Retrosigmoid Approach Research Articles

Graftless Primary Dural Closure Following Retrosigmoid Approach: Doing More With less

Achieving watertight dural closure without grafts via the retrosigmoid approach can be challenging, contributing to a significant rate of postoperative cerebrospinal fluid (CSF) leaks. This study describes a dural incision technique for achieving primary dural closure without grafts following the retrosigmoid approach and presents clinical data from the authors' experience. Clinical and surgical data of 227 patients who underwent the dural incision technique following the retrosigmoid approach for various pathologies were retrospectively reviewed. To achieve no-graft watertight dural closure, the dural incision involves two critical steps: a 1 cm transverse incision of the dura parallel to the foramen magnum to drain CSF from the cisterna magna, and a vertical linear opening of the retrosigmoid dura. Dural incisions were closed watertight with vicryl 4/0 running sutures, without the use of grafts, fibrin glue, hemostatic overlays, or dural substitutes. Pre- or postoperative lumbar drainage was not employed. Primary watertight dural closure was successfully achieved in all patients without the use of grafts or duraplasty. The average duration of dura closure was 17.7 minutes. During an average follow-up period of 49.3 months, there were no instances of CSF leaks or meningitis. In the authors' preliminary experience, the linear dural incision described herein was effetcive for achieving a no-graft, watertight primary dural closure in the retrosigmoid approach, with no CSF leaks or meningitis in our series. Validation of these preliminary data in a larger patient cohort is necessary.

Clinical, Anatomical, and Histological Features of the Rhomboid Lip and Considerations for Surgery Using a Retrosigmoid Approach: A Retrospective Study

The rhomboid lip is a neural tissue encountered during cerebellopontine angle surgery, with differing shape and extent among individuals. This study aimed to investigate the variation of rhomboid lips during posterior fossa surgery. In this retrospective study, we examined posterior cranial fossa surgeries performed using a retrosigmoid approach. Rhomboid lips were classified according to thickness, extent, and appearance, with some subjected to histological analysis. T2-weighted magnetic resonance imaging (MRI) of rhomboid lips was conducted. Among 304 surgeries, rhomboid lips were observed in 75 patients who underwent schwannoma or meningioma resection, facial spasm-related neurovascular decompression, and other surgeries (37, 2, 32, and 4 patients, respectively). Rhomboid lips were categorized based on apparent thickness: thin membranous type, resembling an arachnoid membrane, and thick parenchymal type. Rhomboid lip extension was classified by position relative to the choroid plexus: non-extension, lateral extension, and jugular foramen (41, 22, and 12 patients, respectively). Veins were observed on the rhomboid lip surface in 37 cases. The rhomboid lip was visible in only one case (parenchymal jugular foramen type) on MRI. Histologically, the rhomboid lip comprised an ependymal cell layer, a glial layer, and connecting tissue. The glial layer thickness determined the rhomboid lip thickness, which was greater in the parenchymal type than in the membrane type. In 42 patients, the rhomboid lip was dissected, with no complications observed. Morphological classification of the rhomboid lip and understanding of its anatomical details contribute to safe surgical field development for neurosurgeons.

Postoperative hemorrhages in vestibular schwannoma surgery pontine hemorrhage. Clinical case report

Vestibular schwannoma (acoustic neuroma) is a benign tumor that develops from Schwann cells and can be life-threatening. Nowadays, surgical treatment is the method of choice in the management of patients with this type of tumor. We present a clinical case report of 71 y.o. patient with vestibular schwannoma (Koos grade IV, Samii grade 4B) with severe compression of the pons and the left cerebellar hemisphere. Microsurgical removal of the tumor was performed via the retrosigmoid approach. Starting from postoperative day 1, signs of respiratory distress developed. Control multislice spiral computed tomography (MSCT) of the brain revealed the area of hemorrhage in the left regions of the pons. On postoperative day 24 the patient's condition rapidly worsened progressing to coma with pronounced arterial hypotonia and cardiac arrest. Hemorrhage in the brain stem structures is a rare and life-threatening postoperative complication in vestibular schwannoma surgery. The incidence of postoperative hemorrhage is 2–11% of cases. Vascular complications are the leading cause of mortality. The key predisposing factors are older age, large and giant size of the tumor, tumor invasion into the pia mater of the brainstem, and vascularization of the tumor stroma. Comprehensive assessment of the tumor blood supply status, the state of the brainstem, intra- and postoperative clinical and neurophysiological monitoring, careful and thorough dissection of the tumor capsule and strict control of blood pressure in the postoperative period are the basis for the prevention of these complications.

