Progressive Loss of Sensitivity to Electrical Stimulation After Cochlear Implantation in X-Linked Incomplete Partition Type III Deafness.

OBJECTIVES: Patients with X-linked incomplete partition type III (IP3) deafness treated with cochlear implants exhibit higher "Most Comfortable Loudness" (MCL) levels of stimulation and more electrode deactivation than patients with normal morphology. We endeavored to analyze the progression of the MCL levels and electrode deactivation over time and assess those factors that could have led to deactivation. Furthermore, we aimed to assess whether speech perception was affected by a progressive loss of neural contact. DESIGN: All 13 patients with the IP3 malformation in our clinical database were analyzed retrospectively with regard to impedance, stimulation levels, deactivated electrodes, and speech perception. A control group of patients with normal anatomy was included. RESULTS: MCL levels increased over time by 2.5 charge units (qu) per year, which was not seen in the control group. Electrode deactivation was more common in IP3 malformation, and it was estimated that 25% of electrodes would be deactivated by 15 years of age. Impedance was stable but higher in the study population. Speech perception was lower in IP3 malformation generally and was correlated to the number of deactivated electrodes. CONCLUSIONS: Patients diagnosed with IP3 malformation deafness may suffer a greater risk of cochlear implant discontinuation compared with those with normal anatomy. A progressive loss of sensitivity to electrical stimulation may indicate a form of neural degradation in the abnormal cochlea. With time, patients in this group, even with cochlear implant technology, may experience gradual deterioration of speech perception. This has clinical implications for the counseling of parents.

X-linked Malformation Deafness: Neurodevelopmental Symptoms Are Common in Children With IP3 Malformation and Mutation in POU3F4.

OBJECTIVE: Incomplete partition type 3 (IP3) malformation deafness is a rare hereditary cause of congenital or rapid progressive hearing loss. The children present with a severe to profound mixed hearing loss and temporal bone imaging show a typical inner ear malformation classified as IP3. Cochlear implantation is one option of hearing restoration in severe cases. Little is known about other specific difficulties these children might exhibit, for instance possible neurodevelopmental symptoms. MATERIAL AND METHODS: Ten 2; 0 to 9; 6-year-old children with IP3 malformation deafness (nine boys and one girl) with cochlear implants were evaluated with a retrospective chart review in combination with an additional extensive multidisciplinary assessment day. Hearing, language, cognition, and mental ill-health were compared with a control group of ten 1; 6 to 14; 5-year-old children with cochlear implants (seven boys and three girls) with another genetic cause of deafness, mutations in the GJB2 gene. RESULTS: Mutations in POU3F4 were found in nine of the 10 children with IP3 malformation. Children with IP3 malformation deafness had an atypical outcome with low level of speech recognition (especially in noise), executive functioning deficits, delayed or impaired speech as well as atypical lexical-semantic and pragmatic abilities, and exhibited mental ill-health issues. Parents of children with IP3 malformation were more likely to report that they were worried about their child's psychosocial wellbeing. Controls, however, had more age-typical results in all these domains. Eight of 10 children in the experimental group had high nonverbal cognitive ability despite their broad range of neurodevelopmental symptoms. CONCLUSIONS: While cochlear implantation is a feasible alternative for children with IP3 malformation deafness, co-occurring neurodevelopmental anomalies, such as attention deficit hyperactivity or developmental language disorder, and mental ill-health issues require an extensive and consistent multidisciplinary team approach during childhood to support their overall habilitation.

Wideband tympanometry in ears with superior canal dehiscence before and after surgical correction.

OBJECTIVES: Wideband tympanometry (WBT) has been shown to be sensitive to mechanical changes in the ear. This study investigated the effect of surgical correction of superior canal dehiscence (SCD) on WBT (i.e. absorbance and middle ear resonance frequency) compared to those on common surgical outcomes such as symptom resolution, vestibular evoked myogenic potentials (VEMP), and hearing thresholds. STUDY SAMPLE AND STUDY DESIGN: Seven patients (eight ears with SCD) who underwent surgical correction of SCD underwent WBT in addition to pure-tone audiometry and VEMP assessment. RESULTS: Postoperatively, all ears showed normalised/decreased absorbance at low frequencies and slightly enhanced absorbance in the middle frequency range (7/8 ears). The middle ear resonance frequency, which was initially lower than normal in most patients, increased in 6/8 operated ears, and decreased in two ears with no/partial symptom relief. In comparison, complete symptom control was observed in 6/8 operated ears, VEMP amplitudes reduced or normalised in all ears, and hearing thresholds remained stable or improved in 6/8 ears and worsened in two ears. CONCLUSIONS: Surgery seems to change the response to WBT in patients with SCD. The results of WBT may represent mechanical changes induced by SCD, and should be considered when evaluating surgical outcomes.

