Asymptomatic intracochlear neurinoma. A temporal bone report

Bilateral intracochlear schwannomas: histopathological confirmation and outcomes following tumour removal and cochlear implantation with lateral wall electrodes

Intracochlear schwannomas (ICS) are very rare benign tumours of the inner ear. We present histopathological proof of the extremely rare bilateral occurrence of intracochlear schwannomas with negative blood genetic testing for neurofibromatosis type 2 (NF2). Bilateral schwannomas are typically associated with the condition NF2 and this case is presumed to have either mosaicism for NF2 or sporadic development of bilateral tumours. For progressive bilateral tumour growth and associated profound hearing loss, surgical intervention via partial cochleoectomy, tumour removal, preservation of the modiolus, and simultaneous cochlear implantation with lateral wall electrode carrier with basal double electrode contacts was performed. The right side was operated on first with a 14-month gap between each side. The hearing in aided speech recognition for consonant-nucleus-consonant (CNC) phonemes in quiet improved from 57% to 83% 12 months after bilateral cochlear implantation (CI). Bilateral intracochlear schwannomas in non-NF2 patients are extremely rare but should be considered in cases of progressive bilateral hearing loss. Successful tumour removal and cochlear implantation utilizing a lateral wall electrode is possible and can achieve good hearing outcomes.

Management of vestibular dysfunction and hearing loss in intralabyrinthine schwannomas

PURPOSE

Intralabyrinthine schwannomas (ILS) are rare, benign, slow-growing tumors arising from schwann cells of the cochlear or vestibular nerves within the bony labyrinth. This study provides insight into the management of this rare tumor through a large case series.

MATERIALS AND METHODS

After Institutional Review Board approval, a retrospective chart review was performed of all ILS patients treated at our institution between 2007 and 2019.

RESULTS

20 patients (9 male, 11 female) with ILS were managed at our institution. The right ear was affected in 9 patients (45%) and the left in 11 (55%). Subjective hearing loss was endorsed by all 20 patients. Average pure tone average at presentation was 72 dB nHL. Nine tumors (45%) were intravestibular, 6 (30%) were intracochlear, 4 (20%) were transmodiolar and 1 (5%) was intravestibulocochlear. Hearings aids were used in 3 patients (15%), BiCROS in 2 (10%), CI in 2 (10%), and bone conduction implant in 1 (5%). Vestibular rehabilitation was pursued in 5 patients. Surgical excision was performed for one patient (5%) via translabyrinthine approach due to intractable vertigo. No patients received radiotherapy or intratympanic gentamicin injections.

CONCLUSION

ILS presents a diagnostic and management challenge given the similarity of symptoms with other disorders and limited treatment options. Hearing loss may be managed on a case-by-case basis according to patient symptoms while vestibular loss may be mitigated with vestibular therapy. Surgical excision may be considered in patients with intractable vertigo, severe hearing loss with concurrent CI placement, or in other case-by-case situations.

Histopathologic Evaluation of Intralabyrinthine Schwannoma

OBJECTIVES

The aim of this study is to perform a histopathologic analysis of temporal bones with an intralabyrinthine schwannoma (ILS) in order to characterize its extension.

METHODS

Archival temporal bones with a diagnosis of sporadic schwannoma were identified. Both symptomatic and occult nonoperated ILS were included for further analysis.

RESULTS

A total of 6 ILS were identified, with 4 intracochlear and 2 intravestibular schwannomas. All intracochlear schwannomas involved the osseous spiral lamina, with 2 extending into the modiolus. The intravestibular schwannomas were limited to the vestibule, but growth into the bone next to the crista of the lateral semicircular canal was observed in 1 patient.

CONCLUSIONS

Complete removal of an ILS may require partial removal of the modiolus or bone surrounding the crista ampullaris as an ILS may extend into these structures, risking damage of the neuronal structures. Due to the slow growth of the ILS, it remains unclear if a complete resection is required with the risk of destroying neural structures hindering hearing rehabilitation with a cochlear implant.

