Tinnitus and treatment-resistant depression.

Tinnitus, a frequent disorder, is the conscious perception of a sound in the absence of a corresponding external acoustic sound source in the sense of a phantom sound. Although the majority of people who perceive a tinnitus sound can cope with it and are only minimaly impaired in their quality of lfe, 2-3% of the population perceive tinnitus as a major problem. Recently it has been proposed that the two groups should be differentiated by distict terms: "Tinnitus" describes the auditory or sensory component, whereas "Tinnitus Disorder" reflects the auditory component and the associated suffering. There is overwhelming evidence that a high tinnitus burden is associated with the increased occurrence of comorbidities, including depression. Since no causal therapeutic options are available for patients with tinnitus at the present time, the identification and adequate treatment of relevant comorbidities is of great importance for the reduction of tinnitus distress. This chapter deals with the relationship between tinnitus and depression. The neuronal mechanisms underlying tinnitus will first be discussed. There will also be an overview about depression and treatment resistant depression (TRD). A comprehensive review about the state-of-the-art evidences of the relationship between tinnitus and TRD will then be provided.

Clinical standardization for the detection of hemispheric dominance for steady-state auditory evoked fields in normal hearing.

BACKGROUND: Steady-state auditory evoked responses (SSAERs) are promising indicators of major auditory function. The improvement in accessibility in the clinical setting depends on the standardization and definition of the characteristics of SSAERs. There have been some insights into the changes in the interhemispheric dominance of SSAERs in some clinical entities. However, the hemispheric asymmetry of SSAERs in healthy controls remains inconclusive. METHODS: Twelve right-handed healthy volunteers with normal hearing were recruited. Steady-state auditory evoked fields (SSAEFs) were measured binaurally using magnetoencephalography (MEG) under pure-tone auditory stimuli at 1000 Hz with an amplitude modulation frequency of 43 Hz. The laterality index, based on the ratio of SSAEF strength over the right hemisphere to that over the left hemisphere, was also analyzed. RESULTS: The SSAEFs source was localized bilaterally on the superior temporal plane, with an orientation centripetal to the auditory cortex. The laterality index ranged from 1.1 to 2.3, and there were no sex differences. In all subjects, the strength of the SSAEFs was significantly weaker in the left hemisphere than in the right hemisphere ( p = 0.014). CONCLUSION: Right-sided dominance of the SSAEFs was verified in subjects with normal hearing. Acoustic sources clinically available in audiometric tests were used as stimuli. Such a simplification of parameters would be helpful for the standardization of precise production and the definition of the characteristics of SSAERs. Because MEG is still not easily accessible clinically, further studies using electroencephalography with larger sample sizes are necessary to address these issues.

Optimizing Location of Subdermal Recording Electrodes for Intraoperative Facial Nerve Monitoring.

OBJECTIVE: The purpose of this study is to determine if different facial muscle groups demonstrate different responses to facial nerve stimulation, the results of which could potentially improve intraoperative facial nerve monitoring (IOFNM). METHODS: IOFNM data were prospectively collected from patients undergoing cochlear implantation. At different stages of nerve exposure, three sites were stimulated using a monopolar pulse. Peak electromyography (EMG) amplitude (µV) in four muscle groups innervated by four different branches of the facial nerve (frontalis-temporal, inferior orbicularis oculi-zygomatic, superior oribularis oris-buccal, and mentalis-marginal mandibular) were recorded. RESULTS: A total of 279 peak EMG amplitudes were recorded in 93 patients. At all three stimulating sites, the zygomatic branch mean peak EMG amplitudes were statistically greater than those of the temporal, buccal, and marginal mandibular branches (P < .05). At stimulating Site C, the marginal mandibular branch mean peak EMG was stronger than the temporal or buccal branches (P < .05). Of the 279 stimulations, the zygomatic branch demonstrated the highest amplitude in 128 (45.9%) trials, followed by the marginal mandibular branch (22.2%). CONCLUSIONS: When utilized, IOFNM should be performed with at least two electrodes, one of which is placed in the orbicularis oculi muscles and the other in the mentalis muscle. However, there is wide variability between patients. As such, in cases of suspected variant nerve anatomy or increased risk of injury (intradural procedures), surgeons should consider using more than two recording electrodes, with at least one in the orbicularis oculi muscle. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:E2329-E2334, 2021.

Extractions of steady-state auditory evoked fields in normal subjects and tinnitus patients using complementary ensemble empirical mode decomposition.

BACKGROUND: Auditory steady-state response (ASSR) induced by repetitive auditory stimulus is commonly used for audiometric testing. ASSR can be measured using electro-encephalography (EEG) and magnetoencephalography (MEG), referred to as steady-state auditory evoked potential (SSAEP) and steady-state auditory evoked field (SSAEF), respectively. However, the signal level of SSAEP and SSAEF are weak so that signal processing technique is required to increase its signal-to-noise ratio. In this study, a complementary ensemble empirical mode decomposition (CEEMD)-based approach is proposed in MEG study and the extraction of SSAEF has been demonstrated in normal subjects and tinnitus patients. METHODS: The CEEMD utilizes noise assisted data analysis (NADA) approach by adding positive and negative noise to decompose MEG signals into complementary intrinsic mode functions (IMF). Ten subjects (five normal and five tinnitus patients) were studied. The auditory stimulus was designed as 1 kHz carrier frequency with 37 Hz modulation frequency. Two channels in the vicinities of right and left temporal areas were chosen as channel-of-interests (COI) and decomposed into IMFs. The spatial distribution of each IMF was correlated with a pair of left- and right-hemisphere spatial templates, designed from each subject's N100m responses in pure-tone auditory stimulation. IMFs with spatial distributions highly correlated with spatial templates were identified using K-means and those SSAEF-related IMFs were used to reconstruct noise-suppressed SSAEFs. RESULTS: The current strengths estimated from CEEMD processed SSAEF showed neural activities greater or comparable to those processed by conventional filtering method. Both the normal and tinnitus groups showed the phenomenon of right-hemisphere dominance. The mean current strengths of auditory-induced neural activities in tinnitus group were larger than the normal group. CONCLUSIONS: The present study proposes an effective method for SSAEF extraction. The enhanced SSAEF in tinnitus group echoes the decreased inhibition in tinnitus's central auditory structures as reported in previous studies.