Cochlear Implantation with the CI512 and CI532 Precurved Electrode Arrays: One-Year Speech Recognition and Intraoperative Thresholds of Electrically Evoked Compound Action Potentials.

INTRODUCTION: Precurved cochlear implant (CI) electrode arrays were developed in an attempt to improve the auditory outcome of cochlear implantation, which varies greatly. The recent CI532 (Cochlear Corp., Sydney, Australia) may offer further advantages as its electrode array is thinner than previous precurved CI electrode arrays. The aims here were to investigate 1-year postoperative speech recognition, intraoperative electrically evoked compound action potentials (ECAPs), and their possible relation in patients implanted with a CI532 or its predecessor CI512. METHODS: A retrospective analysis of data from 63 patients subjected to cochlear implantation at the Karolinska University Hospital, Sweden, was performed. Speech recognition of the implanted ear was evaluated using phonemically balanced monosyllabic Swedish words at 65 dB SPL. ECAPs were evaluated using the intraoperative ECAP threshold across ≥8 electrodes generated by the automated neural response telemetry of the CI. RESULTS: The median aided speech recognition score (SRS) 1 year after implantation was 52% (quartile 1 = 40%, quartile 3 = 60%, n = 63) and did not differ statistically significantly between patients with CI512 (n = 38) and CI532 (n = 25). The mean ECAP threshold was 188 CL (current level; SD = 15 CL, n = 54) intraoperatively and did not differ statistically significantly between patients with CI512 (n = 32) and CI532 (n = 22), but the threshold for each electrode varied more between patients with a CI512 (p < 0.0001). A higher mean ECAP threshold was associated with a worse SRS (Spearman's ρ = -0.46, p = 0.0004, n = 54). The association remained among those with a CI512 (Spearman's ρ = -0.62, p = 0.0001, n = 32) when stratified by CI electrode array. CONCLUSION: No statistically significant difference in speech recognition 1 year after cochlear implantation or in mean threshold of ECAP intraoperatively was found between patients with a CI512 and the more recent, slim CI532, but the ECAP thresholds varied more between those with a CI512. A statistically significant association between SRS and mean ECAP threshold was found, but stratified analysis suggests that the association may be true only for patients with a CI512.

Cochlear implants in the etiopathogenesis of glioblastoma--an interesting observation or independent finding?

Various risk factors have been implicated in the pathogenesis of glioblastomas including ionizing radiation. Recent evidence has suggested a possible association between exposure to nonionizing radiofrequency electromagnetic fields (RF-EMF) generated from mobile phones and wireless devices to cause malignant transformation of the neuroglial cells, albeit this is widely debated. In this report, we discuss the development of glioblastoma in two geopolitically unrelated patients, an elderly male from the United States and a middle-aged woman from Sweden, with long-standing cochlear implants (CI). We hypothesize that the low-frequency RF-EMF emanating from the transcutaneous link of the CI prosthesis over a long period has potentially triggered tumor development in these patients.

Long-Term Follow-Up in Active Transcutaneous Bone Conduction Implants.

OBJECTIVE: To evaluate long-term outcomes of active transcutaneous bone conduction implants (atBCIs) regarding safety, hearing, and quality of life. STUDY DESIGN: A clinical study with retrospective medical record analysis combined with prospective audiometry and quality of life questionnaires. SETTING: Three secondary to tertiary care hospitals. PATIENTS: All subjects operated with an atBCI in three regions in Sweden were asked for informed consent. Indications for atBCI were single-sided deafness (SSD) and conductive or mixed hearing loss (CMHL). INTERVENTION: Evaluation of atBCI. MAIN OUTCOME MEASURES: Pure tone and speech audiometry and Glasgow Benefit Inventory (GBI). RESULT: Thirty-three subjects were included and 29 completed all parts. The total follow-up time was 124.1 subject-years. Nineteen subjects had CMHL and in this group, pure tone averages (PTA4) were 56.6 dB HL unaided and 29.6 dB HL aided, comparable with a functional gain of 26.0 dB. Effective gain (EG) was -12.7 dB. With bilateral hearing, Word Recognition Scores (WRS) in noise were 36.5% unaided and 59.1% aided. Fourteen subjects had SSD or asymmetric hearing loss (AHL) and in this group, PTA4 were >100 dB HL unaided and 32.1 dB HL aided with the contralateral ear blocked. EG was -9.1 dB. With bilateral hearing, WRSs were 53.2% unaided and 67.9% aided. The means of the total GBI scores were 31.7 for CMHL and 23.6 for SSD/AHL. CONCLUSION: Few complications occurred during the study. The atBCI is concluded to provide a safe and effective long-term hearing rehabilitation.

Expert opinion on candidacy for bone conduction hearing implants Osia System and Baha Connect System.

