Lateral supracerebellar transtentorial approach for petroclival meningiomas: operative technique and outcome

Surgical Anatomy of the Retrosigmoid Approach With Transtentorial Extension: Protecting the 4th Cranial Nerve

BACKGROUND AND OBJECTIVES

The retrosigmoid approach with transtentorial extension (RTA) allows us to address posterior cranial fossa pathologies that extend through the tentorium into the supratentorial space. Incision of the tentorium cerebelli is challenging, especially for the risk of injury of the cranial nerve (CN) IV. We describe a tentorial incision technique and relevant anatomic landmarks.

METHODS

The RTA was performed stepwise on 5 formalin-fixed (10 sides), latex-injected cadaver heads. The porus trigeminus's midpoint, the lateral border of the suprameatal tubercle (SMT)'s base, and cerebellopontine fissure were assessed as anatomic landmarks for the CN IV tentorial entry point, and relative measurements were collected. A clinical case was presented.

RESULTS

The tentorial opening was described in 4 different incisions. The first is curved and starts in the posterior aspect of the tentorium. It has 2 limbs: a medial one directed toward the tentorium's free edge and a lateral one that extends toward the superior petrosal sinus (SPS). The second incision turns inferiorly, medially, and parallel to the SPS down to the SMT. At that level, the second incision turns perpendicular toward the tentorium's free edge and ends 1 cm from it. The third incision proceeds posteriorly, parallel to the free edge. At the cerebellopontine fissure, the incision can turn toward and cut the tentorium-free edge (fourth incision). On average, the CN IV tentorial entry point was 12.7 mm anterior to the SMT base's lateral border and 20.2 mm anterior to the cerebellopontine fissure. It was located approximately in the same coronal plane as the porus trigeminus's midpoint, on average 1.9 mm anterior.

CONCLUSION

The SMT and the cerebellopontine fissure are consistently located posterior to the CN IV tentorial entry point. They can be used as surgical landmarks for RTA, reducing the risk of injury to the CN IV.

Anatomical Comparison of Endoscopic and Microscopic Exposure of the Petroclinal Core Area Through the Extended Middle Skull Base Approach

OBJECTIVE

To compare the range of endoscopic and microscopic exposure of the petroclival core area through the middle skull base and to observe the corresponding anatomical structures.

METHODS

Ten intact adult cadaveric head specimens fixed with formaldehyde were craniotomized through an expanded middle skull base epidural approach on 20 sides. The distance from the greater superficial petrosal nerve to the petrous ridge was measured. When different degrees (1-3 degrees) of the Kawase triangle bone were removed, the exposed anatomical structure was observed, and the exposed core area of the rock slope was measured under an endoscope and microscope.

RESULTS

The average distance from the greater superficial petrosal nerve to the petrous ridge was 14.26 mm. During 1 to 2 degrees of bone removal, the petrous segment of the internal carotid artery (ICA) was not exposed, whereas during 3 degrees of bone removal, the petrous segment of the ICA was exposed. At 1 degree of bone removal, 400.62 ± 15.73 mm2 of the area was exposed by endoscopy and 170.87 ± 8.93 mm2 by microscopy, and the abducens nerve was not exposed. However, there was a significant difference between the two areas (P < 0.001). During 2 degrees of bone removal, 689.30 ± 32.06 mm2 of the abducens nerve was exposed by endoscopy, but 366.84 ± 30.30 mm2 of the abducens nerve could not be exposed by microscopy; moreover, there was a significant difference in the area of exposure between the two (P < 0.001). At 3 degrees of bone removal, the endoscopic exposure area was 875.92 ± 31.87 mm2, the microscopic exposure area was 699.26 ± 48.00 mm2, and the abducens nerves were exposed. There were significant differences between the two areas (P < 0.001). However, the difference between the 2-degree endoscopic exposure area and the 3-degree microscopic exposure area was studied by using paired t tests, and there was no difference (P > 0.05).

CONCLUSION

When the same degree of the Kawase triangle bone was removed, the extent of endoscopic exposure of the petroclival core area was significantly greater than the extent of microscopic exposure. At 2 degrees of bone removal, an endoscopic application can maximally expose the petroclival core area, thus reducing the probability of exposure damage to the ICA and abductor nerve.

Suprafloccular transhorizontal fissure approach to the cerebellopontine angle: an anatomical study with case series

The suprafloccular transhorizontal fissure approach is a modified variant of the classical retrosigmoid approach option to be chosen for cerebellopontine angle lesions. In this study, we aimed to demonstrate a previously described but not widely used method, the suprafloccular transhorizontal fissure approach with anatomical dissection on the cadaver, accompanied by a case presentation with the largest clinical series in the literature. Klingler's protocol was used to prepare 8 silicone injected and 8 non-silicone injected human hemispheres. A total of 210 patients who underwent surgery in the cerebellopontine angle between 2019 and 2022 were evaluated in our clinic. Of these, the suprafloccular transhorizontal fissure approach was applied in 33 patient, and it was successful in 26 patient, but this approach could not be achieved in 7 patients. The transhorizontal fissure is a fissure in the cerebellum located between the superior semilunar lobule and the inferior semilunar lobule. In the 26 patients we operated with the suprafloccular transhorizontal fissure approach, there was no need for retraction and no complications developed. However, in 7 patients, this fissure could not be dissected due to adhesions. Suprafloccular approach is an alternative to the classical retrosigmoid approach in tumours smaller than 2 cm, medially localised with little cerebellar oedema and neurovascular compression syndrome. Because in this approach, no cerebellum retraction is required, vascular structures are better preserved and the surgical time is shortened. This approach can be applied in smaller tumours than 2 cm when the sulcal anatomy is appropriate.

Surgical morbidity of the extradural anterior petrosal approach: the Lariboisière experience

OBJECTIVE

Concerns about the approach-related morbidity of the extradural anterior petrosal approach (EAPA) have been raised, especially regarding temporal lobe and venous injuries, hearing impairment, facial nerve palsy, cerebrospinal fluid fistula, and seizures. There is lack in the literature of studies with detailed analysis of surgical complications. The authors have presented a large series of patients who were treated with EAPA, focusing on complications and their avoidance.