[Bilateral intracochlear schwannomas in a patient with no genetic or clinical features of neurofibromatosis type 2. German version]

Schwannomas of the eighth cranial nerve are benign tumours commonly found in the internal auditory meatus or in the cerebellopontine angle. In most cases, they arise from the inferior or vestibular portion of the vestibular nerve. Rarely, these tumours present in the inner ear and are then called intralabyrinthine schwannomas. Bilateral schwannomas are known in neurofibromatosis type 2 (NF2). Bilateral and ipsilateral, multilocular sporadic schwannomas of the eighth cranial nerve have been described as extremely rare findings. This report describes the first case of bilateral sporadic intracochlear schwannomas in a patient with no genetic or clinical features of NF2.

Intralabyrinthine Schwannomas: Disease Presentation, Tumor Management, and Hearing Rehabilitation

Intralabyrinthine schwannomas (ILS) are rare tumors that frequently cause sensorineural hearing loss. The development and increased use of magnetic resonance imaging in recent years have facilitated the diagnosis of these tumors that present with otherwise nondiscriminant symptoms such as tinnitus, vertigo, and hearing loss. The following is a review of the presentation, pathophysiology, imaging, and treatment with a focused discussion on auditory rehabilitation options of ILS.

Clinical presentation of intralabyrinthine schwannomas: a multicenter study of 110 cases

OBJECTIVE

To describe the presentation of intralabyrinthine schwannomas (ILSs).

STUDY DESIGN AND SETTING

Retrospective multicenter study involving 12 European skull base surgery tertiary referral centers.

PATIENTS

One hundred ten patients with the diagnosis of ILS, either labyrinth confined or extending into the internal auditory meatus for less than 50% of their volume.

MAIN OUTCOME MEASURES

Data collected were age, sex, nature and timing of presenting symptoms, hearing (according to the AAO-HNS grading system), results of vestibular tests (caloric tests and cervical vestibular-evoked myogenic potentials [c-VEMPs]), and tumor localization. Presenting symptoms and laboratory test results were studied according to the extension of the lesion into the cochlea (C) and vestibule (V), on one hand, and according to unifocal (L1) or plurifocal (L2) extension into the labyrinth, on the other.

RESULTS

Intracochlear type was more common (50%) than vestibular (19.1%) and more diffuse forms (30.9%). The mean delay for diagnosis was long (72.5 mo; SD, 76.6). Mean age was 53.9 years (SD, 13.2). Deafness was the most common symptom (77.8 dB HL [SD, 33.6], with only 24.6% of patients keeping viable hearing. Caloric tests (65.5% of patients) were abnormal in 77.8% of cases. c-VEMPs were abnormal in 65.7% of the 36 cases analyzed. In V forms, hearing was significantly better (class A + B in 21.1% in C and 45.8% in V forms) (p = 0.03), and vestibular function was more altered (C: 57%, V: 100%, p = 0.0009*). L2 forms were diagnosed later (L1: 59.1 mo, L2: 104.5 mo; p = 0.004*) and were associated more frequently with a dead ear (L1: 13.1%, L2: 41.2%, p = 0.002*) than L1 forms.

CONCLUSIONS

This series, which is the largest in the literature, demonstrates that even very small and localized ILSs heavily compromise labyrinthine functions.

Intralabyrinthine schwannomas: Symptoms and managements

OBJECTIVE

To describe the characteristic presentations, radiologic findings and managements of the intralabyrinthine schwannomas.

METHOD

Retrospective review of patient records, their managements, and review of the literature.

RESULT

Four patients with a variety of otologic symptoms including hearing loss, vertigo, and tinnitus were found to have a schwannomas involving the labyrinth. In all cases, the inner ear lesions were preoperatively identified on magnetic resonance imaging, and the surgical removals were performed in all patients without serviceable hearing. The patients experienced improvement in their vertigo and tinnitus after surgery. Two patients were implanted the Bone-Anchored Hearing Aid (BAHA) to reconstruct the pseudo-stereophonic hearing.

