Administration of the combination clonazepam-Deanxit as treatment for tinnitus. Otol Neurotol. 2011;32:701-709. [PMID: 21358561 DOI: 10.1097/MAO.0b013e31820e737c]

The potassium channels: Neurobiology and pharmacology of tinnitus

Tinnitus is a widespread public health issue that imposes a significant social burden. The occurrence and maintenance of tinnitus have been shown to be associated with abnormal neuronal activity in the auditory pathway. Based on this view, neurobiological and pharmacological developments in tinnitus focus on ion channels and synaptic neurotransmitter receptors in neurons in the auditory pathway. With major breakthroughs in the pathophysiology and research methodology of tinnitus in recent years, the role of the largest family of ion channels, potassium ion channels, in modulating the excitability of neurons involved in tinnitus has been increasingly demonstrated. More and more potassium channels involved in the neural mechanism of tinnitus have been discovered, and corresponding drugs have been developed. In this article, we review animal (mouse, rat, hamster, and guinea-pig), human, and genetic studies on the different potassium channels involved in tinnitus, analyze the limitations of current clinical research on potassium channels, and propose future prospects. The aim of this review is to promote the understanding of the role of potassium ion channels in tinnitus and to advance the development of drugs targeting potassium ion channels for tinnitus.

Consensus on the pharmacological treatment of acute stress disorder in Chinese pilots: a Delphi study

BACKGROUND

Appropriate medication is very important for pilots with acute stress disorder. Improper medication can not only affect the physical and mental health of the pilots but can also endanger flight safety. Hence, we aimed to quickly and effectively relieve symptoms and restore cognitive function by forming a consensus of Chinese experts on the pharmacological treatment of acute stress disorder in pilots using the Delphi method.

METHODS

Relevant literature was searched to enumerate the current status of pharmacological treatment of acute stress disorder in pilots, followed by two rounds of expert consultation and discussion according to the listed status of the survey using the Delphi method. A descriptive statistical method was used to analyze the basic information, authority coefficients, concentration of opinions, and survey items of the experts to develop a consensus on the pharmacological treatment of acute stress disorder in pilots.

RESULTS

A total of 16 experts in psychiatry, pharmacology, and aerospace medicine from different provinces and cities across China were invited for consultation. The recovery rate of the two rounds of consultation was 100%, and the expert authority coefficients were 0.897 and 0.906, respectively. Kendall's coefficient of concordance of indicators at all levels was 0.564-0.594 (p < 0.01). Based on the number of votes received, alprazolam tablets (16), eszopiclone tablets (15), and lorazepam tablets (14) were recommended for the treatment of excitatory psychomotor symptoms of acute stress disorder; paroxetine tablets (15) and sertraline tablets (15) were available for psychomotor depressive symptoms; olanzapine tablets (15), olanzapine orally disintegrating tablets (14), and quetiapine fumarate tablets (14) were selected for psychotic symptoms.

CONCLUSIONS

This study formed a consensus on rapid and effective pharmacological treatment for different symptoms of acute stress disorder pilots, which provides a reference for clinical treatment.

Investigating the efficacy of fluoxetine vs. fluoxetine plus alprazolam (single therapy vs. combination therapy) in treatment of chronic tinnitus: A placebo-controlled study

OBJECTIVE

To investigate the effect of combination therapy (fluoxetine + alprazolam) and fluoxetine alone in treatment of tinnitus.

MATERIAL AND METHODS

147 participants with chronic tinnitus were divided into three groups (fluoxetine, fluoxetine+ alprazolam, and placebo). Tinnitus Handicap Inventory (THI), Visual Analogue Scale (VAS), Tinnitus Severity Index (TSI), Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) used to assess tinnitus. Effect size according to partial Eta square calculated and level of significance was considered as P < 0.05.

RESULTS

Fluoxetine reduced VAS, THI, BDI, and increased BAI. The combination therapy significantly reduced VAS, THI, BAI, and BDI. None of them reduced the TSI. The effect size for BAI and BDI were 0.135 (medium) and 0.075 (small), respectively. There was no significant difference between combination and single-drug therapy.

CONCLUSION

Both groups improved THI and VAS. Combination therapy was not significantly different from single-drug treatment. Combination therapy can be considered only according to the psychiatric needs of patients.

