Instant improvement in monaural spatial hearing abilities through cognitive feedback.

Several studies report that sound localization performance of acute and chronic monauralized normal-hearing listeners can improve through training. Typically, training sessions are administered daily for several days or weeks. While this intensive training is effective, it may also be that monaural localization abilities improve instantly after providing explicit top-down information about the direction dependent change in timbre and level. The aim of the present study was to investigate whether cognitive feedback (i.e., top-down information) could instantly improve sound localization in naive acutely monauralized listeners. Forty-three normal-hearing listeners (experimental group), divided over five different centers, were tested. Two control groups, consisting of, respectively, nine and eleven normal-hearing listeners, were tested in one center. Broadband sounds (0.5-20 kHz) were presented from visible loudspeakers, positioned in azimuth (- 90° to 90°). Participants in the experimental group received explicit information about the noticeable difference in timbre and the poor localization in the monauralized listening condition, resulting in an instant improvement in sound localization abilities. With subsequent roving of stimulus level (20 dB), sound localization performance deteriorated immediately. The reported improvement is related to the context of the localization test. The results provide important implications for studies investigating sound localization in a clinical setting, especially during closed-set testing, and indicate the importance of top-down information.

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.

Short and long term preservation of hearing thresholds corrected for natural hearing loss in cochlear implant recipients using a straight electrode.

Objectives: The aim of this study is to investigate short and long term residual hearing preservation (HP), corrected for the natural progress of hearing loss, in cochlear implant (CI) patients receiving a straight electrode array using a round window (RW) approach.Methods: A retrospective and cross-sectional analysis on patients who received a CI with a straight electrode using a RW approach (n = 60) was performed. Audiometric data were obtained at three time points, preoperatively, at first fitting, and one year or more postoperatively. The HP outcome was calculated according to the HP definition as reported by Skarzynski with a PTA of 250, 500, and 1000 Hz (PTA3) and a PTA of 250, 500, 1000, and 2000 Hz (PTA4).Results: The HP outcome at first fitting and at long term follow up fell into the partial HP category, 63.5% (PTA3) and 40.5% (PTA4), respectively according to the Skarzynski definition. A decline in pure-tone average (PTA) was found in the CI ear and in the contralateral ear over time (p < 0.05). Interaural differences remained relatively stable at all frequencies on the long term, except for the frequency 250 Hz (p < 0.05).Discussion: After the initial loss of residual hearing, the hearing thresholds of the CI ear remain relatively stable at long term follow up when corrected for the natural course of hearing loss, except at 250 Hz.Conclusion: CI candidates should be counseled on the risk of long term deterioration of the residual hearing in both the CI ear and the contralateral ear.

Hearing Preservation in Cochlear Implant Surgery: A Meta-Analysis.

OBJECTIVE(S): The aim of the present meta-analysis is to assess the effects of hearing preservation (HP) methods on residual hearing in patients undergoing cochlear implant (CI) surgery and to look at the effect of follow-up time on HP outcome. DATA SOURCES: A systematic search was conducted in PubMed, Embase, and Cochrane Library. Only articles in English were included. STUDY SELECTION: Prospective studies published until January 2018 on hearing preservation methods were included. DATA EXTRACTION: Studies were assessed on unaided pre- and postoperative hearing thresholds, follow up time, and methodological quality. DATA SYNTHESIS: A random-effects meta-regression was performed for the HP outcome in relation to surgical technique, electrode array design, inserted electrode length, insertion speed, and corticosteroid use for different follow up times (1 month, 6 months, and 12 months or more postoperatively). CONCLUSION: Hearing preservation in cochlear implant surgery is feasible. A statistically significant difference was found between the round window procedure and cochleostomy approach, in favor of the round window procedure at 6 months postoperatively (p = 0.001). A statistically significant difference was found between the straight and the perimodiolar electrode array at 1 month postoperatively in favor of the straight electrode array (p < 0.001). No statistically significant difference was found between the other HP methods. The round window approach with the straight electrode array might result in a better HP outcome at 1 month and 6 months postoperatively compared with the cochleostomy approach with the perimodiolar electrode array. A declining trend in HP outcome in both combinations was seen over time.

