Neural activity underlying tinnitus generation: Results from PET and fMRI

Tinnitus is the percept of sound that is not related to an acoustic source outside the body. For many forms of tinnitus, mechanisms in the central nervous system are believed to play an important role in the pathology. Specifically, three mechanisms have been proposed to underlie tinnitus: (1) changes in the level of spontaneous neural activity in the central auditory system, (2) changes in the temporal pattern of neural activity, and (3) reorganization of tonotopic maps. The neuroimaging methods fMRI and PET measure signals that presumably reflect the firing rates of multiple neurons and are assumed to be sensitive to changes in the level of neural activity. There are two basic paradigms that have been applied in functional neuroimaging of tinnitus. Firstly, sound-evoked responses as well as steady state neural activity have been measured to compare tinnitus patients to healthy controls. Secondly, paradigms that involve modulation of tinnitus by a controlled stimulus allow for a within-subject comparison that identifies neural activity that may be correlated to the tinnitus percept. Even though there are many differences across studies, the general trend emerging from the neuroimaging studies, is that tinnitus in humans may correspond to enhanced neural activity across several centers of the central auditory system. Also, neural activity in non-auditory areas including the frontal areas, the limbic system and the cerebellum seems associated with the perception of tinnitus. These results indicate that in addition to the auditory system, non-auditory systems may represent a neural correlate of tinnitus. Although the currently published neuroimaging studies typically show a correspondence between tinnitus and enhanced neural activity, it will be important to perform future studies on subject groups that are closely matched for characteristics such as age, gender and hearing loss in order to rule out the contribution of these factors to the abnormalities specifically ascribed to tinnitus.     

225例耳鸣患者的康复训练与研究

目的 探讨耳鸣患者康复指导的方法。方法 将225例长期主观耳鸣患者分为2组，实验组117例，在医护人员指导下采用长期坚持不全掩蔽、松弛训练、转移注意力和心理咨询等康复训练，并且使用有声材料如耳鸣掩蔽器、助听器、音乐光盘、收音机、磁带等以协助达到对耳鸣适应和习惯的目的。对照组108例不给予任何指导，在治疗后2个月、6个月、12个月对两种康复方法进行分析。结果 实验组117例患者中2个月适应率为17．09％、6个月适应率为82．05％、12个月适应率为88．03％。对照组108例患者2个月适应率为2．78％、6个月适应率为26．85％、12个月适应率为41．67％。两组分别在2个月、6个月、12个月比较（χ^2 检验），均有显著性差异（P＜0．01）。结论 耳鸣患者的不全掩蔽、松弛训练、转移注意力和心理咨询等训练方法有利于患者康复。     

Increases in spontaneous activity in the dorsal cochlear nucleus of the rat following exposure to high-intensity sound

The effects of intense sound exposure on neural activity in the dorsal cochlear nucleus (DCN) were studied in the rat. Seventeen anesthetized adult rats were exposed to a 10-kHz tone at 125–130 dB SPL for 4 h. Fourteen unexposed rats served as controls. Spontaneous activity (SA) and neural thresholds at the characteristic frequency were measured in three rows of 8–12 sites along the mediolateral, tonotopic, axis of the DCN surface 27–61 days after exposure. The results showed that intense tone exposure induced chronic increases in SA. This hyperactivity was found to be distributed broadly across the DCN with an emphasis around the 10-kHz locus and was associated with shifted response thresholds. These findings demonstrate the usefulness of the rat for studies of physiological phenomena related to noise-induced tinnitus and hearing loss.     

Situationally influenced tinnitus coping strategies: a mixed methods approach

Abstract

Purpose: The primary aim of this study was to identify coping strategies used to manage problematic tinnitus situations. A secondary aim was to determine whether different approaches were related to the level of tinnitus distress, anxiety, depression, and insomnia experienced.