METHODS

The authors carried out a retrospective review of patients who underwent EAPA at their institution between 2012 and 2021. They collected preoperative clinical characteristics, operative reports, operative videos, findings on neuroimaging, histological diagnosis, postoperative course, and clinical status at last follow-up. For pathologies without petrous bone invasion, the amount of petrous apex drilling was calculated and classified as low (< 70% of the volume) or high (≥ 70%). Complications were dichotomized as approach related and resection related.

RESULTS

This study included 49 patients: 26 with meningiomas, 10 brainstem cavernomas, 4 chondrosarcomas, 4 chordomas, 2 schwannomas, 1 epidermoid cyst, 1 cholesterol granuloma, and 1 osteoblastoma. The most common approach-related complications were temporal lobe injury (6.1% of patients), seizures (6.1%), pseudomeningocele (6.1%), hearing impairment (4.1%), and dry eye (4.1%). Approach-related complications occurred most commonly in patients with a meningioma (p = 0.02) and Meckel's cave invasion (p = 0.02). Gross-total or near-total resection was correlated with a higher rate of tumor resection-related complications (p = 0.02) but not approach-related complications (p = 0.76). Inferior, lateral, and superior tumoral extension were not correlated with a higher rate of tumor resection-related complications. No correlation was found between high amount of petrous bone drilling and approach- or resection-related complications.

CONCLUSIONS

EAPA is a challenging approach that deals with critical neurovascular structures and demands specific skills to be safely performed. Contrary to general belief, its approach-related morbidity seems to be acceptable at dedicated skull base centers. Morbidity can be lowered with careful examination of the preoperative neuroradiological workup, appropriate patient selection, and attention to technical details.

Supracerebellar Infratentorial Approach, Indications, and Technical Pitfalls

Posterior tentorial incisura not infrequently requires to be exposed for tumors of pineal gland, pulvinar, midbrain and cerebellum, aneurysms, arteriovenous malformations. Residing almost at the center of the brain, this area is almost equal distance to any point on the calvarium behind coronal sutures enabling alternative routes to encounter. Compared to supratentorial routes either subtemporal or suboccipital approach, infratentorial supracerebellar route has several advantages as providing shortest, most direct approach to the lesions of this area without encountering any important arteries and veins. Since its initial description at the early twentieth century, a wide range of complications arising from cerebellar infarction, air embolism, and neural tissue damage have been encountered. Working in a deep, narrow corridor without enough illumination and visibility under very limited anesthesiology support hindered popularization of this approach. In the contemporary era of neurosurgery, advanced diagnostic tools and surgical microscopes with state-of-the-art microsurgery techniques coupled with modern anesthesiology have eliminated almost all drawbacks of infratentorial supracerebellar approach.

Endoscopic-enhanced supra-cerebellar trans-tentorial (SCTT) approach to temporo-mesial region: a multicenter study

Surgical access to the temporo-mesial area may be achieved by several routes such as the sub-temporal, the temporal trans-ventricular, the pterional/trans-sylvian, and the occipital interhemispheric approaches; nonetheless, none of them has shown to be superior to the others. The supra-cerebellar trans-tentorial approach allows a great exposure of the middle and posterior temporo-mesial region, while avoiding temporal lobe retraction. A prospective multicenter study was designed to collect data on patients undergoing endoscopic-enhanced SCTT approach to excise left temporo-mesial lesions. The study involved 5 different neurosurgical European centers and ran from 2015 to 2020. All patients had preoperative as well as postoperative brain MRI and ophthalmology evaluation. A total of 30 patients were included in this study, the mean follow-up was 44 months (range 18 to 84 months), male/female ratio was 16/14, and mean age was 39 years. A gross total resection was achieved in 29/30 (96.7%) cases. All surgical procedures were uneventful, without transient or permanent neurological deficits thanks to the preservation of the posterior cerebral artery. The endoscopic-enhanced SCTT approach provides satisfactory exposure to the left temporo-mesial region. Its minimally invasive nature helps minimize the surgical risks related to vascular and white tract manipulation, which represent known limitations of open microsurgical as well as other approaches.

Midline Skull Base Meningiomas: Transcranial and Endonasal Perspectives

Simple Summary

Skull base meningiomas have always represented a challenge for neurosurgeons. Despite their histological nature, they may be associated with unfavorable outcomes due to their deep-seated location and the surrounding neurovascular structures. Over time, several corridors have been proposed, each one carrying its own pros and cons. During the last decades, the endoscopic endonasal route has been asserted among the classic routes for a growing number of midline and paramedian lesions. Therefore, the aim of our paper is to present a comprehensive review of the indications and techniques for the management of skull base meningiomas, emphasizing the ambivalent and complementary role of the low and high routes.

Abstract

Skull base meningiomas have always represented a challenge for neurosurgeons. Despite their histological nature, they may be associated with unfavorable outcomes due to their deep-seated location and the surrounding neurovascular structures. The state of the art of skull base meningiomas accounts for both transcranial, or high, and endonasal, or low, routes. A comprehensive review of the pertinent literature was performed to address the surgical strategies and outcomes of skull base meningioma patients treated through a transcranial approach, an endoscopic endonasal approach (EEA), or both. Three databases (PubMed, Ovid Medline, and Ovid Embase) have been searched. The review of the literature provided 328 papers reporting the surgical, oncological, and clinical results of different approaches for the treatment of skull base meningiomas. The most suitable surgical corridors for olfactory groove, tuberculum sellae, clival and petroclival and cavernous sinus meningiomas have been analyzed. The EEA was proven to be associated with a lower extent of resection rates and better clinical outcomes compared with transcranial corridors, offering the possibility of achieving the so-called maximal safe resection.

The mini-combined transpetrosal approach: an anatomical study and comparison with the combined transpetrosal approach

BACKGROUND

The combined transpetrosal approach (CTPA) is a versatile technique suitable for challenging skull base pathologies. Despite the advantages provided by a wide surgical exposure, the soft tissue trauma, complex and time-consuming bony work, and cosmetic issues make it far from patient expectations. In this study, the authors describe a less invasive modification of the CTPA, the mini-combined transpetrosal approach (mini-CTPA), and perform a quantitative comparison between these two approaches.