CONCLUSION

Intralabyrinthine schwannomas are the rare tumours in the otology. The tumour can be removed by surgical approach, but we do not propose surgical excision for the patients with serviceable hearing. BAHA can give patients a post-operative monaural pseudo-stereophonic hearing.

Diagnosis and Management of Intracochlear Schwannomas

OBJECTIVE

To describe and analyze a series of intracochlear schwannomas.

METHODS

From 1987 to 2005, 19 patients with schwannomas involving the cochlea were included in this series. Clinical, audiovestibular, and imaging data concerning initial and follow-up visits were collected.

RESULTS

The mean age was 54 years (range, 25-71 yr). The series comprised 10 women and 9 men, 18 solitary tumors and 1 neurofibromatosis Type 2 patient. The mean diagnosis delay was 11 years (range, 1-31 yr). At diagnosis, a total or profound hearing loss (Class D of American Academy of Otolaryngology-Head and Neck Surgery classification) was noted in 17 patients (89%), and a severe loss (Class C) was reported in 2 patients (11%). Facial paresis was reported in 2 patients (11%; Grades 2 and 4 of House and Brackmann classification). Magnetic resonance imaging showed an involvement of the posterior labyrinth in 8 patients (37%), an extension of the schwannoma to the internal auditory meatus in 8 patients (37%), and a cerebellopontine angle extension in 7 patients (32%). In 11 patients (58%), the schwannoma was removed through a transotic route. In the 8 remaining patients, a watch-and-rescan policy was decided. The postoperative course was uneventful. Postoperative follow-up period was 27 months (range, 6-88 mo). Postoperative facial function was assessed as Grade 1 in 7 patients, as Grade 2 in 4, and as Grade 4 in 1 patient.

CONCLUSION

The diagnosis of intracochlear schwannomas can be difficult on magnetic resonance imaging. The diagnosis should be considered in all unilateral hearing losses.

Cochlear schwannomas

In a series of 179 cerebellopontine angle (CPA) tumors, the authors present nine cases (5%) that were cochlear nerve neuromas. There were six men and three women (mean age, 51 years). Preoperative magnetic resonance imaging confirmed the diagnosis in one case with a labyrinthine extension and raised suspicions in the other four cases, which were confirmed during surgery. The remaining neuromas were discovered intraoperatively. The mean time between first observation and surgery was 9 months. Preoperatively, all patients underwent a complete otoneurological assessment. The middle fossa approach was used for the patient with the labyrinthine extension, and the retrosigmoid approach was used for the other eight cases. In all patients facial nerve function was preserved. Sudden or major hearing loss without associated vestibular symptoms or preoperative facial paralysis may be predictive of a cochlear component of a CPA tumor. The near-field relationships of cochlear neuromas located at the level of the acoustic and facial nerves can be appreciated because of their small size and strong contrast enhancement.

Intralabyrinthine Schwannomas: Diagnosis, Management, and a New Classification System

OBJECTIVE

To outline the diagnosis and management of intralabyrinthine schwannomas and to propose a new classification system to further define them.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center at a university hospital.

PATIENTS

Twenty-eight patients seen at the institution with intralabyrinthine schwannomas between 1996 and 2002 were included in the study.

INTERVENTIONS

Diagnosis was made with magnetic resonance imaging in all but one case. Our ability to detect these tumors has been greatly enhanced by the introduction of high-resolution T2-weighted magnetic resonance imaging. Treatment options were observation with serial magnetic resonance imaging versus complete surgical removal via a translabyrinthine or transotic approach. Surgery was indicated for dizziness caused by the tumor or extralabyrinthine growth.

MAIN OUTCOME MEASURES

Clinical features, audiology, radiology, and management outcomes were evaluated.

RESULTS

Eight patients have undergone successful surgery with removal of their tumors and resolution of symptoms. One patient chose to have stereotactic radiotherapy. Of the 20 patients who were managed with observation and serial magnetic resonance imaging, only 1 has shown significant growth requiring surgical removal.

