Neuro-functional imaging and profound deafness

This paper deals with the subject of the place of neuro-functional imaging in cochlear implantation. Neuro-functional imaging is a means to assess the functioning of the brain in some normal or pathological conditions. Deafness is a model of sensorineural deprivation. Cochlear implantation offers to clinicians and neuroscientists a model for understanding influence of deafness on cerebral connectivity, and to assess mechanisms of plasticity when the auditory inputs are given again to a deaf cochlea. This paper proposes a brief review of the literature on cochlear implantation and neuro-functional imaging. Patients can be scanned pre- or post-operatively, thus different questions can be investigated about neurobiology of the consequences of deafness and auditory rehabilitation by cochlear implantation, and about the possible role of neuro-functional imaging in cochlear implant candidates to predict the future benefit of the implantation.     

Prognostic factors in cochlear implantation in adults: Determining central process integrity

The purpose of this study is to examine various preoperative factors that can play a role in the auditory rehabilitation outcome of cochlear implant (CI) recipients.In order to determine the level of integrity of central processing preoperatively, special attention was given to residual hearing, duration of deafness, and cochlear nerve diameter as prognostic factors.A cohort of 232 (272 CI implantations) postlingually deafened adults was evaluated in this study. Hearing results at 1, 2 and up to 3 years postoperatively were compared with various preoperative factors: promontory stimulation testing, residual hearing, duration of deafness, and magnetic resonance imaging of the cochlear nerve. Postoperative hearing performance was measured based on the German Freiburg monosyllabic word test and the Oldenburg sentence test.Postoperative hearing performance showed a significant improvement in each consecutive year after implantation. Duration of deafness showed a negative correlation to word recognition and a positive correlation to increased signal-to-noise-ratio in sentence testing. A significant decline in hearing outcome was shown starting around the second decade of deafness corresponding to 66% of life spent in deafness. MR imaging of cochlear nerve diameter shows a positive correlation of larger nerve diameter to better speech understanding. Promontory stimulation testing did not show any prognostic value.In this retrospective review it could be shown that there is an intricate interaction in the preoperative variables: duration of deafness – as well as the ratio of life spent in deafness; residual hearing; and cochlear nerve diameter.     

The effect of psychosocial factors on outcomes of cochlear implantation

Conclusion: Psychosocial factors should be considered during cochlear implantation (CI). There were differences in psychosocial characteristics according to the etiology of deafness. The outcomes may be affected by psychosocial variables such as the severity of mental distress and social problems as well as duration of deafness. Objective: To evaluate the psychosocial characteristics of deaf people undergoing CI and to determine which psychosocial factors affect performance after CI. Methods: A total of 289 subjects who underwent CI were enrolled. The participants were classified into prelingually deaf (pre-LD) and postlingually deaf groups (post-LD), including progressive and sudden deafness subgroups. The Minnesota Multiphasic Personality Inventory (MMPI) was administered before CI to measure psychosocial and emotional problems. To measure CI outcomes, speech perception ability was assessed by the open-set Korean version of the Central Institute of Deafness (K-CID) test and categories of auditory performance (CAP) scores before and after CI. Results: Approximately 45% of subjects experienced psychological problems before undergoing CI. Subjects in the Pre-LD group had more psychosocial distress and were more likely to be oversensitive in interpersonal situations, while those in the post-LD group were more depressed. Deafness duration and psychosocial factors significantly predicted hearing ability after CI. Deafness duration directly and indirectly affected the outcome of CI. That is, duration of deafness caused psychosocial problems, which may have resulted in negative effects on outcomes of CI.     

Pre-operative Brain Imaging Using Functional Near-Infrared Spectroscopy Helps Predict Cochlear Implant Outcome in Deaf Adults

