Lower glutamate and GABA levels in auditory cortex of tinnitus patients: a 2D-JPRESS MR spectroscopy study.

We performed magnetic resonance spectroscopy (MRS) on healthy individuals with tinnitus and no hearing loss (n = 16) vs. a matched control group (n = 17) to further elucidate the role of excitatory and inhibitory neurotransmitters in tinnitus. Two-dimensional J-resolved spectroscopy (2D-JPRESS) was applied to disentangle Glutamate (Glu) from Glutamine and to estimate GABA levels in two bilateral voxels in the primary auditory cortex. Results indicated a lower Glu concentration (large effect) in right auditory cortex and lower GABA concentration (medium effect) in the left auditory cortex of the tinnitus group. Within the tinnitus group, Glu levels positively correlated with tinnitus loudness measures. While the GABA difference between groups is in line with former findings and theories about a dysfunctional auditory inhibition system in tinnitus, the novel finding of reduced Glu levels came as a surprise and is discussed in the context of a putative framework of inhibitory mechanisms related to Glu throughout the auditory pathway. Longitudinal or interventional studies could shed more light on interactions and causality of Glu and GABA in tinnitus neurochemistry.

[Neurofeedback for the treatment of chronic tinnitus : Review and future perspectives]. / Neurofeedback in der Behandlung des chronischen Tinnitus : Überblick und Ausblick.

Neurofeedback is a noninvasive neuromodulation technique employing real-time display of brain activity in terms of electroencephalography (EEG) signals to teach self-regulation of distinct patterns of brain activity or influence brain activity in a targeted manner. The benefit of this approach for control of symptoms in attention deficit disorders, hyperactivity, depression, and migraine has been proven. Studies in recent years have also repeatedly shown this treatment to improve tinnitus symptoms, although it has not become established as routine therapy. The primary focus of this review is the rational of EEG neurofeedback for tinnitus treatment and the currently available data from published studies. Furthermore, alternative neurofeedback protocols using real-time functional magnetic resonance imaging (fMRI) measurements for tinnitus control are considered. Finally, this article highlights how modern EEG analysis (source localization, connectivity) and the improving understanding of tinnitus pathology can contribute to development of more focused neurofeedback protocols for more sustainable control of tinnitus.

Efficacy of different protocols of transcranial magnetic stimulation for the treatment of tinnitus: Pooled analysis of two randomized controlled studies.

OBJECTIVES: Tinnitus is related to alterations in neuronal activity of auditory and nonauditory brain areas. Targeted modulation of these areas by repetitive transcranial magnetic stimulation (rTMS) has been proposed as a new therapeutic approach for chronic tinnitus. METHODS: Two randomized, double-blind, parallel-group, controlled clinical trials were performed subsequently and pooled for analysis. A total of 192 tinnitus patients were randomly allocated to receive 10 stimulation sessions of either sham rTMS, PET-based neuronavigated 1 Hz rTMS, 1Hz r TMS over the left auditory cortex, or combined 20 Hz rTMS over the left frontal cortex, followed by 1 Hz rTMS over the left auditory cortex. RESULTS: rTMS treatment was well tolerated and no severe side effects were observed. All active rTMS treatments resulted in significant reduction of the TQ as compared to baseline. The comparison between treatment groups failed to reach significant differences. The number of treatment responders was higher for temporal rTMS(38%) and combined frontal and temporal rTMS (43%), as compared to sham (6%). CONCLUSIONS: This large study demonstrates the safety and tolerability of rTMS treatment in patients with chronic tinnitus. While the overall effect did not prove superior to placebo, secondary outcome parameters argue in favour of the active stimulation groups, and specifically the combined frontal and temporal rTMS protocol.

Resequencing of the auxiliary GABA(B) receptor subunit gene KCTD12 in chronic tinnitus.