Hearing Restoration in Cochlear Nerve Deficiency: the Choice Between Cochlear Implant or Auditory Brainstem Implant, a Meta-analysis.

OBJECTIVE: To answer the dilemma clinician's face when deciding between cochlear implant (CI) and auditory brainstem implant (ABI) treatment options in patients with cochlear nerve deficiency (CND). STUDY DESIGN: Case study supplemented with literature review and meta-analysis. SETTING: Tertiary referral center. PATIENT(S): Child with CHARGE syndrome and congenital deafness. INTERVENTION(S): ABI as there was no benefit after bilateral cochlear implantation. MAIN OUTCOME MEASURES: Speech and language development, quality of life. RESULTS: In one ear the cochleovestibular nerve was present on magnetic resonance imaging (MRI) without preoperative ABR responses. In the contra lateral ear the nerve could not be identified, despite present ABR responses. Nevertheless, there was no positive outcome with CI. The patient had improved speech and language and quality of life with ABI. Of the 108 patients with CND and CI identified in the literature review, 25% attained open-set speech perception, 34% attained closed-set speech perception, and 41% detected sounds or less. The appearance of the cochlear nerve on MRI was a useful predictor of success, with cochlear nerve aplasia on MRI associated with a smaller chance of a positive outcome post cochlear implantation compared with patients with cochlear nerve hypoplasia. CONCLUSION: Although patients with (apparent) cochlear nerve aplasia are less likely to benefit from CI, CI before ABI is supported as some patients attain closed or open-set levels of speech perception after cochlear implantation.

There is no functional small-fibre neuropathy in prurigo nodularis despite neuroanatomical alterations.

Prurigo nodularis (PN) is a pruritic condition with altered epidermal neuroanatomy as demonstrated previously. Here we elucidated neuroimmunological mechanisms by combining functional, morphological and gene expression experiments in twelve subjects with PN and eight healthy controls. Subjects with PN showed a reduced intra-epidermal nerve fibre density (IENFD) in lesional skin. Quantitative sensory testing indicated maintenance of somatosensory function compared to controls. None of the tested molecular markers including the neuron-distracting SEMA3A and neuron-attracting NGF were altered in lesional vs non-lesional skin in PN subjects. Accordingly, we speculate that scratching may contribute to reduced IENFD rather than an authentic endogenous neuropathy.

Suggestions for a Guideline for Cochlear Implantation in CHARGE Syndrome.

OBJECTIVE: Identifying aspects for establishing cochlear implantation guidelines for patients with ocular coloboma, heart defects, atresia of the choanae, retardation (of growth and/or of development), genital anomalies, and ear anomalies (CHARGE) syndrome (CS). STUDY DESIGN: Explorative retrospective study. SETTING: Cochlear implant (CI)-centers of tertiary referral centers in The Netherlands. PATIENTS: Ten patients with CS who received a CI between 2002 and 2012. INTERVENTIONS: Describing the challenges and benefits of cochlear implantation in CS. MAIN OUTCOME MEASURES: Imaging and surgical findings, language development, and Quality-of-life (QoL), compared with two control groups: 1) 34 non-syndromic CI-users and 2) 13 patients with CS without CI because of sufficient hearing. RESULTS: Subjective and objective audiometry and magnetic resonance imaging were necessary to confirm the presence of the cochlear nerve. Surgery in CS was challenging because of enlarged emissary veins, semi-circular-canal aplasia, aberrant facial nerve, and dysplastic cochlear windows, making computed tomography indispensable in surgical preparations. No major intraoperative complications occurred. Despite additional handicaps, all patients showed auditory benefit and improvement in disease-specific QoL. Patients implanted at a relatively young age (≤37 months) followed by a long period of CI-use (>5 years) and with minor additional problems, developed spoken language at a basic level comparable to that of the control group of CS patients. CONCLUSION: A CI should be considered in all patients with CS and severe sensorineural hearing loss. A careful work-up is required, comprising computed tomography, magnetic resonance imaging, objective, and subjective audiometry and assessment by a specialized multidisciplinary team. Cochlear implantation in CS might be complicated by syndrome-related temporal-bone anatomy, and the outcome of the CI is more individually determined. Early implantation should be aimed for.