Cortical reorganization following auditory deprivation predicts cochlear implant performance in postlingually deaf adults.

Long-term hearing loss in postlingually deaf (PD) adults may lead to brain structural changes that affect the outcomes of cochlear implantation. We studied 94 PD patients who underwent cochlear implantation and 37 patients who were MRI-scanned within 2 weeks after the onset of sudden hearing loss and expected with minimal brain structural changes in relation to deafness. Compared with those with sudden hearing loss, we found lower gray matter (GM) probabilities in bilateral thalami, superior, middle, inferior temporal cortices as well as the central cortical regions corresponding to the movement and sensation of the lips, tongue, and larynx in the PD group. Among these brain areas, the GM in the middle temporal cortex showed negative correlation with disease duration, whereas the other areas displayed positive correlations. Left superior, middle temporal cortical, and bilateral thalamic GMs were the most accurate predictors of post-cochlear implantation word recognition scores (mean absolute error [MAE] = 10.1, r = .82), which was superior to clinical variables used (MAE: 12.1, p < .05). Using the combined brain morphological and clinical features, we achieved the best prediction of the outcome (MAE: 8.51, r = .90). Our findings suggest that the cross-modal plasticity allowing the superior temporal cortex and thalamus to process other modal sensory inputs reverses the initially lower volume when deafness becomes persistent. The middle temporal cortex processing higher-level language comprehension shows persistent negative correlations with disease duration, suggesting this area's association with degraded speech comprehensions due to long-term deafness. Morphological features combined with clinical variables might play a key role in predicting outcomes of cochlear implantation.

Interpreting auditory brainstem evoked responses and distortion product otoacoustic emissions in diabetic patients with normal hearing.

OBJECTIVE: Hearing impairment is a reported late complication of diabetes mellitus (DM). Previous studies have suggested that microangiopathic complications may cause cochlear nerve function deterioration. We evaluated the auditory brainstem evoked responses (ABRs) and distortion product otoacoustic emission (DPOAE) results according to the presence of DM in subjects with normal hearing. METHODS: A cross-sectional comparative study was conducted from January 2016 to January 2018. Auditory function tests including ABR and DPOAE were performed for outpatients complaining of unilateral tinnitus. All of analyses were conducted in ears without tinnitus on contralateral side of tinnitus ears. We included subjects showing hearing thresholds within 25 dB at 0.5, 1k, 2k, and 4k on pure tone audiometry. 45 ears in patients with type 2 diabetes mellitus and 85 ears in non-diabetic patients were finally enrolled in our study. RESULTS: Diabetic subjects showed significantly more prolonged absolute peak latencies (I, III, V) and inter-peak latencies (I-V, III-V) than non-diabetic subjects. However, there was no significant difference in the inter-peak latency (I-III) between these two groups. Diabetic subjects also showed significantly lower amplitudes at f2 frequencies of 1001, 1200, 1587, 4004, 5042, and 6348 Hz than non-diabetic subjects. Additionally, the prevalence of a DPOAE response, defined as 3 dB above the noise floor, was significantly lower in diabetic subjects than that in non-diabetic subjects. CONCLUSION: Diabetic patients with normal hearing can still have abnormal ABR and DPOAE results due to diabetic neuroangiopathy. ABR and DPOAE assessments can help in detecting subclinical auditory dysfunction, which precedes the manifestation of hearing impairment in diabetic patients.

Hyperbaric oxygen (HBO) therapy as an effective approach to the treatment of patients with severe idiopathic sudden sensorineural hearing loss.

Background: The potential etiology of idiopathic sudden sensorineural hearing loss (ISSNHL) is cochlear ischemia, therefore, hyperbaric oxygen (HBO) therapy is a promising treatment, particularly in patients with severe hearing loss (≥70 dB).Aims/objectives: To evaluate the efficacy of HBO therapy.Material and methods: The medical records of patients diagnosed with ISSNHL were retrospectively reviewed (≥70 dB). Patients received HBO therapy 14 times in addition to systemic and intratympanic steroid therapy (HBO group), or systemic and intratympanic steroid therapy only (control group).Results: Data from a total of 82 patients (83 ears) were included in the analysis; 37 (38 ears) in the HBO group and 45 (45 ears) in the control group. After 2 weeks' treatment, hearing was significantly improved in the HBO group versus controls (weighted four-frequency average 28.1 ± 26.9 dB versus 14.8 ± 13.5 dB, respectively; p < .05), particularly in the low frequency groups (0.5 kHz, 1 kHz, 2 kHz; p < .05).Conclusion and significance: These data demonstrate that HBO therapy is an effective initial treatment option for patients with ISSNHL suffering from severe hearing loss.

Combination of plasma with a honeycomb-structured catalyst for automobile exhaust treatment.

To activate a catalyst efficiently at low temperature by plasma for environmental control, we developed a hybrid reactor that combines plasma with a honeycomb-structured catalyst in a practical manner. The reactor developed generated stable cold plasma at atmospheric pressure because of the dielectric and conductive nature of the honeycomb catalyst by consuming low amounts of power. In this reactor, the applied voltage and temperature determined the balance between the oxidation and adsorption by the plasma and catalyst. The synergistic reaction of the plasma and catalyst was more effective at low temperatures, resulting in a reduction in a lowered light-off temperature.

Effects of a zinc-deficient diet on hearing in CBA mice.

This study investigated the effect of a zinc-deficient diet on the hearing in CBA mice and aimed to verify whether this hearing change is reversible by supplementation of zinc afterwards. We assessed hearing through an auditory brainstem response (ABR) with tone burst stimulation in 4, 8, 16, and 32 kHz and distortion product otoacoustic emissions in 5.6, 8, 11.3, and 16 kHz every week. The ABR threshold started to increase after 4 weeks on a zinc-deficient diet. The difference in the threshold between control and zinc-deficient animals became greater over time and plateaued at about 6 weeks. The ABR threshold differences between control and zinc-deficient mice were greater at higher frequencies. Four weeks of normal diet, following 8 weeks of a zinc-deficient diet, restored the ABR threshold to normal at all measured frequencies. Zinc-deficient mice did not show any distortion product otoacoustic emission threshold change at all frequencies. This finding suggests that a zinc-deficient diet increased the ABR threshold in CBA mice and a zinc-adequate diet restored the ABR threshold to normal.