Cerebrospinal fluid leakage prevention using the anterior transpetrosal approach with versus without postoperative spinal drainage: an institutional cohort study.

The efficacy of spinal drain (SD) placement for cerebrospinal fluid (CSF) leakage prevention after the anterior transpetrosal approach (ATPA) remains unclear. Thus, we aimed to assess whether postoperative SD placement improved postoperative CSF leakage after a skull base reconstruction procedure using a small abdominal fat and pericranial flap and clarify whether bed rest with postoperative SD placement increased the length of hospital stay. This retrospective cohort study included 48 patients who underwent primary surgery using ATPA between August 2011 and February 2022. All cases underwent SD placement preoperatively. First, we evaluated the necessity of SD placement for CSF leakage prevention by comparing the postoperative routine continuous SD placement period to a period in which the SD was removed immediately after surgery. Second, the effects of different SD placement durations were evaluated to understand the adverse effects of SD placement requiring bed rest. No patient with or without postoperative continuous SD placement developed CSF leakage. The median postoperative time to first ambulation was 3 days shorter (P < 0.05), and the length of hospital stay was 7 days shorter (P < 0.05) for patients who underwent SD removal immediately after surgery (2 and 12 days, respectively) than for those who underwent SD removal on postoperative day 1 (5 and 19 days, respectively). This skull base reconstruction technique was effective in preventing CSF leakage in patients undergoing ATPA, and postoperative SD placement was not necessary. Removing the SD immediately after surgery can lead to earlier postoperative ambulation and shorter hospital stay by reducing medical complications and improving functional capacity.

Simplified anterior transpetrosal approach without superior petrosal sinus and tentorial incision for lesions centered in Meckel's cave.

OBJECTIVE: The anterior transpetrosal approach (ATPA) is an effective method to reach lesions in the petroclival region. This approach involves many steps, including superior petrosal sinus (SPS) ligation and tentorial cutting. It is sometimes unnecessary to perform all procedures in the ATPA for certain lesions, especially those centered in the Meckel's cave. Here, we present a simplified anterior transpetrosal approach (SATPA) without superior petrosal sinus and tentorial incision for lesions centered in the Meckel's cave as a modified ATPA. METHODS: This study included 13 patients treated with SATPA. The initial steps of SATPA are similar to ATPA, excluding a middle cranial fossa dural incision, SPS dissection, or tentorial incision. Histological examination was performed to understand the membrane structure of the trigeminal nerve, which runs through the Meckel's cave. RESULTS: Pathology revealed trigeminal schwannoma (n=11), extraventricular central neurocytoma (n=1), and a metastatic tumor (n=1). The average tumor size was 2.4 cm. The total removal rate was 76.9% (10/13). Permanent complications included trigeminal neuropathy in four cases and cerebrospinal fluid leakage in one case. Histological examination revealed the trigeminal nerve traverses the subarachnoid space from the posterior fossa subdural space to the Meckel's cave and is covered with the epineurium in the inner reticular layer. CONCLUSIONS: We used SATPA for lesions located in the Meckel's cave identified using histological examination. This approach may be considered for small- to medium-sized lesions centered in the Meckel space. CLINICAL TRIAL REGISTRATION NUMBER: None.

Anatomical variations and flow alterations of the uncal vein and its clinical implications in petroclival meningiomas.

BACKGROUND: The Uncal vein (UV), downstream of the deep middle cerebral vein (DMCV), has a similar drainage pattern to the superficial middle cerebral vein (SMCV) and may be involved in venous complications during the anterior transpetrosal approach (ATPA). However, in petroclival meningioma (PCM), where the ATPA is frequently used, there are no reports evaluating drainage patterns of the UV and the risk of venous complications associated with the UV during the ATPA. METHODS: Forty-three patients with petroclival meningioma (PCM) and 20 with unruptured intracranial aneurysm (control group) were included. Preoperative digital subtraction angiography was used to evaluate UV and DMCV drainage patterns on the side of the tumor and bilaterally in patients with PCM and the control group, respectively. RESULTS: In the control group, the DMCV drained to the UV, UV and BVR, and BVR in 24 (60.0%), eight (20.0%), and eight (20.0%) hemispheres, respectively. Conversely, the DMCV in the patients with PCM drained to the UV, UV and BVR, and BVR in 12 (27.9%), 19 (44.2%), and 12 (27.9%) patients, respectively. The DMCV was more likely to be drained to the BVR in the PCM group (p < 0.01). In three patients with PCM (7.0%), the DMCV drained only to the UV, and furthermore, the UV drained to the pterygoid plexus via the foramen ovale, posing a risk for venous complications during the ATPA. CONCLUSIONS: In the patients with PCM, the BVR functioned as a collateral venous pathway of the UV. Preoperative evaluation of the UV drainage patterns is recommended to reduce venous complications during the ATPA.