Materials and methods: A cross-sectional survey design was implemented. The study sample was adults interested in undertaking an Internet-based intervention for tinnitus. Self-reported measures assessed the level of tinnitus distress, depression, anxiety, and insomnia. An open-ended question was used to obtain information about how problematic tinnitus situations were dealt with. Responses were investigated using qualitative content analysis to identify problematic situations. Further data analysis comprised of both qualitative and quantitative methods.

Results: There were 240 participants (137 males, 103 females), with an average age of 48.16 years (SD: 22.70). Qualitative content analysis identified eight problematic tinnitus situations. Participants had either habituated to their tinnitus (7.9%), used active (63.3%), or passive (28.8%) coping styles to manage these situations. Those who had habituated to tinnitus or used active coping strategies had lower levels of tinnitus distress, anxiety, and depression.

Conclusions: The main problematic tinnitus situations for this cohort were identified. Both active and passive coping styles were applied to approach these situations. The coping strategies used most frequently and utilised in the widest range of problematic situations were using sound enrichment and diverting attention.

• Implications for Rehabilitation

• The main problematic tinnitus situations for this group of participants were identified.

• Overall, a limited range of strategies were used to deal with individual problematic situations. The use of sound enrichment and diverting attention was applied in the widest range of problematic situations.

• The use of both active and passive coping styles was evident to approach these situations. The use of passive strategies in certain situations was associated with higher levels of tinnitus distress, depression, and anxiety over the last week as measured by self-reported questionnaires.

     

Systematic review of evidence on the association between personality and tinnitus

IntroductionThe scientific literature demonstrates that personality traits are associated with the individual's adaptation to chronic diseases, and can be an important factor in the etiology and prognosis of physical illness. Some studies indicate that personality characteristics may influence the perception of tinnitus.ObjectiveTo assess the scientific evidence of the association between tinnitus and personality.MethodsA systematic review of the following databases: PubMed, SciELO, LILACS, and Web of Knowledge. Only studies of patients older than 18 years published in English, Portuguese, or Spanish that established an association between tinnitus and personality were selected.ResultsSeventeen of the 77 articles found were selected: 13 cross-sectional studies, two longitudinal studies, one validation study, and one birth cohort study. The samples ranged from 27 to 970 patients.ConclusionSome personality traits, especially neuroticism, psychasthenia, and schizoid aspects, may be associated with tinnitus perception and with the annoyance due to this symptom.     

Interpreting the Tinnitus Questionnaire (German version): what individual differences are clinically important?

Objective: Reporting of clinical significance is recommended because findings can be statistically significant without being relevant to patients. For aiding clinical interpretation of the Tinnitus Questionnaire (TQ), many investigators use a 5-point change cut-off as a minimal clinically important difference (MCID). But there are shortcomings in how this value was originally determined. Design: The MCID was evaluated by analysing retrospective clinical data on the TQ (German version). Following recommended standards, multiple estimates were computed using anchor- and distribution-based statistical methods. These took into account not only patients’ experience of clinical improvement, but also measurement reliability. Study sample: Pre- and post-intervention scores were assessed for 202 patients. Results: Our six estimates ranged from 5 to 21 points in TQ change score from pre- to post- intervention. The 5-point TQ change score was obtained using a method that considered change between groups, and did not account for measurement error or bias. The size of the measurement error was considerable, and this comprises interpretation of individual patient change scores. Conclusions: To enhance confidence that a TQ change over time in individual patients is clinically meaningful, we advise at least the median MCID of 12 points.     

Uncomfortable loudness levels among children and adolescents seeking help for tinnitus and/or hyperacusis

Objective: To assess the prevalence of hyperacusis and severe hyperacusis among children and adolescents seen at an audiology outpatient tinnitus and hyperacusis service.

Design: This was a retrospective study. Hyperacusis was considered as present if the average uncomfortable loudness level (ULL) at 0.25, 0.5, 1, 2, 4 and 8?kHz for the ear with the lower average ULL, which is denoted as ULLmin, was ≤77?dB HL. Severe hyperacusis was considered as present if the ULL was 30?dB HL or less for at least one of the measured frequencies for at least one ear.

