Effect of deep learning-based reconstruction on high-resolution three-dimensional T2-weighted fast asymmetric spin-echo imaging in the preoperative evaluation of cerebellopontine angle tumors.

PURPOSE: We aimed to evaluate the effect of deep learning-based reconstruction (DLR) on high-spatial-resolution three-dimensional T2-weighted fast asymmetric spin-echo (HR-3D T2-FASE) imaging in the preoperative evaluation of cerebellopontine angle (CPA) tumors. METHODS: This study included 13 consecutive patients who underwent preoperative HR-3D T2-FASE imaging using a 3 T MRI scanner. The reconstruction voxel size of HR-3D T2-FASE imaging was 0.23 × 0.23 × 0.5 mm. The contrast-to-noise ratios (CNRs) of the structures were compared between HR-3D T2-FASE images with and without DLR. The observers' preferences based on four categories on the tumor side on HR-3D T2-FASE images were evaluated. The facial nerve in relation to the tumor on HR-3D T2-FASE images was assessed with reference to intraoperative findings. RESULTS: The mean CNR between the tumor and trigeminal nerve and between the cerebrospinal fluid and trigeminal nerve was significantly higher for DLR images than non-DLR-based images (14.3 ± 8.9 vs. 12.0 ± 7.6, and 66.4 ± 12.0 vs. 53.9 ± 8.5, P < 0.001, respectively). The observer's preference for the depiction and delineation of the tumor, cranial nerves, vessels, and location relation on DLR HR-3D T2FASE images was superior to that on non-DLR HR-3D T2FASE images in 7 (54%), 6 (46%), 6 (46%), and 6 (46%) of 13 cases, respectively. The facial nerves around the tumor on HR-3D T2-FASE images were visualized accurately in five (38%) cases with DLR and in four (31%) without DLR. CONCLUSION: DLR HR-3D T2-FASE imaging is useful for the preoperative assessment of CPA tumors.

Fully Endoscopic Retrosigmoid Approach for Cerebellopontine Angle Tumors.

BACKGROUND: Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic retrosigmoid approach for cerebellopontine angle tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with few series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure, neurovascular injury, and decreased visibility may explain this fact. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic retrosigmoid approach and present an overview of the published series. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic retrosigmoid approach for cerebellopontine angle tumors were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic retrosigmoid approach was formulated. CONCLUSION: The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Microsurgical anatomy of the glossopharyngeal nerve.

The glossopharyngeal nerve is a complicated and mixed nerve including sensory, motor, parasympathetic, and visceral fibers. It mediates taste, salivation, and swallowing. The low cranial nerves, including IXth, Xth, and XIth, are closely related, sharing some nuclei in the brainstem. The glossopharyngeal nerve arises from the spinal trigeminal nucleus and tract, solitary tract and nucleus, nucleus ambiguous, and inferior salivatory nucleus in the brainstem. There are communicating branches forming a neural anastomotic network between low cranial nerves. Comprehensive knowledge of the anatomy of the glossopharyngeal nerve is crucial for performing surgical procedures without significant complications. This review describes the microsurgical anatomy of the glossopharyngeal nerve and illustrates some pictures involving the glossopharyngeal nerve and its connective and neurovascular structures.

Clinicopathological characteristics of secondary trigeminal neuralgia due to cerebellopontine angle tumors. / æ¡¥å°è„‘è§’è‚¿ç˜¤ç»§å‘æ€§ä¸‰å‰ç¥žç»ç—›çš„ä¸´åºŠç— ç†ç‰¹å¾.

