Cerebellopontine angle and intracanalicular masses mimicking vestibular schwannomas

A Scoping Review of Otologic Manifestations of Hematologic Malignancies

OBJECTIVE

To examine the otologic and neurotologic symptoms, physical examination findings, and imaging features secondary to hematologic malignancies.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, databases, including PubMed, Scopus, and CINAHL, were searched for articles including patients with otologic manifestations of leukemia, lymphoma and multiple myeloma. Data collected included patient and study demographics, specific hematologic malignancy, timing and classification of otologic symptoms, physical examination findings, imaging features and methods of diagnosis. Pooled descriptive analysis was performed.

RESULTS

Two hundred seventy-two articles, of which 255 (93.8%) were case reports and 17 (6.2%) were case series, reporting on 553 patients were identified. Otologic manifestations were reported on 307 patients with leukemia, 204 patients with lymphoma and 42 patients with multiple myeloma. Hearing loss and unilateral facial palsy were the most common presenting symptoms for 111 reported subjects with leukemia (n = 46, 41.4%; n = 43, 38.7%) and 90 with lymphoma (n = 38, 42.2%; n = 39, 43.3%). Hearing loss and otalgia were the most common presenting symptoms for 21 subjects with multiple myeloma (n = 10, 47.6%; n = 6, 28.6%). Hearing loss and unilateral facial palsy were the most common otologic symptoms indicative of relapse in subjects with leukemia (n = 14, 43.8%) and lymphoma (n = 5, 50%).

CONCLUSION

Hearing loss, facial palsy, and otalgia might be the first indication of a new diagnosis or relapse of leukemia, lymphoma, or multiple myeloma. Clinicians should have a heightened level of suspicion of malignant etiologies of otologic symptoms in patients with current or medical histories of these malignancies.

Internal Auditory Canal Glioneural Hamartoma: A Rare Mass Masquerading as a Vestibular Schwannoma

Glioneural hamartomas are exceedingly rare lesions. When localized to the internal auditory canal (IAC), they can cause symptoms referrable to seventh and eighth cranial nerve compression. Here, the authors present a rare case of an IAC glioneural hamartoma. A 57-year-old male presented for evaluation of presumed intracanalicular vestibular schwannomas found on work-up of dizziness and progressive right-sided hearing loss. Surgical intervention pursued progressive symptoms and new onset headaches. The patient underwent uncomplicated retrosigmoid craniectomy for gross total resection. Histopathological evaluation revealed a glioneural hamartoma. A MEDLINE database search used the terms' cerebellopontine angle' OR 'internal auditory canal' AND 'hamartoma' OR 'heterotopia'. Clinicopathological characteristics and outcomes of the present case were compared to those in the literature. The literature review yielded nine articles describing 11 cases (eight females, three males; median age 40 years, range 11-71) of intracanalicular glioneural hamartomas. Patients most commonly presented with hearing loss and were presumed to have a diagnosis of vestibular schwannoma before histologic diagnosis. Glioneural hamartomas are rare lesions that may be found in the IAC. Although benign, they may be safely resected for cranial nerve function preservation goals with a low risk of recurrence.

Let Us Not Forget About Bleeding: A Case Report and Brief Literature Review on Hemorrhagic Vestibular Schwannoma

Hemorrhagic vestibular schwannoma (HVS) consisting of acute intratumoral and subarachnoid hemorrhage is a rare phenomenon. We present the case of a 31-year-old woman who attended the Otorhinolaryngology department with right-sided intense tinnitus, dizziness, imbalance, and headache. Brain computed tomography revealed a spontaneous hyperdensity in the posterior fossa with marked deformation of the brainstem, middle cerebral peduncle, and cerebellum, with the near collapse of the fourth ventricle. Ophthalmology evaluation confirmed bilateral papilledema. Brain magnetic resonance imaging confirmed a voluminous 33 x 28 x 29 mm extra-axial lesion centered on the right pontine-cerebellar angle cistern, extending from the plane of the trigeminal nerve/tent of the cerebellum. The acoustic pore was enlarged. The patient underwent retrosigmoid craniotomy and microscopic tumor resection showing significant improvement in the follow-up. Pathological findings confirmed HVS. Delayed treatment of HVS can increase morbidity or even be fatal. The objective of this work is to describe and revise HVS, in order to bring awareness to this uncommon entity.

