Adjunctive Role of Bifrontal Transcranial Direct Current Stimulation in Distressed Patients with Severe Tinnitus

Initial Response to Combination Therapies for Tinnitus: Lessons Learned From a Retrospective Analysis

OBJECTIVE

To investigate the initial reduction of tinnitus effects by combining common therapies applicable in general otology clinics and establishing optimal treatment strategies.

STUDY DESIGN

Retrospective cohort study.

SETTING

A tertiary university hospital.

PATIENTS

Patients with nonpulsatile subjective tinnitus who visited the hospital between January and December 2022.

INTERVENTIONS

Combination therapies consisting of at least one of the directive counseling based on the neurophysiological model, hearing aids, medication, and/or neuromodulation were performed.

MAIN OUTCOME MEASURES

Tinnitus Handicap Inventory (THI) questionnaire at both their initial visit and 1-month follow-up.

RESULTS

A total of 151 patients were enrolled. THI improvement of 20 points or more was observed in 31.8% of participants. One-way analysis of variance revealed that counseling had a significant reduction in THI, whereas neuromodulation, medication, and hearing aids did not. THI improvement was significantly associated with received counseling, severity of initial THI, and mean loudness discomfort level. Hearing aids and neuromodulation were not significant prognostic factors for improvement.

CONCLUSION

Counseling alone is the best treatment for most patients with tinnitus. There will be other patients with tinnitus that, in addition to counseling, would benefit from hearing aids, medications, and/or certain forms of neuromodulation.

The Tinnitus Handicap Inventory is a better indicator of the overall status of patients with tinnitus than the Numerical Rating Scale

OBJECTIVES

The Tinnitus Handicap Inventory (THI) and Numerical Rating Scale (NRS) for awareness, annoyance, loudness, and effect on life are two of the most commonly used questionnaires for patients with tinnitus. This study aimed to determine whether these two questionnaires can comprehensively evaluate the patient's condition and which questionnaire is better as a primary endpoint for tinnitus.

MATERIALS AND METHODS

Data from 90 patients who visited a university hospital with subjective, non-pulsatile tinnitus and without a history of any psychiatric disorders were reviewed between March 2020 and May 2022. The patients' medical histories, audiological profiles, questionnaires including the THI and NRS, Beck Depression Inventory (BDI), Beck Anxiety Depression (BAI), Hospital Anxiety-Depression Scale (HAD), and the Brief Encounter Psychosocial Instrument (BEPSI) were analyzed.

RESULTS

The THI had a moderately positive correlation with the NRS for effect on life, annoyance, and loudness. It also had a low positive correlation with the BDI, HAD-A, BEPSI, and BAI. Considering annoyance and loudness, the NRS did not correlate with the other questionnaires, except for the THI (p > 0.05). The NRS for tinnitus awareness correlated with most audiological profiles. The ROC curve analysis revealed that the THI significantly predicted depression, anxiety, and stress. Conversely, none of the four NRS items significantly predicted these psychiatric problems (p > 0.05).

CONCLUSIONS

Using the THI as a primary endpoint after interventions rather than the NRS is more reasonable because the THI covers the emotional, functional, and catastrophic aspects of tinnitus, although not the audiological status. To compensate for this, the auxiliary use of NRS for awareness should also be considered.

State of the art: non-invasive electrical stimulation for the treatment of chronic tinnitus

Subjective tinnitus is the perception of sound in the absence of external stimulation. Neuromodulation is a novel method with promising properties for application in tinnitus management. This study sought to review the types of non-invasive electrical stimulation in tinnitus to provide the foothold for further research. PubMed, EMBASE, and Cochrane databases were searched for studies on the modulation of tinnitus by non-invasive electrical stimulation. Among the four forms of non-invasive electrical modulation, transcranial direct current stimulation, transcranial random noise stimulation, and transauricular vagus nerve stimulation yielded promising results, whereas the effect of transcranial alternating current stimulation in the treatment of tinnitus has not been confirmed. Non-invasive electrical stimulation can effectively suppress tinnitus perception in some patients. However, the heterogeneity in parameter settings leads to scattered and poorly replicated findings. Further high-quality studies are needed to identify optimal parameters to develop more acceptable protocols for tinnitus modulation.

