Cerebellopontine Angle Tumor Resection Research Articles

Utility and Prognostic Value of Intraoperative Blink Reflex in Trigeminal or Facial Nerve Monitoring in Skull Base Surgeries: A Systematic Review

Blink reflex (BR) is an oligosynaptic reflex that involves the ophthalmic branch of the trigeminal nerve (TN), ipsilateral main sensory and trigeminospinal nuclei, bilateral facial nuclei, and the facial nerves (FNs). Theoretically, as BR tests the function of both TN and FNs simultaneously, it is an ideal tool for monitoring the status of TN and FNs during skull base surgeries. Nevertheless, it has been used only recently in surgeries as the use of anesthesia limits its use. For this systematic review, 2 authors input the search terms [(Blink Reflex) AND (Intraoperative Neuromonitoring OR Neuro Intraoperative Monitoring OR Intraoperative OR NIOM OR IONM) AND (skull base surgery OR Facial Nerve OR Trigeminal Nerve OR Microvascular Decompression OR Hemifacial Spasm)] in MEDLINE through its PubMed interface and other search engines. Articles that fulfilled the inclusion and exclusion criteria were obtained and scrutinized. Seven observational articles with a total of 437 participants were included. All 5 studies that described the use of BR in FN surgery noted that intraoperative BR is beneficial, safe, sensitive, specific, and predictive of outcomes, while 2 articles describing patients with trigeminal neuralgia recommended use of BR in microvascular decompression of TN. Intraoperative BR is a sensitive, specific, and safe monitoring technique that has good predictability of facial paresis and paresthesia among patients undergoing MVD for trigeminal neuralgia and primary hemifacial spasm and patients undergoing cerebellopontine angle tumor resection.

Predictive value of Blink reflex and facial corticobulbar motor evoked potential in cerebellopontine angle tumor surgery

ObjectiveThe current study examined the efficacy of the facial corticobulbar motor evoked potentials (FCoMEPs) and blink reflex (BR) on predicting postoperative facial nerve function during cerebellopontine angle (CPA) tumor surgery. MethodsData from 110 patients who underwent CPA tumor resection with intraoperative FCoMEPs and BR monitoring were retrospectively reviewed. The association between the amplitude reduction ratios of FCoMEPs and BR at the end of surgery and postoperative facial nerve function was determined. Subsequently, the optimal threshold of FCoMEPs and BR for predicting postoperative facial nerve dysfunction were determined by receiver operating characteristic curve analysis. ResultsValid BR was record in 103 of 110 patients, whereas only 43 patients successfully recorded FCoMEP in orbicularis oculi muscle. A reduction over 50.3% in FCoMEP (O. oris) amplitude was identified as a predictor of postoperative facial nerve dysfunction (sensitivity, 77.1%; specificity, 83.6%). BR was another independent predictor of postoperative facial nerve deficit with excellent predictive performance, especially eyelid closure function. Its optimal cut-off value for predicting long-term postoperative eyelid closure dysfunction was was 51.0% (sensitivity, 94.4%; specificity, 94.4%). ConclusionsBR can compensate for the deficiencies of the FCoMEPs. The combination of BR and FCoMEPs can be used in CPA tumor surgery. SignificanceThe study first proposed an optimal cut-off value of BR amplitude deterioration (50.0%) for predicting postoperative eyelid closure deficits in patients undergoing CPA tumor surgery.

Fully neuroendoscopic resection of cerebellopontine angle tumors through a retrosigmoid approach: a retrospective single-center study

Fully neuroendoscopic resection of cerebellopontine angle tumors through a retrosigmoid approach: a retrospective single-center study

Anticipating Facial Nerve Position Using Three-Dimensional Tractography During the Preoperative Assessment of Cerebellopontine Angle Tumors

We aim to evaluate the usefulness of preoperative facial nerve tractography in determining the facial nerve position in cerebellopontine angle tumor resection and its value in helping to preserve facial nerve function during surgery. A prospective study was designed to include patients presenting with cerebellopontine angle tumors. Three-dimensional reconstruction of facial nerve tractography was performed and added to the usual preoperative testing in all patients. Facial nerve position was compared between tractography results and surgical findings. Moreover, facial nerve function was evaluated at baseline and during follow-up. Fifteen patients were included for analysis. Complete resection was obtained in 5 patients, near-total resection was achieved in 8 patients, and partial resection in 2 patients. We found a strong statistically significant concordance between the preoperative facial nerve tractography reconstruction and the intraoperative findings (complete concordance in 86.66% of all the cases; κ= 0.784; P < 0.0001). Facial nerve anatomic structure was preserved in all patients during surgery. At 6 months follow-up, 66.66% of patients had a facial nerve normal function or a mild dysfunction. Preoperative facial nerve tractography reconstruction showed a high correlation with intraoperative findings. Preoperative tractography information regarding facial nerve position and its cisternal course is valuable information and could help the surgeon in increasing the safety of the procedure during cerebellopontine angle tumor surgery.