A Retrospective Clinicoradiologic Study of 126 Cerebellopontine Angle Tumors to Predict the Outcome of House–Brackmann Status to Prognosticate Them: A Single-Center Tertiary Care Perspective

Introduction House–Brackmann (HB) grading had been described to quantify the facial nerve involvement in cerebellopontine angle (CPA) tumors, a very common tumor in neurosurgical practice. Very few studies have specifically looked into the factors predicting the facial nerve morbidity and its severity. Here, we try finding these while going through the clinicoradiologic factors and its natural course to help us prognosticate the patients.

Objective To analyze the size of tumor and duration of symptoms to predict the severity of HB status of facial nerve presentation and outcome, and to study the course of the disease to help prognosticate the patients with respect to facial nerve status.

Materials and Methods This was a retrospective analysis of 126 operated CPA tumors, where we studied the natural course of HB status with respect to size and duration of symptoms of patients at our institute between December 2016 to February 2020.

Results Average duration of symptoms were 33.8 days with increasing risk of HB outcome after 36 days of symptoms. All patients improved to their preoperative facial nerve status at 3 months and only 18 maintained the worsened HB status. Average size of tumor was 3.53 cm, and size higher than 3.8 cm was associated with poorer HB outcome.

Conclusion Although there can be a significant deterioration of HB status in immediate postoperative period, it improves to preoperative status in due time. Tumor larger than 3.8 cm and symptom duration more than 36 days are two important factors predicting poorer HB outcome.

The Preoperative Diagnostic Value of MRI and Otoneural Tests in Acoustic Neuroma

Objectives

To determine the preoperative diagnostic accuracy of MRI and otoneural tests (ONT) for acoustic neuroma (AN) in a cohort of unselected patients with pontocerebellar angle tumors. To find a convenient way to screening out the potential asymptomatic AN patient earlier.

Design

This diagnostic accuracy study was performed in a central hospital and included a consecutive sample of unilateral incipient pontocerebellar angle tumor patients referred for MRI and ONT before surgery. Different AN features of MRI and ONT were collected and concluded into preoperative diagnostic variables or variable combinations. Those of MRI and ONT are analyzed and compared with biopsy results by multivariable receiver operating characteristic (ROC) analysis. The early-stage group, the course of which is 1 year or less, was separately computed and compared.

Results

Eighty-three subjects were collected from June 2013 to June 2019; 62 were confirmed AN postoperatively by biopsy, whereas others are not AN. The area under the curve (AUC) of MRI was 0.611, whereas the AUC of ONT was 0.708. In the early-stage group, the AUC of MRI was 0.539, and the AUC of ONT was 0.744.

Conclusions

ONT was able to identify more subjects affected by unilateral incipient AN than MRI preoperatively. Given that ONT is a functional test for internal auditory canal nerves, it is an optimal screening test for AN patients because it provides more information than MRI for the further clinical plan. It is particularly noteworthy for identifying asymptomatic AN patients and for early stage. Therefore, it may help more patients from unnessesary surgery. Furthermore, an MRI follow-up is suggested if the patient was found alert in ONT.

Developmentally anomalous cerebellar encephalocele arising within the cerebellopontine angle and extending into the adjacent skull base in a pediatric patient

Lesions of the cerebellopontine angle (CPA) in young children are rare, with the most common being arachnoid cysts and epidermoid inclusion cysts. The authors report a case of an encephalocele containing heterotopic cerebellar tissue arising from the right middle cerebellar peduncle and filling the right internal acoustic canal in a 2-year-old female patient. Her initial presentation included a focal left 6th nerve palsy. Magnetic resonance imaging was suggestive of a high-grade tumor of the right CPA. The lesion was removed via a retrosigmoid approach, and histopathologic analysis revealed heterotopic atrophic cerebellar tissue. This report is the first description of a heterotopic cerebellar encephalocele within the CPA and temporal skull base of a pediatric patient.

