[AUDITORY BRAINSTEM IMPLANTS (ABI) IN CHILDREN: CASE SERIES IN SHAARE ZEDEK MEDICAL CENTER].

BACKGROUND: Cochlear implants (CI) are the treatment of choice for individuals with severe to profound sensorineural hearing loss. A small group of patients, with pathology central to the cochlea, cannot benefit from CI. Examples in children include absence of the cochlear-nerve or cochlear aplasia. In these cases, implantation of an auditory brainstem implant (ABI), directly stimulating the cochlear nucleus, bypassing the inner-ear and auditory-nerve, may be beneficial. OBJECTIVES: Describe a series of children with ABI's treated in Shaare-Zedek, including the first ABI implantation in Israel (2017). METHODS: Of 9 patients with ABI's treated in Shaare Zedek Medical Center ,7 were children implanted between ages 2-8.6 years. Five boys and two girls. Surgeries were conducted in collaboration between neurosurgeons, neurotologists and audiologists (five implanted in Shaare-Zedek and two in New-York University). Follow-up was between 2-6 years. Hearing evaluation was conducted, mainly, with audiograms, categories of auditory performance (CAP), speech perception testing when possible and estimation of device use per day. RESULTS: Six of the seven children, who initially underwent unsuccessful CI, had deficient auditory-nerves. One child had cochlear-aplasia. In 3 children hearing loss was part of the CHARGE syndrome. CAP scores ranged from 0-7 (0,1,3,5,5,7). One child was able to achieve open-set speech perception. CONCLUSIONS: Although functional auditory outcomes for children with ABI are inferior to CI recipients and are highly variable, some children were able to obtain significant benefit. In these children, who are not candidates for CI, the ABI presents the only chance for auditory awareness and may be recommended. DISCUSSION: John Thomas Roland is a consultant and recipient of research support from Cochlear Americas.

Force and pressure measurements in temporal bones.

PURPOSE: Some cochlear implant (CI) patients lose their residual hearing during surgery. Two factors that might play a role in residual hearing loss are the change in intracochlear hydraulic pressure and force on the cochlear wall during electrode insertion. The aim of this study is to investigate whether a difference in peak hydraulic pressure and peak force on the cochlear wall exists during a CI electrode insertion with different insertion techniques. MATERIALS AND METHODS: Twenty fresh frozen temporal bones were used. Hydraulic pressure and force on the cochlear wall were recorded during straight electrode insertions with 1) slow versus fast insertion speed, 2) manual versus automatic insertion method and 3) round window approach (RWA) versus extended RWA (ERWA). RESULTS: When inserting with a slow compared to a fast insertion speed, the peak hydraulic pressure is 239% (95% CI: 130-399%) higher with a RWA and 58% (95% CI: 6-137%) higher with an ERWA. However, the peak force on the cochlear wall is a factor 29% less (95% CI: 13-43%) with a slow insertion speed. No effect was found of opening and insertion method. CONCLUSIONS: As contradictory findings were found for hydraulic pressure and force on the cochlear wall on insertion speed, it remains unclear which insertion speed (slow versus fast) is less traumatic to inner ear structure.

Salvage Management of Vestibular Schwannoma.

The current management of vestibular schwannomas (VS) includes observation, microsurgery (MS), and stereotactic radiosurgery (SRS) or radiotherapy, and treatment failures may occur with any primary modality. SRS is most often used for microsurgical failures, as it carries a low risk of adverse events. Salvage MS following previous MS is reserved for specific cases and can present certain surgical challenges. Irradiation failures can be managed with both salvage MS and repeat SRS. This article is intended to review an approach to the failure of primary interventions for VS, with a focus on the time interval between modalities, rates of tumor control, functional outcomes, and possible complications.

Cochlear Implantation in Sporadic Vestibular Schwannoma and Other Retrocochlear Pathology: A Case Series.