METHODS

Five human specimens were used for this study. CTPA was performed on one side and mini-CTPA on the opposite side. The surgical freedom, petroclival and brainstem area of exposure, and maneuverability for 6 anatomical targets, provided by the CTPA and mini-CTPA, were calculated and statistically compared. The bony volumes corresponding to each anterior petrosectomy were also measured and compared. Three clinical cases with an operative video are also reported to illustrate the effectiveness of the approach.

RESULTS

The question-mark skin incision done along the muscle attachments permits an optimal cosmetic result. Even though the limited incision, the smaller craniotomy, and the less extensive bone drilling of mini-CTPA provide a smaller area of surgical freedom, the areas of exposure of petroclival region and brainstem were not statistically different between the two approaches. The antero-posterior maneuverability for the oculomotor foramen (OF), Meckel's cave (MC) and the REZ of trigeminal nerve, and the supero-inferior maneuverability for OF, MC, Dorello's canal, and REZ of CN VII are significantly reduced by the smaller opening. The bony volume of anterior petrosectomy resulted similar among the approaches.

CONCLUSIONS

The mini-CTPA is an interesting alternative to the CTPA, providing comparable surgical exposure both for petroclival region and for brainstem. Although the lesser soft tissue dissection and bony opening decrease the surgical maneuverability, the mini-CTPA may reduce surgical time, potential approach-related morbidities, and improve cosmetic and functional outcomes for the patients.

Endoscopic Far-Lateral Supracerebellar Infratentorial Approach for Petroclival Region Meningioma: Surgical Technique and Clinical Experience

BACKGROUND

The management of petroclival region meningioma remains the ultimate achievement in neurosurgery, because of the formidable technical challenges involved.

OBJECTIVE

To describe the technique and feasibility of the purely endoscopic far-lateral supracerebellar infratentorial approach (EF-SCITA) for the treatment of petroclival region meningiomas.

METHODS

We reviewed the clinical data of 10 consecutive cases of petroclival region meningiomas treated with the EF-SCITA from August 2018 to August 2020. The clinical outcomes were analyzed. The patient was placed in the lateral position, and then, a "C" shaped incision and craniotomy with exposed sigmoid and transverse sinuses were performed. With the endoscopic holder, endoscopic procedures were performed using standard 2-hand microsurgical techniques. Whether the tentorium or Meckel cave was handled depended on the tumor extension.

RESULTS

The mean diameter was 45 × 25 mm. Dizziness and headache were the main symptoms. All 10 patients achieved gross total or subtotal resection (Petroclival Meningioma Grade I-III) with good neurological outcomes. The EF-SCITA provides satisfactory, direct exposure to the petroclival region. Cranial nerve deficits are the main postoperative complications. Two patients had a trochlear nerve injury, 3 patients had transient facial paralysis, and 2 patients had oculomotor paralysis (1 total and 1 incomplete), but both of them recovered during the follow-up period. One patient experienced an ipsilateral superior cerebellar artery infarction, and another patient had transient hemiparesis.

CONCLUSION

The EF-SCITA is effective for most petroclival region meningiomas, except for the cavernous sinus type. This approach simplifies craniotomy procedures, omits burdensome petrosectomy, and avoids crossing posterior neurovascular structures.

Factors Associated With Abducens Nerve Palsy in Patients Undergoing Surgery for Petroclival Meningiomas

BACKGROUND

During the surgical resection of petroclival meningiomas, preserving the cranial nerves is crucial. The abducens nerve is particularly vulnerable during surgery. However, the preoperative risk factors and postoperative prognosis of abducens nerve palsy (ANP) are poorly understood.

METHODS

We retrospectively analyzed 70 patients who underwent surgery for petroclival meningiomas between May 2010 and December 2019, divided into gross-total resection (GTR) and subtotal resection (STR) groups. The relationship of preoperative clinical factors with the incidence and recovery of postoperative ANP was analyzed.

RESULTS

Postoperative ANP was observed in 23 patients (32.9%). Multivariable logistic regression revealed that the tumor-to-cerebellar peduncle T2 imaging intensity index (TCTI) (P < 0.001) and internal auditory canal invasion (P = 0.033) contributed to postoperative ANP. GTR was achieved in 37 patients (52.9%), and 10 (27.0%) of them showed ANP. STR was achieved in 33 patients (47.1%), and 13 (39.4%) of them showed ANP. Recovery from ANP took a median of 6.6 months (range, 4.5-20.3 months). At 6 months after the operation, recovery of the abducens nerve function was observed in 16 patients (69.0%); of whom, 4 (40.0%) were in the GTR group and 12 (92.3%) were in the STR group (P = 0.025).

CONCLUSIONS

TCTI and internal auditory canal invasion were the risk factors for postoperative ANP. Although intentional STR did not prevent ANP immediately after the operation, recovery of the abducens nerve function after surgery was observed more frequently in the STR group than in the GTR group.

Mortality and morbidity in surgically treated patients with petroclival meningiomas: a systematic review and meta-analysis of case series

BACKGROUND

Reports on petroclival meningioma (PCM) surgical mortality and morbidity often deviate from established standards; as such, a comprehensive summary is lacking.

METHODS

Eligibility/sources. Peer-reviewed case series of at least 10 PCM patients identified from PubMed, Web of Science, Ovid, or Google Scholar. Outcomes. Primary: mortality, tumor recurrence, any cranial nerve deficit (CND); other: individual CNDs, other complications. Data synthesis. Random-effects meta-analysis/meta-regression [effects: surgical approach (supratentorial, S; infratentorial, I; combined, (C), average age and follow-up, sample size, and percent of patients with gross-total resection (GTR)] of logit-transformed proportions.