Tinnitus is a common and often incapacitating hearing disorder marked by the perception of phantom sounds. Susceptibility factors remain largely unknown but GABA(B) receptor signaling has long been implicated in the response to treatment and, putatively, in the etiology of the disorder. We hypothesized that variation in KCTD12, the gene encoding an auxiliary subunit of GABA(B) receptors, could help to predict the risk of developing tinnitus. Ninety-five Caucasian outpatients with a diagnosis of chronic tinnitus were systematically screened for mutations in the KCTD12 open reading frame and the adjacent 3' untranslated region by Sanger sequencing. Allele frequencies were determined for 14 known variants of which three (rs73237446, rs34544607, and rs41287030) were polymorphic. When allele frequencies were compared to data from a large reference population of European ancestry, rs34544607 was associated with tinnitus (p = 0.04). However, KCTD12 genotype did not predict tinnitus severity (p = 0.52) and the association with rs34544607 was weakened after screening 50 additional cases (p = 0.07). Pending replication in a larger cohort, KCTD12 may act as a risk modifier in chronic tinnitus. Issues that are yet to be addressed include the effects of neighboring variants, e.g., in the KCTD12 gene regulatory region, plus interactions with variants of GABA(B1) and GABA(B2).

[Glossopharyngeal neuralgia after resection of a glossopharyngeal schwannoma]. / Glossopharyngeusneuralgie nach Resektion eines Glossopharyngeusschwannoms.

Glossopharyngeal neuralgia is a rare condition and the origin is mostly idiopathic. Causes of symptomatic glossopharyngeal neuralgia can be tumors, infarction or trauma. We report the case of a 28-year-old patient who developed glossopharyngeal neuralgia after resection of a glossopharyngeal schwannoma, which is an extremely rare tumor. Treatment consisted of orally administered pregabalin and a series of injections of buprenorphine in the superior cervical ganglion (ganglionic local opioid application/analgesia, GLOA) which led to a substantial decrease in the frequency of pain attacks. This improvement was maintained at 1-year follow-up. This is the first report of development of glossopharyngeal neuralgia after resection of a glossopharyngeal schwannoma.

rTMS for the treatment of tinnitus: the role of neuronavigation for coil positioning.

Tinnitus affects 10% of the population, its pathophysiology remains incompletely understood, and treatment is elusive. Both animal models and functional imaging data in tinnitus patients suggest that tinnitus is associated with increased neuronal activity, increased synchronicity and functional reorganisation in the auditory cortex. Therefore, targeted modulation of auditory cortex has been proposed as a new therapeutic approach for chronic tinnitus. Repetitive transcranial magnetic stimulation (rTMS), a non invasive method for modulation of cortical activity, has been applied in different ways in patients with chronic tinnitus. Single sessions of high-frequency rTMS over the temporal cortex have been used to transiently interfere with the intensity of tinnitus. Repeated sessions of low-frequency rTMS have been investigated as a treatment for tinnitus. Here, we review data from clinical trials and discuss potential neurobiological mechanisms with special focus on the relevance of the stimulation target and the method of TMS coil positioning. Different functional neuroimaging techniques are used for detecting tinnitus-related changes in brain activity. They converge in the finding of increased neuronal activity in the central auditory system, but they differ in the exact localisation of these changes, which in turn results in uncertainty about the optimal target for rTMS treatment. In this context, it is not surprising that the currently available studies do not demonstrate clear evidence for superiority of neuronavigational coil positioning. Further development of rTMS as a treatment for tinnitus will depend on a more detailed understanding of both the neuronal correlates of the different forms of tinnitus and of the neurobiological effects mediating the benefit of TMS on tinnitus perception.

Left temporal low-frequency rTMS for the treatment of tinnitus: clinical predictors of treatment outcome--a retrospective study.

BACKGROUND: There is increasing evidence that repetitive transcranial magnetic stimulation (rTMS) can reduce chronic tinnitus. However, treatment results are characterized by high interindividual variability. Therefore, the identification of predictors for treatment response is of high clinical relevance. METHODS: Clinical data of 194 patients with tinnitus were evaluated. All patients were treated with a standardized rTMS procedure (1 Hz, 10 days, 2000 stimuli/day, over the left temporal cortex). A potential influence on the outcome was analysed for the following parameters: age, gender, depression scores in Beck Depression Inventory (BDI) and tinnitus severity (TQ) before rTMS, lateralization, frequency and duration of tinnitus and extent of hearing loss. RESULTS: An effect of tinnitus laterality was observed. In patients with left-sided or bilateral tinnitus, rTMS resulted in a statistically significant reduction of TQ scores, whereas patients with right-sided tinnitus did not show a significant improvement after rTMS treatment. However, in correlation analyses, we found a trend which did not reach statistical significance that in the subgroup of treatment responders tinnitus duration influenced rTMS outcome. In addition, a multiple regression analysis identified the TQ score at baseline as a significant predictor for treatment outcome. For all other investigated parameters, no statistically significant effects were found. CONCLUSIONS: This study suggests that left temporal low-frequency rTMS has beneficial effects in left-sided and bilateral tinnitus, but not in right-sided tinnitus. In line with the results from earlier studies involving smaller samples, tinnitus duration was found to influence rTMS outcome.

