Common Cerebellopontine Angle Tumors Research Articles

Development and application of explainable artificial intelligence using machine learning classification for long-term facial nerve function after vestibular schwannoma surgery

PurposeVestibular schwannomas (VSs) represent the most common cerebellopontine angle tumors, posing a challenge in preserving facial nerve (FN) function during surgery. We employed the Extreme Gradient Boosting machine learning classifier to predict long-term FN outcomes (classified as House-Brackmann grades 1–2 for good outcomes and 3–6 for bad outcomes) after VS surgery.MethodsIn a retrospective analysis of 256 patients, comprehensive pre-, intra-, and post-operative factors were examined. We applied the machine learning (ML) classifier Extreme Gradient Boosting (XGBoost) for the following binary classification: long-term good and bad FN outcome after VS surgery To enhance the interpretability of our model, we utilized an explainable artificial intelligence approach.ResultsShort-term FN function (tau = 0.6) correlated with long-term FN function. The model exhibited an average accuracy of 0.83, a ROC AUC score of 0.91, and Matthew’s correlation coefficient score of 0.62. The most influential feature, identified through SHapley Additive exPlanations (SHAP), was short-term FN function. Conversely, large tumor volume and absence of preoperative auditory brainstem responses were associated with unfavorable outcomes.ConclusionsWe introduce an effective ML model for classifying long-term FN outcomes following VS surgery. Short-term FN function was identified as the key predictor of long-term function. This model’s excellent ability to differentiate bad and good outcomes makes it useful for evaluating patients and providing recommendations regarding FN dysfunction management.

Atypical Manifestation in Vestibular Schwannoma

The cerebellopontine angle (CPA) is a cerebrospinal fluid-filled space, found at the junction between the cerebellum and pons. Vestibular schwannoma (VS) is the most common CPA tumor. Typical initial symptoms are unilateral or asymmetrical hearing impairment, tinnitus in the affected ear, or imbalance or vertigo. We report an unusual case of the patient who presented with right sensorineural hearing loss but was found to have left VS in the normal hearing ear.

Correlation between Cranial Nerve Microstructural Characteristics and Vestibular Schwannoma Tumor Volume.

Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.

Correlation of Preoperative Cranial Nerve Diffusion Tensor Tractography with Intraoperative Findings in Surgery of Cerebellopontine Angle Tumors

Imaging to visualize nerves around tumors preoperatively could help the surgeon to plan the surgery and excise the tumor with preservation or improvement in patients' quality of life. In the present prospective study, we attempted to correlate the preoperative cranial nerves (i.e., trigeminal, abducens, facial, and vestibulocochlear diffusion tensor tractography and anatomic magnetic resonance imaging [MRI] findings) with intraoperative findings during cerebellopontine angle (CPA) tumor surgery. The 40 enrolled patients had CPA tumors (31 vestibular schwannomas, 5 epidermoid tumors, 2 meningiomas, 2 trigeminal schwannomas). All the patients were undergoing microsurgery for the first time. They underwent preoperative MRI for anatomic and diffusion tensor imaging (DTI) data. The imaging series were postprocessed, and 3-dimensional images were obtained. The location of the involved nerves around the tumors was recorded during surgery by the senior surgeon, who was kept unaware of the results of the fiber tracking, and a correlation was performed. We evaluated the correlation between the DTI and intraoperative findings for the nerve location in relation to the tumor in the CPA. The correlation between the DTI and intraoperative findings for the facial, trigeminal, and vestibulocochlear nerves was 85% (34 of 40), 85% (34 of 40), and 75% (12 of 16), respectively. The modified technical parameters proposed could lead to better preservation of cranial nerve function, especially for patients with large tumors. To the best of our knowledge, the present study is the first systematic study of relevant cranial nerves in 40 patients with demonstration of the vestibulocochlear bundle by preoperative MRI in the most common CPA tumors using advanced MRI sequences such as diffusion tensor tractography and capturing the data in a multiplanar format.

Nonvestibular Schwannoma Tumors in the Cerebellopontine Angle: A Single-Surgeon Experience.

Background:The most common cerebellopontine angle (CPA) tumor is a vestibular schwannoma. Schwannomas account for 8.5% of all intracranial tumors and more than 90% of the tumors originate from the eighth cranial nerve, but one in five CPA tumors are not vestibular schwannoma. These tumors may have different manifestations and require different management strategies.Methods:We report 224 consecutive NVCPAT operated in the Department of Neurosurgery, P.D. Hinduja National Hospital and Medical Research Centre, Mumbai, by the senior author between 2001 and 2014 and discuss the different approaches and outcomes in NVCPAT.Results:The age range was 20–60 years and there were 129 females and 95 male patients. The clinical material consisted of 81 cases of meningioma (36.1%), 44 cases of epidermoid (19.64%), 34 cases of trigeminal schwannoma (15.17%), 26 cases of jugular foramen schwannoma (11.60%), and 39 cases of other tumors (17.41%). In nonvestibular schwannoma (NVS), symptoms and signs from cranial nerve VIII are less frequent and other cranial nerves and cerebellar symptoms and signs predominate.Conclusion:Symptoms and signs are different in NVCPAT from those found in patients with vestibular schwannoma. Hearing loss is not the predominant symptoms. Cerebellar signs and trigeminal dysfunction are more common. The most common approach used in the current series was retrosigmoid craniotomy. Gamma knife radiosurgery was a useful adjunct in a subset of these patients.