Pre- and intra-operative prognostic factors of facial nerve function in cerebellopontine angle surgery

PurposeThe study assesses whether pre- and intraoperative factors linked to electromyography and direct electrical stimulation (DES) of facial nerve can predict facial nerve function in the short- (12 days) and long-term (1 year) after cerebellopontine angle (CPA) tumor resection.Methods157 patients who underwent surgical resection of CPA tumors with facial nerve monitoring. Pre-operative factors (age, tumor size, pure tone average), surgical time and intra-operative parameters regarding facial function, minimum stimulation threshold (MST), compound muscle action potential (CMAP) and the difference between proximal and distal CMAP (DPDC) were evaluated.ResultsA correlation between tumor size, MST, CMAP and facial function in both short and long term was found. A higher grade of immediate facial paralysis corresponded to a higher risk of poor outcome after one year. A postoperative House–Brackmann (HB) score of V or VI was correlated with poor outcome in 88.8% and 93.8% of cases. A risk of HB 3 or more, in the long term, was correlated with a tumor size of 20.2 mm. Using an MST of 0.1 mA, for long-term predictions, sensitivity and specificity were 0.62 (95% CI 0.46–0.75) and 0.73 (95% CI 0.61–0.82), respectively. With a CMAP cut-off < 200 µV, for long-term prediction, sensitivity was 0.73 (95% CI 0.53–0.87) and specificity 0.73 (95% CI 0.55–0.85).ConclusionThe assessment based on the cut-offs described increases the ability to predict facial function. Improving predictive accuracy enables surgeons to address patients’ expectations and to establish an intervention timeline for planning facial reanimation.

Intraoperative Corticobulbar Motor Evoked Potential in Cerebellopontine Angle Surgery: A Clinically Meaningful Tool to Predict Early and Late Facial Nerve Recovery.

Intraoperative neuromonitoring is crucial for facial nerve preservation in cerebellopontine angle (CPA) surgery. Among the available techniques, the role of intraoperative corticobulbar facial motor evoked potentials (FMEPs) is unclear. To evaluate the significance of intraoperative FMEPs as indicators for early and late postoperative facial nerve function (FNF) in CPA tumor resection and the feasibility of their integration with standard monitoring techniques. An institutional series of 83 patients who underwent surgery under intraoperative monitoring for CPA extra-axial tumor resection was reported. A pair of needle electrodes was used to record FMEP from orbicularis oculi (OOc) and orbicularis oris (OOr) muscles at baseline, at the end of surgery and minimum values recorded. From FMEP amplitudes, minimum-to-baseline amplitude ratio (MBR), final-to-baseline amplitude ratio (FBR), and recovery value, intended as FBR minus MBR, were calculated. These indices were correlated with early and late postoperative FNF. Our analysis demonstrated that higher FBR (both from OOc and OOr) and MBR (from OOr only) were associated with a good early and late FNF; a higher MBR from OOc was significantly associated with a good late FNF. The most accurate index in predicting early FNF was FBR measured from OOr with a cutoff of 35.56%, whereas the most accurate index in predicting late FNF was FBR as measured from OOc with a cutoff of 14.29%. Our study confirmed that FMEPs are reliable predictors of early and late postoperative FNF in CPA surgery and could be easily integrated with standard intraoperative neuromonitoring techniques.

Advances and future directions in the care of patients with facial paralysis

Advances and future directions in the care of patients with facial paralysis

Hearing recovery after surgical resection of non-vestibular schwannoma cerebellopontine angle tumors.