The BDNF Val66Met polymorphism regulates vulnerability to chronic stress and phantom perception

Auditory phantom percepts, such as tinnitus, are a heterogeneous condition with great interindividual variations regarding both the percept itself and its concomitants. Tinnitus causes a considerable amount of distress, with as many as 25% of affected people reporting that it interferes with their daily lives. Although previous research gives an idea about the neural correlates of tinnitus-related distress, it cannot explain why some tinnitus patients develop distress and while others are not bothered by their tinnitus. BDNF Val⁶⁶Met polymorphism (rs6265) is a known risk factor for affective disorders due to its common frequency and established functionality. To elucidate, we explore the neural activation pattern of tinnitus associated with the BDNF Val⁶⁶Met polymorphism using electrophysiological data to assess activity and connectivity changes. A total of 110 participants (55 tinnitus and 55 matched control subjects) were included. In this study, we validate that the BDNF Val⁶⁶Met polymorphism plays an important role in the susceptibility to the clinical manifestation of tinnitus-related distress. We demonstrate that Val/Met carriers have increased alpha power in the subgenual anterior cingulate cortex that correlates with distress levels. Furthermore, distress mediates the relationship between BDNF Val⁶⁶Met polymorphism and tinnitus loudness. In other words, for Val/Met carriers, the subgenual anterior cingulate cortex sends distress-related information to the parahippocampus, which likely integrates the loudness and distress of the tinnitus percept.

Paradoxical relationship between distress and functional network topology in phantom sound perception

Distress is a domain-general symptom that accompanies several disorders, including tinnitus. Based on previous studies, we know that distress is encoded by changes in functional connectivity between cortical and subcortical regions. However, how distress relates to large-scale brain networks is not yet clear. In the current study, we investigate the relationship between distress and the efficiency of a network by examining its topological properties using resting state fMRI collected from 90 chronic tinnitus patients. The present results indicate that distress negatively correlates with path length and positively correlates with clustering coefficient, small-worldness, and efficiency of information transfer. Specifically, path analysis showed that the relationship between distress and efficiency is significantly mediated by the resilience of the feeder connections and the centrality of the rich-club connections. In other words, the higher the network efficiency, the lower the resilience of the feeder connections and the centrality of the rich-club connections, which in turn reflects in higher distress in tinnitus patients. This indicates a reorganization of the network towards a paradoxically more efficient topology in patients with high distress, potentially explaining their increased rumination on the tinnitus percept itself.

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.

Bioequivalence Study Of A Fixed-Dose Combination Tablet Containing Melitracen 10 mg And Flupentixol 0.5 mg In Healthy Chinese Volunteers Under Fasted And Fed Conditions

Purpose

A fixed-dose combination (FDC) tablet of melitracen/flupentixol has been widely used for depression. The purpose of this study was to assess the safety profile and the relative bioavailability of two FDC products containing 10 mg melitracen and 0.5 mg flupentixol from two different manufacturers, in order to acquire adequate pharmacokinetic evidence for registration approval of the test formulation.

Methods

The study was designed as a single-dose, randomized, open-label, 2-period crossover study under fasted or fed conditions in healthy Chinese subjects. Twenty-four subjects (16 men and 8 women) were selected for fasted study, and another 24 cases (16 men and 8 women) were in fed study. Each subject was randomized at the beginning to receive either a single dose of the reference FDC or the test FDC tablet during the first period. Following two-week washout period, all subjects received the alternate formulation during the second period. Blood samples were collected up to 144 hrs after administration. Pharmacokinetic parameters, including C_max, T_max, AUC_0-t, AUC_0-∞, t½, CL/F, and V_d/F were acquired based on the time versus concentration profiles. Then, the geometric mean ratios (GMR) and corresponding 90% CIs were calculated for the determination of bioequivalence analysis. Safety assessment included changes in vital signs and laboratory tests, physical examination findings, and incidence or reports of adverse events (AEs).

Results

The present study has clearly indicated the test and the reference FDC products are bioequivalent in terms of rate and extent of drug absorption. GMR of C_max, AUC_0-t, and AUC_0-∞ for both flupentixol and melitracen between the two formulation FDC products, and corresponding 90% CIs, were all within the range of 80% to 125% under fasted or fed conditions. Both the test and the reference FDC products indicated good tolerance in all volunteers. Chinese Clinical Trials Registry identifier: CTR20171256.

Patients' feedback on the Changi General Hospital tinnitus counselling protocol

INTRODUCTION

Many tinnitus service providers advocate counselling as an initial and important approach for the management of tinnitus. Our tinnitus counselling clinic (TCC) developed a counselling protocol to deliver information and educate patients on self-help strategies. We aimed to obtain feedback on the components of the initial session and the self-help choices made by patients who returned for follow-up.

METHODS

All patients who were attending the TCC completed a Tinnitus Handicap Inventory (THI) questionnaire during their first and follow-up sessions. At follow-up, patients were asked to rate how helpful each counselling component was and their choice of self-help strategy for tinnitus.

