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Deep brain stimulation of the central auditory pathway is emerging as a promising treatment modality for tinnitus. Within this pathway, the dorsal cochlear nucleus (DCN) plays a key role in the pathophysiology of tinnitus and is believed to be a tinnitus generator. We hypothesized that high-frequency stimulation (HFS) of the DCN would influence tinnitus-related abnormal neuronal activity within the auditory pathway and hereby suppress tinnitus. To this end, we assessed the effect of HFS of the DCN in a noise-induced rat model of tinnitus. The presence of tinnitus was verified using the gap prepulse inhibition of the acoustic startle response paradigm. Hearing thresholds were determined before and after noise trauma by measuring the auditory brainstem responses. In addition, changes in neuronal activity induced by noise trauma and HFS were assessed using c-Fos immunohistochemistry in related structures. Results showed tinnitus development after noise trauma and hearing loss ipsilateral to the side exposed to noise trauma. During HFS of the DCN, tinnitus was suppressed. There was no change in c-Fos expression within the central auditory pathway after HFS. These findings suggest that DCN-HFS changes patterns of activity and results in information lesioning within the network and hereby blocking the relay of abnormal tinnitus-related neuronal activity.

OBJECTIVE: Electrically evoked auditory brainstem responses (eABRs) can be recorded before cochlear implant (CI) surgery to verify auditory nerve function, and is particularly helpful in to assess the function of the auditory nerve in cases of auditory nerve hypoplasia. This is the first study to compare three preimplant eABRs recording techniques: 1) standard extracochlear, 2) novel intracochlear, and 3) conventional intracochlear with the CI. STUDY DESIGN: A within-participants design was used where eABRs were sequentially measured during CI surgery using three methods with stimulation from: 1) an extracochlear electrode placed at the round window niche, 2) two different electrodes on a recently developed Intracochlear Test Array (ITA), and 3) two different electrodes on a CI electrode array. SETTING: New adults implantees (n = 16) were recruited through the Manchester Auditory Implant Centre and eABR measurements were made in theater at the time of CI surgery. PATIENTS: All participants met the clinical criteria for cochlear implantation. Only participants with radiologically normal auditory nerves were recruited to the study. All participants were surgically listed for either a MED-EL Synchrony implant or a Cochlear Nucleus Profile implant, per standard practice in the implant centre. OUTCOME MEASURES: Primary outcome measures were: 1) charge (μC) required to elicit a threshold response, and 2) latencies (ms) in the threshold waveforms. Secondary outcome measures were: 1) morphologies of responses at suprathreshold stimulation levels and 2) wave V growth patterns. RESULTS: eABRs were successfully measured from 15 participants. In terms of primary outcome measures, the charge required to elicit a response using the extracochlear electrode (median = 0.075 μC) was approximately six times larger than all other electrodes and the latency of wave V was approximately 0.5 ms longer when using the extracochlear electrode (mean = 5.1 ms). In terms of secondary outcomes, there were some minor quantitative differences in responses between extracochlear and intracochlear stimulation; in particular, ITA responses were highly variable in quality. The ITA responses were rated poor quality in 33% of recordings and in two instances did not allow for data collection. When not disrupted by open circuits, the median ITA response contained one more waveform than the median extracochlear response. CONCLUSIONS: In this first study comparing intracochlear and extracochlear stimulation, the results show that both can be used to produce an eABR that is representative of the one elicited by the CI. In the majority of cases, extracochlear stimulation was the preferred approach for preimplant auditory nerve function testing because of consistency, recordings that could be analyzed, and because extracochlear placement of the electrode does not require a cochleostomy to insert an electrode.

