessed anthropometric measurements during VR planning and evaluated surgical operability during anatomical dissections. RESULTS: Surgical field depths measured between 75.6 and 85.3 mm to mammillary bodies and habenular commissure, which were in mean 20.2 mm away. An 18-mm movement was estimated for 15°-posterior tilting of a 70-mm long VBAS. Excellent exposure and maneuverability were achieved within the TV through a 2.47 cm2 portal working area. The 30°-endoscope assistance expanded the access towards the anterior and posterior walls of the TV particularly to the infundibular recess, mammillary bodies, habenular commissure and pineal recess. CONCLUSIONS: We documented the utility of a step-by-step VR planning and simulation followed by anatomical dissections to study surgical approaches to deep brain areas. The TEPSEA exploits the portal system and endoscopic assistance to access the entire TV minimizing cortical and white matter manipulation.

Impact of C-shaped skin incision on surgical operability in the retrosigmoid approach: when a good start is half of the job.

BACKGROUND: The retrosigmoid approach (RSA) is one of the routes of choice to approach tumors and vascular lesions of the cerebellopontine angle. Among different types of skin incisions and soft tissue dissection techniques, the most widely used variants comprise the straight/lazy S-shaped and the C-shaped incisions. Several reports discuss advantages in terms of functional and clinical outcomes of the C-shaped incision, but scientific considerations about the critical impact of this kind of incision on surgical operability are still extremely limited. OBJECT: Authors comparatively analyze the advantage provided by C-shaped incision in RSA in terms of anatomic exposure and surgical operability, compared with straight/lazy S-shaped one. METHODS: A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability. RESULTS: C-shaped incision, providing a significant reduction of the overall working distance (-13%) together with an overall increase of the maneuverability area (+ 204.9%), did improve the conizing effect on the surgical corridor. It optimized overall maneuverability of surgical instruments, in terms of angle of attack (+ 27.7%), as well as maneuverability arc (+ 122%), on the entire surgical field. C-shaped incision ensured good operability on all surgical targets (OS ranging from 2 to 3), most significantly improving surgical maneuverability at the porus trigeminus and internal acoustic meatus. CONCLUSION: C-shaped incision in the RSA significantly improves anatomic exposure and surgical operability as compared with straight/lazy S-shaped incision.

The translabyrinthine approach in residency training. "Step by step" surgical anatomy from the dissection laboratory to the operative room.

Surgical anatomy training in a dedicated research laboratory and attendance to focused "hands-on" dissection courses are of high educational importance in order to acquire and maintain surgical expertise in skull base surgery, both for young and more experienced surgeons. Nevertheless, transitioning surgical skills and anatomic knowledge from the laboratory to the operative room it is not free of challenges, especially during skull base approaches where the three-dimensional surgical orientation can be quite complex. We present a "step-by-step" and "side-by-side" surgical anatomy report on a translabyrinthine approach that was practiced in the laboratory then performed in the operative room by the surgical team, and we compare surgical anatomy exposures while discussing intraoperative techniques, nuances and challenges, both in the laboratory and the operative room.

Endoscope-Assisted Neuroportal Transcerebellar Approach to the Fourth Ventricle: An Anatomical Study.

BACKGROUND AND STUDY AIMS: Minimally invasive approaches to deep-seated lesions still represent a fundamental issue in modern neurosurgery. Tubular retractors allow to enhance the operability of intraventricular lesions, minimizing the risk of damages to brain parenchyma. Increasing interest for portal devices has been mainly focused on supratentorial pathologies, while transportal approaches in the posterior cranial fossa have been rarely described. In the present study, the authors aimed to investigate the surgical exposure and operability obtained with a microsurgical neuroportal transcerebellar approach targeting the fourth ventricle, assisted by endoscopic exploration. MATERIAL AND METHODS: Six cadaveric specimens were provided for anatomical microsurgical dissection and Vycor ViewSite Brain Access System was used as tubular retractor. Surgical feasibility of the neuroportal transcerebellar approach was demonstrated through a definable and measurable parameter, the operability score. RESULTS: The neuroport provided a surgical corridor away from eloquent structures to target the whole fourth ventricle cavity, preventing injury to cerebellar nuclei and white matter pathways and, potentially, minimizing the risk of surgical morbidity. Maximal operability was reached in the pontomedullary junction and medullary area of the ventricular floor. Transportal endoscopic assistance contributed to a further extension of surgical exposure in blind spots, corresponding to the ipsilateral lateral recess, the uppermost part of the fourth ventricle, and the obex. CONCLUSION: The neuroportal transcerebellar approach represents a viable alternative route to the fourth ventricle, avoiding vermian splitting or subarachnoid dissection of the cerebellomedullary cistern. Endoscopic assistance enhances the exposure of the surgical field and accomplishes a valid instrument for intraventricular orientation to ease microsurgical procedures.