OBJECTIVES: Cerebellopontine angle (CPA) tumors are a common cause of secondary trigeminal neuralgia (TN), characterized by their concealed location, slow progression, and difficulty in early detection. This study aims to explore the clinicopathological characteristics of patients with secondary TN due to CPA tumors to enhance understanding and management of secondary TN. METHODS: A retrospective analysis was conducted on clinical data and pathological results of 116 patients with CPA tumor-related TN treated at Xiangya Hospital of Central South University from January 1, 2017 to December 31, 2022. The study analyzed the relationship of tumor pathological types with clinical manifestations, tumor location, surgical methods, and treatment outcomes. RESULTS: Among the cases, 95.7% (111/116) were benign tumors, 3.4% (4/116) were malignant tumors, and 0.9% (1/116) were borderline tumors. Benign tumors were predominantly acoustic neuromas, meningiomas, and schwannomas. Among the patients, 46.6% (54/116) presented with isolated TN, while 53.4% (62/116) exhibited other associated symptoms depending on factors such as tumor growth location and rate. The complete resection rate in this group was over 90%, with 41.4% (48/116) of patients undergoing concurrent microvascular decompression after tumor resection, predominantly for schwannomas. The overall effective rate of surgical treatment reached 93.9%, with schwannomas showing higher efficacy rates compared with acoustic neuromas and meningiomas (P<0.05). The recurrence rate of acoustic neuromas was significantly higher than that of meningiomas and schwannomas (P<0.05). CONCLUSIONS: CPA tumors are a major cause of secondary TN, predominantly benign, with occasional underdiagnosed malignant tumors. Early diagnosis and treatment significantly impact prognosis. Different tumor types vary in clinical symptoms, surgical approaches, and treatment efficacy. Surgical strategies should balance tumor resection extent and neural function preservation, with microvascular decompression as necessary.

Cochlear Obliteration after Translabyrinthine Resection for Large Cerebellopontine Angle Tumor.

INTRODUCTION: The aim of this study was to better understand the onset time and factors associated with cochlear obliteration following translabyrinthine approach (TLA) surgery for large cerebellopontine angle tumors. METHODS: This retrospective cohort study included 117 patients with large cerebellopontine angle tumor (tumor diameter >2 cm) treated by TLA surgery from June 2011 to March 2019 in a single tertiary referral center. The Kaplan-Meier method with log-rank test was used to estimate cochlear patency survival and the association between survival and covariates, and the Cox proportional hazards regression analysis was used to identify possible factors associated with cochlear obliteration. RESULTS: Of the 117 patients included in our analysis, the median follow-up was 24.8 months. There were 30 (25.6%) patients in the cochlear obliteration group, and 87 (74.4%) in the patent cochlear group. Various degrees of cochlear obliteration was found in 25.6% patients in final MRI scan, comprised of 50% grade I, 30% grade II, and 20% grade III. Cochlear patency survival curves showed 94.0% at 3 months, 73.0% at 18 months, which plateaued after 20 months with a survival rate of 71.6%. In the multivariate Cox proportional hazards model, patients presented with postoperative hyperintense T1W cochlear signal had poorer cochlear patency survival compared to isointense T1W (HR = 4.15). Similarly, postoperative deteriorated facial function (HR = 4.52) and full IAC involvement of tumor (HR = 2.33) demonstrated a higher risks of cochlear obliteration after TLA surgery. CONCLUSION: The 2-year estimated cochlear patency rate was 71.6% in patients that received TLA. Cochlear obliteration can develop as early as 3 months post-surgery, with no new obliteration 20 months after the surgery and half of these patients got severe obliteration. Three factors associated with cochlear obliteration were identified including full IAC involvement of tumor, postoperative facial function deterioration, and postoperative hyperintense T1W cochlear signal.

Trigeminal Schwannoma Surgery: Challenges in Preserving Facial Sensation.