<b>Introduction:</b> Bone conduction hearing implants (BCHI) are a widely used rehabilitation solution for patients with conductive hearing loss (CHL), mixed hearing loss (MHL), or single-sided deafness (SSD).<b>Aim:</b> This expert review presents candidacy criteria considerations when choosing between active transcutaneous bone-conduction hearing devices (Osia System) and passive percutaneous bone-conduction hearing devices (Baha Connect System) to help streamline the decision-making process in those contexts where economics have a major impact on professionals' and patients' choice.<b>Methods:</b> Eight experts participated in two online surveys and two virtual meetings to discuss real-world clinical experience to highlight treatment approaches and factors considered when counseling the patients and selecting an optimal BCHI solution. Key considerations for decision-making were recorded following consensus from all experts.<b>Conclusions:</b> Aspects in decision making include the requirement to use local <i>versus</i> general anesthesia for the implantation procedure, bone thickness, considerations for future magnetic resonance imaging (MRI) procedures, and patient preference. Increased risk of skin infections, requirements for cleaning and managing the implant site, particularly for those with limited dexterity, as well as esthetic concerns could make the Baha Connect System unsuitable for some patients. In these cases, the Osia System may provide clear advantages, particularly in patients for whom good hearing performance is a priority, and this would need to be discussed individually with the patient in a multidisciplinary setting. Conversely, for patients requiring minimally invasive surgery, who have contraindications for general anesthesia or require frequent head MRI scans in the future, the Baha Connect System may be more suitable.

Occurrence of primary brain tumors in cochlear implant patients in Sweden between 1989 and 2014.

PURPOSE: Cochlear implants are widely used for hearing rehabilitation of deaf children with congenital deafness or adults with acquired severe-to-profound hearing loss. The sound processor antenna creates a radio frequency-electromagnetic field transmitting the sound signal to the implant, similar to that in a mobile phone. A recent case report suggested a relationship between cochlear implants and malignant glioma, and some epidemiological studies have suggested an increased glioma and acoustic neuroma risk associated with long hours of mobile phone use. An epidemiological study is warranted to evaluate such a relationship in patients with cochlear implants. PATIENTS AND METHODS: To examine whether this chronic radio frequency-electromagnetic field signaling is associated with an increased brain tumor risk, a population-based cohort study was performed examining all 2,748 patients receiving a cochlear implant in Sweden during the years 1989-2014. In all, 3,169 surgeries were performed in the total cohort. The expected occurrence of glioma, meningioma, and acoustic neuroma in the patient cohort was calculated using specific national incidence rates in the Swedish population. RESULTS: Four patients were diagnosed with a brain tumor during follow-up, three of them having meningioma compared with 0.95 expected (standardized incidence ratio =3.16, 95% CI 0.65-9.24), and one had glioma compared with 1.34 expected (standardized incidence ratio =0.75, 95% CI 0.02-4.15). No case of acoustic neuroma was observed compared with 0.09 expected. CONCLUSION: In this study, we did not find support for concerns raised in a previous case report regarding a potentially higher risk of glioma. The number of brain tumors observed was well within the numbers expected from national incidence figures. Although this was a relatively small cohort with a limited follow-up time, it is the largest epidemiological study to date to address this concern.

X-linked Malformation and Cochlear Implantation.

OBJECTIVE: To evaluate if cochlear implantation is safe and constitutes an option for hearing rehabilitation of children with x-linked inner ear malformation. STUDY DESIGN: Retrospective patient review in combination with a multidisciplinary follow-up. SETTING: Tertiary referral hospital and cochlear implant program. PATIENTS: Ten children with severe-profound mixed hearing loss and radiological findings consistent with Incomplete Partition type 3 cochlear malformation received cochlear implants during the years 2007 to 2015. Nine of the children had a mutation affecting the gene POU3F4 on Xq21. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Surgical events, intraoperative measures and electrical stimulation levels, hearing and spoken language abilities. RESULTS: In all, 15 cochlear implantations were performed. In three cases the electrode was found to be in the internal auditory canal on intraoperative x-ray and repositioned successfully. One child had a postoperative rhinorrhea confirmed to be cerebrospinal fluid but this resolved on conservative treatment. No severe complications occurred. Postoperative electrical stimulation levels were higher in 9 of 10 children, as compared with typically reported average levels in patients with a normal cochlea. Eight patients developed spoken language to various degrees while two were still at precommunication level. However, speech recognition scores were lower than average pediatric cases. CONCLUSION: Cochlear implantation is a safe procedure for children with severe-profound mixed hearing loss related to POU3F4 mutation inner ear malformation. The children develop hearing and spoken language but outcome is below average for pediatric CI recipients.

Correlations of External Landmarks With Internal Structures of the Temporal Bone.