Management of Cerebellopontine Angle Tumors

Abstract Background Cerebellopontine angle (CPA) tumors are the most common neoplasms in the posterior fossa. Most CPA tumors are benign, with 80-94% being vestibular schwannomas (acoustic neuromas), lipomas, vascular malformations, and hemangiomas. Treatment options include observation, radiosurgery, and microsurgery. Aim and Objectives Evaluation of the clinical presentation of various lesions in the Cerebellopontine Angle area and evaluate the different surgical approaches for management of these lesions. Subjects and Methods The study included cases of CPA tumors that were admitted and treated in the neurosurgical departments in Ain Shams University Hospital as well as Al Galaa Armed Forces Hospital and Al Maadi Armed ForcesHospital. Result Abnormal planter response were the most frequent neurological abnormality (72.0%). The most cranial nerve affected was the vestibulocochlear nerve (60.0%). Conclusion CPA tumors are challenging lesions to be treated surgically, which requires a high level of surgical experience. Retrosigmoid and middle fossa approaches accomplished significant outcome among patients with CPA tumors. Preoperative V-P shunt procedure improved noticeably the manifestations of increased intracranial tension.

Trigeminal Microvascular Decompression and Meckel's Cave Tumor Resection via Retrosigmoid Approach With Suprameatal Extension: 2-Dimensional Operative Video.

The leading cause of trigeminal neuralgia (TGN) relies on the microvascular conflict between the superior cerebellar artery (SCA) loop and the dorsal root entry zone of the trigeminal nerve (TN). However, lesions along the TN have been described as a possible cause of TGN for direct mass effect or indirect vascular transposition. Thus, the surgical approach to TGN in patients harboring cerebellopontine angle or Meckel's cave tumor should be methodically chosen. The retrosigmoid (RS) approach with suprameatal extension offers direct access to the TN in both its cisternal and Meckel's cave segment, allowing optimal TN decompression from vascular and tumoral components. Although the RS approach with suprameatal extension has been described in numerous studies,1-4 videos detailing its key steps in addressing a multicomponent TGN are lacking. In this video, we highlight the case of a 46 year-old woman with 6 months of medically refractory typical TGN with a right en plaque meningioma involving the petrous bone, petroclival junction, Meckel's cave, and tentorium. In addition, magnetic resonance imaging was suspicious for a compressive SCA loop over the dorsal root entry zone. The patient underwent a RS approach with suprameatal extension for subtotal resection of the tumor and microvascular decompression of the TGN. The patient recovered with no complications and TGN resolved.

Development and Evaluation of a Mixed Reality Model for Training the Retrosigmoid Approach

IntroductionThe use of simulation has the potential to accelerate the learning curves and increase the efficiency of surgeons. However, there is currently a scarcity in models dedicated to skull base surgical approaches. Thus, the objective of this study was to develop a cost-effective mixed reality system consisting of an ultrarealistic physical model and augmented reality (AR) and evaluate its use in training surgeons on the retrosigmoid approach. Materials and methodsThe virtual models were developed from images of patients with vestibular schwannoma. The tumor was mirrored to allow bilateral approaches and the model has drawers for repositioning structures, allowing reuse of the material and cost reduction. Pre and post-test assessments were applied to ten residents and young neurosurgeons, divided into control and test groups. Only the control group was exposed to the model. The difference in scores obtained by participants before and after exposure to the models was considered for analysis and participants in the control group answered self-satisfaction questionnaires. ResultsThe mean differences were 4.80 in the control group (95%CrI = 1.08-9.79) and 5.43 in the test group (95%CrI = 1.67-8.20). The average score of the self-satisfaction questionnaires was 24.0 (23-25). ConclusionThe ultrarealistic model efficiently allowed retromastoid access to the cerebellopontine angle. A tendency towards greater gains in performance in the group exposed to the model was verified. Scores from the self-satisfaction questionnaires demonstrated that participants considered the model relevant for neurosurgical training and increased confidence among surgeons.