Post-operative outcomes for hearing after resection surgery to remove cerebellopontine angle (CPA) tumors other than vestibular schwannomas (VS) are not well understood. This study presents a series of patients with significant post-operative hearing recovery, trying to define the incidence among all patients operated on for removal of non-VS CPA tumors. This is a retrospective observational case series of 8 patients among 69 operated on for removal of non-VS CPA tumors between 2012 and 2020. All patients had pre- and post-operative hearing measurement with pure-tone average (PTA) and speech discrimination score (SDS), according to the American Academy of Otolaryngology-Head and Neck Surgery recommendations, auditory brainstem response (ABR) measurements and imaging. Six meningiomas and two lower cranial nerve schwannomas operated on with a retrosigmoid approach were included for analysis. The mean pre-operative PTA and SDS were 58 ± 20.7dB and 13 ± 17.5%, respectively. All patients had pre-operative class D hearing and asynchronous ABRs. They all showed significant hearing recovery, with an improvement of 36 ± 22.2dB (p = 0.0025) and 85 ± 16.9% (p = 0.0001) in PTA and SDS, respectively, with mean follow-up of 21 ± 23.5months. Seven patients recovered to a class A hearing level and one patient to class B. The ABRs became synchronous for three patients. The incidence of auditory recovery was 13% for patients operated on with a conservative approach (n = 60). A significant post-operative improvement in hearing could be a reasonable expectation in non-VS tumors extending into the CPA and a retrosigmoid approach should always be considered regardless of pre-operative hearing status.

Effect of Household Income on Short-Term Outcomes Following Cerebellopontine Angle Tumor Resection.

Objectives The objective of this study is to elucidate the impact of income on short-term outcomes in a cerebellopontine angle (CPA) tumor resection population. Design This is a retrospective regression analysis. Setting This study was done at a single, multihospital, urban academic medical center. Participants Over 6 years (from June 7, 2013, to April 24, 2019), 277 consecutive CPA tumor cases were reviewed. Main Outcome Measures Outcomes studied included readmission, emergency department evaluation, unplanned return to surgery, return to surgery after index admission, and mortality. Univariate analysis was conducted among the entire population with significance set at a p -value <0.05. The population was divided into quartiles based on median household income and univariate analysis conducted between the lowest (quartile 1 [Q1]) and highest (quartile 4 [Q4]) socioeconomic quartiles, with significance set at a p -value <0.05. Stepwise regression was conducted to determine the correlations among study variables and to identify confounding factors. Results Regression analysis of 273 patients demonstrated decreased rates of unplanned reoperation ( p = 0.015) and reoperation after index admission ( p = 0.035) at 30 days with higher standardized income. Logistic regression between the lowest (Q1) and highest (Q4) socioeconomic quartiles demonstrated decreased unplanned reoperation ( p = 0.045) and decreasing but not significant reoperation after index admission ( p = 0.15) for Q4 patients. No significant difference was observed for other metrics of morbidity and mortality. Conclusion Higher socioeconomic status is associated with decreased risk of unplanned reoperation following CPA tumor resection.

The utility of augmented reality in lateral skull base surgery: A preliminary report

ObjectiveTo discuss the utility of augmented reality in lateral skull base surgery. PatientsThose undergoing lateral skull base surgery at our institution. Intervention(s)Cerebellopontine angle tumor resection using an augmented reality interface. Main outcome measure(s)Ease of use, utility of, and future directions of augmented reality in lateral skull base surgery. ResultsAnecdotally we have found an augmented reality interface helpful in simulating cerebellopontine angle tumor resection as well as assisting in planning the incision and craniotomy. ConclusionsAugmented reality has the potential to be a useful adjunct in lateral skull base surgery, but more study is needed with large series.

The role of socioeconomic status on outcomes following cerebellopontine angle tumor resection

Purpose It is well documented that the interaction between many social factors can affect clinical outcomes. However, the independent effects of economics on outcomes following surgery are not well understood. The goal of this study is to investigate the role socioeconomic status has on postoperative outcomes in a cerebellopontine angle (CPA) tumor resection population. Materials and methods Over 6 years (07 June 2013 to 24 April 2019), 277 consecutive CPA tumor cases were reviewed at a single, multihospital academic medical center. Patient characteristics obtained included median household income, Charlson Comorbidity Index (CCI), race, BMI, tobacco use, amongst 23 others. Outcomes studied included readmission, ED evaluation, unplanned return to surgery (during and after index admission), return to surgery after index admission, and mortality within 90 days, in addition to reoperation and mortality throughout the entire follow-up period. Univariate analysis was conducted amongst the entire population with significance set at a p value <0.05. The population was divided into quartiles based on median household income and univariate analysis conducted between the lowest (Q1) and highest (Q4) socioeconomic quartiles, with significance set at a p value <0.05. Stepwise regression was conducted to determine the correlations amongst study variables and identify confounding factors. Results Regression analysis of 273 patients did not find household income to be associated with any of the long-term outcomes assessed. Similarly, a Q1 vs Q4 comparison did not yield significantly different odds of outcomes assessed. Conclusion Although not statistically significant, the odds ratios suggest socioeconomic status may have a clinically significant effect on postsurgical outcomes. Further studies in larger, matched populations are necessary to validate these findings.