[Anterior transpetrosal (Kawase) approach for petroclival meningioma with trigeminal neuralgia: case report and literature review]. / Perednii transpiramidnyi dostup (dostup Kawase) pri petroklival'noi meningiome s trigeminal'noi nevralgiei: opisanie klinicheskogo nablyudeniya i obzor literatury.

The authors present a patient with petroclival meningioma complicated by trigeminal neuralgia. Resection of tumor via anterior transpetrosal approach with microvascular decompression of the trigeminal nerve was performed. A 48-year-old female patient presented with left-sided (V1-V2) trigeminal neuralgia. Magnetic resonance imaging revealed a tumor 33´27´25 mm with a base adjacent to the top of petrous part of the left temporal bone, tentorium cerebelli and clivus. Intraoperative examination revealed true petroclival meningioma extending to trigeminal notch of petrous part of temporal bone. There was additional compression of trigeminal nerve by caudal branch of superior cerebellar artery. Total resection of tumor was followed by disappearance of vascular compression of trigeminal nerve and regression of trigeminal neuralgia. Anterior transpetrosal approach provides early devascularization and resection of true petroclival meningioma, as well as wide imaging of anterolateral surface of the brainstem, identification of neurovascular conflict and vascular decompression.

Epidural and subdural interdural approach to the lateral wall of the cavernous sinus for preserving the laterocavernous sinus in trigeminal schwannoma.

Evacuation of middle fossa trigeminal schwannomas (TS) warrants a subtemporal interdural approach through the lateral wall of the cavernous sinus (CS). The dura comprises the dura propria, which follows the trigeminal nerve and develops into the epineurium, and periosteal layer. The interdural approach involves peeling off the dura propria and exposing the epineural sheath. The venous route around the CS is often obstructed due to TS progression. The interdural approach based on venous route preservation remains to be discussed. The laterocavernous sinus (LCS) is formed in these layers, draining to either the medial or lateral route. In the lateral route, the LCS drains to the pterygoid plexus via the middle cranial fossa foramen. Exposure of the interdural space disturbs the lateral route's venous flow. We describe an operative strategy for venous route preservation in TS via the LCS lateral route. The venous route can be preserved by peeling off the dura propria from the posterior end of the foramen ovale short of the venous drainage route to the pterygoid plexus epidurally and then cutting from the middle cranial fossa dura posterior to the venous route subdurally to the exposed interdural space. This technique helps in avoiding postoperative venous complications.

Advantages of petrosectomy for superficial temporal artery to superior cerebellar artery bypass based on three-dimensional distance measurements using cadaver heads.

Superficial temporal artery (STA) to superior cerebellar artery (SCA) bypass is usually performed via the subtemporal approach (StA), anterior transpetrosal approach (ApA), or combined petrosal approach (CpA), but no study has yet reported a quantitative comparison of the operative field size provided by each approach, and the optimal approach is unclear. The objective of this study is to establish evidence for selecting the approach by using cadaver heads to measure the three-dimensional distances that represent the operative field size for STA-SCA bypass. Ten sides of 10 cadaver heads were used to perform the four approaches: StA, ApA with and without zygomatic arch osteotomy (ApA-ZO- and ApA-ZO+), and CpA. For each approach, the major-axis length and the minor-axis length at the anastomosis site (La-A and Li-A), the major-axis length and the minor-axis length at the brain surface (La-B and Li-B), the depth from the brain surface to the anastomosis site (Dp), and the operating angles of the major axis and the minor axis (OAa and OAi) were measured. Shallower Dp and wider operating angle were obtained in the order CpA, ApA-ZO+, ApA-ZO-, and StA. In all parameters, ApA-ZO- extended the operative field more than StA. ApA-ZO+ extended La-B and OAa more than ApA-ZO-, whereas it did not contribute to Dp and OAi. CpA significantly decreased Dp, and widened OAa and OAi more than ApA-ZO+. ApA and CpA greatly expanded the operative field compared with StA. These results provide criteria for selecting the optimal approach for STA-SCA bypass in light of an individual surgeon's anastomosis skill level.