Meningioma originating from the superior petrosal vein without dural attachment: A case report

BACKGROUND Meningioma in the cerebellopontine angle (CPA) without dural attachment is extremely rare. We report a unique case of meningioma derived from the superior petrosal vein without dural attachment. CASE SUMMARY A 44-year-old right-handed woman presented with a two-month history of headache and tinnitus. Brain magnetic resonance imaging showed a well-defined contrast-enhancing lesion in the right CPA without a dural tail sign. Tumor resection was performed using a right retro sigmoid approach. A dural attachment was not seen at the tentorium or posterior surface of the petrous pyramid. The tumor was firmly adherent to the superior petrosal vein. The origin site was cauterized and resected with the preservation of the superior petrosal vein. A diagnosis of meningothelial meningioma was made. The patient’s headache and tinnitus gradually disappeared, and a recurrence was not observed five years after the surgery. CONCLUSION The rare occurrence of meningioma without dural attachment makes it difficult to determine dural attachment before surgery. The absence of dural attachment makes it easy to completely resect such tumors. Vessels related to tumors should be removed carefully, considering the possible presence of tumor stem cells in the microvessels.

Factors affecting facial nerve outcome in vestibular Schwannoma surgery

Background: Preservation of facial nerve injury is a key important factor in vestibular schwannoma surgery as facial paralysis has devastating functional and psychological consequences for patients. Objective: To correlate different factors resulting in facial nerve preservation in vestibular schwannoma surgery by retro mastoid retro sigmoid approach. Method: This is a retrospective analysis of facial nerve status of 212 cases of vestibular schwannoma microsurgery through Retrosigmoid Retromastoid (RSRM) approach. This study was carried out in National Neurosurgical Referral Center(NNRC), National Academy Of Medical Sciences (NAMS), Bir hospital between January 2016 to December 2022.Preoperative and post operative details of facial nerve function status compared according to House and Brackmann (H and B) grading system, and factors influencing outcome in facial nerve preservation were analyzed. Recurrent and residual tumors were excluded. Results: A total of 212 cases of vestibular schwannoma were operated during the study period. The average age of presentation was 47 years. Most common affected age group was 51-60 years. Female to male ratio was 3:2.5. The most common clinical symptoms for vestibular schwannoma were sensorineural hearing loss followed by headache and difficulty in limb coordination. Tumor size and consistency was most important indicator of facial nerve function outcome. Conclusion: The incidence of post operative facial palsy is found to be correlated to tumor size and consistency. Improvement of the facial nerve outcome is detected in patients undergone simultaneous intraoperative monitoring (IONM).

Comparative Analysis on Vestibular Schwannoma Surgery with and without Intraoperative Fluorescein Sodium Enhancement