Treatments of schwannoma have dramatically improved in the previous few decades, but preservation of the functions of the originating nerve, such as facial sensation in trigeminal schwannomas, still remains challenging. As the preservation of facial sensation in trigeminal schwannomas has not been analyzed in detail, we here review our surgical experience of more than 50 trigeminal schwannoma patients, particularly focusing on their facial sensation. Since the facial sensation in each trigeminal division showed a different perioperative course even in a single patient, we investigated patient-based outcomes (average of the three divisions in each patient) and division-based outcomes separately. In the evaluation of patient-based outcomes, facial sensation remained postoperatively in 96% of all the patients, and improved in 26% and worsened in 42% of patients with preoperative hypesthesia. Posterior fossa tumors tended to most rarely disrupt facial sensation preoperatively, but were the most difficult to preserve facial sensation postoperatively. Facial pain was relieved in all six patients with preoperative neuralgia. In the division-based evaluation, facial sensation remained postoperatively in 83% of all the trigeminal divisions, and improved in 41% and worsened in 24% of the divisions with preoperative hypesthesia. The V3 region was most favorable before and after surgery, with the most frequent improvement and the least frequent functional loss. To clarify current treatment outcomes of the facial sensation and to achieve more effective preservation, standardized assessment methods of perioperative facial sensation may be required. We also introduce detailed MRI investigation methods for schwannoma, including contrast-enhanced heavily T2-weighted (CISS) imaging, arterial spin labeling (ASL), and susceptibility-weighted imaging (SWI), preoperative embolization for rare vascular-rich tumors, and modified techniques of the transpetrosal approach.

Nationwide clinico-epidemiological treatment analysis of adult patients with tumors of cerebellopontine angle and internal acoustic meatus in Poland during 2011-2020.

OBJECTIVE: The aim of this study is to report the epidemiologic characteristics of tumors of the cerebellopontine angle (CPAT) and internal acoustic meatus in adult Polish population throughout the second decade of XXI century and to analyze their treatment. MATERIAL AND METHODS: A retrospective analysis of patients with cerebellopontine angle (CPA) and internal acoustic meatus tumors diagnosed in Poland in 2011-2020 was performed. Data recorded in the National Health Fund (NHF) database were analyzed. International Classification of Diseases codes (ICD-9 and ICD-10) were used to identify study group patients and treatment procedures. RESULTS: From 2011 to 2020 6,173 Polish adult patients were diagnosed with cerebellopontine angle and internal acoustic meatus tumors. The average incidence in Poland is 1.99 per 100,000 residents/year. It mostly affects women (61.64%), and the average age of patients is 53.78 years. The incidence has steadily increased over the past decade. Treatment has changed significantly over the years, with a definite increase in the number of patients treated with radiotherapy (from 0.54 to 19.34%), and a decrease in surgical therapies (from 41.67 to 6.8%). The most common symptoms were vertigo and/or dizziness (43.48%) and sensorineural hearing loss (39.58%). 4.65% of patients suffered from sudden deafness, in this group of patients the risk of CPAT detection was the highest (6.25 / 1000 patients). CONCLUSIONS: The total incidence of CPAT and demographic characteristics of patients were comparable to other studies. Our study demonstrated the increased number of patients are being treated with radiotherapy and fewer with microsurgery. Sudden sensorineural hearing loss (SSNHL) is an uncommon manifestation of CPAT but proper diagnosis should be undertaken because the risk of diagnosis such tumors is greater in this group.

The cerebellopontine angle cistern volumetric differences in trigeminal neuralgia patients with and without vertebrobasilar compression: a case-matched study.

Previous studies have indicated that the small cerebellopontine angle (CPA) cistern plays a role in the pathogenesis of trigeminal neuralgia (TN), but they are likely not involved in TN associated with vertebrobasilar artery (VBA) compression because of its rarity. Forty-four patients with VBA-associated TN and 44 age-, sex-, and hypertension-matched TN patients without VBA compression (non-VBA-associated) were included. All patients underwent high-resolution MRI. The CPA cistern volumes were measured bilaterally. The presence of vertebrobasilar dolichoectasia (VBD) and laterality of the vertebrobasilar junction (VBJ) were observed. The CPA cistern volume on the affected side was smaller than the unaffected side (714.4 ± 372.8 vs 890.2 ± 462.2 mm3, p < 0.001) in non-VBA-associated TN patients, while VBA-associated TN patients show a larger CPA cistern on the affected side than the unffected side (1107.0 ± 500.5 vs 845.3 ± 314.8 mm3, p < 0.001). The prevalence of VBD was higher in patients with VBA-associated TN than in matched non-VBA-associated TN patients (90.9% vs 4.5%, p < 0.001). A positive correlation between the laterality of VBJ and the affected side was found in the VBA-associated TN group (p < 0.0001). Large CPA cistern may be a neuroradiological feature of VBA-associated TN, and most of the VBA-associated TN is accompanied by VBD. The presence of VBD and the lateral shift of VBJ may expand the CPA cistern by squeezing the surrounding tissue on the affected side and also increase the chance of VBA compression on the trigeminal nerve, resulting in the genesis of VBA-associated TN.