OBJECTIVE: To describe outcomes with cochlear implantation (CI) for rehabilitation of hearing loss in patients with sporadic vestibular schwannomas (VS) and other retrocochlear pathologies. STUDY DESIGN: Retrospective review. SETTING: Tertiary-care center. PATIENTS: Twenty three cases in 19 patients (53% men, mean age 55.8 yr) with non-neurofibromatosis type 2 related retrocochlear pathology. INTERVENTIONS: Unilateral or bilateral CI. MAIN OUTCOME MEASURES: Word recognition score, device usage. RESULTS: Etiology of deafness included sporadic VS (n = 9, 39%), radiation after head and neck or central nervous system (CNS) malignancy (n = 8, 35%), superficial siderosis (n = 3, 13%), neurosarcoidosis (n = 2, 9%), and pontine stroke (n = 1, 4%). Mean follow-up duration was 2.3 years (standard deviation [SD] 3.0; range, 0.2-9.4). Auditory perception was achieved in 20 out of 22 patients (91%) who have been activated. Mean WRS in patients with sporadic VS was 18% (SD 20; range, 0-44). Mean WRS in patients with non-VS retrocochlear pathology was 55% (SD 30; range, 0-94). Data logs showed 7.0 h/d of average use (SD 4.3; range, 0-13). CONCLUSIONS: Appropriately selected patients with retrocochlear pathology may benefit from CI so long as the patient has a cochlear fluid signal and an intact cochlear nerve. Patients with sporadic VS patients and normal contralateral hearing exhibited guarded outcomes with CI, whereas most patients with non-VS retrocochlear pathologies demonstrated open-set speech understanding scores comparable to or slightly worse than conventional CI candidates. Since variable performance benefit is observed with CI in patients with retrocochlear pathology, counseling is imperative to align patient expectations with realistic outcomes.

Cochlear Implant Outcomes in Neurofibromatosis Type 2: Implications for Management.

OBJECTIVE: To describe our institutional experience with cochlear implantation (CI) for rehabilitation of hearing loss in Neurofibromatosis type 2 (NF2) patients. STUDY DESIGN: Retrospective review between 1989 and 2019. SETTING: Tertiary-care center. PATIENTS: Twenty-four patients (67% female, mean age 45.6years) with NF2. Management of their ipsilateral vestibular schwannoma included microsurgery (n=12), stereotactic radiation (n=5), and observation (n=7). INTERVENTIONS: Cochlear implantation. MAIN OUTCOME MEASURES: Ability to obtain open-set speech, daily device usage and long-term device benefit. RESULTS: All patients achieved some degree of sound awareness with CI. Nineteen patients (79%) achieved open-set speech understanding with a mean word-recognition score of 43% (range 0-88%). Patients with tumors 1.5 cm or less demonstrated the better speech understanding, without significant differences among treatment modalities. For tumors greater than 1.5 cm, patients who underwent microsurgery had a lower rate of open-set speech understanding compared to those treated with radiation or observation. Regular daily device use in 83% of patients was found. Long-term use (>10years) was observed in several patients, though some ultimately required reimplantation with an auditory brainstem implant due to progressive tumor growth. Mean follow-up duration was 4.1 years (range 0.4-15). CONCLUSIONS: Cochlear implantation can be an effective treatment for hearing loss in NF2 patients provided the cochlear nerve is intact, regardless of prior management for the ipsilateral tumor. The degree of benefit varies and is influenced by tumor size. Management strategies that preserve the cochlear nerve maximize the interval during which a CI could be of benefit to NF2 patients.

An evidence-based algorithm for intraoperative monitoring during cochlear implantation.