Currently, it is not possible to accurately predict how well a deaf individual will be able to understand speech when hearing is (re)introduced via a cochlear implant. Differences in brain organisation following deafness are thought to contribute to variability in speech understanding with a cochlear implant and may offer unique insights that could help to more reliably predict outcomes. An emerging optical neuroimaging technique, functional near-infrared spectroscopy (fNIRS), was used to determine whether a pre-operative measure of brain activation could explain variability in cochlear implant (CI) outcomes and offer additional prognostic value above that provided by known clinical characteristics. Cross-modal activation to visual speech was measured in bilateral superior temporal cortex of pre- and post-lingually deaf adults before cochlear implantation. Behavioural measures of auditory speech understanding were obtained in the same individuals following 6 months of cochlear implant use. The results showed that stronger pre-operative cross-modal activation of auditory brain regions by visual speech was predictive of poorer auditory speech understanding after implantation. Further investigation suggested that this relationship may have been driven primarily by the inclusion of, and group differences between, pre- and post-lingually deaf individuals. Nonetheless, pre-operative cortical imaging provided additional prognostic value above that of influential clinical characteristics, including the age-at-onset and duration of auditory deprivation, suggesting that objectively assessing the physiological status of the brain using fNIRS imaging pre-operatively may support more accurate prediction of individual CI outcomes. Whilst activation of auditory brain regions by visual speech prior to implantation was related to the CI user’s clinical history of deafness, activation to visual speech did not relate to the future ability of these brain regions to respond to auditory speech stimulation with a CI. Greater pre-operative activation of left superior temporal cortex by visual speech was associated with enhanced speechreading abilities, suggesting that visual speech processing may help to maintain left temporal lobe specialisation for language processing during periods of profound deafness.

     

人工耳蜗植入术后听觉言语效果的影响因素

目的〓〖HTK〗探讨影响人工耳蜗植入术后听觉言语恢复效果的相关因素。〖HTW〗方法〓〖HTK〗对24例双耳重度或极重度感音神经性耳聋患者,术前进行智力、听力学、影像学检查,配带助听器评估,并严格掌握手术适应证,经乳突－面隐窝进路行人工耳蜗植入术,记载术中情况,术终测电极电阻,术后1个月开机调试,语前聋者进行听觉语言培训,术后追踪随访疗效满意度和言语可懂度,对所得临床资料进行分析。〖HTW〗结果〓〖HTK〗23例耳蜗植入手术一次成功,1例电极移位二次手术成功,术后暂时性面瘫2例、眩晕1例,两周X线颞骨拍片证实耳蜗电极位于耳蜗内,1个月开机调试,全部病例获取听力。3例语后聋患者听觉言语恢复,其他语前聋患者均行半年以上的听觉语言培训,随访4～6年,半开放式言语识别率＞80％,全部患者及家属达到术前的期望值。〖HTW〗结论〓〖HTK〗人工耳蜗是治疗重度极重度感音神经性耳聋及全聋的有效方法,术后效果主要与人工耳蜗植入时的年龄、术前听力与言语基础、听神经及其传导功能、智力、植入电极在规定的部位、术后调机与康复的有效性等关系密切。     

Voice intensity of prospective cochlear implant candidates and normal hearing adult males

Voice intensity in 19 prospective cochlear implant candidates, all adventitiously profoundly sensorineurally deaf adult males, was investigated. For the first time with objective data, it was shown that such deaf subjects spoke with significantly increased voice intensity and with greater intensity fluctuations than normal hearing male speakers. Neither length of time of profound deafness nor history of hearing aid use significantly affected voice intensity. Based on quantitative data, rehabilitation of voice intensity problems in the adventitiously deaf is indicated.     

Auditory and communication learning in patients with cochlear implants

Nowadays the cochlear implant (CI) offers a new method of hearing, especially for deaf patients who do not benefit from conventional hearing aids. However, it may be difficult to get used to this kind of hearing advice. CI users have special problems in interpreting strange acoustic sensations and relating them to auditory features of language and noise they knew before the onset of deafness. An interdisciplinary approach is very important for rehabilitation. Beside otological examination and the surgical implantation, audiological assessment is needed for the correct adjustment of the speech processor and for measurement of performance. Also auditory management and counselling of deaf patients is an important part of CI rehabilitation. A learning programme in hearing and communicating ("hearing training") is offered to CI users that takes account of different linguistic levels. Auditory learning by the use of CI is based on different abilities of the deaf patient, of which the most important are speech skills and learning capacity. Although success rates vary, it certainly improves speech intelligibility during lip reading, communication behaviour, and recognition of environmental noise. The latter ability improves orientation in the acoustic surroundings. CI rehabilitation may improve the psychosocial attitude of the deaf.     