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

The objective of this study is to preliminarily investigate the surgical safety, efficacy, techniques, and clinical value of fully neuroendoscopic surgery for the resection of cerebellopontine angle (CPA) tumors via a retrosigmoid approach. The clinical data of 47 cerebellopontine angle area (CPA) tumors that were treated by full neuroendoscopic surgery from June 2014 to June 2023 were retrospectively analyzed. The efficacy and advantages of the surgical techniques were evaluated based on indicators such as duration of the surgery, neuroendoscopic techniques, intraoperative integrity of nerves and blood vessels, extent of tumor resection, outcomes or postoperative symptoms, and incidence of complications. The 47 cases of cerebellopontine angle tumors include 34 cases of epidermoid cysts, 7 cases of vestibular schwannomas, and 6 cases of meningiomas. All patients underwent fully neuroendoscopic surgery. Twenty tumors were removed using the one-surgeon two-hands technique, and 27 tumors were removed using the two-surgeons four-hands technique. The anatomical integrity of the affected cranial nerves was preserved in all 47 cases. None of the patients suffered a postoperative hemorrhage, cerebrospinal fluid leak, and aseptic or septic meningitis, or died. The rate of total tumor resection was 72.3% (34/47), and the symptom improvement rate was 89.4% (42/47). All patients were followed up for 2 to 12 months, and none died nor showed any signs of tumor recurrence. By analyzing 47 fully neuroendoscopic resections of CPA tumors using the posterior sigmoid sinus approach in our center, we believe that such method allows complete, safe, and effective resection of CPA tumors and is thereby worthy of clinical promotion.

Schwannomas of Brain and Spinal Cord.

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

How I do it: cerebellopontine angle epidermoid cyst removal with endoscopic assistance.

BACKGROUND: Epidermoid cyst in the cerebellopontine angle (CPA) can involve numerous critical structures. Endoscopic assistance following microscopic removal via a retrosigmoid approach can expand the surgical corridor, allowing for more complete resection. METHOD: We describe in a stepwise fashion the surgical steps for the microscopic removal of an epidermoid cyst of the CPA with endoscopic assistance. CONCLUSION: Endoscopically assisted microscopic removal for CPA epidermoid cysts provides wide access to the CPA and its adjacent structures and shows to be an effective option in selected cases.

Microsurgical anatomy and pathoanatomy of the outer arachnoid membranes in the cerebellopontine angle: cadaveric and intraoperative observations.

PURPOSE: The cerebellopontine angle (CPA) is a frequent region of skull base pathologies and therefore a target for neurosurgical operations. The outer arachnoid is the key structure to approach the here located lesions. The goal of our study was to describe the microsurgical anatomy of the outer arachnoid of the CPA and its pathoanatomy in case of space-occupying lesions. METHODS: Our examinations were performed on 35 fresh human cadaveric specimens. Macroscopic dissections and microsurgical and endoscopic examinations were performed. Retrospective analysis of the video documentations of 35 CPA operations was performed to describe the pathoanatomical behavior of the outer arachnoid. RESULTS: The outer arachnoid cover is loosely attached to the inner surface of the dura of the CPA. At the petrosal surface of the cerebellum the pia mater is strongly adhered to the outer arachnoid. At the level of the dural penetration of the cranial nerves, the outer arachnoid forms sheath-like structures around the nerves. In the midline, the outer arachnoid became detached from the pial surface and forms the base of the posterior fossa cisterns. In pathological cases, the outer arachnoid became displaced. The way of displacement depends on the origin of the lesion. The most characteristic patterns of changes of the outer arachnoid were described in case of meningiomas, vestibular schwannomas, and epidermoid cysts of the CPA. CONCLUSION: The knowledge of the anatomy of the outer arachnoid of the cerebellopontine region is essential to safely perform microsurgical approaches as well as of dissections during resection of pathological lesions.

