Contralateral hearing loss after neurotologic surgery

Hearing Loss in the Unoperated Ear After High-Speed Drilling in Otologic and Skull Base Surgery

OBJECTIVE

To evaluate if permanent hearing loss occurred in the unoperated ear of patients undergoing otologic and skull base surgery with high-speed otologic drilling.

STUDY DESIGN

We retrospectively studied 250 patients (mean age 57.8 yr; 120 males, and 130 females) undergoing otologic or skull base surgery with high-speed drilling between 2013 and 2019.

SETTING

The University of Pittsburgh Medical Center.

PATIENTS

We evaluated preoperative and postoperative audiograms for patients undergoing surgery for cochlear implantation (95 patients, 38.0%), cholesteatoma or chronic ear disease (88 patients, 35.2%), repair of lateral skull base encephalocele (26 patients, 10.4%), resection of vestibular schwannoma or meningioma of the cerebellopontine angle (23 patients, 9.2%), lateral temporal bone resection (8 patients, 3.2%), microvascular decompression (7 patients, 2.8%), or other operations involving a high-speed otologic drill (3 patients, 1.2%).

MAIN OUTCOME MEASURES

Hearing threshold shift, measured as the difference between postoperative threshold and preoperative threshold for each frequency. The association of age, gender, tested frequency, and surgery type with hearing threshold shift was investigated with analysis of covariance.

RESULTS

A total of 102 patients (40.8%) had a 10-dB or greater worsening of their hearing in at least one frequency on their postoperative audiogram in the contralateral, unoperated ear. One hundred six subjects (42.4%) had no change in hearing of 10 dB or greater at any frequency. Among patients with longitudinal postoperative audiograms, accelerated age-related hearing loss was observed in low frequencies.

CONCLUSIONS

A significant number of patients demonstrated poorer hearing thresholds in the contralateral, unoperated ear after otologic and skull base surgery.

Bilateral Low-Frequency Hearing Impairment After Microvascular Decompression Surgery

BACKGROUND

Hearing impairment is an important complication of microvascular decompression (MVD). In patients after MVD, we have occasionally noted slight to moderate hearing deterioration at low frequencies that is difficult to detect using pure tone average.

OBJECTIVE

To assess the incidence and features of low-frequency hearing impairment (LF-HI) after MVD and evaluate its associated factors.

METHODS

This single-center, retrospective observational study assessed the audiometric outcome of 270 patients who underwent MVD between January 2015 and December 2020. Preoperative and postoperative hearing levels were compared for each frequency. LF-HI was defined as a hearing deterioration of ≥15 dB at 125, 250, or 500 Hz. The incidence, symptoms, and associated factors of LF-HI were analyzed.

RESULTS

Statistical analysis of the patients overall demonstrated slight but significant decreases in the hearing level after MVD at lower frequencies on both the operative and contralateral sides. Eighty-one patients (30.0%) had LF-HI: 49 on the operative side, 24 on the contralateral side, and 8 on both sides, while pure tone average was worsened in 5 patients (1.8%). Subjective symptoms, including hearing deterioration, ear fullness, tinnitus, and dizziness, developed in 10.4% of the patients with LF-HI but improved subsequently within several weeks. "Older age" and "operative side" were associated with LF-HI.

CONCLUSION

Decreases in lower-frequency hearing levels in both the ipsilateral and contralateral (nonoperative) ears were observed after trigeminal neuralgia and hemifacial spasm surgery. LF-HI does not cause permanent symptoms but may be a noteworthy phenomenon, possibly involved in the contralateral hearing loss encountered occasionally after other types of posterior cranial fossa surgery.

Retrospective Investigation of Contralateral Hearing Thresholds of Patients With Sporadic Vestibular Schwannoma

OBJECTIVE

The aim of this study was to investigate the contralateral hearing of patients with sporadic vestibular schwannoma (VS).

STUDY DESIGN

Retrospective cohort study.

SETTING

Pure-tone audiograms of the contralateral ear from patients with a wait-and-scan strategy were compared to the ones who received therapy. Due to a possible bias caused by the therapy, hearing thresholds before and after radiotherapy or surgery were compared separately with the wait-and-scan group.

METHODS

From 1979 to 2017, 508 patients with sporadic VS could be included in the study. Of these, 240 received regular controls in the sense of wait-and-scan, 72 underwent radiotherapy (63 audiograms before and 43 after radiotherapy), and 196 had a surgery (186 audiograms before and 146 after surgery). Age-normalized hearing thresholds of the contralateral ear from patients with a wait-and-scan strategy were compared to ones who received therapy. In addition, hearing thresholds were compared to norm values.