HYPOTHESIS: The internal anatomy of a temporal bone could be inferred from external landmarks. BACKGROUND: Mastoid surgery is an important skill that ENT surgeons need to acquire. Surgeons commonly use CT scans as a guide to understanding anatomical variations before surgery. Conversely, in cases where CT scans are not available, or in the temporal bone laboratory where residents are usually not provided with CT scans, it would be beneficial if the internal anatomy of a temporal bone could be inferred from external landmarks. METHODS: We explored correlations between internal anatomical variations and metrics established to quantify the position of external landmarks that are commonly exposed in the operating room, or the temporal bone laboratory, before commencement of drilling. Mathematical models were developed to predict internal anatomy based on external structures. RESULTS: From an operating room view, the distances between the following external landmarks were observed to have statistically significant correlations with the internal anatomy of a temporal bone: temporal line, external auditory canal, mastoid tip, occipitomastoid suture, and Henle's spine. These structures can be used to infer a low lying dura mater (p = 0.002), an anteriorly located sigmoid sinus (p = 0.006), and a more lateral course of the facial nerve (p < 0.001). In the temporal bone laboratory view, the mastoid tegmen and sigmoid sinus were also regarded as external landmarks. The distances between these two landmarks and the operating view external structures were able to further infer the laterality of the facial nerve (p < 0.001) and a sclerotic mastoid (p < 0.001). Two nonlinear models were developed that predicted the distances between the following internal structures with a high level of accuracy: the distance from the sigmoid sinus to the posterior external auditory canal (p < 0.001) and the diameter of the round window niche (p < 0.001). CONCLUSION: The prospect of encountering some of the more technically challenging anatomical variants encountered in temporal bone dissection can be inferred from the distance between external landmarks found on the temporal bone. These relationships could be used as a guideline to predict challenges during drilling and choosing appropriate temporal bones for dissection.

High-frequency hearing, tinnitus, and patient satisfaction with stapedotomy: A randomized prospective study.

Otosclerosis is a common disorder that leads to conductive hearing loss. Most patients with otosclerosis also have tinnitus, and surgical treatment is known to improve hearing as well as tinnitus. Some patients however experience worsening of tinnitus after the operation, but there are no known factors that allow surgeons to predict who will be at risk. In this prospective observational study on 133 patients undergoing stapedotomy, we show that postoperative air conduction thresholds at very high stimulus frequencies predict improvement of tinnitus, as assessed with proportional odds logistic regression models. Young patients were significantly more likely to experience reduction of tinnitus and patients whose tinnitus became better were also more satisfied with the outcome of the operation. These findings have practical importance for patients and their surgeons. Young patients can be advised that surgery is likely to be beneficial for their tinnitus, but a less positive message should be conveyed to older patients.

Clinical performance of a new magnetic bone conduction hearing implant system: results from a prospective, multicenter, clinical investigation.

OBJECTIVE: The aim of the investigation was to prospectively evaluate, in a multicenter setting, the clinical performance of a new magnetic bone conduction hearing implant system. METHODS: The test device was the Cochlear Baha Attract System (Cochlear Bone Anchored Solutions AB, Mölnlycke, Sweden). Instead of the skin-penetrating abutment of traditional bone conduction hearing implants, the test device uses an implantable and an external magnet to transmit sound from the sound processor (SP) through intact skin to the skull bone. Twenty-seven adult patients with a conductive or mild mixed hearing loss or single-sided sensorineural deafness were included in the clinical investigation across four investigational sites. The patients were followed for 9 months after implantation. The study evaluated efficacy in terms of hearing performance compared with unaided hearing and with hearing with the SP on a softband. Patient benefit, soft tissue status, device retention, and safety parameters were monitored continuously throughout the investigation. RESULTS: Surgery and healing was uneventful. Statistically significant improvements in audibility and speech understanding in noise and quiet were recorded for the test device compared with preoperative unaided hearing. Speech recognition was similar or better than tests performed with the same SP on a softband. Good soft tissue outcomes were reported, without major pressure-related complications. At the end of the investigation, all patients continued to use and benefit from the device. CONCLUSION: The test device provides good hearing performance in patients with a conductive hearing loss or single-sided sensorineural deafness, with good wearing comfort and minimal soft tissue complications.

A randomised, double blind trial of N-Acetylcysteine for hearing protection during stapes surgery.

BACKGROUND: Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. METHODS: We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. FINDINGS: One year after surgery, high-frequency hearing had improved 2.7 ± 3.8 dB in the placebo group (67 patients analysed) and 2.4 ± 3.7 dB in the treated group (72 patients; means ± 95% confidence interval, p = 0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. CONCLUSIONS: N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy. TRIAL REGISTRATION: ClinicalTrials.gov NCT00525551.