Background: Vestibular schwannoma (VS), also known as acoustic neuroma, is a benign, well-encapsulated, and slow-growing tumor that originates from Schwann cells, which form the myelin sheath around the vestibulocochlear nerve (VIII cranial nerve). The surgical treatment of this condition presents a challenging task for surgeons, as the tumor’s location and size make it difficult to remove without causing damage to the surrounding structures. In recent years, fluorescein sodium (FS) has been proposed as a tool to enhance surgical outcomes in VS surgery. This essay will provide an analytical comparison of the use of FS in VS surgery, evaluating its benefits and limitations and comparing surgical outcomes with and without FS-assisted surgery. Methods: In a retrospective study conducted at San Filippo Neri Hospital, we examined VS cases that were operated on between January 2017 and December 2023. The patients were divided into two groups: group A, which consisted of patients who underwent surgery without the use of FS until January 2020 (102 cases), and group B, which included patients who underwent surgery with FS after January 2020 (55 cases). All operations were performed using the retrosigmoid approach, and tumor size was classified according to the Koos, et al. classification system. The extent of surgical removal was evaluated using both the intraoperative surgeon’s opinion and postoperative MRI imaging. Preoperatively and postoperatively, facial nerve function and hearing were assessed. In group B, FS was used to assist the surgical procedures, which were performed using a surgical microscope equipped with an integrated fluorescein filter. Postoperative clinical and MRI controls were performed at six months and annually, with no patients lost to follow-up. Results: This study investigated the impact of intraoperative fluorescein exposure on tumor resection and clinical outcomes in patients with VS. The study found a statistically significant difference in the tumor resection rates between patients who received fluorescein intraoperatively (p = 0.037). Further analyses using the Koos classification system revealed a significant effect of fluorescein exposure, particularly in the Koos 3 subgroup (p = 0.001). Notably, no significant differences were observed in hearing loss or facial nerve function between the two groups. A Spearman correlation analysis revealed a positive correlation between tumor size and Koos, age, and size, but no significant correlation was found between facial nerve function tests. Conclusions: FS-assisted surgery for VS may potentially enhance tumor resection, allowing for more comprehensive tumor removal.

Translabyrinthine approach in acoustic neuroma surgery – case report

Introduction. Acoustic neuroma is a benign tumor that arises from the glial Schwann sheath junction of the vestibulocochlear nerve. It has an incidence of 1:100000 population. Despite the fact that this is a rare tumor, it accounts for approximately 6% of all intracranial tumors and 80% of tumors localized in cerebellopontine angle. Treatment of acoustic neuroma is represented by “Wait and Scan” monitoring, radiologic and surgical treatment. The latter remains the primary treatment for acoustic neuroma and consists of 3 main approaches: retrosigmoid approach, middle cranial fossa approach and translabyrinthine approach. Until now, in our country, acoustic neuroma surgery was done only by retrosigmoid approach. Case presentation. The first translabirinthine surgery for acoustic neuroma in our country was done on 09.12.2021 on a 60-year-old patient who, during preparation for cochlear implant surgery, was accidentally diagnosed with 3rd grade right acoustic neuroma, according to Koos classification. Patient had cophosis on the right ear and moderate hearing loss in the left ear. During the surgery, a gross total resection of the tumor was accomplished. The patient was discharged from the medical institution on 20.12.2021 in a satisfactory condition. Magnetic resonance imaging performed 3 months and 1 year after the surgery showed no complications or tumor remnants. Conclusion. The current report, which describes an accidental diagnosis of acoustic neuroma during preparation for a cochlear implantation surgery, resulted in acoustic neuroma surgery through the translabyrinthine approach. This serves as an eloquent example of why it is necessary to perform initially a magnetic resonance examination in cases of sensorineural hearing loss or tinnitus. The translabyrinthine approach in acoustic neuroma surgery allows for the removal of tumors of any size without affecting the brain, especially the cerebellum. In our case, where the patient had cophosis on the side of the tumor, this was the most appropriate surgical approach.

Morphometric Analysis of the Retrolabyrinthine Approach to the Posterior Fossa

The retrolabyrinthine approach provides shorter working distance and less cerebellar retraction compared with the retrosigmoid approach to the internal acoustic canal (IAC) and cerebellopontine angle cistern. However, exposure of the ventral surface of the brainstem and petroclival region may be restricted. Trautmann's triangle (TT), an area intimately related to this region, demonstrates significant anatomical variability, which may adversely affect the ease of the approach. The aim of this study is to evaluate anatomic parameters of the posterior fossa that may anticipate a challenging situation in approaching the IAC and the petroclival region through the retrolabyrinthine approach. It was performed a radioanatomic analysis of 75 cerebral angiotomography exams to identify parameters that could potentially reduce areas of surgical exposure. Large variations were observed in the area of exposure of the TT (553%) and the height of the jugular bulb (234%). Shorter distances from the sigmoid sinus to the posterior semicircular canal and high-riding jugular bulb were associated with smaller areas of exposure. Dominant and laterally positioned sigmoid sinuses and less pneumatized mastoids were associated with potentially unfavorable conditions, including a narrower angle of attack to the IAC. Increased petrous slopes and petroclival angles were associated with smaller petroclival areas and shallower clival depths. This study of the posterior fossa reveals remarkable anatomic variation in the region. These findings should be taken into consideration during the preoperative planning of retrolabyrinthine approaches in order to offer safer and more effective surgical procedures.

