Unresolved questions regarding human hereditary deafness

Human hearing loss is a common neurosensory disorder about which many basic research and clinically relevant questions are unresolved. This review on hereditary deafness focuses on three examples considered at first glance to be uncomplicated, however, upon inspection, are enigmatic and ripe for future research efforts. The three examples of clinical and genetic complexities are drawn from studies of (i) Pendred syndrome/DFNB4 (PDS, OMIM 274600), (ii) Perrault syndrome (deafness and infertility) due to mutations of CLPP (PRTLS3, OMIM 614129), and (iii) the unexplained extensive clinical variability associated with TBC1D24 mutations. At present, it is unknown how different mutations of TBC1D24 cause non‐syndromic deafness (DFNB86, OMIM 614617), epilepsy (OMIM 605021), epilepsy with deafness, or DOORS syndrome (OMIM 220500) that is characterized by d eafness, o nychodystrophy (alteration of toenail or fingernail morphology), o steodystrophy (defective development of bone), mental r etardation, and s eizures. A comprehensive understanding of the multifaceted roles of each gene associated with human deafness is expected to provide future opportunities for restoration as well as preservation of normal hearing.     

葛根素注射液联合巴曲酶治疗突发性耳聋的临床疗效观察

目的 研究葛根素注射液联合巴曲酶治疗突发性耳聋的临床效果。方法 选择2016年2月—2016年12月在榆林市星元医院进行诊治的突发性耳聋患者78例,随机分为两组,每组各39例。对照组给予巴曲酶注射液,每次10 BU,加入500 mL生理盐水中稀释后进行静脉滴注,每两天1次。观察组在对照组基础上联合静脉滴注葛根素注射液治疗,将0.4 g葛根素注射液加入250 mL生理盐水中进行静脉滴注,每天1次。两组均治疗10 d。比较两组的临床治疗效果,以及治疗前后的活化部分凝血活酶时间、凝血酶时间、凝血酶原时间和血浆纤维蛋白原,全血黏度低切、血细胞比容、全血黏度高切、血浆黏度和纯音听阈值。结果 观察组的有效率为89.74%,明显高于对照组的71.79%,差异有统计学意义（P<0.05）。两组治疗后的凝血酶时间、活化部分凝血活酶时间以及凝血酶原时间均明显升高,血浆纤维蛋白原明显降低,同组治疗前后比较差异有统计学意义（P<0.05）;且两组间相比差异有统计学意义（P<0.05）。两组治疗后的全血黏度低切、血细胞比容、全血黏度高切及血浆黏度均明显降低,同组治疗前后比较差异有统计学意义（P<0.05）;且观察组明显低于对照组,差异有统计学意义（P<0.05）。两组治疗后的纯音听阈值均明显改善,同组治疗前后比较差异有统计学意义（P<0.05）;且观察组明显优于对照组,差异有统计学意义（P<0.05）。结论 葛根素注射液联合巴曲酶治疗突发性耳聋的临床效果明显优于单独使用巴曲酶,不仅可以有效改善患者的临床症状还可以改善血液流变学状态以及血液高凝状态。     

高压氧联合地塞米松治疗突发性耳聋的疗效及相关影响因素分析

目的 分析高压氧联合地塞米松治疗突发性耳聋（SD）的疗效及相关影响因素。方法 回顾性分析 2014年 1 月—2016 年 12 月我院 200 例采用高压氧联合地塞米松治疗的 SD 患者的临床资料,根据疗效分为有效组（n=182 例）与无效组（n=18 例）,比较 2 组性别、年龄、发病至就诊时间、耳别、听力损失、听力曲线类型、伴眩晕情况、伴耳鸣情况、合并疾病（高血压或糖尿病）、血浆黏度及血清 C 反应蛋白（CRP）等指标,并采用 Logistic 回归筛选影响SD 疗效的危险因素。结果 200 例患者经治疗后,总有效 182 例（91.00%）,无效 18 例(9.00%）。有效组年龄>50岁、发病至就诊时间>7 d、听力损失≥60 dB、听力曲线类型为高频型或全聋型、伴眩晕、合并高血压、合并糖尿病、血浆黏度≥2 mPa·s、血清 CRP≥20 μmol/L 的比例明显低于无效组（P＜0.05）。Logistic 回归分析显示,年龄（>50 岁）、发病至就诊时间（>7 d）、听力损失（≥60 dB）、听力曲线类型为高频型或全聋型、伴眩晕、合并高血压、合并糖尿病、血浆黏度（≥2 mPa·s）、血浆 CRP（≥20 μmol/L）为影响 SD 疗效的危险因素（P＜0.05）。结论 高压氧联合地塞米松是治疗SD 的有效方案,但影响其疗效的因素众多,临床治疗时有必要考虑患者临床与病理特征。     

