Clinical features of vestibular schwannomas in patients who experience hearing improvement after surgery

Feasibility Analysis and Surgical Details of Vestibular Schwannoma Resection via Retrolabyrinthine Approach With Preservation of Endolymphatic Sac

Objectives: To study the feasibility of reserving the endolymphatic sac in the cerebellopontine angle (CPA) and the fundus of the internal auditory canal (IAC) by the retrolabyrinthine approach. Design: Single-center retrospective study. Methods: Through 3-dimensional preoperative computed tomography reconstruction, vestibular schwannoma (VS) resection was performed using a retrolabyrinthine approach with preservation of the endolymphatic sac in selected patients, and hearing and facial nerve functions were followed to assess the feasibility of this operation and the effectiveness of function preservation. Results: VS was completely removed in all cases and the postoperative detectable hearing retention rate (AAO-HNS hearing rating grade A, B, and C) was 80% (4/5). Postoperative facial nerve function was well preserved (HB grade I), no leakage of cerebrospinal fluid or other cranial complications was observed in all patients, and no recurrence was observed during follow-up. Conclusions: With less trauma and a promising route for hearing preservation and facial nerve functions, the retrolabyrinthine approach is a potential choice for the treatment of VS located in the IAC-CPA.

Features of postoperative hearing function changes in patients with cerebellopontine angle and intratemporal tumors other than vestibular schwannomas

OBJECTIVE

Tumors around the cerebellopontine angle (CPA) and temporal bone can potentially affect hearing function. In patients with such tumors other than vestibular schwannomas (VSs), auditory tests were investigated before and after surgery to characterize the auditory effect of each tumor and to determine prognostic factors.

METHODS

A total of 378 patients were retrospectively evaluated for hearing functions before and after surgery. These 378 patients included 168 with CPA meningioma, 40 with trigeminal schwannoma (TS), 55 with facial nerve schwannoma (FNS), 64 with jugular foramen schwannoma (JFS), and 51 with CPA epidermoid cyst (EPD).

RESULTS

Preoperative hearing loss was observed in 124 (33%) of the 378 patients. Of these 124 patients, 38 (31%) experienced postoperative hearing improvement. Postoperative hearing deterioration occurred in 67 (18%) of the 378 patients. The prognostic factors for postoperative hearing improvement were younger age and the retrocochlear type of preoperative hearing disturbance. Tumor extension into the internal auditory canal was correlated with preoperative hearing loss and postoperative hearing deterioration. Preoperative hearing loss was observed in patients with FNS (51%), JFS (42%), and MGM (37%), and postoperative hearing improvement was observed in patients with JFS (41%), MGM (31%), and FNS (21%). Postoperative hearing deterioration was observed in patients with FNS (27%), MGM (23%), and EPD (16%).

CONCLUSIONS

According to the results of this study in patients with CPA and intratemporal tumors other than VS, preoperative retrocochlear hearing disturbance was found to be a prognostic factor for hearing improvement after surgery. Among the tumor types, JFS and MGM had a particularly favorable hearing prognosis. The translabyrinthine approach and cochlear nerve section should be avoided for these tumors, regardless of the patient's preoperative hearing level.

Preoperative Facial Nerve Palsy in Patients With Vestibular Schwannoma: Clinical Features and Postoperative Functional Prognosis in a Case Series of 34 Among 1228 Consecutive Patients

BACKGROUND

Facial nerve palsy is a rare presenting symptom of vestibular schwannomas and has not been investigated in detail.

OBJECTIVE

To investigate the incidence, clinical features, and postoperative long-term outcomes of facial nerve function in patients with vestibular schwannomas causing preoperative facial nerve palsy.

METHODS

After excluding patients with neurofibromatosis type 2 and those with prior treatment, 1228 consecutive patients who underwent vestibular schwannoma surgery were retrospectively investigated. Patients with and without preoperative facial nerve palsy were compared statistically to clarify their clinical features.

