Effect of the Timing of Hyperbaric Oxygen Therapy on the Prognosis of Patients with Idiopathic Sudden Sensorineural Hearing Loss.

This study aimed to evaluate the effects of hyperbaric oxygen therapy (HBOT) on the hearing recovery of patients with idiopathic sudden sensorineural hearing loss (ISSNHL). The clinical data of 79 patients diagnosed with ISSNHL and treated with HBOT between January 2017 and December 2019 were retrospectively reviewed. The pure tone audiometry (PTA) scores before and after HBOT were recorded. The associations of HBOT efficacy with demographic and clinical characteristics and the duration from disease onset to HBOT administration were determined. The average PTA score was 80.06 ± 25.94 dB before and 60.75 ± 21.26 dB after HBOT; the difference was significant. HBOT improved the hearing of 55.7% of the patients with ISSNHL (defined as an average PTA ≥ 11dB or a final average PTA score below 29 dB). There was a significant inverse relationship between the duration from symptom onset to HBOT administration and PTA score reduction after HBOT, which was adjusted for factors including age, sex, laterality of hearing loss, initial PTA score, reception of intratympanic steroid injections, tinnitus, dizziness, vertigo, diabetes, hypertension, and coronary artery disease. Commencing HBOT at an earlier stage is closely linked to greater improvements in hearing for patients with ISSNHL.

Sensorineural Hearing Loss and Its Relationship with Duration of Chelation Among Major ß-Thalassemia Patients.

Introduction Thalassemia is a common genetic disorder worldwide, also occurring frequently in Karachi, Pakistan. Beta (ß)-thalassemia major patients need repeated transfusions which cause iron overload. Patients are treated with chelating agents to reduce the high serum ferritin level and to decrease morbidity and mortality due to increased iron levels. This combined therapy also leads to some complications. One of them is the sensorineural hearing loss (SNHL). To date, no data is available in Pakistan regarding SNHL among major ß-thalassemia patients on chelating therapy.  Methods A cross-sectional study was performed in collaboration with the Thalassemia Center and Dr. Ruth Pfau at the Department of Ear, Nose, and Throat, Civil Hospital, Karachi, Pakistan. The variable to detect hearing was pure tone air and bone conduction thresholds at the frequencies of 250 - 4,000 Hz. Clinical data, such as chelating agent dose, duration, and hearing status, were recorded. Demographic characteristics, like age, gender, height, and weight, were noted. The hemoglobin and serum ferritin levels of the subjects were also included. Results Forty-five percent of cases of thalassemia were suffering from SNHL. In the right ear, the Pearson correlation of chelating agent dose (mg) with SNHL was mildly positive and statistically significant (r = 0.261, p < 0.001), (r = 0.337, p < 0.001), (r = 0.198, p = 0.005), and (r = 0.207, p = 0.003) at the frequencies of 250, 500, 1,000, and 2,000 Hz, respectively, and the Pearson correlation of chelating agent used (in months) with SNHL was mildly positive and statistically significant (r = 0.232, p = 0.001), and (r = 0.301, p < 0.001) at frequencies 250 to 500 Hz, respectively. In the left ear, the Pearson correlation of chelating agent dose (mg) with SNHL was mildly positive and statistically significant, (r = 0.191, p = 0.007), (r = 0.202, p = 0.004), (r = 0.297, p < 0.001), (r = 0.183, p = 0.010) and (r = 0.221, p = 0.002) at frequencies 250, 500, 1,000, 2,000, and 4,000 Hz, respectively, and Pearson correlation of chelating agent used (months) with SNHL was mildly positive and statistically significant only at the frequency of 2,000 Hz (r = 140, p = 0.049).  Conclusion Chelation therapy and regular blood transfusions, apart from prolonging the life of thalassemic patients, also leads to some complications. With this survey, it was concluded that almost half of the patients had normal hearing, while the other half had sensorineural hearing loss after the use of deferasirox. It is inferred that the incidence of SNHL is not only dose-related but the duration of use of a chelating agent is also a contributing factor.

Reduced sound-evoked and resting-state BOLD fMRI connectivity in tinnitus.

The exact neurophysiological basis of chronic tinnitus, which affects 10-15% of the population, remains unknown and is controversial at many levels. It is an open question whether phantom sound perception results from increased central neural gain or not, a crucial question for any future therapeutic intervention strategies for tinnitus. We performed a comprehensive study of mild hearing-impaired participants with and without tinnitus, excluding participants with co-occurrences of hyperacusis. A right-hemisphere correlation between tinnitus loudness and auditory perceptual difficulty was observed in the tinnitus group, independent of differences in hearing thresholds. This correlation was linked to reduced and delayed sound-induced suprathreshold auditory brain responses (ABR wave V) in the tinnitus group, suggesting subsided rather than exaggerated central neural responsiveness. When anatomically predefined auditory regions of interest were analysed for altered sound-evoked BOLD fMRI activity, it became evident that subcortical and cortical auditory regions and regions involved in sound detection (posterior insula, hippocampus), responded with reduced BOLD activity in the tinnitus group, emphasizing reduced, rather than increased, central neural gain. Regarding previous findings of evoked BOLD activity being linked to positive connectivities at rest, we additionally analysed r-fcMRI responses in anatomically predefined auditory regions and regions associated with sound detection. A profound reduction in positive interhemispheric connections of homologous auditory brain regions and a decline in the positive connectivities between lower auditory brainstem regions and regions involved in sound detection (hippocampus, posterior insula) were observed in the tinnitus group. The finding went hand-in-hand with the emotional (amygdala, anterior insula) and temporofrontal/stress-regulating regions (prefrontal cortex, inferior frontal gyrus) that were no longer positively connected with auditory cortex regions in the tinnitus group but were instead positively connected to lower-level auditory brainstem regions. Delayed sound processing, reduced sound-evoked BOLD fMRI activity and altered r-fcMRI in the auditory midbrain correlated in the tinnitus group and showed right hemisphere dominance as did tinnitus loudness and perceptual difficulty. The findings suggest that reduced central neural gain in the auditory stream may lead to phantom perception through a failure to energize attentional/stress-regulating networks for contextualization of auditory-specific information. Reduced auditory-specific information flow in tinnitus has until now escaped detection in humans, as low-level auditory brain regions were previously omitted from neuroimaging studies. TRIAL REGISTRATION: German Clinical Trials Register DRKS0006332.