Meningiomas of the Internal Auditory Canal

OBJECTIVE

Identify and define specific preoperative and postoperative characteristics of intracanalicular meningiomas (ICMs) in order to improve their diagnosis and management, and to differentiate them from intrameatal vestibular schwannomas (IMVSs).

METHODS

Preoperative symptomatology, magnetic resonance imaging (MRI), and postoperative outcomes of 28 ICMs were analyzed. The results were compared to the literature and IMVSs treated by our group.

RESULTS

Anacusis and progressive hearing loss were more frequent in the present population than the cases reviewed (P = .0064 and P = .0001, respectively). Hearing loss affected more than 90% of the patients, with anacusis in 32.1% of the cases. Facial palsy affected 17.9% of the patients. In comparison to IMVSs, preoperative anacusis was more associated to meningiomas (P = .0037), and the facial nerve was more compromised in ICMs than IMVSs, both preoperatively (P = .0011) and at follow-up (P < .0001). According to a re-evaluation of preoperative MRIs and comparison with IMVSs, linear tumor borders, and linear morphology along the internal auditory canal wall, but not the presence of a dural tail, were significantly more present in ICMs (P = .0035, P = .0004, P = .1963, respectively). These characteristics could have led to a correct preoperative diagnosis in 61% of our cases.

CONCLUSION

Contrariwise to IMVSs, the frequent preoperative anacusis and facial palsy demonstrate the more aggressive nature of ICMs, which also carry a higher risk of postoperative facial palsy and difficulty to preserve hearing. An attentive evaluation of imaging should ease diagnosis, and asymptomatic or stable ICMs should be enrolled in a wait-and-scan protocol.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E413-E419, 2021.

Clinical and Radiological Characteristics of Malignant Tumors Located to the Cerebellopontine Angle and/or Internal Acoustic Meatus

OBJECTIVE

Metastatic lesions to the internal auditory meatus (IAM) and/or the cerebellopontine angle (CPA) are rare and may appear like a vestibular schwannoma (VS). We herein raise the issue of the diagnosis and treatment of nine malignant cases of the CPA and IAM among three referral centers in France and Japan. The aim of this study was 1) to report malignant lesions of the CPA, their diagnosis and treatment, 2) to review the literature, 3) to propose criteria of suspicion for malignant tumors of the CPA.

METHODS

Nine patients who had malignant lesions of the CPA and/or IAM for whom the final diagnosis was made by surgery, lumbar puncture, or PET scan were included. The main outcomes measured were: rapid onset of symptoms, association of cochlea-vestibular symptoms with facial palsy, and MRI analysis.

RESULTS

Among the nine patients with malignant tumor of the CPA, 8 of them (89%) had a facial palsy associated with cochlea-vestibular symptoms. Rapid growth of the tumor was observed in 77% (7/9) of the cases in a mean time interval of 4.6 months. The initial diagnosis evoked was VS in 44% of the cases (4/9). Atypical MRI aspect was seen in 67% of the cases (6/9) with bilateral tumors in 55% of cases (5/9).

CONCLUSION

Although rare, malignant tumors of the CPA and/or IAM should be evoked in case of association of cochleovestibular symptoms and facial palsy, rapid onset and atypical MRI aspect.

Contralateral sensorineural hearing loss after vestibular schwannoma surgery

INTRODUCTION

Contralateral sensorineural hearing loss (CSNHL) after vestibular schwannoma (VS) is a severe complication, especially in those cases in which hearing preservation in the operated side was not possible. There are several theories that attempt to explain this issue, but there is no established guideline of treatment.