The Pathological Mechanisms and Treatments of Tinnitus

Tinnitus is defined as the ringing, hissing, clicking or roaring sounds an individual consciously perceives in the absence of an external auditory stimulus. Currently, the literature on the mechanism of tinnitus pathology is multifaceted, ranging from tinnitus generation at the cellular level to its perception at the system level. Cellular level mechanisms include increased neuronal synchrony, neurotransmission changes and maladaptive plasticity. At the system level, the role of auditory structures, non-auditory structures, changes in the functional connectivities in higher regions and tinnitus networks have been investigated. The exploration of all these mechanisms creates a holistic view on understanding the changes the pathophysiology of tinnitus undertakes. Although tinnitus percept may start at the level of cochlear nerve deafferentation, the neuronal changes in the central auditory system to the neuronal and connectivity changes in non-auditory regions, such as the limbic system, become cardinal in chronic tinnitus generation. At the present moment, some tinnitus generation mechanisms are well established (e.g., increased neuronal synchrony) whereas other mechanisms have gained more traction recently (e.g., tinnitus networks, tinnitus-distress networks) and therefore, require additional investigation to solidify their role in tinnitus pathology. The treatments and therapeutics designed for tinnitus are numerous, with varied levels of success. They are generally two-fold: some treatments focus on tinnitus cessation (including cochlear implants, deep brain stimulation, transcranial direct current stimulation and transcranial magnetic stimulation) whereas the other set focuses on tinnitus reduction or masking (including hearing aids, sound therapy, cognitive behavioral therapy, tinnitus retraining therapy, and tailor made notched musical training).  Tinnitus management has focused on implementing tinnitus masking/reducing therapies more than tinnitus cessation, since cessation treatments are still lacking in streamlined treatment protocols and long-term sustainability and efficacy of the treatment. This review will focus on concisely exploring the current and most relevant tinnitus pathophysiology mechanisms, treatments and therapeutics.

Transcranial direct current stimulation for auditory verbal hallucinations: a systematic review of clinical trials

Transcranial direct current stimulation (tDCS) has been reportedly beneficial for different neurodegenerative disorders. tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallucination (AVH). This study aims to review the effects of tDCS on AVH in patients with schizophrenia through combining the evidence from randomized clinical trials (RCTs). The databases of PsycINFO (2000-2019), PubMed (2000-2019), EMBASE (2000-2019), CINAHL (2000-2019), Web of Science (2000-2019), and Scopus (2000-2019) were systematically searched. The clinical trials with RCT design were selected for final analysis. A total of nine RCTs were eligible and included in the review. Nine RCTs were included in the final analysis. Among them, six RCTs reported a significant reduction of AVH after repeated sessions of tDCS, whereas three RCTs did not show any advantage of active tDCS over sham tDCS. The current studies showed an overall decrease of approximately 28% of AVH after active tDCS and 10% after sham tDCS. The tDCS protocols targeting the sensorimotor frontal-parietal network showed greater treatment effects compared with the protocols targeting other regions. In this regard, cathodal tDCS over the left temporoparietal area showed inhibitory effects on AVHs. The most effective tDCS protocol on AVHs was twice-daily sessions (2 mA, 20-minute duration) over 5 consecutive days (10 sessions) with the anode over the left dorsolateral prefrontal cortex and the cathode over the left temporal area. Some patient-specific and disease-specific factors such as young age, nonsmoking status, and higher frequencies of AVHs seemed to be the predictors of treatment response. Taken together, the results of tDCS as an alternative treatment option for AVH show controversy among current literatures, since not all studies were positive. However, the studies targeting the same site of the brain showed that the tDCS could be a promising treatment option to reduce AVH. Further RCTs, with larger sample sizes, should be conducted to reach a conclusion on the efficacy of tDCS for AVH and to develop an effective therapeutic protocol for clinical setting.

Somatic Modulation in Tinnitus: Clinical Characteristics and Treatment Outcomes

OBJECTIVES

We aimed to evaluate the clinical significance of the somatic modulation test in patients with tinnitus and analyze the treatment outcomes.

MATERIALS AND METHODS

Medical records of patients who visited the tinnitus clinic at a local university hospital between October 2018 and April 2019 were retrospectively reviewed.

RESULTS

The data of 81 patients were analyzed for this study, of which 61.7% (n=51) showed tinnitus modulation after one or more neck or jaw maneuvers. Patients with narrow-band noise tinnitus tended to show maneuver-induced modulation more frequently than those with pure-tone tinnitus (85.7% vs. 53.3%, p=0.010). Neck maneuvers reduced tinnitus loudness in 29.6% of the patients, while 27.2% of patients (n=22) reported worsening of tinnitus loudness, and 23.5% of patients (n=19) reported tinnitus suppression after jaw maneuvers. None of the patients with noise exposure history reported tinnitus modulation. Backward regression analysis revealed that age was an independent risk factor for improvement (Exp [B]=0.703, p=0.034, 95% CI=0.508-0.974). However, somatic modulation or medical treatments targeting somatic modulation were not related to improvement.

CONCLUSION

Patients showing modulation after neck or jaw maneuvers have specific clinical characteristics. However, somatic modulation itself does not affect the final treatment outcome.

Auditory Neural Plasticity in Tinnitus Mechanisms and Management

Tinnitus, which is the perception of sound in the absence of a corresponding external acoustic stimulus, including change of hearing and neural plasticity, has become an increasingly important ailment affecting the daily life of a considerable proportion of the population and causing significant burdens for both the affected individuals and society as a whole. Here, we briefly review the epidemiology and classification of tinnitus, and the currently available treatments are discussed in terms of the available evidence for their mechanisms and efficacy. The conclusion drawn from the available evidence is that there is no specific medication for tinnitus treatment at present, and tinnitus management might provide better solutions. Therapeutic interventions for tinnitus should be based on a comprehensive understanding of the etiology and features of individual cases of tinnitus, and more high quality and large-scale research studies are urgently needed to develop more efficacious medications.