耳蜗植入患者残存听神经的不应期恢复函数

OBJECTIVE: To evaluate the cochlear implant recipient's electrical auditory temporal properties in order to estimate the maximum stimulating rate which can be reached when they adopted some speech coding strategies based on time mechanism, such as continuous interleaved sampling (CIS). METHODS: Thirty-eight Nucleus CI24 cochlear implant recipients were divided into 4 groups by etiology and history. Their survival auditory nerve fibers' refractory recovery time function was measured via neural response telemetry (NRT). Electrical pulses with the amplitude of recipient's loudest acceptable presentation were stimulated in mono-polar mode, with the width of 25 microseconds and the frequency of 80 Hz. Least-squares regression procedures were used to fit individual recovery functions with the equation A = C + K e(-t/tau), in which tau is the time constant of recovery from refractory state. Statistic analysis showed the relationship between the time constants of individuals and etiology as well as electrode position in the cochlea. RESULTS: Congenital deaf patient's recovery time constants were shorter than that of postnatal deaf groups of ototoxicity (P = 0.0056) and large vestibular aqueduct syndrome (P = 0.0349). There was no significant difference between the recovery time constants of congenital deaf patients and those of group with long history of deafness. The ANOVA of the recovery time constants of 5th, 10th, 15th electrode showed no significant statistical difference (P > 0.05). CONCLUSION: The recovery time constants are related with etiology. In mono-polar mode, the time constants of congenital deafness or subjects with short duration of deafness are shorter than those of postnatal deafness or subjects with long duration of deafness. Time constants do not vary systematically with electrode location along the implanted array. The reciprocal of individual electrode seems to be used in determining the maximum of stimulating rate of CIS strategy and as criteria of choosing the usable channels from 22 electrode bands.     

Successful cochlear implantation in prelingual profound deafness resulting from the common 233delC mutation of the GJB2 gene in the Japanese

OBJECTIVES: Recently, we identified three novel mutations of the GJB2 gene in Japanese families with autosomal-recessive non-syndromic deafness.1 Seven of 11 mutated chromosomes (63.6%) contained a 233delC allele, suggesting that the 233delC mutation is the most common mutation of the GJB2 gene in the Japanese population. After it was recognized that cochlear implantation (CI) is of benefit to children with prelingual deafness, we have had a number of prelingual pediatric CI patients. Because children carrying the homozygous 233delC mutation show bilateral prelingual profound deafness, they could be enrolled in the CI program at Osaka University Graduate School of Medicine. The purposes of this study were 1) to analyze the occurrence of the GJB2 mutations in our 15 prelingual pediatric CI patients in whom the cause of non-syndromic deafness was unknown, and 2) to evaluate the auditory function and postoperative speech perception with CI of those GJB2-related deaf subjects. STUDY DESIGN: Retrospective analysis. METHODS: Mutation analysis of the GJB2 gene by direct sequencing was performed with genomic DNA from 15 children born profoundly deaf as a result of unknown causes and implanted with CI. Intraoperative electrically evoked auditory brainstem response (EABR) and intra-/postoperative EAP were measured. The speech perception was evaluated with Infants and Toddlers Meaningful Auditory Integration Scale (IT-MAIS). RESULTS AND CONCLUSIONS: We identified 4 CI patients (26.7%) out of 15 children carrying the homozygous 233delC mutation. Intra- and postoperative evaluation of the auditory system revealed almost intact cochlear and retrocochlear auditory function in these 4 patients. Postoperative auditory testing indicates that their speech perception had become significantly higher in comparison with that of other prelingual CI patients. These results suggest that prelingual deaf children carrying the homozygous 233delC mutation of the GJB2 gene can benefit from CI.     

Unimodal and cross-modal plasticity in the ‘deaf’ auditory cortex

Congenital auditory deprivation leads to deficits in the auditory cortex. The present review focuses on central aspects of auditory deprivation: development, plasticity, corticocortical interactions, and cross-modal reorganization. We compile imaging data from human subjects, electroencephalographic data from cochlear implanted children, and animal research on congenital deafness. Behavioral, electroencephalographic, and imaging data in humans correspond well to data behavioral and neurophysiological data obtained from congenitally deaf cats. The available data indicate that auditory deprivation leads to ‘decoupling’ of the primary auditory cortex from cognitive modulation of higher-order auditory areas. Higher-order auditory areas undergo a strong cross-modal reorganization and take-over new functions. Due to these and other deficits of intrinsic microcircuitry, the cortical column can not integrate bottom-up and top-down influences in deaf auditory cortex. In the ultimate consequence perceptual learning is compromised, resulting in sensitive periods.     