Microsurgical Resection of the Epidermoid Tumor in the Cerebellopontine Angle.

In this video, we demonstrate epidermoid tumor microsurgical resection of the cerebellopontine angle (CPA) performed by the senior author (K.I.A.). Epidermoid tumors arise from ectoderm trapped within/displaced into the central nervous system. They show predilection for CPA Angle (up to 40%), 4th ventricle, suprasellar region, and spinal cord. 1 They are the 3rd most common CPA tumor, comprising approximately 7% of CPA pathology. CPA lesions can produce 5th and 7–12th cranial nerve neuropathies. 2 3 4 Recurrent episodes of aseptic meningitis caused by cyst content rupture may occur. Symptoms include fever, meningeal irritation, and hydrocephalus. A 26-year-old female presented with headaches. Head magnetic resonance imaging (MRI) revealed right CPA tumor with brain stem compression ( Fig. 1 , A – C ). There was evidence of restricted diffusion in diffusion-weighted imaging, typical of epidermoid tumor. Surgery was performed in prone position with head turned 25 degrees to the ipsilateral side using retrosigmoid craniotomy. 5 Tumor was ventral to the 7th and 8th cranial nerve complexes, between the 5th nerve as well as toward the brainstem. The surgical plan was gross total resection with tumor capsule resection to prevent recurrence. 6 (Small residuals can be left behind when capsule is adherent to critical structures.) Tumor was adherent to brain stem perforators which were preserved using meticulous dissection. Cranial nerves and vascular structures were also left intact. We irrigated with antibiotic saline and used perioperative treatment to prevent aseptic meningitis. The pathohistological diagnosis revealed epidermoid tumor cyst. Postoperative MRI revealed complete resection ( Fig. 1 , D – F ). The patient recovered fully and was neurologically intact. The link to the video can be found at: https://youtu.be/LyWl-KZUSGY .

The Management and Imaging of Vestibular Schwannomas.

Vestibular schwannomas are the most common cerebellopontine angle tumor. During the past century, the management goals of vestibular schwannomas have shifted from total resection to functional preservation. Current treatment options include surgical resection, stereotactic radiosurgery, and observation. Imaging has become a crucial part of the initial screening, evaluation, and follow-up assessment of vestibular schwannomas. Recognizing and understanding the management objectives, various treatment modalities, expected posttreatment findings, and complications allows the radiologist to play an essential role in a multidisciplinary team by providing key findings relevant to treatment planning and outcome assessment. The authors provide a comprehensive discussion of the surgical management, role of radiation therapy and observation, imaging differential, and pre- and posttreatment imaging findings of vestibular schwannomas.

Vestibular Schwannoma with Contralateral Facial Nerve Palsy: A False Localizing Sign

AbstractVestibular schwannomas are the most common cerebellopontine angle tumors. These tumors commonly present with ipsilateral dysfunction of acoustic, vestibular, trigeminal, and facial nerves. Vestibular schwannoma with involvement of contralateral facial nerve is very unusual, and whenever present, it is considered as a false localizing sign. It seems that displacement and distortion of the brainstem by the large mass lesion may lead to this atypical presentation. We report a case of vestibular schwannoma with contralateral abducens and facial nerve paresis.