RESULTS

Preoperative tumoral facial nerve palsy was seen in 34 patients (2.8%). Their clinical features included older age, having large cystic tumors with significant meatal extension, and showing abnormal electrogustometric responses, compared with patients without preoperative facial nerve palsy. Owing to the frequent insufficient intraoperative responses on facial nerve electromyography, the tumor resection rate was lower in the group with preoperative facial nerve palsy (mean: 95.2%). Among the 33 patients with sufficient follow-up data (mean: 63.9 mo), additional treatment was required only in 1 patient and facial nerve function improved in 25 patients (75.8%) within 2 yr postoperatively.

CONCLUSION

Facial nerve palsy is a rare preoperative symptom that occurs in less than 3% of patients with vestibular schwannoma. Tumor resection in such patients tends to be challenging owing to their advanced age, having large cystic tumors with significant meatal extension, and difficulties in intraoperative facial nerve monitoring, but surgical decompression of the facial nerve can assist in the improvement of their long-term functions.

Hearing improvement after vestibular schwannoma surgery in the era of the hearing preservation rule - case report and literature review

OBJECTIVES

Hearing preservation after vestibular schwannoma (VS) surgery remains a surgical challenge. In some patients with preserved inner ear function, hearing improvement is achievable. As it is currently impossible to determine which patients will present this outcome, predictions must rely on previously published reports. Our case report describes a patient who experienced hearing improvement from an unuseful level to a useful one after vestibular schwannoma surgery.

METHODS

Surgery was performed via suboccipital retrosigmoid approach. The patient underwent a basic audiovestibular protocol before and after the surgery - pure tone and speech audiometry, otoacoustic emissions, auditory brainstem responses, electronystagmography - together with a detailed questionnaire study. Usefulness of hearing was evaluated using the AAO-HNS guidelines, supplemented by a frequency of 4 kHz.

RESULTS

Hearing was preserved and even improved from an unuseful level to a useful one. Based on the available literature, the most informative predictive factors for such a result seem to be: sudden sensorineural hearing loss prior to surgery, elicitable otoacoustic emissions and the origin from the superior vestibular nerve.

CONCLUSION

There are a limited number of studies on this topic and it is still impossible to regularly improve hearing in properly selected patients. Furthermore, the importance of postoperative hearing quality compared to other symptoms and complications remains debatable.

Hearing preservation/rehabilitation surgery for small vestibular schwannoma: preliminary experience with the presigmoid retrolabyrinthine approach

BACKGROUND

The presigmoid retrolabyrinthine approach (PRA) for small vestibular schwannoma (VS) has unique advantages. Combination with partial labyrinthectomy further makes up its defect of high demand for anatomy.

OBJECTIVE

Aimed to describe our use of the PRA with partial labyrinthectomy in VS surgery.

METHODS

We retrospectively analyzed 10 patients diagnosed with VS who underwent PRA between September 2017 and November 2020. Their perioperative data were analyzed.

RESULTS

Six tumors were on the left and three were on the right. One case was due to neurofibromatosis type 2 with bilateral involvement and underwent internal auditory canal decompression by PRA without tumor removal; all other patients underwent total tumor resection. Four patients underwent cochlear implantation simultaneously because of hearing loss that was detected during surgery. Three patients underwent partial labyrinthectomy. Five patients achieved hearing preservation, and one experienced hearing improvement. One of the three patients who underwent partial labyrinthectomy maintained hearing. All patients' pre- and postoperative facial nerve functions were House-Brackmann grade I. After a median follow-up time of 13 months, no tumors recurred.

CONCLUSIONS

PRA for small VS is a safe and effective surgery that can achieve facial nerve and hearing preservation. Combination with partial labyrinthectomy can also preserve hearing.

Long-term prognosis of preserved useful hearing after surgery in patients with vestibular schwannoma: a study of 91 cases

BACKGROUND

In patients with a vestibular schwannoma, some studies have reported that useful hearing preserved initially after surgery deteriorates gradually in the long term. Studies with more patients are needed to clarify the maintenance rate of postoperative hearing function and to identify prognostic of hearing function.