P.083 Use of jugular venous pressure to optimize outcomes of vestibular schwannoma resection: a review of the literature and proof of concept

Background: Surgical resection of vestibular schwannoma (VS) is often curative if gross total resection is achieved, however, it is a delicate procedure with high risk to the facial nerve. With retrosigmoid approach for resection, the head is positioned to maximize lateral head rotation and neck flexion in order to optimize the surgical field. However, this may inadvertently occlude cerebral venous drainage, elevating intracranial pressure (ICP) and increasing intraoperative bleeding. Methods: Here, we review relevant literature regarding the effects of head rotation and neck flexion on internal jugular vein (IJV) occlusion and ICP, and highlight the notion that head rotation and flexion may occlude the ipsilateral IJV, increasing ICP. Subsequently, we propose a novel technique using continuous, real-time monitoring of jugular bulb pressure (JBP) to detect obstructions in jugular venous flow and guide optimal head positioning prior to VS resection. Results: As proof of concept, we present a case in which JBP monitoring was employed to optimize head positioning prior to a VS resection, which shows a significant reduction in JBP compared to traditional positioning. Conclusions: This innovative approach offers promise in enhancing the safety and efficacy of intracranial surgery for VS and potentially other neurosurgical procedures.

Applying the Full Endoscopic Keyhole Technique to CPA Lesions: A Single-Center Study.

In recent years, endoscopy has become an increasingly common tool used during neurosurgical procedures. However, its application in treating cerebellopontine angle (CPA) lesions has not progressed as rapidly. In this study, the authors present their initial experience with surgically treating CPA lesions using a fully endoscopic keyhole retrosigmoid approach. They conducted a retrospective analysis of clinical data from patients who underwent endoscopic keyhole CPA surgery at their center between May 2017 and April 2022. They provide a comprehensive explanation of this method and an overview of the strategies that have been developed to achieve better clinical outcomes. The study included 107 patients, consisting of 10 cases of vestibular schwannoma, 21 cases of epidermoid cyst, 32 cases of trigeminal neuralgia, and 44 cases of hemifacial spasm. The authors analyzed the clinicodemographic details of the patients. Among the 31 tumor cases, gross total resection was achieved in 25 patients (80.6%), while near-total resection was performed in 6 patients (19.4%). In patients with trigeminal neuralgia, facial pain resolved in 31 out of 32 patients (96.9%). Similarly, facial convulsions disappeared or were relieved in all 44 patients (100%) with hemifacial spasms after the operation. Postoperative complications included facial nerve paresis (n=9, 8.4%), with improvement observed in 6 cases during follow-up, transient facial hypoesthesia (n=3, 2.8%), cerebrospinal fluid rhinorrhea (n=3, 2.8%), transient abducens paresis (n=1, 0.9%), and postoperative hemorrhage (n=1, 0.9%). Endoscopy provides improved deep illumination and, combined with close-up observation, enhances the visualization of structures within the CPA region. The fully endoscopic keyhole technique is a safe and effective method for managing CPA lesions.