Surgical outcomes of anterior cerebellopontine angle meningiomas using the anterior transpetrosal approach compared with the lateral suboccipital approach.

BACKGROUND: Anterior transpetrosal approach (ATPA) and lateral suboccipital approach (LSO) are the major surgical approaches for cerebellopontine angle (CPA) meningiomas. Particularly, anterior CPA meningiomas are challenging lesions to be treated surgically. To date, only a few studies have directly compared the outcomes of both approaches focusing on the anterior CPA meningiomas. METHODS: For the comparative analysis, anterior CPA meningiomas that were eligible for both APTA and LSO were collected in our hospital from April 2005 to March 2017. Anterior CPA meningiomas targeted for this study were defined as follows: (1) without cavernous sinus, clivus, and middle cranial fossa extension, (2) the posterior edge is 1 cm behind the posterior wall of the internal auditory canal, and (3) the inferior edge is above the jugular tuberculum. Based on these criteria, the operative outcomes of 17 patients and 13 patients who were operated via ATPA and LSO were evaluated. RESULTS: The complication rate of the LSO group was significantly higher than that of the ATPA group (30.7% vs. 0%, p = 0.033). The removal rate did not differ between the ATPA and LSO groups (97.35% vs. 99.23%, p = 0.12). The operative time was significantly shorter in the LSO group than in the ATPA group (304.3 min vs. 405.8 min, p = 0.036). CONCLUSIONS: Although the LSO is more widely used for CPA meningiomas, ATPA is also considered for these anterior CPA meningiomas.

Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach.

BACKGROUND: The bridging vein (BV) and the tentorial sinus (TenS) are important venous structures in neurological surgery. These venous structures during the anterior transpetrosal approach (ATPA) have not been reported. The objective of this study is to examine the BV and the TenS in the subtemporal corridor during the ATPA and propose a technique to identify the BV preoperatively. METHODS: This study included 126 patients treated via the ATPA. The BV and the TenS located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius). RESULTS: Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003). CONCLUSIONS: We showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, we found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively.

Intradural anterior transpetrosal approach.

The standard anterior transpetrosal approach (ATPA) for petroclival lesions is fundamentally an epidural approach and has been practiced for many decades quite successfully. However, this approach has some disadvantages, such as epidural venous bleeding around foramen ovale. We describe here our experience with a modified technique for anterior petrosectomy via an intradural approach that overcomes these disadvantages. Five patients with petroclival lesions underwent surgery via the intradural ATPA. The intraoperative hallmarks are detailed, and surgical results are reported. Total removal of the lesions was achieved in two patients with petroclival meningioma and two patients with pontine cavernoma, whereas subtotal removal was achieved in one patient with petroclival meningioma without significant morbidity. No patient experienced cerebrospinal fluid leakage. The intradural approach is allowed to tailor the extent of anterior petrosectomy to the individually required exposure, and the surgical procedure appeared to be more straightforward than via the epidural route. Caveats encountered with the approach were the temporal basal veins that could be spared as well as identification of the petrous apex due to the lack of familial epidural landmarks. The risk of injury to the temporal bridging veins is higher in this approach than in the epidural approach. Intradural approach is recommended in patients with a large epidural venous route, such as sphenobasal and sphenopetrosal vein. Navigation via bone-window computed tomography is useful to identify the petrous apex.

The Evolution of Anterior Transpetrosal Approach for the Treatment of Petroclival Meningiomas: A Single-Center 128-Case Experience.

BACKGROUND: The profound understanding of anterior transpetrosal approach (ATPA) is increasingly used to treat petroclival meningiomas (PCMs). We introduce the evolution of ATPA and the outcomes of PCMs treatment. METHODS: Between January 2013 and December 2019, 128 patients with PCMs underwent surgery. According to tumor extension, we classified the 128 patients into 5 types (I-V), introduced key technologies of ATPA into different types for the first time, and achieved a supreme surgical technology. Clinical data, radiological findings, surgical treatments, complications, and patient outcomes were retrospectively analyzed. RESULTS: A total of 22 (17.2%), 44 (34.4%), 25 (19.5%), 29 (22.7%), and 8 (6.3%) patients had type I, II, III, IV, and V disease, respectively. Tumors were gross totally removed (Simpson I and II) in 100 patients (78.1%), subtotally removed (Simpson III) in 20 patients (15.6%), and partially removed (Simpson IV) in 8 patients (6.3%). The progression or recurrence rates were 5% (5/100) for gross totally removed, 22.3% (6/20) for subtotally removed, and 62.5% (5/8; 1 died) for partially removed. According to the Karnofsky Performance Scale and Glasgow Outcome Scale, 108 patients had good recovery (84.4%, 108/128) and 115 were independent (89.8%, 115/128) at the end of follow-up. CONCLUSIONS: Because some key technologies were used in ATPA, the application of ATPA was extended, and greater tumor resection and nerve function protection could be achieved in the treatment of PCMs.