Gender is associated with long-term mortality after cerebellopontine angle tumor resection

ObjectiveGender can contribute to adverse patient outcomes through social and biological factors. It is important to assess the effects of gender on long-term patient outcomes after care has already been accessed, in order to improve quality of care and mitigate healthcare disparities. Patients and Methods277 consecutive patients undergoing cerebellopontine angle tumor resection over a six-year period (June 09, 2013 – April 29, 2019) at a university health system were retrospectively evaluated. Outcomes included 90-day emergency department (ED) visit, readmission, reoperation and mortality following resection. Male and female patients in the whole population were analyzed by logistic regression. Thereafter, Coarsened Exact Matching was used to match female and male on important demographic factors, including history of prior surgery, median household income, and Charlson Comorbidity Index (CCI) score, among others. Regression was carried out in the matched population, with significance set at a p-value < 0.05. ResultsIn the matched population analysis, males were significantly more likely to experience mortality during the length of follow-up (p = 0.03) but not within 90-days of resection. There were no significant differences in 90-day mortality or reoperation during the length of follow-up in either the matched or pre-matched populations. No significant differences were found in any of the 90-day morbidity outcomes in either the matched or pre-matched populations. ConclusionGender may predict long-term outcomes in patients following CPA tumor resection. It is possible that gender also contributes to outcome disparities in other neurosurgical procedures, which future studies should evaluate.

Association of Neurosurgical Work Relative Value Units with Objective Markers of Operative Complexity

Relative value units (RVUs) form the backbone of health care service reimbursement calculation in the United States. However, it remains unclear how well RVUs align withobjective measures of procedural complexity within neurosurgery. The 2018 American College of Surgeons National Surgical Quality Improvement Program database was queried for neurosurgical procedures with >50 patients, using Current Procedural Terminology (CPT) codes. Length of stay (LOS), operative time, mortality, and readmission and reoperation rates were collected for each code and a univariate correlation analysis was performed, with significant predictors entered into a multivariate logistic regression model, which generated predicted work RVUs, which were compared with actual RVUs to identify undervalued and overvalued procedures. Among 64 CPT codes, LOS, operative time, mortality, readmission, and reoperation were significant independent predictors of work RVUs and together explained 76% of RVU variance in a multivariate model (R2= 0.76). Using a difference of >1.5 standard deviations from the mean, procedures associated with greater than predicted RVU included surgery for intracranial carotid circulation aneurysms (CPTs 61697 and 61700; residual RVU= 12.94 and 15.07, respectively), and infratemporal preauricular approaches to middle cranial fossa (CPT 61590; residual RVU= 15.39). Conversely, laminectomy/foraminotomy for decompression of additional spinal cord, cauda equina, and/or nerve root segments (CPT 63048; residual RVU= -21.30), transtemporal craniotomy for cerebellopontine angle tumor resection (CPT 61526; residual RVU= -9.95), and brachial plexus neuroplasty (CPT 64713; residual RVU= -11.29) were associated with lower than predicted RVU. Work RVUs for neurosurgical procedures are largely predictive of objective measures of surgical complexity, with few notable exceptions.

Prognostic value of a bilateral motor threshold criterion for facial corticobulbar MEP monitoring during cerebellopontine angle tumor resection.

In intraoperative neuromonitoring (IONM), facial nerve motor function (FaNMF) is assessed by facial muscle corticobulbar motor evoked potentials (FMcoMEP). Mostly only amplitude decrease is used as warning criterion. We related a refined criterion for FMcoMEP consisting of a bilateral final-to-baseline motor threshold ratio with standard criteria and postoperative FaNMF. 79 patients (45 females; 48 ± 16years) undergoing IONM-guided cerebellopontine angle tumor surgery were retrospectively analyzed. An intraoperative final-to-baseline motor threshold increase ≥ 20% ipsi- versus contralaterally (bFBMT20) was correlated to postoperative FaNMF at day 1 (D1), 7 (D7) and 3months (3M). An ipsilateral-only final-to-baseline motor threshold increase ≥ 20mA (iAMT20) and amplitude decrement ≥ 50% (iAR50) served as reference. Tumors included vestibular schwannomas (68%), meningiomas (19%) and others (13%). Mean tumor diameter was 2.7 ± 1.1cm. Postoperatively, HB-increase ≥ 2 was seen in 27% (D1), 17% (D7), and 6% (3M) of patients, respectively. FMcoMEP were obtained in 75/79 cases. Pathological bFBMT20, iAMT20 and iAR50 were seen in 17, 17, and 46 cases, respectively. Area under the ROC curve for bFBMT20 (iAMT20) was 0.894 (0.868) at D1; 0.903 (0.822) at D7 and 0.941 (0.959) at 3M. iAR50 performed worse at all time points. Diagnostic odds ratios were highest for bfBMT20 compared to iAMT20 and iAR50 for D1 (172.5 vs. 8.7 vs. 0.45) and D7 (51.4 vs. 6.1 vs. 0.8). The refined parameter bFBMT20 provides a valuable contribution to the prognostic assessment of FaNMF. Due to its bihemispheric character, it might thus circumvent false-positive events which affect FMcoMEP bilaterally.