RESULTS

203 patients attended the follow-up session, representing 60.1% of patients initially counselled. THI scores improved, with 45.8% more patients categorised as having no handicap at follow-up compared to the initial 26.1%. Two most helpful counselling components (rated on a 5-point scale) were explanation of self-help strategies (mean score 4.40 ± 0.68) and illustration of healthy and damaged hair cells (mean score 4.30 ± 0.74). The most popular choice for self-help was using a sound strategy plus change in thinking (41.9%, n = 85). A few (32.5%, n = 66) patients were able to change their perception of tinnitus without any sound enrichment, while 17 (8.4%) patients relied solely on sound strategy. Most (97.5%) patients found the initial counselling session helpful. However, 92 (45.3%) patients were still seeking a cure for their tinnitus.

CONCLUSION

Most patients found the counselling helpful at follow-up. Counselling offered them the opportunity to actively manage their tinnitus.

Top-down and Bottom-up Regulated Auditory Phantom Perception

Auditory phantom percepts such as tinnitus are associated with auditory deafferentation. The idea is that auditory deafferentation limits the amount of information the brain can acquire to make sense of the world. Because of this, auditory deafferentation increases the uncertainty of the auditory environment. To minimize uncertainty, the deafferented brain will attempt to obtain or fill in the missing information. A proposed multiphase compensation model suggests two distinct types of bottom-up related tinnitus: an auditory cortex related tinnitus and a parahippocampal cortex related tinnitus. The weakness of this model is that it cannot explain why some people without hearing loss develop tinnitus, whereas conversely others with hearing loss do not develop tinnitus. In this human study, we provide evidence for a top-down type of tinnitus associated with a deficient noise-cancelling mechanism. A total of 72 participants (age: 40.96 ± 7.67 years; males: 48; females: 24) were recruited for this study. We demonstrate that top-down related tinnitus is related to a change in the pregenual anterior cingulate cortex that corresponds to increased activity in the auditory cortex. This is in accordance with the idea that tinnitus can have different generators as proposed in a recent model that suggests that different compensation mechanisms at a cortical level can be linked to phantom percepts.SIGNIFICANCE STATEMENT Chronic tinnitus affects 15% of the population worldwide. The term "tinnitus" however represents a highly heterogeneous condition, as evidenced by the fact that there are no effective treatments or even an adequate understanding of the underlying neural mechanisms. Consistent with this idea, our research shows that tinnitus indeed has different subtypes related to hearing loss. In a human study tightly controlled for hearing loss, we establish a tinnitus subtype associated with a deficient top-down noise-cancelling mechanism, which distinguishes it from bottom-up subtypes. We demonstrate that top-down related tinnitus relates to a change in the pregenual anterior cingulate cortex that corresponds to increased activity in the auditory cortex, whereas bottom-up tinnitus instead relates to changes in the parahippocampal cortex.

Therapeutic Approaches to the Treatment of Tinnitus

Tinnitus is a highly prevalent condition that is associated with hearing loss in most cases. In the absence of external stimuli, phantom perceptions of sounds emerge from alterations in neuronal activity within central auditory and nonauditory structures. Pioneering studies using lidocaine revealed that tinnitus is susceptible to pharmacological interventions. However, lidocaine is not effective in all patients, and no other drug has been identified with clear efficacy for the long-term treatment of tinnitus. In this review, we present recent advances in tinnitus research, including more detailed knowledge of its pathophysiology and involved neurotransmitter systems. Moreover, we summarize results from animal and clinical treatment studies as well as from studies that identified tinnitus as a side effect of pharmacological treatments. Finally, we focus on challenges in the development of pharmacological compounds for the treatment of tinnitus, namely the limitations of available animal models and of standardized clinical research methodologies.

Effect of distress on transient network dynamics and topological equilibrium in phantom sound perception

Distress is a domain-general behavioral symptom whose neural correlates have been under investigation for a long time now. Although some studies suggest that distress is encoded by changes in alpha activity and functional connectivity between specific brain regions, no study that we know has delved into the whole brain temporal dynamics of the distress component. In the current study, we compare the changes in the mean and variance of functional connectivity and small-worldness parameter over 3 min of resting state EEG to analyze the fluctuation in transient stable states, and network structure. On comparing these measures between healthy controls and patients experiencing low and high levels of distress due to a continuous ringing in the ear (tinnitus), we observe an increase in fluctuation between transient stable states characterized by an increase in both variance of functional connectivity and the small-worldness parameter. This results in a possible increase in degrees of freedom leading to a paradoxical equilibrium of the network structure in highly distressed patients. This may also be interpreted as a maladaptive compensation to look for information in order to reduce the hyper-salience in highly distressed individuals. In addition, this is correlated with the amount of distress only in the high distress tinnitus group, suggesting a catastrophic breakdown of the brain's resilience. Distress not only accompanies tinnitus, but other disorders such as somatic disorders, fibromyalgia, post-traumatic stress disorder, etc. Since the current study focuses on a disorder-general distress symptom, the methods and results of the current study have a wide application in different neuropathologies.