Prevention of Cerebrospinal Fluid Leakage in the Anterior Transpetrosal Approach.

Background: The anterior transpetrosal approach (ATPA) is effective for reaching petroclival lesions, and it allows for complications such as impaired venous return and neuropathy to be resolved. However, there is still room for improvement regarding cerebrospinal fluid (CSF) leakage. Here, we aim to focus on describing specific preoperative, intraoperative, and postoperative countermeasures for preventing CSF leakage when using the ATPA. Methods: Eleven patients treated using the ATPA, who were treated at our hospital from June 2019 to February 2023, were included in this descriptive study. Preoperatively, we performed a 3D simulation of the opened air cells. Then, we classified patterns of dural closure into three types based on intradural manipulation and whether it involved opened air cells or not. Intraoperatively, we performed a dural closure that included the use of more-watertight sutures (DuraGen®) and an endoscope. Furthermore, temporal bone air cell volume measurements were performed to confirm the correlation between the volume and factors related to CSF leakage. Results: No postoperative CSF leakage was observed in any patient. The temporal bone air cell volumes significantly corelated with the air cells of the petrous apex, the high-risk tract in the petrous apex, and postoperative fluid collection in mastoid air cells. Conclusions: We have described countermeasures for preventing CSF leakage when using the ATPA. Preoperative simulations and the use of multiple-layered dural reconstructions with endoscopes could be considered more reliable methods for preventing CSF leakage when using the ATPA.

Purely endoscopic subtemporal keyhole anterior transpetrosal approach to access the petrous apex region: surgical techniques and early results.

OBJECTIVE: The anterior transpetrosal approach using a microscope to provide wider access to the petrous apex region has been described for radical resection of lesions of the middle and posterior skull base. The microscopic anterior transpetrosal approach (mATPA) requires a wide craniotomy and meticulous epidural procedures to minimize temporal lobe retraction. Recently, the clinical application of transcranial endoscopic keyhole approaches for minimally invasive surgery has been steadily expanding. In this study, the details of the purely endoscopic subtemporal keyhole ATPA (eATPA) for petrous apex lesions are described and its initial results are reported. METHODS: Between May 2022 and May 2023, the authors performed eATPA in 10 patients with petrous apex lesions, of which 6 were meningiomas, 3 were trigeminal schwannomas, and 1 was epidermoid cyst. The surgical procedure of the purely eATPA is as follows. After a small temporal craniotomy, the endoscopic procedure is started. The anterior rim of the petrous bone and Meckel's cave are exposed via an intradural subtemporal approach. The lesion is removed with additional drilling of Kawase's triangle, cutting the superior petrosal sinus, opening Meckel's cave, and cutting the tentorium. The authors also compared the outcomes of mATPA versus eATPA for consecutive cases of petrous apex lesions. RESULTS: Gross-total resection was achieved in 8 of the 10 patients. The average operative time was 4 hours 13 minutes. There were 3 cases of transient abducens nerve palsy and 1 case of trochlear nerve palsy in the postoperative period. No new-onset motor deficits or CSF leakage was noted in any of these patients. Only 1 patient exhibited postoperative asymptomatic temporal lobe edema. The Karnofsky Performance Scale (KPS) scores remained unchanged or improved for all patients postoperatively. Compared with mATPA, eATPA achieved a similar extent of resection and comparable postoperative KPS scores with a significantly shorter mean operative time, much smaller temporal craniotomy, and thus less mean blood loss during surgery with lower rates of new-onset temporal lobe edema in the postoperative period. CONCLUSIONS: An eATPA allows a direct route to access Meckel's cave and posterior cranial fossa lesions similar to conventional mATPA, with shortening the operative time and reducing the risk of postoperative temporal lobe edema. This eATPA is considered one of the new surgical techniques that can be expected to develop in the future.

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.

Trigeminal neuralgia secondary to osteoma and vascular compression: illustrative case.