RESULTS

There was no evidence for a difference in the contralateral hearing of patients with sporadic VS between the wait-and-scan and therapy groups. The mean difference of hearing thresholds in our sample to norm values was found to be larger for the high frequencies and more pronounced in male patients.

CONCLUSION

There was no evidence for a difference in the contralateral hearing loss of patients with sporadic VS between the wait-and-scan and therapy groups. However, there was some indirect indication of poorer contralateral hearing in all patients with sporadic VS compared to normative values.

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.

Sensorineural Hearing Loss in the Nonimplanted Ear Following Cochlear Implantation in a Patient With Bilateral Enlarged Vestibular Aqueducts

OBJECTIVE

To document the case of a patient with bilateral enlarged vestibular aqueducts who experienced sensorineural hearing loss in the nonimplanted ear following unilateral cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion and to highlight the need to counsel regarding the risk of potential hearing loss to the contralateral ear when preparing for cochlear implants in the setting of inner ear malformations.

PATIENTS

One patient with bilateral enlarged vestibular aqueducts in a tertiary referral center.

INTERVENTION(S)

Cochlear implantation complicated by perilymph gusher requiring lumbar drain insertion.

MAIN OUTCOME MEASURE(S)

Bone conduction hearing thresholds, word recognition scores.

RESULTS

The patient underwent unilateral cochlear implantation, which was complicated by a perilymphatic gusher and necessitated placement of an intraoperative lumbar drain. On postoperative day 1, the patient reported hearing loss in the opposite ear. The word recognition score in the contralateral ear dropped from 24% at preimplantation to 8% at 2-weeks postimplantation, and did not improve at 6 months postimplantation. Moreover, the bone conduction threshold at 1 kHz worsened from 20 dB preoperatively to no response at 75 dB (the limit of the testing equipment) at 2-weeks postoperatively and only partially improved to 40 dB at 6 months postimplantation.

CONCLUSION

As patients with inner ear malformations potentially have direct high-pressure anatomical connections between the perilymphatic spaces and the cerebrospinal fluid, they are at risk of hearing loss in the nonimplanted ear during cochlear implantation. This case highlights the need for potential additional patient counseling regarding this risk in the nonimplanted ear.

"Wait and scan" management of patients with vestibular schwannoma and the relevance of non-contrast MRI in the follow-up

Vestibular schwannoma (VS) is a slow-growing benign neoplasm. There has been an evolution in the management of VS from active treatments (microsurgery and stereotactic radiotherapy) to conservative management (wait and scan). Regular MRI scanning is necessary to monitor tumor progression. Conservative management causes significantly less complications and offers a higher quality of life compared with active treatments. The mean growth rate of VS varies from 0.4 to 2.9 mm/year, and spontaneous shrinkage is observed in 3.8 percent of tumors during observation. If significant growth occurs, active treatment is considered. Significant growth is defined as an increase of at least 3 mm in the largest extrameatal diameter in any plane between the first and last available scans. The vestibulocochlear nerve is surrounded by cerebrospinal fluid, which provides natural contrast for MRI; thus, gadolinium may not be needed to detect VS. Specific sequences have high sensitivity, specificity, and accuracy for detection of progression. Hypointense signal in the ipsilateral inner ear fluid might be a useful sign to distinguish VS from meningioma. In this paper, we summarize the current status of research on conservative management and non-contrast MRI for the detection of VS.

Contralateral hearing loss and facial palsy in an operated case of vestibular schwannoma-Case report

•

Rare complication of contralateral hearing loss and facial palsy following vestibular schwannoma surger.

•

The exact cause is uncertain and various theories are proposed to ascertain the cause.

•

Treatment options are limited.

Introduction

Contralateral ear hearing loss (CHL) is an extremely rare but a potentially devastating complication in a patient with already compromised hearing due to a Vestibular schwannoma (VS). Our patient had CHL accompanied by contralateral facial palsy. Our case is only the second case reported in literature to the best of our knowledge.