OBJECTIVE: To generate an evidence-based algorithm for the use of intraoperative testing during cochlear implantation (CI). STUDY DESIGN: Retrospective review. SETTING: Tertiary referral center. PATIENTS: A total of 277 children (aged 6 mo to 17 yr) and adults 18 years and older with normal cochlear anatomy who underwent primary and revision cochlear implantation at a single center between 2005 and 2010 were included. INTERVENTION: Intraoperative electrophysiologic monitoring and intraoperative Stenver's view plain film radiography. MAIN OUTCOME MEASURE: Intraoperative testing included the following: 1) individual electrode impedance measurements; 2) neural response telemetry (tNRT) levels for electrodes E20, E15, E10, and E5; and 3) plain film radiograph assessment of electrode position. RESULTS: No patient demonstrated abnormalities on all 3 modalities. Open or short electrodes on impedance testing were found in 6% of patients; half of these normalized when remeasured. Absent tNRT responses on 1 or more electrodes occurred in 14% of patients, although complete lack of response was rare (1.4%) and did not correlate with a dysfunctional device. Spread of excitation was performed in 1 patient and was consistent with a tip rollover. Intraoperative radiography identified tip-rollover and extracochlear electrode placement in all cases (n = 5, 1.8%) and prompted the use of the backup device. CONCLUSION: Immediate intraoperative determination of device functionality and optimal electrode placement is advantageous. Of the modalities tested, including electrode impedance, tNRT, and plain radiograph, only the radiographic results impacted intraoperative surgical decision making and led to the use of the backup device.

Intraoperative neural response telemetry as a predictor of performance.

OBJECTIVE: To determine whether intraoperative neural response telemetry (tNRT) is predictive of postoperative speech perception. STUDY DESIGN: Retrospective review. SETTING: Tertiary referral center. PATIENTS: Children (n = 24) aged between 5 and 17 years and adults 18 years and older (n = 73) with severe-to-profound hearing loss and implanted with the Nucleus Freedom device between 2005 and 2008 and observed at least 1 year were included. INTERVENTION: Intraoperative neural response telemetry after insertion of the electrode array. MAIN OUTCOME MEASURE: Measures included 1) intraoperative tNRT measurements and 2) preoperative and 1-year postoperative open-set word recognition scores using age-appropriate open-set tests for children and adults. Intraoperative neural response telemetry levels for electrodes E20, E15, E10, and E5 in each patient were correlated to performance at the 1-year evaluation interval. RESULTS: No correlation existed between tNRT responses and open-set speech performance at the 1-year evaluation. Several patients had absent tNRT in the OR but developed speech recognition abilities, whereas the remaining patients had intraoperative responses with levels of postoperative performance ranging from 0% to 100%. CONCLUSION: This study suggests that there is no significant correlation between intraoperative tNRT and speech perception performance at 1 year. At the time of surgery, tNRT provides valuable information regarding the electrical output of the implant and the response of the auditory system to electrical stimulation and preliminary device programming data; however, it is not a valuable predictor of postoperative performance. Furthermore, the absence of tNRT does not necessarily indicate a lack of stimulation.

Revision cochlear implantation.

PURPOSE OF REVIEW: Cochlear implantation is a well tolerated and effective procedure in the rehabilitation of profoundly and severely hearing-impaired individuals. Cochlear reimplantation may be necessary for a variety of reasons. The recent literature regarding the indications, surgical considerations, and outcomes in revision cochlear implant (RCI) surgery is reviewed here. RECENT FINDINGS: A small but significant percentage (3-8%) of all cochlear implant procedures requires RCI surgery. The most common indication for RCI is hard failure (40-80%), but other common indications include soft failures, wound complications, infection, improper initial placement, and electrode extrusions. There is a high rate of surgical success in RCI with preservation or improvement of preoperative performance in the majority of patients, in addition to the alleviation of prereimplantation symptoms. Both children and adults benefit from RCI when indicated and experience similar auditory successes following RCI. SUMMARY: The need for RCI is uncommon, but the potential for restoration or improvement in speech perception and alleviation of symptoms exists. Regardless of indication, RCI surgery is well tolerated, and, with thoughtful preparation, individualized patient counseling, and proper surgical technique, most patients can expect successful outcomes.