Functional imaging of chronic tinnitus: the use of positron emission tomography.

Recent advances in functional imaging have opened new possibilities for understanding tinnitus. Especially, positron emission tomography (PET) has been increasingly used in the last two decades to identify cortical networks, which are involved in the generation of various forms of chronic tinnitus. PET studies have confirmed that the anatomical location of the anomalies that cause many forms of tinnitus are regions of the brain that are normally involved in auditory processing as well as regions engaged in emotional processing. These findings have contributed to the development of new more causally oriented treatment strategies. In particular, identification of increased activity of the auditory cortex by PET has prompted the use of focal brain stimulation techniques such as electrical or transcranial magnetic stimulation in treatment of tinnitus. PET studies that map distinct neurochemical pathways and receptors by the use of specific ligands may in the future provide new possibilities for pharmacologically based treatment of some forms of tinnitus.

Genetics of chronic tinnitus.

Susceptibility to chronic tinnitus is highly variable and of particular interest when it comes to defining strategies for prevention and treatment. While several rare monogenic disorders have been described that are associated with tinnitus, the genetic underpinnings of the more common forms of the syndrome are still poorly understood. The present article incorporates recent advancements in the field, including the epidemiology of tinnitus in subjects with neuropsychiatric illness, and highlights pilot studies of candidate genes.

Tinnitus severity, depression, and the big five personality traits.

A growing number of self-report measures for the evaluation of tinnitus severity has become available to research and clinical practice. This has led to an increased awareness of depression and personality as predictors of tinnitus severity in addition to loudness and other psychoacoustic measures. However, the net impact of personality dimensions on tinnitus ratings has not been investigated when the effect of depressed mood is controlled. In the present study, we demonstrate the role of the big five personality traits, 'Neuroticism', 'Extraversion', 'Openness', 'Agreeableness', and 'Conscientiousness', in affecting scores on two standard instruments for grading tinnitus-related complaints, the tinnitus handicap inventory (THI), and the tinnitus questionnaire (TQ). When 72 individuals with chronic tinnitus were examined, 'Agreeableness' negatively correlated with THI scores (p=.003), whereas the anxiety trait 'Neuroticism' correlated both with depressive symptomatology (p<.001) and TQ scores (p=.028), but not with THI ratings (n.s.). In addition to confirming the established roles of trait anxiety and depression, low 'Agreeableness' was thus identified as a novel predictor of tinnitus severity on the THI.

Transcranial magnetic stimulation (TMS) for treatment of chronic tinnitus: clinical effects.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive method used to induce electrical current in the brain through impulses of strong magnetic fields applied externally. The technique can relieve tinnitus by modulating the excitability of neurons in the auditory cortex to decrease the hyperexcitability that is associated with generating the neural activity that causes some form of tinnitus. This chapter will review clinical studies using rTMS for the treatment of tinnitus.

TMS for treatment of chronic tinnitus: neurobiological effects.

Results of neurophysiological and neuroimaging studies suggest that some forms of chronic tinnitus can be regarded to be "hyperexcitability syndromes", caused by abnormal focal brain activity. Low frequency repetitive magnetic stimulation (rTMS) is an efficient method to selectively reduce the abnormally increased activity in distinct cortical areas. An increasing amount of clinical data suggest that low frequency rTMS might be an effective therapy that is directed at the cause of some forms of chronic tinnitus. To further explore the underlying neurobiological mechanisms we investigated the effect of rTMS on cortical excitability in healthy human subjects using the protocol, which has been successfully used for the treatment of tinnitus. We determined different parameters of motor cortex excitability (resting motor threshold, RMT; active motor threshold, AMT; short intracortical inhibition, ICI; short intracortical facilitation, ICF; and the duration of the cortical silent period, CSP) before and after 5 days of low frequency rTMS (2000 stimuli/day at 110% of RMT) over the left auditory cortex. Five sessions of low frequency rTMS resulted in a significant prolongation of the CSP. All other signs of cortical excitability that we studied remained unchanged. These findings suggest, that low frequency rTMS may evoke long-term depression (LTD)-like effects resulting in enhancement of subcortical inhibition.