Presentation of case

A 55-year elderly male presented with right sided sensorineural hearing loss, cerebellar signs and Grade II House & Brackmann (H&B) facial nerve weakness for last1-year. Magnetic resonance imaging (MRI) scan revealed a large right sided vestibular schwannoma (VS) with severe compression of the ipsilateral pons. The pre-operative pure tone audiometry (PTA) documented severe sensory neural hearing loss (SNHL) on the right side along with mild SNHL on the left side. A right retromastoid suboccipital craniotomy was performed and VS was completely excised. The ipsilateral facial nerve was preserved anatomically. On the 4th post-operative day he developed severe pain and tinnitus in left ear. In the next 24-h there were hearing loss and grade II facial nerve paresis. The PTA done on the 5th post-operative day revealed severe SNHL on both sides. He was managed conservatively with steroids and vasodilators. At 6-months of follow-up the left side hearing loss and facial weakness had significantly recovered. The PTA showed significant improvement in the left side SNHL

Discussion

Contralateral hearing disturbance with contralateral facial palsy after acoustic neuroma surgery is extremely rare. The exact etiopathogenesis of this unusual phenomenon is not clear and various theories have been proposed. There is no standard recommendation for treatment of these rare complications and the etiology remains obscure.

Conclusion

Hearing loss and facial palsy on the contralateral side after VS surgery is extremely rare. It is imperative that this rare complication should be considered following VS surgery.

Impact of Elevation of Temporal Lobe During Middle Fossa Acoustic Neuroma Surgery on Contralateral Speech Discrimination

AIM

For middle fossa acoustic neuroma approach, retractors are needed to elevate the temporal lobe to be able to access the internal auditory meatus. The temporal lobe hosts the primary and secondary auditory fields. The question arises regarding whether this elevation affects the functionality of the auditory cortex.

MATERIAL AND METHODS

In patients, who underwent acoustic neuroma surgery, contralateral speech discrimination was tested pre- and postsurgery using different speech discrimination tests. Results of patients with a middle fossa approach were compared with patients with a translabyrinthine approach.

RESULTS

No major differences between the translabyrinthine and the middle fossa approach could be detected.

CONCLUSION

Elevation of the temporal lobe during middle fossa approach for acoustic neuroma surgery does not lead to short-term impaired contralateral speech discrimination compared with translabyrinthine approach.

The effect of drill-generated noise in the contralateral healthy ear following mastoid surgery: The emphasis on hearing threshold recovery time

In mastoid surgeries, contralateral ear noise exposure is a known, identified factor leading to high-frequency hearing loss due to the wide variety of surgical devices that may be used during the surgery. However, the hearing threshold recovery time after this trauma was uncertain. The present study aimed to assess this time. In this prospective survival analysis study, 28 consecutive patients with chronic otitis media who were undergoing tympanomastoidectomy were assessed. Standard pure-tone audiometry (PTA) and distortion-product otoacoustic emission (DPOAE) were measured in all contralateral ears before and 6 h, 24 h, 48 h, 72 h, and 96 h after the surgery. Based on the PTA postoperative hearing loss, survival rates at frequencies of 3000 Hz, 4000 Hz, 6000 Hz, and 8000 Hz were 44.4%, 36.4%, 51.7%, and 47.4%, 24 h after surgery; 11.1%, 9.1%, 10.3%, and 13.2%, 48 h after surgery; and 0%, 0%, 3.4%, and 2.6%, 72 h after surgery, respectively. Based on the PTA and DPOAE, survival rates at all frequencies were 0%, 96 h after the surgery. According to the PTA, mean hearing recovery times were 61.98 ± 26.76 h (3000 Hz), 62.73 ± 26.50 h (4000 Hz), 67.08 ± 25.90 h (6000 Hz), 70.70 ± 24.13 h (8000 Hz), and with regard to DPOAE the recovery times were 58.58 ± 28.39 h (2000 Hz), 63.32 ± 28.83 h (4000 Hz), 65.22 ± 29.13 h (6000 Hz), and 75.14 ± 22.70 h (8000 Hz), respectively. To conclude, high-frequency hearing loss usually occurs following mastoid surgeries that is mainly temporary and reversible after 72 h.

Stapedial synkinesis causing change in hearing threshold with facial motion

OBJECTIVE

Synkinetic facial movement after facial nerve regeneration is a well-documented phenomenon. Rarely, patients recovering from facial nerve injury report feelings of auditory ringing, fullness, and a sensation of ear tightness as a result of stapedial muscle involvement. It is exceedingly rare for such synkinesis to produce perceivable changes in hearing threshold. We report a unique case of stapedial synkinesis causing pure-tone changes in hearing threshold with activation of the facial musculature.

PATIENT

A single patient is presented who developed stapedial synkinesis after suboccipital resection of a unilateral acoustic neuroma.