MATERIAL AND METHODS

We report 4 patients treated in our institution who developed a severe CSNHL after surgery.

RESULTS

Of the 185 cases of VS treated with surgery, 4 patients (2.2%) developed a CSNHL after VS surgery. After medical treatment, partial recovery of hearing occurred in one patient the other 3 patients presented a well-established severe SNHL.

CONCLUSIONS

Established treatment guidelines do not exist, but the use of high doses of corticosteroids has been recommended and cochlear implant in cases with no recovery and complete hearing loss may be useful.

Cerebellopontine angle schwannomas arising from the intermediate nerve: a scoping review

Intermediate nerve schwannomas (INS) are extremely rare lesions in literature. They have been described mimicking facial nerve schwannomas, but not vestibular schwannomas (VS). We aimed to review the previously published cases, as well as the evidence to believe that they are far more common, though usually misdiagnosed as facial or VS. We performed a review of PubMed/Medline and Embase of "intermediate nerve schwannoma," "facial nerve schwannoma," "greater superficial petrosal nerve schwannoma," "geniculate ganglion schwannoma," and "chorda tympani schwannoma" to identify all cases of INS, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement. Furthermore, 2 cases operated at our center are shown to exemplify the proposed hypotheses. No article was excluded from review. Thirteen cases of INS, 11 cases of chorda tympani schwannoma, and 18 cases of greater superficial petrosal nerve schwannoma were found in literature. In facial nerve schwannomas, the predilection of schwannomas for sensory nerves, and the ability to preserve the motor facial nerve during tumor resection support the hypothesis of intermediate nerve as the nerve of origin. For VSs, the different arachnoidal arrangement of medial VS, the sharing of pia mater by the intermediate nerve and vestibular nerve, and the medial Obersteiner-Redlich zone of the intermediate nerve, support the hypothesis of intermediate nerve origin of some VS. The correct identification of the intermediate nerve as a nerve of origin of cerebellopontine angle schwannomas is of uttermost importance, especially when mistaken for VS, as this may account for the heterogeneity of facial and cochlear outcomes after surgery.

Translabyrinthine microsurgical resection of small vestibular schwannomas

OBJECTIVE

Translabyrinthine resection is one of a number of treatment options available to patients with vestibular schwannomas. Though this procedure is hearing destructive, the authors have noted excellent clinical outcomes for patients with small tumors. The authors review their experience at a tertiary acoustic neuroma referral center in using the translabyrinthine approach to resect small vestibular schwannomas. All operations were performed by a surgical team consisting of a single neurosurgeon and 1 of 7 neurotologists.

METHODS

Data from a prospectively maintained clinical database were extracted and reviewed. Consecutive patients with a preoperative diagnosis of vestibular schwannoma that had less than 1 cm of extension into the cerebellopontine angle, operated on between 2008 and 2013, were included. Patents with neurofibromatosis Type 2, previous treatment, or preexisting facial weakness were excluded. In total, 107 patients were identified, 74.7% of whom had poor hearing preoperatively.

RESULTS

Pathologically, 6.5% of patients were found to have a tumor other than vestibular schwannoma. Excluding two malignancies, the tumor control rates were 98.7%, as defined by absence of radiographic disease, and 99.0%, as defined by no need for additional treatment. Facial nerve outcome was normal (House-Brackmann Grade I) in 97.2% of patients and good (House-Brackmann Grade I–II) in 99.1%. Complications were cerebrospinal fluid leak (4.7%) and sigmoid sinus thrombosis (0.9%), none of which led to long-term sequelae.

CONCLUSIONS

Translabyrinthine resection of small vestibular schwannomas provides excellent results in terms of complication avoidance, tumor control, and facial nerve outcomes. This is a hearing-destructive operation that is advocated for selected patients.