The role of the dorsal Anterior Cingulate Cortex (dACC) in a cognitive and emotional counting Stroop task: Two cases

BACKGROUND

The anterior cingulate cortex (ACC) has been implicated in both cognitive and emotional processing, with cognitive information proposed to be processed through the dorsal/caudal ACC and emotional information through the rostral/ventral ACC.

OBJECTIVE

The objective of this study is to investigate the role of the dorsal anterior cingulate cortex (dACC) in cognitive and emotional processing using a cognitive and emotional counting Stroop task in two patients in whom abnormalities in the dACC were identified and treated.

METHODS

Two patients performed the cognitive and emotional counting Stroop task before and after treatment to examine whether the dACC has a specific or more general processing function.

RESULTS

We observed an overall improvement in the emotional, cognitive, and neutral trials of the counting Stroop task after the intervention, indicating that the dACC is not a subregion of the ACC that only contributes to a specific domain.

CONCLUSION

This study reveals that the dACC is not just a subregion of the ACC that contributes to a specific cognitive function, but is rather part of a salience network that influences general brain functioning, influencing cognitive as well as emotional processing.

Evidence for Behaviorally Segregated, Spatiotemporally Overlapping Subnetworks in Phantom Sound Perception

One of the most intriguing questions in neuroscience is to understand the mechanism of information transfer between different brain areas. Recently, network theory has gained traction and is at the forefront of providing a possible explanation to not only the mechanism of information transfer but also in the identification of different neuropathologies. The perception of a phantom ringing in the ear called tinnitus, similar to other neuropathologies, has been shown to be accompanied by aberrant functional connectivity between different brain areas. Although, there have been independent studies showing that specific groups of areas encode individual symptoms of tinnitus, there has not been one study to show that tinnitus is the unified percept of distinguishable subnetworks encoding different behavioral aspects. This study combines resting-state functional connectivity obtained from the source-localized electroencephalography of 311 tinnitus patients and 264 controls, and a k-fold cross-validation machine learning algorithm to develop a predictive model that verifies the presence of behaviorally specific, spatiotemporally overlapping subnetworks in tinnitus. This reorganization is found to be exclusive to tinnitus, even when compared to physiologically similar disorders such as chronic pain, with each behavioral symptom having a unique oscillatory signature. This frequency-specific transmission of information, called multiplexing, enables different types of information to be carried between two brain regions through the same anatomical connection. In addition to understanding the efficient compensation mechanism of the brain in the presence of multisymptom disorders, the exclusivity of the prediction model presents an encouraging possibility for an objective neural marker for tinnitus.

Evidence and evidence gaps in tinnitus therapy

A nearly endless number of procedures has been tried and in particular sold for the treatment of tinnitus, unfortunately they have not been evaluated appropriately in an evidence-based way. A causal therapy, omitting the tinnitus still does not exist, actually it cannot exist because of the various mechanisms of its origin. However or perhaps because of that, medical interventions appear and reappear like fashion trends that can never be proven by stable and reliable treatment success. This contribution will discuss and acknowledge all current therapeutic procedures and the existing or non-existing evidence will be assessed. Beside external evidence, the term of evidence also encompasses the internal evidence, i.e. the experience of the treating physician and the patient's needs shall be included. While there is no evidence for nearly all direct procedures that intend modulating or stimulating either the cochlea or specific cervical regions such as the auditory cortex, there are therapeutic procedures that are acknowledged in clinical practice and have achieved at least a certain degree of evidence and generate measurable effect sizes. Those are in particular habituation therapy and psychotherapeutic measures, especially if they are combined with concrete measures for improved audio perception (hearing aids, CI, hearing therapies).

Psychological mediators of chronic tinnitus: The critical role of depression

BACKGROUND

Maintenance of chronic tinnitus has been proposed to result from a vicious cycle of hypervigilance occurring when a phantom sound is associated with anxiety and limbic system overactivity. Depression, obsessive-compulsiveness, illness attitudes and coping strategies are known to impact tinnitus, but their relationship with the vicious cycle is unknown. As such, we aimed to identify psychological mediators of the vicious cycle. We also examined the relationship between coping strategies and any identified mediators to facilitate the translation of our research to treatment settings.

METHODS

We comprehensively assessed a heterogeneous community sample of 81 people with chronic tinnitus who completed measures assessing their tinnitus and psychological wellbeing. Specifically, we examined the mediating role of depressive symptoms, illness attitudes, and obsessive-compulsiveness in the vicious cycle.