RESULTS

Data. 73 case-series/3553 patients. Mortality. Adjusted predicted mortalities of 2.4%, 2.5%, and 1.2% (50-month follow-up) for the S, I, and C approaches, respectively, with the upper limits of the 95% credibility intervals at 3.3%, 3.7%, and 3.6%, respectively. Recurrence. Adjusted predicted recurrences of 5.5%, 11.1%, and 12.0% (50-month follow-up and 57% GTR) for the S, I, and C approaches, respectively; recurrence was positively associated with follow-up period and negatively associated with having received GTR. At all covariates at median values but at GTR 90% predictions: 3.1% (95%CI 3.1-9.8), 6.3% (3.8-10.4), and 6.9% (3.4-13.2) with the S, I, and C; prediction credibility intervals 1-4% and 22.4%. Any CND. Adjusted predicted probabilities of 37.2%, 23.4%, and 29.5% (at median covariate values) for the S, I, and C approaches, respectively; prediction credibility intervals ranged from <10% to 78%. Other outcomes. The most common individual CNDs were nVII (14.4%), nV (11.5%), and nIII (10.2%); other common complications included motor deficit (10.8%), infection (9.8%), and CSF leak (7.5%).

CONCLUSION

This is the first systematic review on PCM surgical mortality, recurrence, and morbidity. Outcomes differ between surgical approaches and reporting quality varies greatly.

Petroclival meningiomas: update of current treatment and consensus by the EANS skull base section

BACKGROUND

The optimal management of petroclival meningiomas (PCMs) continues to be debated along with several controversies that persist.

METHODS

A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the management of these tumors. To achieve this, the task force reviewed in detail the literature in this field and had formal discussions within the group.

RESULTS

The constituted task force dealt with the existing definitions and classifications, pre-operative radiological investigations, management of small and asymptomatic PCMs, radiosurgery, optimal surgical strategies, multimodal treatment, decision-making, and patient's counselling.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the management of PCMs.

Clip retraction of the tentorium: application of a novel technique for tentorial retraction during supracerebellar transtentorial approaches

Supracerebellar transtentorial (SCTT) approaches have become a popular option for treatment of a variety of pathologies in the medial and basal temporal and occipital lobes and thalamus. Transtentorial approaches provide numerous advantages over transcortical approaches, including obviating the need to traverse eloquent cortex, not requiring parenchymal retraction, and circumventing critical vascular structures. All of these approaches require a tentorial opening, and numerous techniques for retraction of the incised tentorium have been described, including sutures, fixed retractors, and electrocautery. However, all of these techniques have considerable drawbacks and limitations. The authors describe a novel application of clip retraction of the tentorium to the supracerebellar approaches in which an aneurysm clip is used to suspend the tentorial flap, and an illustrative case is provided. Clip retraction of the tentorium is an efficient, straightforward adaptation of an established technique, typically used for subtemporal approaches, that improves visualization and surgical ergonomics with little risk to nearby venous structures. The authors find this technique particularly useful for the contralateral SCTT approaches.

Petroclival meningiomas: the risk of post-operative cranial nerve deficits among different surgical approaches-a systematic review and meta-analysis

BACKGROUND

The surgical resection of petroclival meningiomas (PCMs) remains a challenge. Both the relationship with neurovascular structures and the deep location of the tumor can affect the extent of resection and the rate of post-operative morbidity.

METHODS

The authors performed a systematic review and meta-analysis of the literature examining the rate of new cranial nerve (CN) deficits after resection of PCM. A systematic search of two databases was performed for studies published between 1990 and 2018. Random-effect meta-analysis was used to pool the rate of post-operative CN deficits, mortality rate, and rate of radical resection.

RESULTS

We included twelve studies and 334 patients harboring PCM. The overall rate of complete resection was 68% (95% CI 57.9-78.2%; p < 0.01; I² = 83%). The rate of early and late post-operative CN deficits was the following: 3.8 and 2.7% (III CN), 6.6 and 3% (IV), 7.3 and 5.5% (V CN), 8 and 3.6% (VI CN), 8.9 and 8.9%% (VIII), and 4 and 2.7% (IX-XI CNs) (I² = 0%, and p < 0.01 for all analyses). The risk of post-operative deficit of the IV CN was higher among the petrosal group (7.6%; I² = 0% vs 2.1%; I² = 0%), whereas the impairment of VII CN function was higher among retrosigmoid group (16.6%; I² = 64.6% vs 11.4%; I² = 52.8%), but it was transient in the majority of cases.

CONCLUSIONS

This systematic review and meta-analysis provides a detailed overview of post-operative CN deficits ensuing surgical resection of PCMs. These findings should be acknowledged when counseling patients with PCMs regarding the more appropriate approach for their tumor.

Petroclival Meningiomas: Factors Determining the Choice of Approach

Objectives  To review a surgical series of petroclival meningiomas and the factors considered in the choice of approach. Design  Retrospective review. Setting  The study was conducted in a university hospital in southern Brazil. Participants  Twenty-two patients with petroclival meningioma originating from the upper two-thirds of the clivus medial to the fifth cranial nerve. Main Outcome Measures  Gross-total resection, mortality, major morbidity, new cranial nerve deficits and tumor progression or recurrence. Results  Retrosigmoid approach was used in tumors <3 cm and in those at or below the internal auditory meatus. Posterior petrosectomy was performed for tumors extending into the middle fossa. Gross-total resection was performed in 11 patients (50%). The mean follow-up time was 32 months (6-75 months). There were four cases of tumor progression or recurrence, which were treated with radiosurgery. Conclusions  Resection of petroclival meningiomas remains challenging. In most cases, the retrosigmoid approach was sufficient, without affecting the degree of tumor resection. Petrosal approaches were reserved for patients with tumor extension into the middle fossa.

Surgical Management of Anterolateral and Posteromedial Incisural Tentorial Meningioma

BACKGROUND

Tentorial meningiomas are a broad and consistent category of tumors but their definition is still unclear and their classification uncertain.

OBJECTIVE

To report the clinical and surgical characteristics of tentorial hiatus meningiomas based on a revised classification of tentorial meningiomas.

METHODS

We reviewed the records of 14 patients who had undergone microsurgical removal of incisural tentorial meningioma. Two tumor subgroups, anterolateral (AL) and posteromedial (PM), were distinguished according to their site of attachment: the middle third and the posterior third of the tentorial free margin, respectively. Clinical presentation, radiological findings, surgical approaches, extent of resection, and outcome were compared.