Long-term sensorineural hearing loss induces functional changes in the rat auditory nerve

Loss of cochlear hair cells in the rat initiates degenerative change within the primary auditory neurons (ANs) of the cochlea. These degenerative changes include loss of peripheral processes, demyelination and ultimately cell death. This pathology will affect the biophysical processes involved in action potential generation and propagation to an electrical stimulus via a cochlear implant. We measured the response properties of ANs, with particular reference to their refractory behaviour, in normal, short- (9 weeks) and long-term (> 52 weeks) deafened rats. AN loss was moderate in the short-term and severe in the long-term deafened animals. AN activity was elicited using a brief electrical stimulus delivered via a bipolar electrode array implanted into the cochlea. The general response properties of ANs recorded from deafened cochleae were similar to those observed in normal cochleae, i.e. a monotonic increase in the probability of firing and a decrease in response latency and temporal jitter with increasing stimulus intensity. However, the absolute refractory period was significantly prolonged in animals deaf for > 12 months (P = 0.0026). Deafened animals also exhibited a highly significant increase in threshold compared with normal controls (P < 0.001). These functional changes have implications for recipients of cochlear implants and potential therapies directed toward halting or reversing AN pathology.     

Early unilateral cochlear implantation promotes mature cortical asymmetries in adolescents who are deaf

Unilateral cochlear implant (CI) stimulation establishes hearing to children who are deaf but compromises bilateral auditory development if a second implant is not provided within ～1.5 years. In this study we asked: 1) What are the cortical consequences of missing this early sensitive period once children reach adolescence? 2) What are the effects of unilateral deprivation on the pathways from the opposite ear? Cortical responses were recorded from 64‐cephalic electrodes within the first week of bilateral CI activation in 34 adolescents who had over 10 years of unilateral right CI experience and in 16 normal hearing peers. Cortical activation underlying the evoked peaks was localized to areas of the brain using beamformer imaging. The first CI evoked activity which was more strongly lateralized to the contralateral left hemisphere than normal, with abnormal recruitment of the left prefrontal cortex (involved in cognition/attention), left temporo‐parietal‐occipital junction (multi‐modal integration), and right precuneus (visual processing) region. CI stimulation in the opposite deprived ear evoked atypical cortical responses with abnormally large and widespread dipole activity across the cortex. Thus, using a unilateral CI to hear beyond the period of cortical maturation causes lasting asymmetries in the auditory system, requires recruitment of additional cortical areas to support hearing, and does little to protect the unstimulated pathways from effects of auditory deprivation. The persistence of this reorganization into maturity could signal a closing of a sensitive period for promoting auditory development on the deprived side. Hum Brain Mapp 37:135–152, 2016. © 2015 Wiley Periodicals, Inc.     

Neural signature of inattentional deafness

Inattentional deafness is the failure to hear otherwise audible sounds (usually alarms) that may occur under high workload conditions. One potential cause for its occurrence could be an attentional bottleneck that occurs when task demands are high, resulting in lack of resources for processing of additional tasks. In this fMRI experiment, we explore the brain regions active during the occurrence of inattentional deafness using a difficult perceptual‐motor task in which the participants fly through a simulated Red Bull air race course and at the same time push a button on the joystick to the presence of audio alarms. Participants were instructed to focus on the difficult piloting task and to press the button on the joystick quickly when they noticed an audio alarm. The fMRI results revealed that audio misses relative to hits had significantly greater activity in the right inferior frontal gyrus IFG and the superior medial frontal cortex. Consistent with an attentional bottleneck, activity in these regions was also present for poor flying performance (contrast of gates missed versus gates passed for the flying task). A psychophysiological interaction analysis from the IFG identified reduced effective connectivity to auditory processing regions in the right superior temporal gyrus for missed audio alarms relative to audio alarms that were heard. This study identifies a neural signature of inattentional deafness in an ecologically valid situation by directly measuring differences in brain activity and effective connectivity between audio alarms that were not heard compared to those that were heard. Hum Brain Mapp 38:5440–5455, 2017. © 2017 Wiley Periodicals, Inc.     