Radiological presence of vascular loops in the cerebellopontine angle region in patients with unilateral Ménière's disease.

OBJECTIVE: The relationship between vascular compression of the vestibulocochlear nerve and audio-vestibular symptoms remains controversial. We aimed to examine the radiological features of vascular loops signs in cerebellopontine angle (CPA) and internal auditory canal (IAC) in patients with unilateral Ménière's disease (MD). METHODS: One hundred and thirty-seven patients with unilateral definite MD and 69 control subjects (138 ears) were enrolled. All subjects received magnetic resonance imaging of CPA-IAC. The configuration of vascular loops in CPA-IAC, based on the Kazawa classification system, from MD-affected, non-affected and control ears were compared. The associations between imaging findings and Ménière's stage, electrocochleogram (EcochG) and caloric test were analyzed. RESULTS: (1) Among the MD-affected ears, 6 cases (4.4%) were classified as Kazawa type IA, 27 cases (19.7%) as IB, 60 cases (43.8%) as IIA, and 44 cases (32.1%) as IIB. No significant interaural difference in the distribution of Kazawa's types was found ([Formula: see text] = 4.737, p = 0.578) in unilateral MD patients. (2) The distribution of Kazawa's types were not significantly different between the MD-affected ears and the control subjects ([Formula: see text] = 2.876, p = 0.411). (3) No relationship was found between Kazawa staging of the MD-affected ear and Ménière's stage (H = 2.679, p = 0.444), EcochG ([Formula: see text] = 0.827, p = 0.867) and caloric test ([Formula: see text] = 4.116, p = 0.248). CONCLUSIONS: In patients with unilateral MD, the configuration of vascular loops in CPA-IAC region, measured by Kazawa criteria, did not correlate with the laterality, clinical stage, the results of EcochG and caloric test, suggesting that vascular loops may be natural anatomical variations for patients with MD.

Secondary cerebellopontine angle oligodendroglioma after cranial irradiation: a case report and literature review.

PURPOSE/AIM: Cerebellopontine angle (CPA) oligodendrogliomas are very rare, and only three preoperative cases have been confirmed. Secondary CPA oligodendrogliomas after radiation therapy are exceptionally rare, and no other cases have been reported. CASE REPORT: We present a case of a 25-year-old male with CPA oligodendroglioma who experienced hearing loss in right ear with walking instability for more than 2 months. The patient underwent craniotomy in our hospital because of grade II astrocytoma of the right temporal lobe 10 years ago. Postoperative radiotherapy lasted for 30 days, and six rounds of chemotherapy were performed. Magnetic resonance imaging (MRI) of the head revealed a cystic lesion located in the right CPA. The patient underwent surgery without obvious complications, and the tumor was subtotally removed. Histopathological examination revealed a diagnosis of oligodendroglioma, World Health Organization (WHO) grade II. The patient was discharged on the tenth postoperative day with a good recovery. Two weeks after discharge, chemotherapy with temozolomide and radiotherapy were performed. The patient remained well at 8 months follow-up. CONCLUSIONS: To the best of our knowledge, no other cases of secondary CPA oligodendroglioma after cranial irradiation have been reported in the literature. Compared with general oligodendroglioma, the tumor has no typical calcification and is more aggressive. The cranial nerves in the CPA area are closely adhered, and the blood supply is abnormally rich. It is difficult to completely remove the tumor. Postoperative radiotherapy and chemotherapy should be carried out as soon as possible.

The shrinking vestibular schwannoma.

We present a case of spontaneous 79% regression in the size of a vestibular schwannoma (VS). A 41-year-old lady with a large (36 mm) vestibular schwannoma underwent serial follow-up MRI scans which demonstrated the shrinkage over 9 years; the highest relative spontaneous regression recorded in the literature for vestibular schwannoma of this size.