Low body mass index and jaw movement are protective of hearing in users of personal listening devices.

OBJECTIVES/HYPOTHESIS: Sound pressure level delivered through personal listening devices (PLDs) and reaching the ear drum might be affected by body size and jaw movements. This study aimed to investigate whether jaw movement and/or smaller body mass index (BMI) resulted in decrease of sound pressure level within the ear canals of PLD users via an earbud earphone. STUDY DESIGN: Case series. METHODS: Forty-five normal-hearing subjects (16 males; mean age, 23.3 years) participated in this study. A probe-microphone system was used to measure sound pressure level in the external ear canal with music delivered from a media player via an earbud earphone. Test materials consisted of two 20-second excerpts from a heavy metal music piece. Subjects were instructed to adjust the volume of the media player to conform to three conditions for sound pressure measurement: comfortable, loud, and maximum. Measurements were then repeated while subjects mimicked chewing action under the same listening conditions. RESULTS: Sound pressure levels were significantly lower when measured with jaw movement than without jaw movement (P < .05). Sound pressure levels monitored with/without jaw movement were generally lower in subjects with a BMI<23 than those with a BMI ≥ 23 (P < .05). CONCLUSIONS: Jaw movement and low BMI (<23) reduced the overall sound level of PLDs at the ear canal. Sound pressure levels detected in the external ear canal of our subjects using earbud earphones were significantly lower under conditions of jaw movement/BMI <23. Our research invites further studies on a larger group of PLD users to correlate these variables with hearing threshold shifts over time.

Neuromagnetic index of hemispheric asymmetry prognosticating the outcome of sudden hearing loss.

The longitudinal relationship between central plastic changes and clinical presentations of peripheral hearing impairment remains unknown. Previously, we reported a unique plastic pattern of "healthy-side dominance" in acute unilateral idiopathic sudden sensorineural hearing loss (ISSNHL). This study aimed to explore whether such hemispheric asymmetry bears any prognostic relevance to ISSNHL along the disease course. Using magnetoencephalography (MEG), inter-hemispheric differences in peak dipole amplitude and latency of N100m to monaural tones were evaluated in 21 controls and 21 ISSNHL patients at two stages: initial and fixed stage (1 month later). Dynamics/Prognostication of hemispheric asymmetry were assessed by the interplay between hearing level/hearing gain and ipsilateral/contralateral ratio (I/C) of N100m latency and amplitude. Healthy-side dominance of N100m amplitude was observed in ISSNHL initially. The pattern changed with disease process. There is a strong correlation between the hearing level at the fixed stage and initial I/C(amplitude) on affected-ear stimulation in ISSNHL. The optimal cut-off value with the best prognostication effect for the hearing improvement at the fixed stage was an initial I/C(latency) on affected-ear stimulation of 1.34 (between subgroups of complete and partial recovery) and an initial I/C(latency) on healthy-ear stimulation of 0.76 (between subgroups of partial and no recovery), respectively. This study suggested that a dynamic process of central auditory plasticity can be induced by peripheral lesions. The hemispheric asymmetry at the initial stage bears an excellent prognostic potential for the treatment outcomes and hearing level at the fixed stage in ISSNHL. Our study demonstrated that such brain signature of central auditory plasticity in terms of both N100m latency and amplitude at defined time can serve as a prognostication predictor for ISSNHL. Further studies are needed to explore the long-term temporal scenario of auditory hemispheric asymmetry and to get better psychoacoustic correlates of pathological hemispheric asymmetry in ISSNHL.

Music training improves pitch perception in prelingually deafened children with cochlear implants.

OBJECTIVE: The comparatively poor music appreciation in patients with cochlear implants might be ascribed to an inadequate exposure to music; however, the effect of training on music perception in prelingually deafened children with cochlear implants remains unknown. This study aimed to investigate whether previous musical education improves pitch perception ability in these children. METHODS: Twenty-seven children with congenital/prelingual deafness of profound degree were studied. Test stimuli consisted of 2 sequential piano tones, ranging from C (256 Hz) to B (495 Hz). Children were asked to identify the pitch relationship between the 2 tones (same, higher, or lower). Effects of musical training duration, pitch-interval size, current age, age of implantation, gender, and type of cochlear implant on accuracy of pitch perception were evaluated. RESULTS: The duration of musical training positively correlated with the correct rate of pitch perception. Pitch perception performance was better in children who had a cochlear implant and were older than 6 years than in those who were aged < or =6 years (ie, preschool). Effect of pitch-interval size was insignificant on pitch perception, and there was no correlation between pitch perception and the age of implantation, gender, or type of cochlear implant. CONCLUSIONS: Musical training seems to improve pitch perception ability in prelingually deafened children with a cochlear implant. Auditory plasticity might play an important role in such enhancement. This suggests that incorporation of a structured training program on music perception early in life and as part of the postoperative rehabilitation program for prelingually deafened children with cochlear implants would be beneficial. A longitudinal study is needed to show whether improvement of music performance in these children is measurable by use of auditory evoked potentials.