Surgical Outcome of Vestibular Schwannoma in a Tertiary Care Hospital, Dhaka

Background: Presenting symptoms, treatment considerations, and outcome are strongly related to the extension of vestibular schwannomas (VS). The aim of the current retrospective study was to analyze the clinical features, microsurgical treatment, and outcome of VS with brainstem compression. Methods: 130 patients presented with VS who had undergone operative procedures performed in our unit from Jan, 2017 to may, 2022. The facial nerve function and hearing assessment was done according to House-Brackmann [HB] grading and pure tone audiometry (PTA) respectively. All patients were operated by retro-sigmoid retromastoid sub-occipital approach. Results: Most patients had large tumors and had no useful hearing (75.38%), had disabling cerebellar ataxia (84.61%) and presented with features of raised intracranial pressure (46.15%). Complete tumor excision was carried out 92.30% and anatomical preservation of facial nerve was achieved in 87.50% cases. Hearing preservation was achieved in eight patients. Cerebrospinal fluid leak with or without meningitis and transient lower cranial nerve paresis were common complications. The mortality rate was 7.69% Conclusions: Complete tumor excision with good facial nerve preservation can be achieved in large vestibular schwannomas. Hearing preservation is difficult in larger tumors. Primary microsurgical resection is an appropriate management option for large VS. In our experience, this goal can be achieved safely and successfully by using the retromastoid retrosigmoid sub-occipital approach. Bang. J Neurosurgery 2023; 12(2): 86-93

Endoscopic Retrolabyrinthine Craniotomy for Exposure of the Trigeminal Nerve Root Entry Zone: Volumetric Analysis of Anatomic Exposure in the Cadaver.

Exposure of the root entry zone (REZ) of the trigeminal nerve (TN) for microvascular decompression is commonly obtained with a retrosigmoid approach, with or without endoscopic assistance. We hypothesized that adequate exposure of the TN REZ could be obtained through an endoscopic retrolabyrinthine (RL) approach. We aim to quantify exposure of the REZ of the TN using endoscopic RL approach, with and without drilling of the suprameatal tubercle of the internal auditory canal. Surgical dissection was performed bilaterally on 3 embalmed cadaveric human heads at the anatomy laboratory of the House Institute. Heads were scanned for volumetric analysis using 3D Slicer software both before and after dissection. Extent of exposure was quantified in 2 ways: first, by assessment of the surgeon's ability to visualize 16 predetermined anatomic landmarks with the endoscope and second, we estimated the "working" area by placing fiducials under the fully endoscopic view and calculating the resultant 3D volume. Using the standard endoscopic RL approach, an average of 13.8 landmarks (range 12-16) was visualized. The estimated working volume exposed by the RL on each side of each head varied from 189.28 to 527.85 mm3. Drilling of the suprameatal tubercle provided both increases in landmark visualization and, on average, an additional 55 mm3 of working volume. The endoscopic RL approach is a viable alternative to the standard retrosigmoid approach. Potential advantages of the RL include a more lateral trajectory that minimizes the need for cerebellar retraction and a shorter working distance and shallower angle to the cerebellopontine angle. Potential disadvantages include longer surgery time, increased technical difficulty of exposure, and potential for cerebrospinal fluid leak and or hearing loss.

Effects of intraoperative low-dose esketamine on postoperative pain after vestibular schwannoma resection: A prospective randomized, double-blind, placebo-controlled study.

Esketamine may reduce acute postoperative pain in several settings. However, the effects of low-dose esketamine on postoperative pain after vestibular schwannoma (VS) resection with propofol/remifentanil total intravenous anaesthesia (TIVA) are unclear. The aim of this study is to observe the effects of intraoperative low-dose esketamine on postoperative pain after vestibular schwannoma resection. This single-centre, randomized, placebo-controlled, double-blind trial included 90 adults undergoing VS resection via the retrosigmoid approach with TIVA. The patients were randomly allocated to two groups: esketamine or control (n = 45 in each group). Patients received low-dose esketamine (0.2 mg/kg) or a similar volume of normal saline after dural closure. The primary outcome was the pain score during movement (gentle head movement) at 24 h postoperatively. Secondary outcomes included recovery time, bispectral index (BIS) values and haemodynamic profiles during the first 30 min after esketamine administration, and adverse effects. Low-dose esketamine did not reduce pain scores at rest (P > .05) or with movement (P > .05) within the first 24 h after surgery. Esketamine moderately increased BIS values for at least 30 min after administration (P < .0001) but did not affect heart rate (P = .992) or mean arterial blood pressure (P = .994). Esketamine prolonged extubation time (P = .042, 95% confidence interval: 0.08 to 4.42) and decreased the effect-site concentration of remifentanil at extubation (P = .001, 95% confidence interval: -0.53 to -0.15) but did not affect the time to resumption of spatial orientation. Postoperative nausea and vomiting rates did not differ between groups, and no hallucinations or excessive sedation was observed. Intraoperative low-dose esketamine did not significantly reduce acute pain after VS resection with propofol/remifentanil TIVA. However, BIS values increased for at least 30 min after esketamine administration.