RESULTS

The 2 subgroups differed by tumor size (larger in PM), incidence of the direction of growth (infratentorial in PM), and hydrocephalus (only in PM), as well as by some clinical aspects. Surgical approach depended on tumor location: lateral (pterional, subtemporal, and retromastoid) for AL lesions; medial (occipital or supracerebellar infratentorial) for PM lesions. Total removal (Simpson grade I-II) was performed in 64% of cases and complications occurred in 14%. Stereotactic radiosurgery was performed in cases of incomplete resection. At a mean follow-up of 104.5 mo, clinical improvement with low recurrence (9%) was achieved.

CONCLUSION

Reallocation of tentorial edge meningiomas is the premise to compare treatment and further improve the approach case-by-case. In spite of their deep site, good outcomes can be achieved in both AL and PM tentorial meningiomas. Also of note is the indolent behavior of residual tumor.

Endoscopic Supracerebellar Transtentorial Approach to Atrium of Lateral Ventricle: Preliminary Surgical and Optical Considerations

OBJECTIVE

We sought to report the operative techniques of the endoscopic supracerebellar transtentorial approach (ESTA) to the atrium of the lateral ventricle, especially focusing on the role of the endoscope and analyzing optically related issues.

METHODS

A retrospective data review was performed on 5 patients with lesions in the atrium of the lateral ventricle undergoing the ESTA. The patients were positioned in the three quarters prone position, and a paramidline linear incision was used. After performing a suboccipital craniotomy extending immediately above the transverse sinus and tentorium incision with precisely neuronavigation, corticotomy in the posterior mediobasal temporal region created a corridor to the tumor. All of the procedures were performed with an endoscope in a pneumatic arm holder. The preoperative and postoperative perimetry test and diffusion tensor imaging fiber tracking of the optic radiations were compared and analyzed.

RESULTS

Three patients had meningiomas, and 2 patients had high-grade gliomas in the atrium. The meningiomas were totally removed, and the gliomas were subtotally resected. One patient with glioblastoma died 2 months later after surgery because of the tumor progression; the remaining 4 patients had a visual field deficit without any other neurologic complications. The endoscope improved the surgical viewing angle, which was restricted by the microscope and slope of the tentorium.

CONCLUSIONS

ESTA is an alternative route to the atrium of the lateral ventricle. However, the collateral sulcus, which is highly relied on in neuronavigation, is illegible in the limited area. And the visual field deficit remains the primary challenge with this approach.

Petroclival meningiomas: Remaining controversies in light of minimally invasive approaches

Surgical resection of petroclival meningiomas remains challenging due to their deep location and relationship to vital neurovascular structures. Although the natural history of these tumors involves a slow course, the incidence of cranial nerve deficits and the extent of tumor resection vary widely in the literature. Some reviews on this topic have been conducted, but data remain fragmentary and based on retrospective case series, which hinders attempts at meta-analysis. Within this context, research into the use of minimally invasive approaches, including in neuroendoscopy, continues to emerge. The objective of this narrative review is to analyze the available literature on the surgical treatment of petroclival meningiomas, with a focus on attempts at endoscopy-assisted resection.

[The paramedian supracerebellar transtentorial approach to the mediobasal temporal region]

The mediobasal temporal region (MTR) is located near the brain stem and surrounded by the eloquent neurovascular structures. The supracerebellar transtentorial approach (STA) is safe access to the posterior MTR structures, however its use for resection of anterior MTR lesions still remains controversial. The article describes the technique and outcome of surgery for different MTR structures using STA.

MATERIAL AND METHODS

The paramedian STA was used in 18 patients (13 females and 5 males) for 7 years. Ten patients presented with glial MTR tumors, 3 patients with cavernomas, 2 patients with arteriovenous malformations (AVMs), 2 patients with intraventricular meningiomas, and 1 patient with mesial temporal sclerosis. The patient age ranged from 19 to 57 years. In 10 cases, lesions were localized on the left. Epilepsy was the leading symptom in 14 cases. Patients underwent preoperative high-resolution MRI, electroencephalography video monitoring before and after surgery, intraoperative corticography (if necessary), and postoperative CT and MRI.

RESULTS

Lesions were located in the anterior third of MTR in 5 patients, in the anterior and middle thirds in 2 patients, in the middle third in 5 patients, in the middle and posterior thirds in 2 patients, in the posterior third in 1 patient, in the anterior, middle, and posterior thirds in 1 patient, and in the ventricular triangle area in 2 patients. In all patients with intraventricular tumors, AVMs, and cavernous malformations and in 8 patients with glial MTR tumors, the lesions were totally resected. Two patients with intracerebral tumors underwent subtotal resection. A patient with intractable epilepsy and mesial temporal sclerosis underwent resection of the anterior two-thirds of the hippocampus and parahippocampal gyrus and, partially, amygdala using intraoperative corticography. There was no surgical mortality; 2 patients developed a transient neurological deficit, and 1 patient had a cerebellar hematoma that was successfully removed during surgery.

CONCLUSION

STA enables resection of lesions localized in all parts of the MTR, without damage to the surrounding nerve and vascular structures.

Surgical Resectability of Skull Base Meningiomas

With recent advances in surgical technology such as preoperative imaging, neuro-monitoring, and surgical instruments, the surgical resectability of intracranial meningiomas has increased over the last two decades. This study reviewed clinical articles regarding the surgical treatment of meningiomas to clarify the role of surgical excision, with a focus on skull base meningiomas. We sub-classified clinical articles about skull base meningiomas into two categories (anterior and middle fossa meningiomas; and posterior fossa meningiomas) and reviewed papers in each category. In cases with anterior and middle fossa meningiomas, surgical resectability has reached a sufficient level to maximize functional preservation. In cases of posterior fossa meningioma, however, surgical respectability remains insufficient even with full use of recent surgical modalities. Continuous refining of operative procedures is required to obtain more satisfactory outcomes, especially for posterior fossa meningioma. In addition, recent long-term outcomes of stereotactic radiosurgery (SRS) were acceptable for controlling the skull base meningiomas. Therefore, combination with surgical excision and SRS should be considered in complicated skull base meningiomas.

Endoscopic and Gravity-Assisted Resection of Medial Temporo-occipital Lesions Through a Supracerebellar Transtentorial Approach: Technical Notes With Case Illustrations

BACKGROUND

Traditional approaches to medial temporo-occipital intra-axial brain tumors carry the risk of visual or language deficits related to brain retraction or transgression of deep fiber tracts. To reduce these risks, the microscopic supracerebellar transtentorial approach with the patient in the sitting position has been previously described for lesions in relative proximity to the tentorium.