RESULTS

Despite facial nerve sparing, surgery resulted in House-Brackmann grade V/VI right facial nerve paralysis that improved to Grade III/VI after 7 months. Synkinesis developed that caused eye closure with puckering of the lips. Puckering of the lips likewise caused decreased hearing in the right ear, corresponding to a measured decrease of 10 dB in the PTA. Over the next several months, facial motion continued to improve, and hearing changes became less bothersome, so no intervention was undertaken.

CONCLUSION

The changes presented in the hearing threshold fit within the classically described 15-dB attenuation provided by the stapedial reflex. Although no intervention was undertaken in this particular case, some patients with unremitting stapedial synkinesis might benefit from sectioning of the stapedial muscle. Thus, consideration should be made for audiometric evaluation with and without facial muscle contraction in the evaluation of individuals with synkinetic facial movement.

CONTRALATERAL HEARING LOSS AFTER VESTIBULAR SCHWANNOMA SURGERY

OBJECTIVE

To describe a case of contralateral hearing loss (CHL) in vestibular schwannoma (VS) surgery and to discuss the factors potentially related with this complication.

CLINICAL PRESENTATION

A 48-year-old man awakened with complete bilateral hearing loss after an uneventful retrosigmoid excision of a 20 mm left-sided VS. The patient had no complaints of vertigo or facial palsy on the contralateral side. The hearing loss proved to be endocochlear in origin and no improvement was observed after a 24-month follow-up period.

DISCUSSION

CHL in VS surgery is not commonly reported but can occur frequently as a subclinical phenomenon if it is specially addressed. The cause is a compensatory endolymphatic hydrops generated by the loss of cerebrospinal fluid. In this circumstance, the hearing loss is usually reversible within 3 months, but irreversible cases have been described. Vascular damage to the cochlea can be another explanation in irreversible cases. The significance of other potential factors described in the literature as a cause of CHL in VS surgery is less clear.

CONCLUSION

A case of CHL after VS surgery is presented. The hearing loss proved to be endochlear in origin and irreversible in nature. Irreversible damage to the cochlea resulting from loss of cerebrospinal fluid or vascular injury is probably related in this case reported.

Delayed-onset facial paralysis after vestibular neurectomy

OBJECTIVES/HYPOTHESIS

Delayed-onset facial paralysis (beginning more than 3 d after the procedure) has been described as a complication of many different types of otological procedures. The incidence of this problem in vestibular neurectomy and the relationship to surgical approach are detailed in the study.

STUDY DESIGN

Retrospective case review.

METHODS

In the setting of a tertiary referral center, vestibular neurectomy was performed in 70 individuals with disabling vertigo unresponsive to medical therapy who elected vestibular neurectomy. The main outcome measure was incidence of delayed onset facial paralysis.

RESULTS

Delayed-onset facial paralysis was significantly more common after the middle fossa (18%) and translabyrinthine (11%) approaches compared with the retrosigmoid approach (0%).

CONCLUSIONS

Surgical approach influences the incidence of delayed-onset facial paralysis. Measures to prevent this complication such as prophylactic antiviral medication or labyrinthine segment decompression may be considered in middle fossa and translabyrinthine operations.

The vestibulocochlear nerve

The eighth nerve provides sensory connection for balance and sound. Our ability to evaluate its morphology and pathology with magnetic resonance imaging (MRI) has been substantially improved over the past 20 years. This article reviews the relevant anatomy of the eighth nerve. A thorough discussion of the potential pathologic processes affecting its function also is included. Foremost, is a review of acoustic schwannomas, emphasizing the role of imaging in the work-up and ongoing evaluation of these patients. Discussion and examples of the plethora of neoplastic, inflammatory, infectious, congenital, ischemic, and compressive pathologies involving the nerve are included as well.

Drill-Induced Hearing Loss in the Nonoperated Ear

The reversible hearing loss in the nonoperated ear noted by patients after ear surgery remains unexplained. This study proposes that this hearing loss is caused by drill noise conducted to the nonoperated ear by vibrations of the intact skull. This noise exposure results in dysfunction of the outer hair cells, which may produce a temporary hearing loss. Estimations of outer hair cell function in the nonoperated ear were made by recording the change in amplitude of the distortion-product otoacoustic emissions before and during ear surgery. Reversible drill-related outer hair cell dysfunction was seen in 2 of 12 cases. The changes In outer hair cell function and their clinical implications are discussed.