Combined, Rib-Sparing, Bilateral Approach to the Ventral Mid and Low Thoracic Spine: Study on Comparative Anatomy and Surgical Feasibility.

BACKGROUND: Pathologies of the ventral thoracic spine represent a challenge, igniting arguments about which should be the ideal surgical approach to access this area. Anterior transthoracic thoracotomy and a number of posterolateral routes have been developed. Among the latter, costotransversectomy has demonstrated to provide good ventral exposure with a lower, but not negligible, morbidity. The optimal approach should be the one minimizing surgical morbidity on both neural and extraneural structures while optimizing exposure. METHODS: The authors described the combined, rib-sparing, bilateral approach (CRBA) to the ventral mid/low-thoracic spine. The technique combines a transfacet pedicle partially sparing approach on one side and a transpedicular with transverse process resection on the contralateral one. A laboratory investigation was conducted. The technique was applied in a surgical setting, and a case was reported. RESULTS: CRBA is rib-sparing, completely extracavitary, and does not require pleural exposure and paraspinal muscle splitting, thus minimizing potential morbidity. The combination of 2 corridors ensures the greatest exposure compared with standard posterolateral approaches. The only blind corner is limited to a small area just in front of the dural sac. A bimanual approach optimizes control during surgical manipulation, even if the area of maneuverability and cross-section areas of surgical corridors are slightly limited compared to traditional costotransversectomy due to the minimally invasive nature of the procedure. CONCLUSIONS: CRBA represents a safe and effective option to access the ventral mid/low thoracic spine. It provides great exposure and bimanual manipulation of the surgical target, minimizes potential morbidity, and avoids entrance into the thoracic cavity and paraspinal muscle splitting.

Endoscopic sublabial transmaxillary approach to the inferior orbit: pearls and pitfalls-A comparative anatomical study.

OBJECTIVE: Although orbital surgery has always represented a challenge for neurosurgeons, keyhole and endoscopic techniques are gradually surging in popularity maximizing functional and esthetic outcomes. This quantitative anatomical study first compared the surgical operability achieved through three endoscopic approaches within the inferior orbit: the endoscopic sublabial transmaxillary (ESTMax), the endoscopic endonasal transethmoidal (EETEth), and the endoscope-assisted lateral orbitotomy (ELO). METHODS: Each of these approaches was performed bilaterally on five specimens. We described the ESTMax step-by-step, underlining its advantages and pitfalls in comparison with EETEth and ELO. Then, we assessed surgical measurements and operability in ESTMax, EETEth, and ELO. RESULTS: The ESTMax provided the most favorable operative window (278.9 ± 43.8 mm2; EETEth: 240.8 ± 21.5 mm2, p < 0.001; ELO: 263.1 ± 19.8 mm2, p = 0.006), the broadest surgical field area (415.9 ± 26.4 mm2; EETEth: 386.7 ± 30.1 mm2, p = 0.041; ELO: 305.2 ± 26.3 mm2, p < 0.001), surgical field depths significantly shorter than EETEth (p < 0.001) but similar to ELO, the widest surgical angles of attack (45°-65°; EETEth: 20°-30°, p < 0.001; ELO: 25°-50°, p < 0.001), and the greatest surgical mobility areas (EETEth: p < 0.001; ELO: p < 0.001). Furthermore, the ESTMax allowed multi-angled exposure and handy maneuverability around all the inferior intraorbital targets. Small anterior antrostomy, blunt intraorbital dissections, direct targets' approach, orbital floor reconstruction, and maxillary bone flap replacement may limit the ESTMax morbidity rates. CONCLUSIONS: The ESTMax is a minimally invasive "head-on" orbital approach that exploits endoscopic surgery advantages avoiding the cranio-orbital and trans-nasal approach limitations and possible complications. It represents a promising alternative to EETEth and ELO because of its optimal operability for resecting lesions extending into the entire inferior orbit.