语前聋患儿一侧人工耳蜗对侧助听器效果分析

目的:通过对人工耳蜗植入对侧耳不同听力损失的患儿联合使用助听器与人工耳蜗语前聋患儿的听觉、语言及学习能力进行评估和比较,探索对患儿更为有效的助听方法,帮助患儿获得最大限度的言语交流。方法:将30例3～6岁语前聋患儿按照植入人工耳蜗对侧耳听力损失程度及是否佩戴助听器,分为一侧人工耳蜗+对侧重度听力损失助听器组(CI+SHA组)、一侧人工耳蜗+对侧极重度听力损失助听器组(CI+PHA组)、单耳人工耳蜗组(CI组)。评估各组在康复3、6、9、12、15、18个月时听觉、语言及学习能力,并记录结果。结果:随着术后康复时间的延长,聋儿听觉、语言及学习能力逐渐提高(P<0.05),CI+SHA组听觉能力优于CI+PHA组及CI组(均P<0.05),语言能力及学习能力无明显差异(P>0.05)。结论:语前聋患儿单耳人工耳蜗植入后,若对侧耳尚有残余听力,佩戴助听器后听觉能力效果显著,长期佩戴有助于患儿的康复。     

人工耳蜗植入后对侧耳是否联合使用助听器声调识别的对比研究

目的 探讨人工耳蜗植入后对侧耳联合使用助听器对声调识别的影响;同时探讨人工耳蜗开机时间、康复训练时间、听障儿童的学习能力等因素对声调识别的影响。 方法 选择3~7岁的人工耳蜗植入儿童27例,采用《言语听觉反应评估》(EARS)中的“封闭式声调测试”作为测试材料,分别单独使用人工耳蜗(CI)和在人工耳蜗对侧耳联合使用助听器(CIHA)在安静和噪声两种环境下进行声调识别的测试,使用SPSS 17.0对测试结果进行统计学分析。 结果 无论在安静环境还是噪声环境下,CIHA的声调测试成绩均优于CI,此优势在噪声环境下更明显;人工耳蜗开机时间、康复训练时间较长者声调测试成绩均优于较短者;听障儿童的希-内学习能力测试结果学习能力DIQ≥100与DIQ<100者声调测试成绩差异无统计学意义。 结论 建议听障儿童人工耳蜗植入后对侧耳联合使用助听器,但助听器需要优化和调整。     

Unimodal and cross-modal plasticity in the 'deaf' auditory cortex

Congenital auditory deprivation leads to deficits in the auditory cortex. The present review focuses on central aspects of auditory deprivation: development, plasticity, corticocortical interactions, and cross-modal reorganization. We compile imaging data from human subjects, electroencephalographic data from cochlear implanted children, and animal research on congenital deafness. Behavioral, electroencephalographic, and imaging data in humans correspond well to data behavioral and neurophysiological data obtained from congenitally deaf cats. The available data indicate that auditory deprivation leads to 'decoupling' of the primary auditory cortex from cognitive modulation of higher-order auditory areas. Higher-order auditory areas undergo a strong cross-modal reorganization and take-over new functions. Due to these and other deficits of intrinsic microcircuitry, the cortical column can not integrate bottom-up and top-down influences in deaf auditory cortex. In the ultimate consequence perceptual learning is compromised, resulting in sensitive periods.     

Effects of central nervous system residua on cochlear implant results in children deafened by meningitis

BACKGROUND: This study explored factors associated with speech recognition outcomes in postmeningitic deafness (PMD). The results of cochlear implantation may vary in children with PMD because of sequelae that extend beyond the auditory periphery. OBJECTIVE: To determine which factors might be most determinative of outcome of cochlear implantation in children with PMD. DESIGN: Retrospective chart review. SETTING: A referral center for pediatric cochlear implantation and rehabilitation. SUBJECTS: Thirty children with cochlear implants who were deafened by meningitis were matched with subjects who were deafened by other causes based on the age at diagnosis, age at cochlear implantation, age at which hearing aids were first used, and method of communication used at home or in the classroom. MAIN OUTCOME MEASURE: Speech perception performance within the first 2 years after cochlear implantation and its relationship with presurgical cognitive measures and medical history. RESULTS: There was no difference in the overall cognitive or postoperative speech perception performance between the children with PMD and those deafened by other causes. The presence of postmeningitic hydrocephalus, however, posed greater challenges to the rehabilitation process, as indicated by significantly smaller gains in speech perception and a predilection for behavioral problems. By comparison, cochlear scarring and incomplete electrode insertion had no impact on speech perception results. CONCLUSIONS: Although the results demonstrated no significant delay in cognitive or speech perception performance in the PMD group, central nervous system residua, when present, can impede the acquisition of speech perception with a cochlear implant. Central effects associated with PMD may thus impact language learning potential; cognitive and behavioral therapy should be considered in rehabilitative planning and in establishing expectations of outcome.     