Cerebellopontine angle epidermoid with ipsilateral external ear atresia: an embryological association or a coincidence?

The cerebellopontine angle (CPA) is the most common site for intracranial epidermoids. They may have varied presentations viz facial pain, hemifacial spasms, headache and uncommonly features of raised intracranial pressure. Their association with external ear atresia has not been reported in literature to date. We present a very rare case of CPA epidermoid with ipsilateral external ear atresia.

Stereotactic radiosurgery for cerebellopontine meningiomas: a systematic review and meta-analysis.

OBJECTIVE: To (1) measure surgical outcomes associated with stereotactic radiosurgery treatment of cerebellopontine angle meningiomas, and (2) determine if differences in radiation dosages or preoperative tumor volumes affect surgical outcomes. METHODS: A systematic search was performed on the PubMed, Medline, Embase and Cochrane Library databases searching for patients under stereotactic radiosurgery for meningiomas of the cerebellopontine angle. After data extraction and Newcastle-Ottawa scale quality assessment, meta-analysis of the data was performed with Review Manager 3.4.5. RESULTS: In total, 6 studies including 406 patients were included. Postprocedure, patients had minimal cranial nerve complications while having an overall tumor control rate of 95.6%. Complications were minimal with facial nerve deficits occurring in 2.4%, sensation deficits of the trigeminal nerve in 4.0%, hearing loss in 5.9%, hydrocephalus in 2.0% and diplopia in 2.6% of all patients. Individuals with tumors extending into the internal auditory canal extension did not have significantly increases in hearing loss. There was a higher likelihood of tumor regression on postprocedure imaging in studies with a median prescription dose of >13 Gy (RR 1.27 [95% CI 1.04-1.56, p = 0.0225). There was no evidence of publication bias detected. CONCLUSIONS: Radiosurgery is an effective modality for offering excellent tumor control of CPA meningiomas while allowing for only minimal complications postprocedure. A higher prescription dose may achieve higher tumor regression at follow up. Future studies should aim at establishing and optimizing accurate dosimetric guidelines for this patient population.

Preoperative assessment of the individual anatomy of the superior petrosal vein complex using balanced fast field echo magnetic resonance imaging.

BACKGROUND: Here, we sought to examine the validity and reproducibility of balanced fast field echo (bFFE) for assessing superior petrosal vein (SPV) complex (SPVC) anatomy. METHODS: Preoperative bFFE or equivalent scans and operative videos were studied and directly compared with regard to the individual anatomical features of SPVCs and their relation to the operative field. The anatomical details of the bFFE findings of the non-operated side (group 2) of all 50 patients were then reviewed, including the presence of petrosal-galenic anastomosis, and finally compared to the operated SPVCs (group 1). RESULTS: A complete correlation between bFFE and intraoperative findings was observed in 62% of cases and had a significant correlation with 3 Tesla magnet strength and higher pixel bandwidth (rbis = - 0.47; p = 0.005). The sensitivity and specificity of bFFE magnetic resonance imaging were 93.7 and 95.2%, respectively, for detecting an SPV disturbing the operative field, and 97.3% and 95% for a disturbing tributary, respectively. Each group had 50 SPVCs, with a total of 70 and 64 SPVs, 10 and 11 general SPVC configurations, as well as 29 and 28 different individual anatomical variations in groups 1 and 2, respectively. Both groups had 1-3 SPVs with a similar distribution of frequencies [Chi-square (4) = 27.56; p = 0.0145 (Fisher's exact test)]. The similarity of the general configurations was not statistically significant. The same four predominant configurations constituted 80% of the SPVCs in each group. The vein of the cerebellopontine fissure was most frequently found in 86% and 88% of cases, and a petrosal-galenic anastomosis was seen in 38% and 40% of groups 1 and 2, respectively. CONCLUSIONS: Individual SPVC variations are extensive. Good quality bFFE or equivalents are feasible for preoperative SPVC assessments. However, methods improving vascular visualization are recommended.