Combined Technique of Temporal Muscle Augmentation for Muscle Reconstruction in Case of Small to Medium Anatomic Defects.

Inadequate temporal muscle (TM) reconstruction after surgery may hesitate in potentially severe functional and aesthetic sequelae, making it of paramount importance to carefully consider TM reconstruction even in case of small deformities.The authors describe the combined temporal muscle augmentation technique (CTMA), an innovative technique for TM augmentation for muscle reconstruction in case of small to medium substance loss.A cadaver study was conducted as preclinical validation of the technique for the assessment of CTMA coverage capability. CTMA consists in a combination of 2 techniques for muscle surface coverage (MSC) increase: the radial (RA) and the longitudinal augmentation (LA), which enables to harvest a radial (RF) and a longitudinal flap (LF), respectively.Each flap derives from a different muscle-bundle, spearing TM segmentation and functional performance, and are supplied by a specific neuro-vascular peduncle, which makes flaps functionally independent.A surgical case is reported to demonstrate the feasibility of the technique.Combined temporal muscle augmentation technique provides an overall coverage surface of 6.5 ± 0.6 cm, which corresponds to a gap distance of 2.5 ± 0.2 cm, with RF providing a statistically significant larger surface of coverage compared to LF (×2.1; P = 0.0001).Combined temporal muscle augmentation technique is easy and fast to perform displaying a good reconstructive capability with complete preservation of temporal muscle anatomic compartmentalization and segmental vasculature. It might be considered as a safe and effective alternative in the reconstruction of small-to medium TM defects.

Mini Fronto-Orbital Approach: "Window Opening" Towards the Superomedial Orbit - A Virtual Reality-Planned Anatomic Study.

BACKGROUND: Surgical approaches to the orbit are challenging and require combined multispecialist skills. Considering its increasing relevance in neurosurgical practice, keyhole surgery could be also applied to this field. However, mastering a minimally invasive approach necessitates an extended learning curve. For this reason, virtual reality (VR) can be effectively used for planning and training in this demanding surgical technique. OBJECTIVE: To validate the mini fronto-orbital (mFO) approach to the superomedial orbit, using VR planning and specimen dissections, conjugating the principles of skull base and keyhole neurosurgery. METHODS: Three-dimensional measurements were performed thanks to Surgical Theater (Surgical Theater© LLC), and then, simulated craniotomies were implemented on cadaver specimens. RESULTS: The mFO approach affords optimal exposure and operability in the target area and reduced risks of surrounding normal tissue injuries. The eyebrow skin incision, the minimal soft-tissue retraction, the limited temporalis muscle dissection and the single-piece craniotomy, as planned with VR, are the key elements of this minimally invasive approach. Furthermore, the "window-opening" cotton-tip intraorbital dissection technique, based on widening surgical corridors between neuromuscular bundles, provides a safe orientation and a deep access inside the orbit, thereby significantly limiting the risk of jeopardizing neurovascular structures. CONCLUSION: The mFO approach associated to the window-opening dissection technique can be considered safe, effective, suitable, and convenient for treating lesions located in the superomedial orbital aspect, up to the orbital apex.

Comparative anatomical study on the role of zygomatic osteotomy in the extradural subtemporal approach to the clival region, when less is more.