Petrous Apex Pneumatization: Influence on Postoperative Cerebellopontine Angle Tumor Cerebrospinal Fluid Fistula.

Multiple investigators have sought to identify risk factors for cerebrospinal fluid (CSF) leak following cerebellopontine angle (CPA) tumor resection. We evaluated whether pneumatization of the petrous apex (PA) is a risk factor for CSF fistula. We conducted a retrospective chart review at 2 major tertiary academic institutions undergoing CPA tumor resection and analyzed their respective head or temporal computed tomography (CT) scans if available. A total of 91 cases were identified; 51 (64%) demonstrated PA pneumatization, and a total of 17 CSF leaks were identified. We discovered higher rates of CSF leak (25.0% vs 13.7%; P = .273) and CSF rhinorrhea (15.0% vs 5.9%; P = .174) in patients with PA pneumatization compared to those without PA pneumatization. Isolated PA pneumatization may be a risk factor and communication pathway for CSF fistula. Further studies will need to be broadened across multiple institutions to draw any additional and stronger conclusions.

Effect analysis of hypoglossal-facial neurorrhaphy using a predegenerated sural nerve autograft for peripheral facial paralysis

Objective To evaluate the treatment effects of hypoglossal-facial 'side’-to-side neurorrhaphy using a predegenerated sural nerve autograft for facial paralysis following tumor resection in cerebellopontine angle (CPA) area. Methods We followed up 48 patients who developed facial paralysis as a result of CPA tumor removal and underwent hypoglossal-facial 'side’-to-side neurorrhaphy using a predegenerated sural nerve autograft between June 2013 to February 2016 at Neurosurgery Department of Beijing Tiantian Hospital, Capital Medical University. Eight other patients who served as controls did not receive any repair treatment. Patients in both groups received rehabilitation exercises and their static and dynamic facial images were collected. Electrophysiological tests of the facial nerve were conducted including electromyography, motor nerve conduction and F wave. The patients' facial nerve functions were assessed according to House-Brackmann grading scale(H-B scale). The follow-up lasted 2-36 months with an average of (12.1±13.4) months. Results In the surgical treatment group, 24/48 patients were found postoperatively to have significant facial function improvement on H-B scale, 21/48 patients to have improvement, and 3/48 remained unchanged. In the control group, 1/8 patient was found to have significant facial function improvement on H-B scale, 2/8 had improvement and 5/8 remained unchanged associated with marked atrophy of paralyzed facial muscles. Significant difference was identified in the facial function improvement on H-B scale between the surgical treatment and control groups (P<0.01). The improvement of facial nerve function was most evident if the surgical repair treatment was performed within the 6 months after the onset of facial paralysis. Conclusions Hypoglossal-facial 'side’-to-side neurorrhaphy may effectively treat facial paralysis resulting from CPA tumor resection. Better recovery of facial nerve function could be achieved when the surgical treatment is performed within the 6 months after the onset of the facial paralysis. Key words: Central nervous system neoplasms; Cerebellopontine angle; Facial paralysis; Transplantation, autologous; 'Side’-to-side neurorrhaphy

Transcochlear Approach to Resection of Cerebellopontine Angle Tumors: Patient Selection, Surgical Technique, and Outcomes

Background: The transcochlear approach extends the anterior exposure afforded by the translabyrinthine technique. Although this wider exposure allows improved access to cranial nerves and the brainstem with less retraction on the cerebellum, the classical description involving facial nerve transposition often results in permanent facial paresis. This study discusses the role of the transcochlear approach in resection of cerebellopontine angle tumors including patient selection, surgical technique, and outcomes.