OBJECTIVE

We describe this approach performed with endoscopic tumor resection to allow better visualization and a more ergonomic operating position.

METHODS

Four consecutive patients harboring a medial temporo-occipital lesion are reported. All were operated on while in the sitting position using frameless navigation and a supracerebellar transtentorial approach. Tumor resection was performed by 2 surgeons with endoscopic visualization.

RESULTS

Pathologies included intraparenchymal metastatic melanoma, cavernous hemangioma, and ganglioglioma, as well as an intraventricular metastatic tumor. The distance from the tentorium to the lesion ranged from 1 to 4 mm. Gross total resection was achieved in 3 of the 4 patients. The patient with a metastatic melanoma had an intentional near-total resection given the tumor encasing a branch of the posterior cerebral artery. The patient with the intraventricular tumor sustained a small but symptomatic infarct of the lateral geniculate region, resulting in a visual field deficit.

CONCLUSION

This small series suggests that the endoscopic supracerebellar transtentorial approach with the patient in the sitting position can be a safe and effective approach for removing medial temporo-occipital lesions. It allows excellent tumor visualization, eliminates the need for brain retraction, minimizes parenchymal transgression, and improves surgical ergonomics. Significant experience in endoscopy and excellent neuroanesthesia support are recommended before undertaking this approach.

The supracerebellar-transtentorial approach to posteromedial temporal lesions in children with refractory epilepsy

OBJECT

Operations on tumors of the posteromedial temporal (PMT) region, that is, on those arising from the posterior parahippocampal, fusiform, and lingual gyri, are challenging to perform because of the deep-seated location of these tumors between critical cisternal neurovascular structures and the adjacent temporal and occipital cortexes. Traditional surgical approaches require temporal or occipital transgression, retraction, or venous sacrifice. These approaches may result in unintended complications that should be avoided. To avoid these complications, the supracerebellar-transtentorial (SCTT) approach to this region has been used as an effective alternative treatment in adult patients. The SCTT approach uses a sitting position that offers a direct route to the posterior fusiform and lingual gyri of the temporal lobe. The authors report the feasibility, safety, and efficacy of this approach, using a modified lateral park-bench position in a small cohort of pediatric patients.

METHODS

The authors carried out a retrospective case review of 5 consecutive patients undergoing a paramedian SCTT approach between 2009 and 2014 at the authors' institution.

RESULTS

The SCTT approach in the park-bench position was used in 3 boys and 2 girls with a mean age of 7.8 years (range 13 months to 16 years). All patients presented with a seizure disorder related to a tumor in a PMT region involving the parahippocampal and fusiform gyri of the left (n = 3) or right (n = 2) temporal lobe. No procedure-related complications were observed. Gross-total resection and control of seizures were achieved in all cases. Tumor classes and types included 1 Grade II astrocytoma, 1 pleomorphic xanthoastrocytoma, 1 ganglioglioma, and 2 glioneural tumors. None of the tumors had recurred by the mean follow-up of 22 months (range 1-48 months). Outcomes of epileptic seizures were excellent, with seizure symptoms in all 5 patients scoring in Engel Class IA.

CONCLUSIONS

The SCTT approach represents a viable option when resecting tumors in this region, providing a reasonable working corridor and low morbidity. The authors' experience in a cohort of pediatric patients demonstrates that complete resection of the lesions in this location is feasible and is safe when involving an approach that involves using a park-bench lateral positioning.

Recurrent petroclival meningiomas: clinical characteristics, management, and outcomes

This study seeks to elucidate the prognostic predictors and outcomes of recurrent/progressive petroclival meningiomas (PCMs). We reviewed our cohort of 39 recurrent/progressive PCMs (27 females, 69.2%) and analyzed the results from the literature. Twenty-three patients underwent reoperations, 2 received radiotherapy alone, and 14 declined any treatment. During a follow-up of 70.4 months, 7 patients experienced a 2nd recurrence/progression (R/P) and 18 patients died. In the 23 patients, gross total resection (GTR), subtotal resection (STR), and partial resection (PR) were achieved in 8, 8, and 7 patients, respectively. The percentage of the 2nd R/P-free survival of GTR, STR, and PR was 88%, 67%, and 40%, respectively. The overall survival following the 1st R/P of GTR, STR, and PR was 88%, 63%, and 33%, respectively. Patients rejecting treatment suffered from significantly poor overall survival (7%; p = 0.001) and short survival duration (42.0 months; p = 0.016) compared with that of the patients receiving treatment (67% and 86.9 months). The GTR was the only independent favorable predictor. In the 21 included studies with 98 recurrent/progressive PCM patients, 17 patients presented with a 2nd R/P and 10 died of a 2nd R/P; patients undergoing observation had a significantly poor tumor regrowth control rate compared with patients undergoing surgery (p = 0.004) or radiotherapy alone (p < 0.001). Proactive treatment should be performed for patients with recurrent/progressive PCMs. Observation can lead to relentless outcome. GTR as a preferential therapeutic strategy should be pursued as far as possible on the condition of minimal functional impairment.

Petroclival meningiomas: an update on surgical approaches, decision making, and treatment results

OBJECT

Petroclival meningiomas remain a formidable challenge for neurosurgeons because of their location deep within the skull base and proximity to eloquent neurovascular structures. Various skull base approaches have been used in their treatment, and deciding which is the optimal one remains controversial. Attempts at achieving gross- or near-total resections are associated with an increased rate of morbidity and mortality. As adjunctive treatment options such as stereotactic radiosurgery have been developed and become widely available, there has been a trend toward accepting subtotal resections in an effort to minimize neurological morbidity. This paper reviews a recent series of patients with petroclival meningiomas and highlights current management trends and important considerations useful in surgical decision making.

METHODS

The records of patients with large (> 3 cm) petroclival meningiomas surgically treated by the senior author over the past 5 years were reviewed. The clinical results are presented as examples of the surgical approaches available for approaching these tumors, and treatment options are reviewed.