CONCLUSION

Intralabyrinthine schwannomas are uncommon tumors that mimic the clinical features of many other neurotologic conditions. A high index of suspicion and precise imaging are often required to detect these tumors. Surgical treatment is indicated for specific indications and will be needed in the minority of patients with this disorder. The classification system that we propose is helpful in both the diagnosis and the management of these tumors.

Intralabyrinthine schwannomas

OBJECTIVE

To describe the patient presentation, radiographic findings, and treatment results in a series of eight patients with a diagnosis of intralabyrinthine schwannoma, and to review the presentation of other cases of intralabyrinthine schwannoma in the English otolaryngologic literature.

METHODS

Retrospective review of patient records, operative reports, and radiologic studies, and review of the literature.

RESULTS

Eight patients with a variety of otologic symptoms including progressive hearing loss, episodic vertigo, and tinnitus were found to have a schwannoma involving the vestibule or cochlea. Surgery was performed to remove the tumors from four patients with nonserviceable hearing. The patients experienced significant improvement in their vertigo and tinnitus after surgery. Observation and serial magnetic resonance imaging were adequate treatment of the four patients with serviceable hearing. In the literature review, 447 cases of intralabyrinthine schwannoma were identified, and the presentations were similar to those in the cases described here.

CONCLUSION

Intralabyrinthine schwannomas are rare tumors that arise from the distal portion of either the vestibular nerve or the cochlear nerve. Consequently, the cochlea, the semicircular canals, the vestibule, or a combination of these structures may become involved with these lesions. Transmastoid labyrinthectomy or a transotic approach can be used to remove intralabyrinthine tumors from patients with nonserviceable hearing and severe vertigo or tinnitus. In addition, these surgical approaches should be used if the tumor grows to involve the internal auditory canal. Observation is an appropriate option for patients who have serviceable hearing.

MR findings in intralabyrinthine schwannomas

AIM

Intralabyrinthine schwannomas (ILS) are rare benign tumours. They are not always recognized on routine magnetic resonance imaging (MRI). We aimed to study the clinical presentation and MRI findings in our patients with ILS.

MATERIALS AND METHODS

Retrospective analysis of patients with vestibular schwannomas treated at this center.

RESULTS

Of 144 vestibular schwannomas studied at this centre, three patients had an ILS. The most common presenting symptoms were unilateral hearing loss, tinnitus and vertigo. Two patients demonstrated a progressive sensorineural hearing loss (SNHL). The third patient had a severe SNHL at presentation. MRI enhanced with contrast medium was positive in the two patients with progressive SNHL and negative in the patient with the severe SNHL.

CONCLUSION

This series demonstrates the ability of MRI to identify schwannomas filling the labyrinth, and also its inability to identify extremely small ILS. It underlines the importance of sending the cristae of patients undergoing labyrinthectomy for presumed Ménière's disease for histological examination.

A comprehensive classification system of vestibular schwannomas

Because traditional classifications of vestibular schwannomas (according to relative size) cannot comprehensively describe lesions that grow in different patterns after arising in regions as diverse as the cerebellopontine (CP) angle, the internal auditory canal, and the region lateral to the fundus of the internal auditory canal (labyrinth), we developed a new system to classify vestibular schwannomas, a system that describes the anatomical structures involved by the tumour, rather than size alone. The vestibular schwannoma is classified first by location and then by extent. Our system provides surgeons information helpful in choosing the surgical approach, in estimating the difficulty of tumour excision, and in determining whether hearing might be preserved. Our system also avoids confusion and misunderstanding in discussions of treatment results because it reflects the diverse biological characteristics of vestibular schwannomas.

Primary tumours of the vestibule and inner ear

Seven primary tumours of the vestibule and inner ear are described, six schwannomas and one traumatic fibroma. Schwannomas in this situation may occur as sporadic tumours, or may be a feature of neurofibromatosis type 2 (NF-2). In the latter condition they may occur in isolation or in association with, but separate from, schwannomas arising in the internal meatus. Direct extension into the vestibule of an intrameatal vestibular schwannoma is well reported, but extension of an intravestibular tumour into the internal meatus is not described. Traumatic fibromas of the vestibule are rare and the trigger could be an attack of labyrinthitis. Intravestibular tumours, although rare, are likely to be diagnosed with increasing frequency with the widespread use of MR imaging.