BACKGROUND: Trigeminal neuralgia (TN) is a common neurosurgical issue that has a detrimental impact on patients' quality of life. Osteoma at the petrous apex is a rare etiology of TN. Here, the authors present a case involving the co-occurrence of petrous osteoma and a vascular loop around the trigeminal nerve. Both exerted pressure or compression on the exit of the trigeminal nerve. OBSERVATIONS: A 46-year-old male presented with a 3-year history of persistent severe pain in the right side of his face. Magnetic resonance tomographic angiography of the trigeminal nerve revealed an abnormal signal in the right prepontine cistern, along with a vascular loop accompanying the right trigeminal nerve. A computed tomography scan of the skull indicated a nodular calcified density. The combined anterior transpetrosal approach for petrous osteoma and microvascular decompression (MVD) for the offending vessel were successfully performed. The patient was discharged without any complications or facial pain. LESSONS: Although extremely rare, TN simultaneously secondary to petrous osteoma and offending vessels should be considered in the diagnosis. In this case, the combined surgical removal of petrous osteoma and MVD for the offending vessels proved to be an effective treatment for TN secondary to osteoma and vascular compression.

A simple combined approach using anterior transpetrosal and retrosigmoid approach: A case report.

Background: A combined transpetrosal approach (CTP) is often used for large lesions in the posterior cranial fossa (PCF). Although CTP provides a wide surgical corridor, it has complex and time-consuming bony work of mastoidectomy and cosmetic issues. Here, we describe a simple combined surgical technique to approach the supratentorial region, anterolateral surface of the brainstem, petroclival region, and foramen magnum by drilling only the petrous apex with a combination of retrosigmoid approach (RA). Clinical presentation: A 27-year-old female was referred with extra-axial left cerebellopontine angle space-occupying epidermoid cyst extending to the prepontine cistern, anterior to the basilar artery, superior to the chiasma, and caudally to the foramen magnum. A one-stage surgical procedure using the anterior transpetrosal approach (ATP) and RA was performed after one-piece temporal-suboccipital craniotomy. These two approaches complemented each other well. Near-total removal was achieved. Conclusion: A one-stage surgical procedure using ATP and RA provides the wider viewing and better visualization of the PCF with minimal technical difficulty.

Anterior transpetrosal resection of the lower ventral pontine cavernous malformation: A technical case report with operative video.

BACKGROUND: Surgical treatment of pontine cavernous malformations (CMs) is challenging due to the anatomical difficulties and potential risks involved. We successfully applied an anterior transpetrosal approach (ATPA) to remove a lower ventral pontine CM, and herein we discuss the outline of our procedure accompanied by a surgical video. CASE DESCRIPTION: A 50-year-old woman presenting with progressively worsening diplopia was urgently admitted to our hospital. Preoperative images showed a lower ventral pontine CM compressing the corticospinal tract posteriorly. Considering the location of the CM, we determined that an ATPA was the appropriate approach to achieve a more anterolateral trajectory. We performed extradural anteromedial petrosectomy and penetrated the brainstem from the point just below the anterior inferior cerebellar artery and above the root exit zone of the abducens nerve, which might be located in the somewhat lowest border of actual maneuverability in the ATPA. Maneuverability through this corridor was sufficient without hindering and darkening the high magnification microscopic view, as demonstrated in our surgical video. CONCLUSION: This report demonstrates surgical treatment of a lower ventral pontine CM using the ATPA. The surgical video we present provides information that is useful for understanding this technique's maneuverability and working window.

Oculomotor Neurofibroma: A Different Histology Implying an Unsatisfying Clinical Outcome.

BACKGROUND: Tumors arising from oculomotor nerve are rare, with few cases reported in the literature. Generally, whereas schwannomas are well encapsulated tumors, neurofibromas tend to invade the entire nerve fibers. These differences influence surgical resection and neurological clinical outcome, with neurofibroma often requiring the sacrifice of the nerve. Accordingly, an incorrect preoperative diagnosis can lead to incomplete patient counseling before surgery. CASE DESCRIPTION: We report 2 cases: a patient with oculomotor schwannoma and a patient with oculomotor neurofibroma. After tumor resection, the patient with a diagnosis of schwannoma recovered with 3rd nerve palsy, while patient with the neurofibroma developed a complete oculomotor nerve deficit. For each patient, surgical strategy and neurological outcome are elucidated in relation with differences in preoperative magnetic resonance imaging and histology. CONCLUSIONS: To the best of our knowledge, this is the first report of an oculomotor neurofibroma. When an oculomotor nerve tumor is suspected, a careful preoperative evaluation of magnetic resonance imaging guides in distinguishing the different histology, in selecting the treatment strategy, and in correctly informing the patient on expected postoperative neurologic outcome.