Consensus for tinnitus patient assessment and treatment outcome measurement: Tinnitus Research Initiative meeting, Regensburg, July 2006.

There is widespread recognition that consistency between research centres in the ways that patients with tinnitus are assessed and outcomes following interventions are measured would facilitate more effective co-operation and more meaningful evaluations and comparisons of outcomes. At the first Tinnitus Research Initiative meeting held in Regensburg in July 2006 an attempt was made through workshops to gain a consensus both for patient assessments and for outcome measurements. It is hoped that this will contribute towards better cooperation between research centres in finding and evaluating treatments for tinnitus by allowing better comparability between studies.

Structural brain alterations following 5 days of intervention: dynamic aspects of neuroplasticity.

Activation-dependent brain plasticity in humans on a structural level has been demonstrated in adults after 3 months of training a visio-motor skill. The exact timescale of usage-dependent structural changes, whether days, months, or years, is, however, still debated. A better understanding of the temporal parameters may help elucidate to what extent this type of cortical plasticity contributes to fast adapting cortical processes that may be relevant to learning and effects of treatments. Using voxel-based morphometry, we are able to show that repetitive transcranial magnetic stimulation delivered to the superior temporal cortex causes macroscopic cortical changes in gray matter (GM) in the auditory cortex as early as within 5 days of continuous intervention. These structural alterations are mirrored by changes in cortical evoked potentials attributed to the GM changes and demonstrate the rapid dynamics of these processes, which occur within a time range characteristic for the onset of behavioral effects induced by a variety of treatment methods for neuropsychiatric diseases. Our finding suggests that cortical plasticity on a structural level in adult humans is already detectable after 1 week, which provides support for fast adjusting neuronal systems, such as spine and synapse turnover, and contradicts slow evolving mechanisms, such as neuronal or glial cell genesis.

[Treatment of chronic tinnitus with neuronavigated repetitive Transcranial Magnetic Stimulation (rTMS)]. / Neuronavigierte repetitive transkranielle Magnetstimulation (rTMS). Ein neuartiges Therapieverfahren zur Behandlung des chronischen Tinnitus.

BACKGROUND AND OBJECTIVE: Idiopathic tinnitus is a frequent and debilitating disorder of largely unknown pathophysiology. Focal brain activation in the auditory cortex has recently been demonstrated in chronic tinnitus. Low-frequency rTMS can reduce cortical hyperexcitability. PATIENTS AND METHODS: In 12 patients with chronic tinnitus, fusion of [18F]deoxyglucose-PET and structural MRI (T1, MPRAGE) scans allowed the area of increased metabolic activity in the auditory cortex to be exactly identified; this area was selected as the target for rTMS. A neuronavigational system adapted for TMS positioning enabled the relative positions of the figure-8 coil and the target area to be monitored. Repetitive TMS (110% motor threshold; 1 Hz; 2000 stimuli per day over 5 days) was performed using a placebo-controlled crossover design. A sham coil system was used for the placebo stimulation. Treatment outcome was assessed with a specific tinnitus questionnaire (Goebel and Hiller). RESULTS: In all 12 patients an asymmetrically increased metabolic activation of the gyrus of Heschl was detected. The tinnitus score was significantly improved after 5 days of active rTMS, an effect not seen after placebo stimulation. CONCLUSION: These preliminary results show that neuronavigated rTMS may improve our understanding and treatment of chronic tinnitus.

[Metastasis in the frontal skull base from hepatocellular carcinoma]. / Metastase eines Leberzellkarzinoms in der Rhinobasis.

Metastatic tumours involving the nose and the paranasal sinuses are rare. Especially metastatic spread to the sphenoid sinus is an extremely rare occurrence. The most common metastatic tumour is the renal cell carcinoma. Only four cases of hepatocellular carcinoma presenting a sphenoid sinus metastasis could be found in a search of the literature. We report on the case of a 59-year-old male who suffered from a sphenoid sinus mass. A biopsy showed the tumour to be a metastatic hepatocellular carcinoma. The suspected primary tumour was then found in the left liver lobe. The early diagnosis of paranasal sinus malignancies is difficult because of the varied and nonspecific symptoms and signs. In cases of late diagnosis, the treatment is usually palliative with a poor prognosis. The importance of endoscopic examination and CT or MRI scan for early detection must be emphasized.