PURPOSE: A great concern in performing the extradural subtemporal approach (ESTA) is the evaluation of the actual advantage provided by zygomatic osteotomy (ZO). Complications related to zygomatic dissection have been widely reported in the literature, making it of paramount importance to balance the actual need to perform it, against the risk of maneuver-related morbidity. Authors comparatively analyze the putative advantage provided by ZO in the ESTA in terms of anatomic exposure and surgical operability. Technical limits and potentials are critically revised and discussed. METHODS: A comparative microanatomical laboratory investigation was conducted. The operability score (OS) was applied for quantitative analysis of surgical operability. RESULTS: ZO was found to provide a weakly significant improvement in the surgical angle of attack (p value 0.01) (mean increase 3°). Maneuverability arch (MAC) increase related to ZO did not reach statistical significance (p value 0.09) (mean increase 2°). The variations provided by MAC increase on the conizing effect (CE) did not lead to an actual advantage in the real surgical scenario, modifying the vision area (VA) in terms of reduction of central vision area (CA) in favor of an increase of peripheral vision area (PA) only in the most caudal part of the surgical field. Ultimately, ZO did not influence the overall OS, scoring both ESTA-ZO+ and ESTA-ZO- 2 out of 3. CONCLUSION: In the ESTA, ZO does not provide an actual significant advantage in terms of surgical operability on clival and paraclival areas.

Temporal Galeofascial Flap for Reconstruction After Transmaxillary Approaches to the Clival Region.

BACKGROUND: A paramount concern after transmaxillary approaches has been skull base reconstruction. Regional pedicled flaps represent the best reconstructive option. We have described a technique to harvest a lateral-based multilayered vascularized flap for skull base reconstruction after resection of large tumors using the transmaxillary transpterygoid approach (TMTPA). METHODS: We performed a cadaver study using the TMTPA to harvest the combined temporal galeofascial flap (CTGF). The first layer, with major sealing capabilities, is composed by a temporoparietal galeal-pericranial flap. The second layer is composed by temporal muscle fascia to provide mechanical support for flap dural engrafting. RESULTS: The CTGF provides excellent coverage of both the clival dural lining and the ipsilateral pterygopalatine fossa structures (×1.6). The CTGF is pliable and easy to harvest. It offers great flexibility in flap content and design, providing a large quantity of vascularized tissue. The vascular pedicle derives from the superficial temporal vessels, which can ensure flap trophism. CONCLUSIONS: CTGF represents an effective option as a regional multilayered pedicled flap for skull base reconstruction after resection of clival tumors using the TMTPA. The flap pedicle, owing to its anatomical location, will often be preserved even after repeated microsurgical or endoscopic procedures, providing a technical alternative for reconstruction even in patients who have undergone multiple surgeries with low residual availability of regional flaps.

Endonasal Endoscopic and Transoral Approaches to the Craniovertebral Junction and the Clival Region: A Comparative Anatomical Study.

OBJECTIVE: Anterior craniovertebral junction (CVJ) surgery has continued to be one of the most debated neurosurgical topics. The transoral approach (TOA) has been considered the choice for this region. However, it has some limitations and a not negligible degree of surgery-related morbidity. With the advent of endoscopy, the endoscopic endonasal approach (EEA) was developed, which minimized morbidity and improved exposure. To the best of our knowledge, despite the extensive reported data, a comparative anatomical study has not been performed and no definitive consensus has been reached on the indications for both approaches. METHODS: We compared the TOA and EEA to the CVJ using the previously described operability score (OS), calculated at 4 different targets: the C1 tubercle (C1), the lowest exposed point of the odontoid process (C2), the basion (BS) and the middle clivus (MC). The higher the OS for the selected targets, the more favorable the approach. RESULTS: The TOA had higher OSs at the MC, C1, and C2 targets, and the EEA showed greater OSs at MC and C1. The TOA and EEA had similar OSs at the BS. These results have shown that the OS is more favorable at C1-C2 using the TOA and the OSs at the MC and BS were similar. CONCLUSIONS: The OS is an effective method to compare surgical approaches. The present study demonstrated the maximal exposure capability of the 2 approaches. The TOA seemed to be superior for lower targets and the EEA for upper targets. Because of the strong variability in the CVJ anatomy and pathological features, we suggest considering the OS as a further tool to better define the best surgical approach.