Surgical Treatment of Symptomatic Small Medial Petrous Meningiomas Causing Trigeminal Neuralgia.

BACKGROUND: Symptomatic trigeminal neuralgia caused by small (<3 cm) skull base meningiomas is treated by radiosurgery or surgical resection. Although radiosurgery is less invasive, surgical resection provides more rapid resolution of symptoms. We reviewed a short series of patients who underwent an anterior transpetrosal approach for surgical resection of meningiomas causing trigeminal neuralgia. METHODS: A retrospective review of 5 consecutive patients with meningiomas causing trigeminal neuralgia of the senior author was included. Preoperative parameters (size, proximity to critical neurovascular structures, presence of brainstem compression), intraoperative parameters (Simpson grade of resection, loss of brainstem evoked potentials, surgical approach), and outcomes (symptom resolution, extent of resection, follow-up) were recorded. RESULTS: Patient median age was 67 years (range, 60-73 years). All patients had symptoms concerning trigeminal neuralgia with 2 having associated areas of facial numbness. The anterior transpetrosal approach was used to achieve complete resection (Simpson grade I). Postresection, the trigeminal nerve and brainstem were clearly visible to evaluate neurovascular structures and ensure decompression. No postoperative complications were reported, and all patients experienced sustained symptomatic relief 1 month postsurgery. CONCLUSIONS: With the advent of radiosurgery for skull base meningiomas, surgical resection is not always considered; however, such meningiomas causing trigeminal neuralgia can be resected safely using the anterior transpetrosal approach allowing rapid resolution of symptoms. This review of operative nuances provides a guide for neurosurgeons to provide safe surgical resection.

Usefulness of the anterior transpetrosal approach for pontine cavernous malformations.

Surgical resection of pontine cavernous malformation remains a particularly formidable challenge. We report the surgical outcome of eight cases with pontine cavernous malformations operated using the anterior transpetrosal approach. All cases presented with neurological deficits caused by hemorrhage before surgery. Gross-total removal was achieved in all cases without any postoperative complication such as worsening of facial nerve palsy, ocular movement disorder, or hemiplegia. A small incision of the pons with multidirectional dissection is the most important factor for minimizing postoperative neurological deficits, so resection of a pontine cavernous malformation via this approach can be an alternative better option. The video can be found here: https://youtu.be/2Q2CUhBbo28.

Microsurgical Resection of a Ventral Pontine Cavernoma via Supratrigeminal Zone by Anterior Transpetrosal Approach: 2-Dimensional Operative Video.

Brainstem cavernomas with recurrent bleeding and gradual neurological deterioration should be considered an indication for surgical treatment. However, surgery is challenging for cavernous hemangiomas located in the ventral part of the pons. In such cases, safe surgical access to the brainstem is limited and obtaining a good surgical field, regardless of the approach selected, is often difficult. Here, we show a 73-year-old man with a history of 3 episodes of intracranial bleeding associated with a cavernous hemangioma located in the right ventral pons. The hemangioma was removed via the supratrigeminal zone of the brainstem using an anterior transpetrosal approach (ATPA). ATPA was first described in 1985 for upper petroclival lesions by Kawase T.1 This approach requires epidural subtemporal procedures to expose the petrous apex adequately. The petrous apex must be totally resected and the dura of the temporal lobe and posterior fossa is then cut to ligate the superior petrosal sinus and tentorium. In this procedure, the most important things are to preserve the internal carotid artery (C2 segment) and greater superficial petrosal nerve (GSPN). To identify the GSPN, facial nerve integrity monitor (Medtronic Inc, Dublin, Ireland) is very useful. In the extradural bone removal, Sonopet Ultrasonic Aspirator (Stryker Ltd, Portage, Michigan) is a very excellent surgical tool for avoiding the injury of the internal carotid artery. As demonstrated by Cavalcanti DD2, ATPA is particularly useful for accessing lesions located in the upper ventral pons via the supratrigeminal zone because it provides a wide and shallow surgical field above the trigeminal nerve without requiring retraction of the cerebellum. We received written informed consent from the patient for this publication.