RESULTS

While the predicted relationship between tinnitus handicap and anxiety was observed, this was fully mediated by depressive symptoms. In addition, we identified avoidant behaviours and self-blame as maladaptive coping strategies in people with chronic tinnitus and depressive symptoms, identifying potential new treatment targets.

LIMITATIONS

This work requires replication in a clinical cohort of people with chronic tinnitus, and further investigations of the role of coping strategies.

CONCLUSIONS

These results extend our understanding of the complex role of psychology in the experience of tinnitus, highlighting the importance of depressive symptoms that may be underpinned by functional disruption of specific neurocognitive networks. We have also identified depressive symptoms and maladaptive coping strategies as new treatment targets to improve the health wellbeing of people with chronic tinnitus.

The Management and Outcomes of Pharmacological Treatments for Tinnitus

Tinnitus, a phantom sensation experienced by people around the world, currently is endured without a known cure. Some find the condition tolerable, while others are tortured on a daily basis from the incessant phantom noises. For those who seek treatment, oftentimes, they have a comorbid condition (e.g., depression, anxiety, insomnia), which is treated pharmaceutically. These products aim to reduce the comorbities associated with tinnitus thereby minimizing the overall burden present. Because of the phantom nature of tinnitus, it is often compared to neurologic pain. Since pain can be managed with pharmaceutical options, it is reasonable to assume that similar agents might work to alleviate tinnitus. The effects of antidepressants, benzodiazepines, anticonvulsants, and glutamate antagonists are reviewed in this paper. Table 1 summarizes the pharmaceutical products discussed. Due to the variety of comorbid factors and potential causes of tinnitus, there may not be one pharmaceutical treatment that will combat every type of tinnitus. Nevertheless, a product that finally addresses the true cause of tinnitus, and not just its comorbidities, will benefit millions of people worldwide.

Clinical effects of flupentixol melitracen for menopausal atrial fibrillation with irritable bowel syndrome

AIM: To evaluate the clinical effects of flupentixol melitracen for menopausal atrial fibrillation with irritable bowel syndrome.

METHODS: One hundred and fourteen patients with menopausal atrial fibrillation and irritable bowel syndrome treated from January 2011 to March 2015 at the First Affiliated Hospital of Guangxi University of Traditional Chinese Medicine were selected. All patients received symptomatic treatment. The control group was additionally given flupentixol, while the observation group was given flupentixol melitracen. Anxiety (HAMD) and depression (HAMA) scores, occurrence of atrial fibrillation, digestive tract symptoms, substance P (SP) and neuropeptide Y (NPY) were compared before and after treatment between the two groups. Adverse reactions occurring during treatment were also compared.

RESULTS: After treatment, HAMD and HAMA scores in the observation group were significantly lower than those in the control group (P < 0.05). Atrial fibrillation episodes and defecation frequency in the observation group were lower than those of the control group (P < 0.05). Duration time of abdominal pain in the observation group was shorter than that of the control group (P < 0.05). SP in the observation group was lower than that of the control group (P < 0.05). NPY in the observation group was higher than that of the control group (P < 0.05). Incidence rates of mouth dryness, tachycardia, extrapyramidal reactions, and insomnia in the observation group were significantly lower than those of the control group (P < 0.05).

CONCLUSION: Flupentixol melitracen for menopausal atrial fibrillation with irritable bowel syndrome can significantly reduce anxiety and depression, improve cardiac arrhythmias and gastrointestinal symptoms, and reduce adverse reactions.

Robustness and dynamicity of functional networks in phantom sound

Phantom sound perception is the perception of a sound in the absence of a corresponding external sound source. It is a common symptom for which no treatment exists. Gaining a better understanding of its pathophysiology by applying network science might help in identifying targets in the brain for neuromodulatory approaches to treat this elusive symptom. Brain networks are commonly organized as functional modules which have a densely connected core network coupled to a communally-organized peripheral network. The core network is called the rich club network and the peripheral network is divided into the feeder and local networks. In current study, we investigate the effects of virtual lesions on the endogenous dynamics, complexity and robustness of the remaining brain. It is hypothesized that depending on whether nodes is functionally central to the network or not, the robustness and dynamics of the network change when a lesion in introduced. We therefore investigate the effect of introducing a virtual focal lesion randomly to different nodes is in the tinnitus network and contrast it to the effect of specifically targeting the nodes of the rich-club, feeder and local nodes in patients experiencing a phantom sound (i.e. tinnitus). The tinnitus and control networks were computed from the source-localized EEG of 311 tinnitus patients and 256 control subjects. The results of the current study indicate that both the tinnitus and control networks are robust to the attack on random and rich club nodes, but are drastically modified when attacked from the periphery, especially while targeting the feeder hubs. In both the tinnitus and control networks, feeder nodes were found to have a higher betweenness centrality value than the rich club nodes. This shows that the feeders have a larger influence on the information transmission through the brain than the rich club nodes, by transferring information from the peripheral communities to the core. Further, evidence for the theoretical model of a multimodal tinnitus network is also presented showing that the tinnitus network is divided into individual, separable modules each possibly encoding a different aspect of tinnitus. The current study alludes to the concept that the efficient modification of the tinnitus network is theoretically possible by disconnecting the individual communities from the core of the pathological network.