Study sample: There were 62 young patients with an average age of 12?years (SD?=?4.1?years, range 4–18?years).

Results: Eighty-five percent of patients had hyperacusis and 17% had severe hyperacusis. On average, ULLs at 8?kHz were 9.3?dB lower than ULLs at 0.25?kHz. For 33% of patients, ULLs were at least 20?dB lower at 8 than at 0.25?kHz.

Conclusions: Among children and adolescents seen at an audiology outpatient clinic for tinnitus and hyperacusis, hyperacusis diagnosed on the basis of ULLs is very prevalent and it is often characterised by lower ULLs at 8 than at 0.25?kHz.     

42例耳鸣伴听觉过敏患者特征分析

目的 探讨耳鸣伴听觉过敏患者的临床、听力及心理声学特征以及对患者的影响。 方法 对2015年3月至2017年3月在广州医科大学附属第二医院耳鼻咽喉科门诊就诊的42例耳鸣合并听觉过敏患者进行纯音测听、耳鸣心理声学特征、响度不适阈(LDL)检测,并对耳鸣及听觉过敏严重程度进行评估。 结果 42例中,24例以耳鸣为第一主诉(A组),18例以听觉过敏为第一主诉(B组)。耳鸣主调以纯音为主,频率以高频为主,响度多数≤5 dB SL。患者听觉过敏表现为对正常环境声过分关注或刻意回避,伴烦躁、心悸、惊慌、恐惧,戴耳塞、不敢出门。分别检测0.125~8 kHz频率的LDL,两组在同一频率的LDL差异无统计学意义(P>0.05)。 结论 不能以响度不适阈判断听觉过敏的严重程度;临床上耳鸣与听觉过敏常相伴随,要重视其对患者工作、生活、睡眠与情绪的影响,应制定和使用适合中国国情的评估量表。     

Intralabyrinthine sporadic endolymphatic sac tumour

IntroductionEndolymphatic sac tumours are benign, slowly growing tumours that invade the temporal bone, and present clinically in the form of unilateral hearing loss. They can be sporadic or occur in the context of Von Hippel-Lindau disease (VHL).Case summaryThe authors report a case of endolymphatic sac tumour arising in the utricle presenting histological and immunohistochemical features corresponding to endolymphatic sac tumour in a patient without VHL.DiscussionEndolymphatic sac tumours invade the posterior part of the petrous temporal bone. According to two studies concerning patients with Von Hippel-Lindau disease, endolymphatic sac tumours arise from the endolymphatic duct. This case of intralabyrinthine sporadic endolymphatic sac tumour supports this hypothesis for sporadic forms, indicating the need for labyrinthectomy associated with tumour resection to avoid recurrence.     

Tinnitus impairs cognitive efficiency

Many people who complain of tinnitus say that the noises impair their mental concentration. This complaint was investigated by self-report (primarily the Cognitive Failures Questionnaire) and by means of five cognitive tasks, four presented via laptop computer and one given manually. The tasks measured performance under single and dual-task conditions and included tests of sustained attention, reaction time, verbal fluency and immediate and delayed memory. Two groups of outpatients attending audiological clinics (tinnitus, n?=?43; hearing impairment, n?=?17) were compared with non-clinical volunteers (n?=?32). The results replicated earlier findings that tinnitus outpatients report significantly more everyday cognitive failures than do controls. The tinnitus group responded significantly more slowly than the two control groups on the variable fore-period reaction time task under dual-task conditions. In general, comparisons between the groups on other tasks showed equivalent performance, but both clinical groups performed more poorly than non-clinical controls on verbal fluency. We conclude that cognitive inefficiency in tinnitus participants is related to the control of attentional processes, consistent with our earlier theoretical speculation about the nature of tinnitus complaint and with published findings on the effects of chronic pain on cognitive processes.