Temporal myofascial segmentation for multilayer reconstruction of middle cranial fossa floor after extradural subtemporal approach to the clival and paraclival region.

BACKGROUND: Skull-base reconstruction represents a concern after resection of middle fossa (MF) tumors by the extradural subtemporal transzygomatic approach (ESTZ). Regional pedicled flaps appear to be the best option. This study describes a technique for temporal myofascial segmentation to harvest a multilayered vascularized flap for MF reconstruction, which might preserve temporal muscle (TM) function and its blood supply. METHODS: The technique to harvest a combined segmented temporal myofascial flap (CSTMF) is described. The flap consists in a temporal fascial (TFF) and a muscle flap (TMF), composed by TM anterior-medial bundle (AMB). RESULTS: CSTMF provides wide coverage of dural lining, through the TFF, and of dead-space, through the TMF. The possibility to tailor TMF according to the need, anatomically preserving the blood supply, enables to significantly increase its volume. CONCLUSION: CSTMF represents an effective option as regional multilayered pedicled flap for MF reconstruction, potentially preserving TM function and minimizing the cosmetic impact.

Anatomic Study on Neuroendoportal Transcortical Approach to Lateral Ventricles.

BACKGROUND: Resection of intraventricular lesions remains a challenge for modern neurosurgery. Endoscopy has provided great advantages in ventricular surgery, even if limited in terms of operability, due to the restricted working channel and impossibility for bimanual surgical manipulation. Tubular approaches have been considered as an option, enabling the use of microsurgical techniques, minimizing violation of brain tissue. The aim of our study was to describe and critically evaluate the use of portal surgery to access lateral ventricles in terms of surgical exposure and operability. METHODS: A microanatomic laboratory cadaver study was conducted with a stepwise description of the surgical technique. The operability score was applied for quantitative analysis of surgical operability, and an illustrative case is reported. RESULTS: Through the anterior approach, the neuroport provides maximal operability at the foramen of Monro and the posterior aspect of the frontal horn, while through the posterior approach maximal operability is achieved in the paratrigonal area. Endoscopic assistance does not affect operability but provides adjunctive exposure in blind spots, as the roof of the frontal horn, the most anterior aspect of the temporal and occipital horn. CONCLUSIONS: Ventricular tubular systems provide adequate visualization, with minimal brain retraction, improving operability as compared with endoscopy. Endoscopic assistance critically widens surgical exposure in blind spots without providing concomitant significant advantage in terms of surgical operability.

Skull Base Neuroendoscopic Training Model Using a Fibrous Injectable Tumor Polymer and the Nico Myriad.

The Myriad is an innovative, high precision tool for tumor resection, designed to work within narrow endoscopic corridors. Due to its application in technically demanding situations, the learning curve associated with its use might be extremely challenging and time-consuming.The authors describe the application of an already validated training model, the skull base injectable tumor model (ITM), to allow trainees to practice with the use of the Myriad during endoscopic skull base procedures.A formalin embalmed cadaveric head was used for technical assessment. Stratathane resin ST-504 derived polymer was injected to mimic skull base tumors and Myriad was used for tumor resection during different endoscopic procedures.An endoscopic endonasal transsphenoidal, a trans-planum trans-tuberculum, and a trans-clival approach have been performed after ITM injection. The Myriad was used for tumor debulking and blunt manipulation, qualitatively evaluating the technical challenges in performing the surgical dissection.Injectable tumor model demonstrates to be a valuable educational tool to train surgeons in the use of Myriad, potentially speeding up the learning curve in the acquirement of necessary technical skills in manipulating the instrument, even in case of demanding surgical situation.

Bilateral Temporal Myofascial Flap for the Reconstruction of Frontal Sinus Defects.