Anterior cingulate implants for tinnitus: report of 2 cases

Tinnitus can be distressful, and tinnitus distress has been linked to increased beta oscillatory activity in the dorsal anterior cingulate cortex (dACC). The amount of distress is linked to alpha activity in the medial temporal lobe (amygdala and parahippocampal area), as well as the subgenual (sg)ACC and insula, and the functional connectivity between the parahippocampal area and the sgACC at 10 and 11.5 Hz.

The authors describe 2 patients with very severely distressing intractable tinnitus who underwent transcranial magnetic stimulation (TMS) with a double-cone coil targeting the dACC and subsequent implantation of electrodes on the dACC. One of the patients responded to the implant and one did not, even though phenomenologically they both expressed the same tinnitus loudness and distress.

The responder has remained dramatically improved for more than 2 years with 6-Hz burst stimulation of the dACC. The 2 patients differed in functional connectivity between the area of the implant and a tinnitus network consisting of the parahippocampal area as well as the sgACC and insula; that is, the responder had increased functional connectivity between these areas, whereas the nonresponder had decreased functional connectivity between these areas. Only the patient with increased functional connectivity linked to the target area of repetitive TMS or implantation might transmit the stimulation current to the entire tinnitus network and thus clinically improve.

Sensorineural Tinnitus: Its Pathology and Probable Therapies

Tinnitus is not a single disease but a group of different diseases with different pathologies and therefore different treatments. Regarding tinnitus as a single disease is hampering progress in understanding of the pathophysiology of tinnitus and perhaps, more importantly, it is a serious obstacle in development of effective treatments for tinnitus. Subjective tinnitus is a phantom sound that takes many different forms and has similarities with chronic neuropathic pain. The pathology may be in the cochlea, in the auditory nerve, or, most commonly, in the brain. Like chronic neuropathic pain tinnitus is not life threatening but influences many normal functions such as sleep and the ability to concentrate on work. Some forms of chronic tinnitus have two components, a (phantom) sound and a component that may best be described as suffering or distress. The pathology of these two components may be different and the treatment that is most effective may be different for these two components. The most common form of treatment of tinnitus is pharmacological agents and behavioral treatment combined with sound therapy. Less common treatments are hypnosis and acupuncture. Various forms of neuromodulation are becoming in use in an attempt to reverse maladaptive plastic changes in the brain.

Emerging hubs in phantom perception connectomics

Brain networks are small-world networks typically characterized by the presence of hubs, i.e. nodes that have significantly greater number of links in comparison to other nodes in the network. These hubs act as short cuts in the network and promote long-distance connectivity. Long-distance connections increase the efficiency of information transfer but also increase the cost of the network. Brain disorders are associated with an altered brain connectome which reflects either as a complete change in the network topology, as in, the replacement of hubs or as an alteration in the connectivity between the hubs while retaining network structure. The current study compares the network topology of binary and weighted networks in tinnitus patients and healthy controls by studying the hubs of the two networks in different oscillatory bands. The EEG of 311 tinnitus patients and 256 control subjects are recorded, pre-processed and source-localized using sLORETA. The hubs of the different binary and weighted networks are identified using different measures of network centrality. The results suggest that the tinnitus and control networks are distinct in all the frequency bands but substantially overlap in the gamma frequency band. The differences in network topology in the tinnitus and control groups in the delta, theta and the higher beta bands are driven by a change in hubs as well as network connectivity; in the alpha band by changes in hubs alone and in the gamma band by changes in network connectivity. Thus the brain seems to employ different frequency band-dependent adaptive mechanisms trying to compensate for auditory deafferentation.

Graph theoretical analysis of brain connectivity in phantom sound perception

Tinnitus is a phantom sound commonly thought of to be produced by the brain related to auditory deafferentation. The current study applies concepts from graph theory to investigate the differences in lagged phase functional connectivity using the average resting state EEG of 311 tinnitus patients and 256 healthy controls. The primary finding of the study was a significant increase in connectivity in beta and gamma oscillations and a significant reduction in connectivity in the lower frequencies for the tinnitus group. There also seems to be parallel processing of long-distance information between delta, theta, alpha1 and gamma frequency bands that is significantly stronger in the tinnitus group. While the network reorganizes into a more regular topology in the low frequency carrier oscillations, development of a more random topology is witnessed in the high frequency oscillations. In summary, tinnitus can be regarded as a maladaptive ‘disconnection’ syndrome, which tries to both stabilize into a regular topology and broadcast the presence of a deafferentation-based bottom-up prediction error as a result of a top-down prediction.