Background Neuromodulation is a promising treatment modality for tinnitus, especially in chronic and severe cases. The auditory thalamus plays a key role in the pathophysiology of tinnitus, as it integrates and processes auditory and limbic information. Objective The effect of high frequency stimulation and low frequency stimulation of the medial geniculate bodies on tinnitus in a noise-induced tinnitus rat model is assessed. Materials and methods Presence of tinnitus was verified using the gap-induced prepulse inhibition of the acoustic startle response paradigm. Hearing thresholds were determined before and after noise trauma with auditory brainstem responses. Anxiety-related side-effects were evaluated in the elevated zero maze and open field. Results Results show tinnitus development after noise exposure and preserved hearing thresholds of the ear that was protected from noise trauma. We found that high frequency stimulation of the medial geniculate bodies suppressed tinnitus. This effect maintained directly after stimulation when the stimulator was turned off. Low frequency stimulation did not have any effects on the gap:no-gap ratio of the acoustic startle response. Conclusion High frequency stimulation of the MGB has a direct and residual suppressing effect on tinnitus in this animal model. Low frequency stimulation of the MGB did not inhibit tinnitus.

OBJECTIVE: To gain insight into health and related costs associated with very preterm births, one needs accurate information about the prevalence of the disabling conditions, including neonatal hearing loss (NHL).STUDY DESIGN: We assessed the prevalence of NHL by week of gestation and categories of birth weight in very preterm neonates. Results of the 2-stage Automated Auditory Brainstem Response nationwide Newborn Hearing Screening Program in Dutch Neonatal Intensive Care Units and diagnostic examinations were centrally registered between October 1998 and December 2012 and included in this study. NHL was defined as impaired when the neonate conventional Auditory Brainstem Response level exceeded 35 dB near Hearing Level at diagnostic examination. Birth weight was stratified into RESULTS: In total, 18,564 very preterm neonates were eligible. The prevalence of NHL consistently increased with decreasing week of gestation (1.2%-7.5% from 31 to 24 weeks) and decreasing birth weight (1.4%-4.8% from ≥ 1500 g to CONCLUSIONS: Gestational age and birth weight quantify the risk of NHL. This information can be used at the individual level for parent counseling and at the population level for medical decision making.

Summary American mink (Neovison vison) kits are born altricial and fully dependent 40 on maternal care, for which the kits' vocalisations appear essential. We used Auditory Brainstem Recording (ABR) to determine (1) hearing sensitivity of adult females from two breeding lines known to differ in maternal behaviour and (2) development of hearing in kits 8-52 days of age. We also studied sound production in 20 kits throughout postnatal days 1 to 44. Adult female mink had a broad hearing range from 1 kHz to above 70 kHz, with peak sensitivity (threshold of 20 dB SPL) at 8-10 kHz, and no difference in sensitivity between the two breeding lines (P>0.22) to explain the difference in maternal care. Mink kits showed no signs of hearing up to postnatal day 24. From day 30 all kits had ABRs indicative of hearing. Hearing sensitivity increased with age, but was still below the adult level at postnatal day 52. When separated from their mothers kits vocalized loudly. Until age 22 days, 90% of all kits vocalized with no significant decline with age (P=0.27). From day 25, concurrent with the start of hearing, the number of vocalizing kits decreased with age (P

A systematic investigation of the incidence and type of peripheral and central auditory and vestibular disorders occurring in different stages of HIV infection was performed: 43 HIV-seropositive patients (14 were symptomatic with manifestation of AIDS or related complex and 29 were clinically asymptomatic) were compared with a matched control group of 33 HIV-seronegative homosexual volunteers. Among the symptomatic patients 8 (57%) out of 14 and among the asymptomatic HIV-positive patients, 13 (45%) out of 29 had abnormal results in various audiological, vestibular and electrophysiological tests. Only minor anomalies were found in 4 (12%) of the 33 seronegative homosexuals. Our results indicate a high incidence of neuro-otological disorders among patients suffering from AIDS. The numerous electrophysiological abnormalities found in asymptomatic HIV-seropositive persons suggest furthermore an early subclinical involvement of the auditory and vestibular systems.