BACKGROUND: A frontal sinus infection, following a transsinus skull base procedure, portends potentially life-threatening complications, making surgical revision mandatory in refractory infections. The authors describe the application of the bilateral temporal myofascial flap (BTMF) as a valuable option for frontal sinus reconstruction, when pericranial or galeal-frontalis myofascial flap (GFMF) is no longer available. METHODS: A microanatomic laboratory cadaver investigation was conducted to obtain anthropometric measurements. Surgical technique is described, and intraoperative images are provided. RESULTS: The surgical steps of this technique and the related intraoperative images are reported. One case illustration regarding frontal sinus reconstruction following a postoperative infection, as a complication after a transsinus procedure, is reported. CONCLUSION: The BTMF should be considered as a valuable option for frontal sinus reconstruction after transsinus skull base procedures when GFMF is not available.

Creating a Culture of Collaboration: A Brief History of Academic Neurosurgery in Washington, DC.

Clinical neurosurgery has been practiced in the US capital for just over 100 years. As former residents and fellows of Drs. Harvey Cushing and Walter Dandy moved to the region, hospitals at Georgetown and George Washington Universities became early adopters of this new surgical discipline. Later academic neurosurgery programs were established at the National Institutes of Health, Walter Reed Medical Center, and Children's National Medical Center. Neurosurgical pioneers at these institutions developed new technologies and diagnostic procedures which continue to inform our current practice. In addition, continued collaboration between the multiple training sites in Washington, DC has uniquely enriched our residents' training experience.

The paramedian supracerebellar transtentorial approach to the posterior fusiform gyrus.

BACKGROUND: The posterior fusiform gyrus lies in a surgically challenging region. Several approaches have been described to access this anatomical area. The paramedian supracerebellar transtentorial (SCTT) approach benefits from minimal disruption of normal neurovascular tissue. The aim of this study was to demonstrate its application to access the posterior fusiform gyrus. METHODS: Three brains and six cadaveric heads were examined. A stepwise dissection of the SCTT approach to the posterior fusiform gyrus was performed. Local cortical anatomy was studied. The operability score was applied for comparative analysis on surgical anatomy. RESULTS: The major posterior landmark used to identify the fusiform gyrus with respect to the medial occipitotemporal gyrus was the collateral sulcus, which commonly bifurcated at its caudal extent. Compared with other surgical approaches addressed to access the region, SCTT demonstrated the best operability in terms of maneuverability arc. Favorable tentorial anatomy is the only limiting factor. CONCLUSIONS: The supracerebellar transtentorial approach is able to provide access to the posterior fusiform gyrus via a minimally disruptive, anatomic, microsurgical corridor.

Endoscope-Assisted Transmaxillosphenoidal Approach to the Sellar and Parasellar Regions: An Anatomic Study.

BACKGROUND: Anterolateral skull base surgery in the sellar and parasellar regions has always represented a technical challenge for neurosurgeons. The microscopic endoscope-assisted transmaxillosphenoidal approach (MEMSA) affords a direct surgical corridor free from critical skull base structures. Here we describe and critically evaluate the use of MEMSA to access the sellar and parasellar areas, in terms of surgical exposure and operability. METHODS: Six cadaveric heads were examined. A stepwise dissection using MEMSA was performed. Relevant anatomy and surgical technique were critically described and comparatively reviewed. The operability score was applied for quantitative analysis of surgical operability. RESULTS: MEMSA provides wide bilateral surgical exposure and vascular control of the sellar, suprasellar, and parasellar regions, achieving the highest operability on the midline and in the parasellar region. The approach can be tailored to the lesion, with the surgical corridor easily widened toward the contralateral pterygopalatine fossa. Anatomic knowledge of maxillary sinus landmarks is key to the use of this approach. Favorable sphenoidal anatomy is the main limiting factor, making MEMSA a surgical alternative to endoscopic endonasal routes in situations where those routes are not feasible, and the approach of choice in selected cases of primarily sellar lesions widely extending contralaterally to the approached maxillary sinus. CONCLUSIONS: MEMSA is a safe and effective technique that provides access to the sellar, suprasellar, and contralateral parasellar areas via a direct, minimally disruptive surgical corridor. The preservation of nasal anatomy ensures the availability of mucosal flaps for use in further reconstruction.