Deafferentation-based pathophysiological differences in phantom sound: Tinnitus with and without hearing loss

Tinnitus has been considered an auditory phantom percept. Recently a theoretical multiphase compensation mechanism at a cortical level has been hypothesized linking auditory deafferentation to tinnitus. This Bayesian brain model predicts that two very different kinds of tinnitus should exist, depending on the amount of hearing loss: an auditory cortex related form of tinnitus not associated with hearing loss, and a (para)hippocampal form associated with hearing loss, in which the auditory cortex might be of little relevance. In order to verify this model, resting state source analyzed EEG recordings were made in 129 tinnitus patients, and correlated to the mean hearing loss, the range of the hearing loss and the hearing loss at the tinnitus frequency. Results demonstrate that tinnitus can be linked to 2 very different mechanisms. In patients with little or no hearing loss, the tinnitus seems to be more related to auditory cortex activity, but not to (para)hippocampal memory related activity, whereas in tinnitus patients with more severe hearing loss, tinnitus seems to be related to (para)hippocampal mechanisms. Furthermore hearing loss seems to drive the communication between the auditory cortex and the parahippocampus, as measured by functional and effective connectivity.

A Systematic Review of Eligibility and Outcomes in Tinnitus Trials

Objective

To analyze existing tinnitus treatment trials with regard to eligibility criteria, outcome measures, study quality, and external validity and to recognize the effect of patient demographics, symptom duration, severity, and otologic comorbidity on research findings to help practitioners apply them to patient encounters.

Data Sources

Systematic literature search conducted by an information specialist for development of the American Academy of Otolaryngology—Head and Neck Surgery Foundation’s tinnitus clinical practice guideline.

Review Methods

Articles were assessed for eligibility with the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-analyses) and data extracted by 2 independent investigators. Studies were assessed for methodological quality, inclusion and exclusion criteria, patient demographics, and outcome measures.

Results

A total of 147 randomized trials met inclusion criteria. Nearly all studies took place in a specialist setting. More than 50% did not explicitly define tinnitus, and 44% used a subjective severity threshold, such as “severely disturbing.” Fifty-four percent required symptom duration of at least 6 months for study eligibility, and up to 33% excluded patients with “organic” hearing loss or otologic conditions. Mean age was 52.2 years, and median follow-up was 3 months. Only 20% had a low risk of bias.

Conclusion

Randomized trials of tinnitus interventions are most applicable to older adults with tinnitus lasting ≥6 months who are evaluated in specialty settings. High risk of bias, short follow-up, and outcome reporting raise concerns about the validity of findings and may influence how clinicians apply trial results to individual patients and establish treatment expectations, thus demonstrating the need for further quality research in this field.

Tinnitus: a large VBM-EEG correlational study

A surprising fact in voxel-based morphometry (VBM) studies performed in tinnitus is that not one single region is replicated in studies of different centers. The question then rises whether this is related to the low sample size of these studies, the selection of non-representative patient subgroups, or the absence of stratification according to clinical characteristics. Another possibility is that VBM is not a good tool to study functional pathologies such as tinnitus, in contrast to pathologies like Alzheimer's disease where it is known the pathology is related to cell loss. In a large sample of 154 tinnitus patients VBM and QEEG (Quantitative Electroencephalography) was performed and evaluated by a regression analysis. Correlation analyses are performed between VBM and QEEG data. Uncorrected data demonstrated structural differences in grey matter in hippocampal and cerebellar areas related to tinnitus related distress and tinnitus duration. After control for multiple comparisons, only cerebellar VBM changes remain significantly altered. Electrophysiological differences are related to distress, tinnitus intensity, and tinnitus duration in the subgenual anterior cingulate cortex, dorsal anterior cingulate cortex, hippocampus, and parahippocampus, which confirms previous results. The absence of QEEG-VBM correlations suggest functional changes are not reflected by co-occurring structural changes in tinnitus, and the absence of VBM changes (except for the cerebellum) that survive correct statistical analysis in a large study population suggests that VBM might not be very sensitive for studying tinnitus.

Targeting the parahippocampal area by auditory cortex stimulation in tinnitus

BACKGROUND

The final common pathway in tinnitus generation is considered to be synchronized auditory oscillatory hyperactivity. Intracranial auditory cortex stimulation (iACS) via implanted electrodes has been developed to treat severe cases of intractable tinnitus targeting this final common pathway, in the hope of being a panacea for tinnitus. However, not everybody responds to this treatment.