Ectopic brain tissue in the trigeminal nerve presenting as rapid-onset trigeminal neuralgia: case report

The authors report the case of a 52-year-old man who presented with rapid-onset lancinating facial pain consistent with trigeminal neuralgia. Magnetic resonance imaging revealed a nonenhancing small lesion on the right trigeminal nerve concerning for an atypical schwannoma or neuroma. The patient underwent resection of the mass via a right retrosigmoid approach. His facial pain completely resolved immediately postoperatively and had not recurred at 6 months after surgery. The mass was consistent with normal brain tissue (neurons and glial cells) without evidence of mitoses. A final histopathological diagnosis of ectopic brain tissue with neural tissue demonstrating focal, chronic T-cell inflammation was made. The partial rhizotomy during resection was curative for the facial pain. To the authors' knowledge, this is the first report of neuroglial ectopia causing trigeminal neuralgia.

Lesions Mimicking Small Vestibular Schwannomas

Objective  Most tumors of the internal auditory canal and cerebellopontine angle (CPA) are vestibular schwannomas (VSs). Preoperative diagnosis is based on typical clinical symptoms and radiological findings. In rare cases, histopathology can, however, show different results. Design  This is a retrospective chart and database review. Setting  The study was conducted at a tertiary skull base referral center at a university hospital. Participants  A total of 207 consecutive cases of VS surgery via the middle cranial fossa approach performed between December 2005 and January 2015 were reviewed. Main Outcome Measures  The main outcome measures were definitive histologic findings in 198 specimens, analysis of preoperative magnetic resonance imaging (MRI) and computed tomography. Results  Histopathology revealed three meningiomas and two cases of lipochoristomas. Clinical presentation was typical for VS in all five cases. In preoperative MRI, all tumors were suspected to be VSs. Retrospective analysis of the preoperative imaging did not lead to a modification of the diagnosis. Intraoperative findings showed increased adherence of the tumor to the adjacent tissue in two of the five cases. Conclusion  CPA lesions other than VSs are unusual but have to be taken into account. In very small tumors, imaging still remains difficult.

Hypervascular Lesions of the Cerebellopontine Angle: The Relevance of Angiography as a Diagnostic and Therapeutic Tool and the Role of Stereotactic Radiosurgery in Management. A Comprehensive Review

BACKGROUND

The cerebellopontine angle (CPA) is a narrowed skull base area containing important cranial nerves and vessels and bordering with eloquent areas of the posterior fossa. Tumors of the CPA are a heterogeneous group and can have extradural, intradural/extra-axial, or intra-axial origins. Their vascular supply changes depending on their anatomic origin. Symptomatic, large CPA tumors require surgical resection in order to prevent irreversible, severe neurological damages. However, its tight and strategical location make surgery in the CPA very challenging and require appropriate pre-surgical planning. Pre-surgical diagnosis is of great importance as it allows us to choose the optimal management for the particular patient. This is of further significance when encountering high-risk lesions such as hypervascular tumors. Neurosurgeons should utilize every available pre-surgical diagnostic modalities as well as neo-adjuvant treatments in order to reduce such risks.

METHODS

We review all reported cases of hypervascular lesions of the CPA and discuss the roles of angiography and stereotactic radiosurgery in their management.

RESULTS

Three lesions of the CPA can be considered as truly hypervascular: hemangioblastomas, hemangiopericytomas and paragangliomas. All lesions share many radiological features. However, each lesion has a different anatomical origin and hence, has a characteristic vascular supply. Pre-surgical angiography can be utilized as a diagnostic tool to narrow down the differential diagnosis of a vascular CPA lesion, based on the predominant supplying vessel. In addition, pre-surgical embolization at time of angiography will narrow the associated surgical risks.

CONCLUSIONS

Angiography is a crucial diagnostic and therapeutic tool, helping both in narrowing the presurgical differential diagnosis and in controlling intraoperative bleeding. Because of the high surgical risks associated with resection of vascular tumors in the CPA, noninvasive treatments, such as stereotactic radiosurgery, also may have a crucial role.