METHOD

Ninety-one patients (mean age, 39.5 years; mean tumor size, 18.9 mm) with preserved useful hearing immediately after surgery were retrospectively analyzed. The useful hearing was defined as the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) classes A and B. Hearing tests, including auditory brainstem responses (ABR) and distortion product otoacoustic emissions (DPOAE), were evaluated preoperatively, immediately after surgery, and at outpatient follow-up.

RESULTS

At the final follow-up (mean, 63.0 months), the useful hearing was maintained in 79 patients (87%), and the hearing class remained unchanged during the follow-up period in 40 patients (44%). Significant predictors of useful hearing maintenance were AAO-HNS class A immediately after surgery, improvement of ABR, and the absence of postoperative DPOAE deterioration. Postoperative DPOAE deterioration correlated with hearing class deterioration.

CONCLUSIONS

Despite hearing being preserved in vestibular schwannoma patients immediately after surgery, Thirteen percent lost their useful hearing during the long follow-up period, and hearing class worsened in 55% of the patients. This study, which analyzed one of the largest series of vestibular schwannoma patients, demonstrated that retrocochlear condition is a key factor for useful hearing maintenance. In patients with vestibular schwannoma who have preserved hearing function, regular postoperative monitoring of hearing function is as important as regular MRI.

Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients

BACKGROUND

Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing.

OBJECTIVE

To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment.

METHODS

The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors.

RESULTS

Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant cross-study heterogeneity was found (I2 = 93%, τ2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%.

CONCLUSION

Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient's expectations for hearing preservation is critical when deciding on VS treatment plans.

Prognostic Factors of Long-Term Hearing Preservation in Small and Medium-Sized Vestibular Schwannomas After Microsurgery

OBJECTIVE

The authors evaluated the long-term hearing outcomes of patients with vestibular schwannoma (VS) to explore appropriate surgical treatment.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

A total of 138 patients diagnosed with small and medium-sized VS with serviceable hearing from January 2006 to December 2015.

INTERVENTIONS

All patients underwent microsurgery via retrosigmoid (RSA) or middle cranial fossa approach (MFA) and were followed up for over 2 years.

MAIN OUTCOME MEASURES

Pre- and postoperative hearing, including pure tone audiometry, speech discrimination score, and auditory brainstem response (ABR), were analyzed.

RESULTS

The mean tumor size and volume were 16.6 ± 3.4 mm and 1711.8 ± 918.5 mm, respectively. Preoperative hearing levels were Class A in 42, Class B in 67, and Class C in 29 patients. Patients with a tumor from the superior vestibular nerve (SVN) had better hearing at diagnosis. Postoperative hearing levels were Class A, B, C, and D for 28, 17, 32, and 61 patients. Hearing outcomes were significantly better in patients with normal intraoperative I wave on ABR. Hearing loss within 6 months had a positive effect on postoperative hearing. Better preoperative hearing and tumors from SVN were correlated with better postoperative hearing outcomes. Tumor size, cystic variation, or extension to the fundus of internal auditory canal had no influence on hearing preservation.

CONCLUSIONS

Better preoperative hearing, shorter hearing loss period, tumors from SVN, and normal intraoperative I wave are prognostic factors for serviceable hearing. RSA and MFA are effective and safe for tumor removal and hearing preservation.

Hearing preservation in vestibular schwannoma surgery via retrosigmoid transmeatal approach

BACKGROUND

Advances in various diagnostic and/or treatment modalities, including radiological imaging, neuromonitoring, and microsurgical techniques, have resulted in treatments of vestibular schwannomas being aimed at preserving facial and hearing functions while achieving optimal tumor control.

METHOD

We describe our surgical technique for hearing preservation in vestibular schwannoma surgery.

CONCLUSION

The retrosigmoid transmeatal approach under continuous neuromonitoring (auditory brainstem response, cochlear nerve action potentials, and continuous facial nerve monitoring) enables gross-total resection of vestibular schwannomas, while preserving hearing and facial functions. Radiological assessment and microsurgical techniques, such as meticulous tumor dissection, are also essential for functional preservation with sufficient tumor removal.