Predictors of hearing functional outcome following surgery for cerebellopontine angle meningioma.

OBJECTIVE: Cerebellopontine angle (CPA) meningiomas can affect hearing function and require expeditious treatment to prevent permanent hearing loss. The authors sought to determine the factors associated with functional hearing outcome in CPA meningioma patients treated with surgery and/or radiation therapy in the form of either stereotactic radiosurgery or stereotactic radiation therapy. METHODS: Consecutive patients with CPA meningiomas who had presented at our hospital from 2008 to 2018 were identified through retrospective chart review. Hearing function (as defined by pure tone average (PTA) and speech discrimination score (SDS) on Audiogram) was assessed before and after surgery for CPA meningioma. Audiograms with PTA > 50 dB and SDS < 69% were defined as poor hearing functional outcome. Multivariable Cox Proportional Hazards Regression Model was used to assess the associations between pre-operative hearing functional assessment and post-operative hearing functional outcomes. RESULTS: The study cohort included 31 patients (80.6% females, with a mean age of 61.3 ± 15.2 years) with a median clinical follow-up of 5 months (range: 1 week-98 months). The mean pre-operative PTA and SDS were 23.8 ± 11.2 dB and 64.4 ± 22.2% respectively. At the last visit, there was significant hearing recovery, with an improvement of 29.7 ± 18.0 dB (p < 0.001) and 87.6 ± 17.8% (p < 0.001) in PTA and SDS respectively. After adjusting for age, gender, tumor volume, location, and tumor classification, Multivariable Cox Proportional Hazards Regression Model was conducted which revealed that patients undergoing surgery through retro sigmoid approach [Hazards Ratio (HR): 32.1, 95% Confidence Interval (CI): 2.11-491.0, p = 0.01] and gross total resection (GTR) (HR: 2.99, 95% CI: 1.09-9.32, p = 0.05) had significantly higher risk of poor hearing functional outcome compared to petrosal approach and near/subtotal resection. Moreover, patients with poor preoperative hearing had 85% higher chance of poor hearing functional outcome postoperatively (HR: 0.15, 95%CI: 0.03-0.59, p = 0.007). CONCLUSION: Postoperative improvement in hearing is a reasonable expectation following surgery for CPA meningioma. Preoperative hearing, surgical approach and extent of surgical resection are predictive factors of postoperative hearing function outcome and can therefore aid in identification of patients at higher risk of hearing loss.

The Impact of Vascular Loops in the Cerebellopontine Angle on Audio-Vestibular Symptoms: A Systematic Review.

It has been suggested that vascular loops in the cerebellopontine angle and internal auditory canal are involved in the etiology of audio-vestibular symptoms. Several studies have focused on the compression of the eighth cranial nerve by vascular loops but have yielded contradictory results regarding their clinical significance. The aim of this study was to investigate whether vascular loops in this region correlate with audio-vestibular symptoms and which loop features - if any - can potentially lead to symptom manifestation. This systematic review was conducted according to the PRISMA guidelines. We performed on PubMed a literature search from November 2005 to October 2020. The search strategy included the following keywords ("vascular loops" OR "AICA loops" OR "vascular compression syndrome") AND ("hearing loss" OR "tinnitus" OR "vertigo"). Fifteen studies were eligible and included in the analysis. Overall, the studies encompassed a total of 11,788 patients included in this review. The significantly larger group of patients (70%), in which no correlation of symptoms with vascular loops was found, suggests that vascular loops are probably anatomic variations in a substantial majority of cases with an uncommon subset causing some audio-vestibular symptoms. Even within the papers claiming a correlation, there is a multitude of symptoms that did not correlate with vascular loops. It has been suggested by most authors that magnetic resonance imaging should be performed to exclude the role of a vascular loop in the etiology of audio-vestibular symptoms only when vascular compression syndrome is suspected based on clinical indications and not routinely. Further studies would be useful in order to detail the relationship between the vascular structures and the nervous system.