Effect of Corticosteroids on Facial Function after Cerebellopontine Angle Tumor Removal: A Double-Blind Study versus Placebo

The aim of this study was to assess the effect of corticosteroids administered intra- and postoperatively on the occurrence of facial palsy after a cerebellopontine angle (CPA) tumor resection, and to investigate pre- and intraoperative prognostic factors. A multicenter, prospective, randomized, double-blind and versus-placebo study was conducted between 2006 and 2010. Three hundred and ten patients operated on for a CPA tumor (96% vestibular schwannomas, 4% miscellaneous) were included by five participating centers. The population was stratified into patients with small (≤15 mm CPA on axial MRI views) and large tumors. In each group, patients were randomized to receive corticosteroid (1 mg/kg/day i.v. methylprednisolone intraoperatively and at postoperative days 1-5) or placebo. Steroids did not affect the facial function at postoperative days 1, 8 and 30 in patients with small or large tumors as evaluated by House and Brackmann grading.

The combined microscopic-endoscopic technique for radical resection of cerebellopontine angle tumors.

The combined microscopic and endoscopic technique has shown significant advantages in the management of various lesions through different approaches. Endoscopic-assisted techniques have frequently been applied to cerebellopontine angle (CPA) surgery in the context of minimally invasive craniotomies. In this paper the authors report on the use of the endoscope in the CPA as a tool to increase the extent of resection, minimize complications, and preserve the function of the delicate CPA structures. They also describe a technique of the simultaneous use of the microscope and endoscope in the CPA and dissection of CPA tumors under tandem endoscopic and microscopic vision to overcome the shortcomings of introducing the endoscope alone in the CPA. The reliability of using the microscope alone in dissecting CPA tumors is evaluated, as is the effectiveness of the combined technique in increasing the resectability of various types of CPA tumors. The authors conducted a retrospective analysis of 50 patients who underwent combined microscopic-endoscopic resection of CPA tumors by the senior author over a period of 3 years (February 2011 to February 2014) at Brigham and Women's Hospital, Harvard Medical School. The reliability of the extent of microscopic removal was evaluated with endoscopic exploration. Additional resection was performed with both microscopic and the combined microscopic-endoscopic technique. Endoscopically verified total resection was validated by intraoperative or postoperative MRI. The function of the cranial nerves was evaluated to assess the impact of the combined technique on their function. A tumor remnant was endoscopically identified in 69% of the 26 patients who were believed to have microscopic total resection. The utilization of the endoscopic visualization and dissection increased endoscopically verified total removal to 38 patients, and 82% of these patients had no sign of residual tumor on postoperative imaging. The technique was most effective with epidermoid tumors. There were a total of 17 new cranial nerve deficits in 10 patients. Preoperative fifth cranial nerve deficits improved in 52% and hearing improved in 29% of patients after surgery. This method provides simultaneous microscopic and endoscopic visualization and dissection techniques through skull-base approaches to CPA tumors. It overcomes some of the shortcomings of endoscopic-assisted surgery, further extends the surgical field, and increases the radicality of tumor resection with good functional outcomes.

Fully endoscopic retrosigmoid approach for posterior petrous meningioma and trigeminal microvascular decompression.

Cerebellopontine angle tumor resection and cranial nerve microvascular decompression are usually performed with the aid of the surgical microscope. The endoscope is commonly used as an adjuvant. A retrosigmoid craniectomy is done. Upon dural opening, the endoscope is inserted into the operative field along the petrotentorial junction. Cerebrospinal fluid drainage provides a wider space for introduction of the endoscope and surgical instruments. Traditional microsurgical techniques are used during the entire procedure. A fully endoscopic retrosigmoid approach is a safe and effective procedure for cerebellopontine angle tumor resection and cranial nerve microvascular decompression. • Careful examination of preoperative studies is needed to identify anatomical peculiarities. • Patient positioning: the head must be gently flexed and its vertex gently tilted toward the floor. • Neurophysiologic monitoring and intraoperative navigation. • Craniectomy: partial exposure of the transverse and sigmoid sinuses. • Curvilinear dural incision reflected laterally to minimize the risk of sinus injury. • Opening the cerebellomedullary cistern for CSF drainage and cerebellar relaxation. • Dynamic endoscopy enhances depth perception and must be performed by a team with experience in endoscopic intracranial surgery. • Traditional microsurgical techniques have to be applied during the entire operation. • Multilayer reconstruction, including watertight dural closure. • Meningiomas causing brainstem shift are not suitable for endoscopic resection.