A petrous bone destructive acoustic neurinoma: a tumor of far-lateral origin?

We report a case of an acoustic neurinoma that recurred more than 11 years after "total" tumor removal through the posterior cranial fossa. Recurrent tumor had obliterated the petrous bone, filled the middle ear, and was visible grossly at the external auditory meatus. The unique behavior of this tumor implied that the site of origin was within the labyrinth, beyond the fundus of the internal auditory canal and far lateral to the usual site of acoustic neurinoma origin. We offer an hypothesis as to why these tumors occasionally recur, even after clinical "total" removal.

MR imaging features of an intracochlear acoustic schwannoma

We present a very unusual case of an acoustic neuroma involving the left cochlea and internal auditory canal of a 24-year-old man. Clinical suspicion was aroused when the patient presented with a left total sensorineural hearing loss and continuing vertigo. The diagnosis was made pre-operatively with MRI after initial CT scanning was normal. The tumour was removed via a transotic approach. This case report demonstrates the MRI features of an intracochlear schwannoma and emphasizes the importance of MRI in patients with significant auditory and clinical abnormalities with normal CT scans of the relevant region.

Preoperatively diagnosed utricular neuroma treated by selective partial labyrinthectomy

Unlike the acoustic neuroma that occupies the internal acoustic meatus and extends into the cerebellopontine angle, the true intralabyrinthine neuroma is an extremely uncommon finding. The majority of the published cases were found at autopsy or during destructive labyrinthectomy for uncontrollable Meniere's syndrome. To the best of our knowledge, we present the smallest exclusively intrautricular neuroma that has ever been diagnosed preoperatively. Detailed magnetic resonance imaging studies allowed the detection of this tumor, measuring only 3.5 mm in diameter. The tumor was removed via atticomastoidectomy and partial labyrinthectomy. The diagnostic workup, radiographic characteristics, and surgical treatment are discussed, together with a review of the literature.

Intralabyrinthine schwannomas

Intralabyrinthine schwannomas are unusual tumors of the vestibule, cochlea, semicircular canals, or some combination of these three, which in the past have been reported as incidental findings at autopsy or surgery. We summarize eight cases of intralabyrinthine schwannomas diagnosed by magnetic resonance imaging at the House Ear Clinic during the past 3 years. We discuss the typical clinical presentation and treatment of cochlear vs. vestibular intralabyrinthine schwannomas.

Temporal bone pathology in intracochlear schwannoma with profound hearing loss

Intracochlear schwannoma was found in the temporal bone of a 85-year-old man in whom audiometric study, 26 days before death, had shown total deafness in the left ear. The tumor occupied the entire lumen of the cochlea in the basal turn involved Rosenthal's canal, but it occupied only the scala tympani in the second turn. Intralabyrinthine schwannomas are difficult to diagnose by clinical examination. They were discovered accidentally during destructive labyrinthectomy for presumed Ménière's disease or discovered incidentally by postmortem temporal bone pathology. Although intralabyrinthine schwannomas are a rare occurrence and cannot usually be diagnosed without surgery or postmortem histopathology, it is important to suspect the possibility of their existence in differential diagnosis of atypical Ménière's disease or unilateral idiopathic progressive deafness. Long-term follow-up is obviously necessary to exclude the tumor.

Primary intralabyrinthine schwannoma

This paper describes a case of primary intralabyrinthine schwannoma removed by transmastoid labyrinthectomy. This case, together with a review of other cases, suggests that the tendency to preserve hearing by surgical treatment of Meniere's disease and the tendency for these tumors not to be discovered unless a labyrinthectomy is performed may mask their occurrence rate. Furthermore, I would hereby introduce both surgical and pathologic evidence suggesting that there may be a predilection in the site of origin of such solitary tumors.