Surgical management of large lower cranial nerves schwannomas: long term results of a less aggressive resection strategy.

In an effort to reduce the high morbidity and life-threatening complications after radical resection in large schwannoma surgery, alternative strategies of nontotal resections have emerged. To evaluate the long term clinical and oncological outcome after lower cranial nerves (LCN) schwannoma surgery operated on with a cranial nerve-sparing technique. Single center retrospective cohort study of 8 consecutive patients harboring LCN schwannomas operated on between March 2005 and October 2021. The mean LCN schwannoma diameter was 33mm (range 26-51). Seven patients (87,5%) underwent a modified retrosigmoid approach. Three patients underwent gross total resection (37,5%), 3 had received neartotal resection (mean tumor residue 0,25cc) and subtotal resection in 2 patients who presented with an extracranial extension of the tumor (mean tumor residue 2,44cc). Both patients had received upfront additional GKRS. The three patients who presented with preoperative CN IX & X injuries recovered within 6months after surgery. All of the five patients freed from any preoperative CNs IX & X symptoms experienced transient (80%) or definitive (one patient) disturbances after surgery. They all improved within 6months but one who required long term gastrostomy feeding tube. This patient harbored a schwannoma originating from the glossopharyngeal nerve, which could not be anatomically preserved during surgery. Tumor control was achieved in 100% of cases with a mean follow-up of 91months. LCN schwannomas could be surgically removed through a less aggressive non-radical resection strategy with acceptable functional results and excellent tumor control.

Microsurgical resection of a large petroclival meningioma through an extended retrosigmoid approach: how I do it.

Petroclival meningiomas are challenging tumors. Several skull base approaches have been proposed in the last decades, with variable rates of postoperative morbidity and extent of resection. We herein reported the step-by-step microsurgical resection of a large petroclival meningioma through an extended retrosigmoid approach. Detailed surgical technique has been accompanied by a 2D operative video. The extended retrosigmoid approach allowed for a safe gross total resection of the tumor, as confirmed by the postoperative MRI. The patient did not experience any new postoperative deficit, despite a transient diplopia, and was discharged on postoperative day 7.

The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study

Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. The PAM was dissected in 10 adult cadaveric heads, and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ, and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neuro-vascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

Retrosigmoid Suprameatal Approach for the Resection of a Petrotentorial and a Petroclival Meningioma: 3-Dimensional Operative Video.

Posterior skull base meningiomas pose a formidable surgical challenge because of their proximity to critical neurovascular structures and the narrow corridor available for their resection. While radiosurgery may be an effective treatment alternative, 1 microsurgery remains superior in addressing associated compressive symptoms. 2 Several approaches have been described to access these lesions, with varying degrees of exposure to the petroclival region. 3-7 The choice of the optimal approach depends on different factors related to the tumor morphological features and the surgeon's preference and experience. The retrosigmoid approach is a straightforward procedure compared with other more laborious skull base approaches to the petroclival region. Its described intradural extensions contribute to its high versatility for posterior skull base tumors. One of these extensions involves drilling the suprameatal tubercle, significantly increasing exposure and maneuverability for tumors located medial to the internal acoustic canal. 8 The semisitting position adds further value as it allows for a gravity-assisted clearance of blood and debris, achieving a clear surgical field. 9 We present 2 patients suffering from trigeminal neuralgia secondary to a petrotentorial and a petroclival meningioma. Given the location of both tumors predominantly medial and superior to the internal acoustic canal, resection was carried out through a retrosigmoid suprameatal approach with the patient in a semisitting position. Relevant anatomic and surgical considerations are discussed and illustrated in this 3-dimensional operative video. Gross total resection was achieved, and both patients remained neurologically intact and pain-free at long-term follow-up. Both patients consented to the procedure and to the publication of their image.