Surgical Outcomes of Cerebellopontine Angle Tumors in 34 Cases

Introduction: Cerebellopontine angle tumors are a surgical challenge to many neurosurgeons who want to operate in this space. Although most of these tumors are benign, they are a challenge because of the complex anatomy and important neurovascular structures that traverse this space. Most common cerebellopontine angle tumor is vestibular schwannoma. The management of these cases is essentially surgical. There has been a change in the surgical strategy over the years from simple intratumoral decompression to complete microsurgical excision, to radical excision with facial nerve and hearing preservation.Objectives: To study the clinical and radiological characteristics, know the pathological types and determine the surgical resectability and outcome of cerebellopontine angle tumor.Materials and Methods: It is a retrospective study done in the department of Neurosurgery, Apollo Hospitals Dhaka. 34 patients diagnosed with cerebellopontine angle tumor were recruited into the study.Results: Among 34 cases of cerebellopontine angle tumors vestibular schwannoma alone constituted 79%. Most of the tumors were large or giant tumors. Total resection was done in 25% of vestibular schwannoma and 50% of meningiomas. Anatomical preservation of facial nerve was achieved in 73% of patients. Facial nerve function as measured by the House Brackmann system. Postoperatively 61% had a score of 1 or 2; 29% had a score of 3 or 4; and 8% had a score of 5 or 6. Other complications included 2 cases of CSF leak, 3 cases of meningitis, 2 cases of lower cranial nerve palsy and 1 patient died.Conclusion: Cerebellopontine angle tumors show high incidence from 3rd to 5th decade with common symptoms being hearing loss and ataxia. Most of the patients presented at a delayed stage with large to giant tumors with no useful hearing. Sub total excision with keeping anterior part of tumor for preserving facial nerve function is the goal.Pulse Vol.8 January-December 2015 p.8-14

Decreased vestibular signal intensity on 3D-FIESTA in vestibular schwannomas differentiating from meningiomas

With reported characteristic MR features, it is difficult to differentiate vestibular schwannomas (VSs) from cerebellopontine angle (CPA) meningiomas (CPAMs) in some cases. This study aimed to evaluate vestibular signal intensity changes in patients with VS and those with CPAM on three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA), and to test the effectiveness of the signal intensity change to differentiate these two common CPA tumors. We retrospectively reviewed 21 patients with unilateral VS, six patients with unilateral CPAM, and 25 control subjects. Setting regions of interest in the bilateral vestibules and cerebellar white matter on 3D-FIESTA, we compared the ratio of the signal intensity (SIR) of the vestibule to that of the cerebellar white matter (SIRv) among the VS, CPAM, and control subject groups. We also compared the ratio of SIRv on the affected side (a-SIRv) to that on the unaffected side (AURv) between the VS and CPAM. The a-SIRv in the VS group was significantly lower than the overall SIRv in the control subjects (pre-contrast, P < 0.001; post-contrast, P < 0.001) and the a-SIRv in the CPAM group (pre-contrast, P = 0.001; post-contrast, P = 0.001). The AURv in the VS group was significantly lower than that in the CPAM groups (pre-contrast, P < 0.001; post-contrast, P < 0.001). Decreased vestibular signal intensity on the affected side on 3D-FIESTA was observed in patients with VS, but not in those with CPAM or in normal subjects. The signal intensity change has the potential to be used in differentiating VS from CPAM.

Surgical Results and Technical Refinements in Translabyrinthine Excision of Vestibular Schwannomas

Vestibular schwannomas (VSs) are the most common cerebellopontine angle tumors, accounting for 75% of all lesions in this location. To evaluate the results after removal of VS through the enlarged translabyrinthine approach, which is a widening of the classic translabyrinthine approach that gives larger access and provides more room to facilitate tumor removal and to minimize surgery-related morbidities. This was a retrospective study of 1865 patients who underwent VS excision through the enlarged translabyrinthine approach between 1987 and 2009. Mean age was 50.39 years. Mean tumor size was 1.8 cm. Median follow-up was 5.7 years. Total removal was achieved in 92.33% of cases; 143 patients had incomplete resection with evidence of regrowth in 8. In the 1742 previously untreated patients, anatomic preservation of facial nerve was achieved in 1661 cases (95.35%), and House-Brackmann grade I or II was reached in 1047 patients (59.87%). Facial nerve outcome was significantly better in tumors ≤ 20 mm. Surgical complications included cerebrospinal fluid leakage in 0.85%, meningitis in 0.10%, intracranial bleeding in 0.80%, non--VII/VIII cranial nerve palsy in 0.96%, cerebellar ataxia in 0.69%, and death in 0.10%. The technical modifications that evolved with increasing experience are described. The enlarged translabyrinthine approach is a safe and effective approach for the removal of VS. In our experience, the complication rate is very low and tumor size is still the main factor influencing postoperative facial nerve function with a cutoff point at around 20 mm.

Nonvestibular Schwannoma Tumors in the Cerebellopontine Angle: A Structured Approach and Management Guidelines

The most common cerebellopontine angle (CPA) tumor is a vestibular schwannoma, but one in five CPA tumors are not vestibular schwannomas. These tumors may require different management strategies. Compared with vestibular schwannomas, symptoms and signs from cranial nerve VIII are less frequent: other cranial nerve and cerebellar symptoms and signs predominate in patients with these less common CPA tumors. Computed tomography and magnetic resonance imaging often show features leading to the correct diagnosis. Treatment most often includes surgery, but a policy of observation or subtotal resection is often wiser. This review provides a structured approach to the diagnosis of nonvestibular schwannoma CPA lesions and also management guidelines.