灯盏细辛注射液与常规西药治疗突发性耳聋随机对照研究

目的对比灯盏细辛注射液与常规西药治疗突发性耳聋的疗效,提供较为规范的随机对照研究方法.方法灯盏细辛注射液治疗作为治疗组,静脉输入低分子右旋糖酐、能量合剂等常规西药治疗作为对照组;每组各50例,对照观察其临床疗效.结果治疗组痊愈21例,显效19例,有效7例,无效2例,总有效率94%,疗效优于常规西药组(P＜0.05).结论灯盏细辛注射液治疗突发性耳聋疗效及对听力的改善优于常规西药对照组.     

针灸结合西医常规疗法治疗突发性耳聋59例

目的观察针灸结合西医常规疗法治疗突发性耳聋的临床疗效。方法将112例患者随机分为治疗组(59例)和对照组(53例),两组均予西医常规疗法,治疗组同时加用针灸治疗。两组疗程均为20天,观察听力、耳鸣及眩晕疗效。结果治疗组听力、耳鸣、眩晕总有效率分别为88.14%、82.98%、89.47%,对照组分别为73.58%、82.93%、82.35%;治疗组在提高患者听力方面明显优于对照组(P0.05)。结论针灸结合西医常规疗法可有效用于治疗突发性耳聋。     

放松训练对突发性耳聋患者的影响

目的 探讨治疗突发性耳聋患者有效的护理措施.方法 将符合突发性耳聋患者60例,按入院顺序随机分为两组,实验组30例,对照组30例.两组患者采用同样的治疗和常规护理外,实验组进行放松训练,对两组患者的焦虑、抑郁值及睡眠情况进行评价.结果 两组患者焦虑及抑郁值比较,实验组较对照组降低,差异有显著性意义(P＜0.05);实验组患者睡眠质量明显改善.结论 放松训练是治疗突发性耳聋患者有效的护理措施.     

Low frequency of deafness-associated GJB2 variants in Kenya and Sudan and novel GJB2 variants

A large proportion of non-syndromic autosomal recessive deafness (NSARD) in many populations is caused by variants of the GJB2 gene. Here, the frequency of GJB2 variants was studied in 406 and 183 apparently unrelated children from Kenya and Sudan, respectively, with mostly severe to profound non-syndromic deafness. Nine (2.2 %) Kenyan and 12 (6.6 %) of the Sudanese children only were carriers of variants within the coding sequence of the GJB2 gene. Variants in the 5'-adjacent region were detected in further 115 individuals. A total of 10 novel variants was recognized, among them four variants in the adjacent 5'-region of the GJB2 coding exon 2 (g.3318-6T>A, g.3318-15C>T, g.3318-34C>T, g.3318-35T>G), a 6 base-pair deletion (g.3455_3460del [p.Asp46_Gln48delinsGlu]), a variant leading to a stop codon (g.3512C>A [p.Tyr65X]), synonymous variants (g.3395C>T [p.Thr26], g.3503C>T [p.Asn62], g.3627A>C [p.Arg104]), and one non-synonymous variant (g.3816C>A [p.Val167Met]). In addition, the previously described variants g.3352delG (commonly designated 30delG or 35 delG), g.3426G>A [p.Val37Ile], g.3697G>A [p.Arg127His], g.3774G>A [p.Val153Ile], and g.3795G>A [p.Gly160Ser] were identified. With the exception of g.3318-34C>T and g.3352delG, all variants occurred heterozygously. For most of the variants identified in the Kenyan and Sudanese study population, a causative association with NSARD appears to be unlikely. Compared to many other ethnic groups, deafness-associated variants of the coding region of GJB2 are rare in Sudan and Kenya, suggesting a role of other genetic, or epigenetic factors as a cause for deafness in these countries.