RESULTS

Of 196 meningiomas surgically treated during the study period, 8 lesions in 8 patients met the study criteria. Overall clinical results were excellent, with no death or major morbidity. Intracranial gross- or near-total resection (Simpson Grade 1, 2, or 3) was achieved in 5 patients (67%). New cranial nerve deficits occurred in 3 patients (37%) and were more common in patients in whom a subtotal resection was performed (2 of 3 cases). A variety of surgical approaches were used. Important considerations determining the best approach include the location of the tumor relative to the internal auditory canal, the presence of preoperative hearing loss, and the location of the tumor relative to the tentorium.

CONCLUSIONS

Achieving gross- or near-total resections of large petroclival meningiomas remains achievable and should be the primary goal of surgical treatment. A retrosigmoid craniotomy remains a workhorse surgical approach for most petroclival tumors of any size. Tumors that are medial to the internal auditory canal and span both middle and posterior cranial fossae are often best treated with a combined transpetrosal approach, which is especially true if there is a preoperative hearing deficit.

Keyhole supracerebellar transtentorial transcollateral sulcus approach to the lateral ventricle

BACKGROUND AND IMPORTANCE

Meningiomas of the lateral ventricles are commonly located in the atria. Surgical access to such tumors is challenging because of their deep location and proximity to critical neurovascular structures, particularly if situated on the dominant side. Although a number of approaches have been described in the literature, most carry the risk of postoperative neuropsychological, visual, or speech deficits, especially when operating on the dominant hemisphere. The supracerebellar transtentorial transcollateral sulcus (STTCS) approach offers the potential to circumvent functionally important structures, reducing the risk of these approach-related neurological deficits.

CLINICAL PRESENTATION

Two patients with dominant hemisphere trigonal meningiomas underwent surgical resection with the use of the STTCS approach. Neuronavigation was used to carefully plan the incision, craniotomy, and exposure, and also intraoperatively to orientate the operating surgeon at key steps, particularly when raising the tentorial flap in line with the tumor. Endoscopy was used to provide increased light intensity, an extended viewing angle, and higher magnification in comparison with a microscope. Specially designed tube-shaft instruments were also used to assist with manipulation through the narrow surgical corridor. In both cases, the tumors were fully resected without approach-related morbidity.

CONCLUSION

The STTCS approach provides good access to tumors located in the trigonal region, reducing the risk of iatrogenic language or visual field deficits. In dominant hemisphere lesions, in the hands of an experienced neurosurgeon, the STTCS approach is an effective alternative to existing techniques.

Anatomy of the superior petrosal veins and their exposure and management during petrous apex meningioma surgery using the lateral suboccipital retrosigmoid approach

During surgeries in the upper cerebellopontine angle (CPA), the superior petrosal veins (SPVs) often act as obstacles; and their sectioning sometimes causes serious complications. In this study, we introduced a classification system for the SPVs wherein their tributaries were classified into four groups on the basis of their courses and draining areas. We furthermore explained the detailed anatomy of the vein of the cerebellopontine fissure, which is the largest tributary. In surgeries of petrous apex meningioma, the knowledge of the displacement pattern of the vein is very helpful for avoiding major venous complications. Therefore, we elucidated its anatomical situation in relation to the original portion of the meningioma and the natural draining point of the vein into the superior petrosal sinus (SPS) in each patient. In addition, we described the methods and techniques used to expose and manage the vein of the cerebellopontine fissure during surgery using the lateral suboccipital retrosigmoid approach. Presenting two illustrative cases, we recommend that the initial exposure of the tumor should be performed through the infratentorial lateral supracerebellar route and that the suprafloccular cistern is the best area to find the vein of the cerebellopontine fissure. We emphasized the importance of the preservation of the vein of the cerebellopontine fissure and also proposed the order for exposure of SPV tributaries during upper CPA surgery using the retrosigmoid approach.

The extended supracerebellar transtentorial approach for resection of medial tentorial meningiomas

BACKGROUND

The supracerebellar transtentorial (SCTT) approach has been established as a safe corridor to access the posteriomedial basal temporal region. Previous reports have demonstrated the efficacy of this route in the resection of intrinsic tumors and small arteriovenous malformations. Only one report in the English literature has described its use to resect a medial tentorial meningioma.

METHODS

The authors discuss the relevant surgical anatomy of this approach and its advantages compared with more traditional routes, and illustrate its application to remove medial tentorial meningiomas through two operative cases with accompanying videos.

RESULTS

In illustrative case one, the patient recovered from surgery with no deficits. All his preoperative symptoms had resolved at 3-month follow-up. At the 4-year follow-up, MRI did not demonstrate any growth of the residual tumor. In case two, gross total resection was achieved and the patient did not suffer any postoperative language or visual deficit. At 2-year follow-up, no tumor recurrence was present.

CONCLUSION

The SCTT approach has a potential to safely access extra-axial lesions located around the medial tentorial incisura. As demonstrated in these two cases, the approach merits consideration in patients with tentorial meningiomas as an alternative to more widely utilized skull base approaches and subtemporal routes.

A Comparison between the Kawase and Extended Retrosigmoid Approaches (Retrosigmoid Transtentorial and Retrosigmoid Intradural Suprameatal Approaches) for Accessing the Petroclival Tumors. A Cadaveric Study

Background The aim of our study was to compare the area of exposure at the ventral brainstem and petroclival region offered by the Kawase, retrosigmoid transtentorial (RTT), and the retrosigmoid intradural suprameatal (RISA) approaches in cadaveric models. Methods We performed 15 approaches (five each of the Kawase, RISA, and RTT approaches) on silicone-injected adult cadaver heads. Ventral brainstem and petroclival areas of exposure were measured and compared. Results The mean ventral brainstem area exposed by the Kawase approach was 55.00 ± 24.1 mm(2), significantly less than that exposed by RTT (441 ± 63.3 mm(2)) and RISA (311 ± 61 mm(2)) (p < 0.05). The area of ventral brainstem exposure was significantly more via RTT than through RISA (p = 0.01). The mean petroclival area of exposure through the Kawase approach was significantly smaller than that obtained through the RTT and RISA approaches (101.7 ± 545.01 mm(2), 696 ± 57.7 mm(2), and 716.7 ± 51.4 mm(2), respectively). Conclusion Retrosigmoid approaches provide a greater exposure of the brainstem and petroclival areas. The Kawase approach is ideally suited for lesions around the Meckel cave with an extension into the middle fossa. These approaches can be used in conjunction with one another to access petroclival tumors.

Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion. Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel's cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel's cave. In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor. The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.

Surgical management and outcomes of petroclival meningiomas: a single-center case series of 259 patients

BACKGROUND

Surgical management of petroclival meningiomas is challenging. Various and inconsistent outcome and prognostic factors of the lesions have been evaluated previously. In the present study, the surgical outcome, philosophy, and experience of petroclival meningiomas are detailed based on a large patient series.

METHODS

A series of 259 patients with petroclival meningiomas (70 males and 189 females) were surgically treated. Clinical charts and radiographs were reviewed. Follow-up results were evaluated.

RESULTS

The preoperative Karnofsky Performance Scale (KPS) score was 74.2 ± 10.5. The mean tumor size was 4.3 ± 1.0 cm. The gross total resection (GTR) rate was 52.5%. During a mean follow-up period of 55.3 months, recurrence/progression (R/P) occurred in 11 patients. The recent KPS score was 78.4 ± 22.7, it improved in 139 (57.2%) patients and stabilized in 53 (21.8%) patients, and 201 (82.7%) patients lived independently. The risk factors affecting the KPS score included (but were not limited to) age ≥ 60, preoperative KPS ≤ 60, and brainstem edema. The adverse factors contributing to R/P-free survival included (but were not limited to) non-total resection and the absence of the subarachnoid space. The R/P-free survival rate was 94.5% at 5 years and 91.2% at 9 years. The overall survival rate was 94.7% at 5 years and 94.7% at 9 years.

CONCLUSIONS

Favorable outcomes from petroclival meningiomas could be achieved by microsurgery. Neurological function and quality of life were prioritized, and GTR was attempted. Risk factors should be considered in surgical schemes, and tumor recurrence should be aggressively monitored and treated.

Quantitative comparison of retrosigmoid intradural suprameatal approach and retrosigmoid transtentorial approach: implications for tumors in the petroclival region

Background Retrosigmoid transtentorial (RTT) and retrosigmoid intradural suprameatal (RISA) approaches have been used in the treatment of petroclival tumors. Objective To compare the area of exposure of brainstem and petroclival region obtained through RTT and RISA in cadaveric specimens. Methods Five cadaveric specimens with a total of 10 sides were analyzed. RTT and RISA were performed on five sides each. Brainstem and petroclival surface exposure were measured using both the approaches. These values were compared between the two approaches. Results Brainstem area exposure with RTT was 441 ± 63 mm(2) and that with RISA was 311 ± 61 mm(2). Student's t-test revealed that the difference was significant (p = 0.01). The area of petroclival exposure medial to the Meckel cave through RTT was 696 ± 57 mm(2), and that through RISA was 716 ± 51 mm(2) (p = 0.69). The area of brainstem exposure between V and VII-VII complex through RTT and RISA was 387 ± 86 mm(2) and 378 ± 76 mm(2) (p = 0.87). Conclusion The RTT approach is an excellent approach to ventrolateral brainstem and petroclival region. It provides greater superoventral exposure of the ventrolateral brainstem than RISA and provides similar petroclival exposure.

[Neurosurgical importance of the superior petrosal venous complex]

OBJECTIVE

To study the microsurgical anatomy of the superior petrosal venous complex (SPVC).

MATERIAL AND METHODS

We conducted a descriptive and prospective study. Six injected specimens were used (12 sides). The microsurgical anatomy of the SPVC was studied by means of an anterior, retrosigmoid and transpetrosal approach. Neurosurgical equipment, 0-degree rigid endoscopy and OPMI-1 surgical microscope with 6× to 20× magnification were all used in this study. The venous drainage pattern toward the superior petrosal sinus was analysed, as were the formation of tributary veins, the relationship with the trigeminal nerve and the anatomical variants of SPVC.

RESULTS

The SPVC was present in all cases. A tributary, cerebellopontine fissure vein was identified in 100% of cases. The venous drainage pattern of the SPVC was divided into medial, intermediate and lateral with respect to the suprameatal crest. The SPVC was simple in 8 sides and duplicate in 4 sides. A triangle formed by the tentorium, the SPVC and part of the tentorial and petrosal surface of the cerebellum was also observed in the study. This triangle was called the petrosal-tentorial triangle.

CONCLUSIONS

It is important to understand the microsurgical anatomy of the SPVC. Therefore, we propose the petrosal-tentorial triangle as a neurosurgical route for the management of pathologies from the cerebellopontine angle to the superior petroclival region.

Supracerebellar transtentorial approach—resection of the tentorium instead of an opening—to provide broad exposure of the mediobasal temporal lobe: anatomical aspects and surgical applications

Object

The aim of this study was to describe the surgical anatomy of the mediobasal aspect of the temporal lobe and the supracerebellar transtentorial (SCTT) approach performed not with an opening, but with the resection of the tentorium, as an alternative route for the neurosurgical management of vascular and tumoral lesions arising from this region.

Methods

Cadaveric specimens were used to illustrate the surgical anatomy of the mediobasal region of the temporal lobe. Demographic aspects, characteristics of lesions, clinical presentation, surgical results, follow-up findings, and outcomes were retrospectively reviewed for patients referred to receive the SCTT approach with tentorial resection.

Results

Ten patients (83%) were female and 2 (17%) were male. Their ages ranged from 6 to 59 years (mean 34.5 ± 15.8 years). All lesions (3 posterior cerebral artery aneurysms, 3 arteriovenous malformations, 3 cavernous malformations, and 3 tumors) were completely excluded or resected. After a mean follow-up period of 143 months (range 10–240 months), the mean postoperative Glasgow Outcome Scale score was 4.9.

Conclusions

Knowledge of the surgical anatomy provides improvement for microsurgical approaches. The evolution from a small opening to a resection of the tentorium absolutely changed the exposure of the mediobasal aspect of the temporal lobe. The SCTT approach with tentorial resection is an excellent alternative route to the posterior part of mediobasal aspect of the temporal lobe, and it was enough to achieve the best neurosurgical management of tumoral and vascular lesions located in this area.