Sequential dual-site High-Definition transcranial Direct Current Stimulation (HD-tDCS) treatment in chronic subjective tinnitus: study protocol of a double-blind, randomized, placebo-controlled trial.

BACKGROUND: Chronic tinnitus is a highly prevalent symptom, with many patients reporting considerable effects of tinnitus on quality of life. No clear evidence-based treatment options are currently available. While counseling-based methods are valuable in some cases, they are not sufficiently effective for all tinnitus patients. Neuromodulation techniques such as high-definition transcranial direct current stimulation (HD-tDCS) are proposed to have positive effects on tinnitus severity but, to date, these effects have not been proven conclusively. The proposed trial will investigate the hypothesis that chronic tinnitus patients receiving HD-tDCS will report a positive effect on the impact of tinnitus on daily life, as compared to patients receiving sham stimulation. METHODS: This study proposes a randomized, double-blind, placebo-controlled trial with parallel group design. A total of 100 chronic tinnitus patients will be randomly allocated to an experimental group or a sham group, with allocation stratified according to gender and tinnitus severity. Patient and researcher will be blinded to the patient's allocation. Patients will undergo six sessions of sequential dual-site HD-tDCS of the left temporal area and the right dorsolateral prefrontal cortex. Evaluations will take place at baseline, immediately following treatment, and at three and six months after the start of the therapy. The primary outcome measure is the change in Tinnitus Functional Index (TFI) score. Secondary outcome measures include audiological measurements, cortical auditory evoked potentials, the Repeatable Battery for the Assessment of Neuropsychological Status adjusted for hearing-impaired individuals (RBANS-H), and supplementary questionnaires probing tinnitus severity and additional symptoms. By use of a linear regression model, the effects of HD-tDCS compared to sham stimulation will be assessed. DISCUSSION: The objective of this study is to evaluate whether HD-tDCS can reduce the impact of tinnitus on daily life in chronic tinnitus patients. To date, published trials on the effects of HD-tDCS on tinnitus suffer from a lack of standardization and few randomized controlled trials exist. The proposed study will be the first adequately powered trial to investigate the effects of sequential dual-site HD-tDCS on tinnitus severity. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03754127 . Registered on 22 November 2018.

Otosclerosis: Shift in bone conduction after stapedotomy.

OBJECTIVES: To analyze changes in bone conduction (BC) thresholds before and after stapedotomy in patients with clinical otosclerosis with a focus on the Carhart notch, which is defined as a significant loss of BC at a certain audiometric frequency. METHODOLOGY: Retrospective case review of pure tone audiometry (PTA) in 213 patients who underwent a stapedotomy at a tertiary referral center between 2004 and 2011. The patients were grouped by age and the frequency of the Carhart notch. The non-operated ear was also evaluated. RESULTS: The Carhart notch was present on pre-operative audiometry in 158 (74%) patients at 0.5 (n = 18, 8.45%), 1 (n = 25, 11.70%), or 2 kHz (n = 115, 54.0%). We measured a mean postoperative improvement in BC of 7.5, 8.4, and 8.8 dB HL. Pre-operatively, 55 (25.8%) patients did not exhibit a typical notch configuration. The mean gain in BC, defined on PTA according to the AAO-HNS criteria (0.5, 1, 2 and 3, or 4 kHz), was 1.8 dB HL after stapedotomy. CONCLUSION: The Carhart notch was not solely related to the 2 kHz frequency. The greatest gain in BC after stapedotomy for otosclerosis occurred at the notch frequency.