OBJECTIVE

The electrical brain activity and functional connectivity at rest might determine who is going to respond or not to iACS and might shed light on the pathophysiology of auditory phantom sound generation.

METHOD

The resting state electrical brain activity of 5 patients who responded and 5 patients who did not respond to auditory cortex implantation are compared using source localized spectral activity (Z-score of log transformed current density) and lagged phase synchronization.

RESULTS

sLORETA source localization reveals significant differences between responders vs non-responders for beta3 in left posterior parahippocampal, hippocampal and amygdala area extending into left insula. Gamma band differences exist in the posterior parahippocampal areas and BA10. Functional connectivity between the auditory cortex and the hippocampal area is increased for beta2, delta and theta2 in responders, as well as between the parahippocampal area and auditory cortex for beta3.

CONCLUSION

The resting state functional connectivity and activity between the auditory cortex and parahippocampus might determine whether a tinnitus patient will respond to a cortical implant. The auditory cortex may only be a functional entrance into a larger parahippocampal based tinnitus network.

Tinnitus and musical hallucinosis: the same but more

While tinnitus can be interpreted as a simple or elementary form of auditory phantom perception, musical hallucinosis is a more complex auditory phantom phenomenon not only limited to sound perception, but also containing semantic and musical content. It most often occurs in association with hearing loss. To elucidate the relation between simple and complex auditory phantom percepts a source localized electroencephalography (EEG) study is performed. The analyses showed in both simple and complex auditory phantoms an increase in theta-gamma activity and coupling within the auditory cortex that could be associated with the thalamocortical dysrhythmia model. Furthermore increased beta activity within the dorsal anterior cingulate cortex and anterior insula is demonstrated, that might be related to auditory awareness, salience and its attribution to an external sound source. The difference between simple and complex auditory phantoms relies on differential alpha band activity within the auditory cortex and on beta activity in the dorsal anterior cingulate cortex and (para)hippocampal area. This could be related to memory based load dependency, while suppression within the primary visual cortex might be due the presence of a continuous auditory cortex activation inducing an inhibitory signal to the visual system. Complex auditory phantoms further activate the right inferior frontal area (right sided Broca homolog) and right superior temporal pole that might be associated with the musical content. In summary, this study showed for the first time that simple and complex auditory phantoms might share a common neural substrate but differ as complex auditory phantoms are associated with activation in brain areas related to music and language processing.

Pinpointing a highly specific pathological functional connection that turns phantom sound into distress

It has been suggested that an auditory phantom percept is the result of multiple, parallel but overlapping networks. One of those networks encodes tinnitus loudness and is electrophysiologically separable from a nonspecific distress network. The present study investigates how these networks anatomically overlap, what networks are involved, and how and when these networks interact. Electroencephalography data of 317 tinnitus patients and 256 healthy subjects were analyzed, using independent component analysis. Results demonstrate that tinnitus is characterized by at least 2 major brain networks, each consisting of multiple independent components. One network reflects tinnitus distress, while another network reflects the loudness of the tinnitus. The component coherence analysis shows that the independent components that make up the distress and loudness networks communicate within their respective network at several discrete frequencies in parallel. The distress and loudness networks do not intercommunicate for patients without distress, but do when patients are distressed by their tinnitus. The obtained data demonstrate that the components that build up these 2 separable networks communicate at discrete frequencies within the network, and only between the distress and loudness networks in those patients in whom the symptoms are also clinically linked.

Tinnitus: network pathophysiology-network pharmacology

Tinnitus, the phantom perception of sound, is a prevalent disorder. One in 10 adults has clinically significant subjective tinnitus, and for one in 100, tinnitus severely affects their quality of life. Despite the significant unmet clinical need for a safe and effective drug targeting tinnitus relief, there is currently not a single Food and Drug Administration (FDA)-approved drug on the market. The search for drugs that target tinnitus is hampered by the lack of a deep knowledge of the underlying neural substrates of this pathology. Recent studies are increasingly demonstrating that, as described for other central nervous system (CNS) disorders, tinnitus is a pathology of brain networks. The application of graph theoretical analysis to brain networks has recently provided new information concerning their topology, their robustness and their vulnerability to attacks. Moreover, the philosophy behind drug design and pharmacotherapy in CNS pathologies is changing from that of "magic bullets" that target individual chemoreceptors or "disease-causing genes" into that of "magic shotguns," "promiscuous" or "dirty drugs" that target "disease-causing networks," also known as network pharmacology. In the present work we provide some insight into how this knowledge could be applied to tinnitus pathophysiology and pharmacotherapy.