Cochlear implants: indications in groups of patients with borderline indications. A review

Cochlear implants (CI) represent the current treatment for patients affected by profound sensorineural hearing loss (SNHL). Initially only deaf adult patients were considered to be candidates for a CI; however, the development of technology and matured experience have expanded the indications for cochlear implantation. Today, CIs are implanted in adults and children and broader indications are followed. There are, however, a number of patients who do not completely fulfill the current indications and who are potential candidates for CI. The duration of deafness and residual hearing represent prognostic indicators for CI performance; however, the candidacy of children with residual hearing and prelingually deafened adults are still under debate. Anatomical variants such as cochlear ossification, cochlear malformation and chronic otitis media represented and still represent for some surgeons a contraindication to CI. The otological experience of CI surgeons and the advent of auditory brainstem implants have changed the approach to these patients, who may still benefit from hearing rehabilitation. This paper briefly analyses and reviews the results obtained in these groups of patients, who were not, at least initially, considered to be candidates for cochlear implantation.     

Problemy zdrowia psychicznego matek i ojców dzieci głuchych z implantem ślimakowym

Introduction

Child's deafness is a risk factor for the mental health of its parents. This study addresses a question whether mothers and fathers of the prelingually deaf children using cochlear implants (CI) experience a different intensity of psychopathology symptoms than parents of the hearing, typically developing children, and also if the intensity of those symptoms experienced by parents is related to how long their child is a cochlear implant user.

Material and methods

In this study participated 153 hearing parents of the deaf children using a single cochlear implant (111 mothers, 42 fathers), and parents of the hearing children. Mean age of deaf children was 72 months, cochlear implant use duration was between 1 and 124 months. The control group of parents has been selected taking into account their typically developing child's sex and age. The parents’ mental health has been assessed with Goldberg General Health Questionnaire GHQ-28 in Polish adaptation.

Results

Mothers of deaf, CI using children experience significantly more symptoms of anxiety and insomnia compared to the mothers of typically developing children, while fathers of these children show the tendency for the increased level of depression symptoms compared to the fathers from the control group. In the group of deaf CI children mothers relate substantially more somatic and anxiety symptoms than fathers, whereas level of experiencing depression symptoms and problems in everyday functioning is similar in mothers and fathers. No relation between the duration of child's CI use and parents’ mental health has been ascertained.

Conclusions

The mental health of parents of the deaf CI using children indicates that both mothers and fathers have problems in this sphere related to their child's deafness, but not to the duration of child's CI use. Parents of deaf, CI using children may need psychological help regardless of the time their child has been using the cochlear implant.     

Cost-utility of the cochlear implant in adults: a meta-analysis.

OBJECTIVE: To conduct a meta-analysis of the cost-utility of the cochlear implant in adults. DATA SOURCES: MEDLINE literature search, review of article bibliographies, and consultation with experts. STUDY SELECTION: Studies that reported (1) data on adults (age > or = 18 years) with bilateral, postlingual, profound deafness; (2) a health-utility gain from cochlear implantation on a scale from 0.00 (death) to 1.00 (perfect health); (3) a cost-utility ratio in terms of dollars per quality-adjusted life-year (QALY); and (4) at least 1 conventional statistical parameter (ie, SD, 95% confidence interval [CI], or P value). DATA EXTRACTION: From each study, we extracted the number of subjects, study design, health-utility instrument used, health-utility associated with profound deafness, health-utility gain from cochlear implantation, cost-utility of cochlear implantation, and reported statistical parameters. DATA SYNTHESIS: Weighted averages were calculated using a statistical weight of 1 per variance. Pooling 9 reports (n = 619), the health-utility of profoundly deaf adults without cochlear implants was 0.54 (95% CI, 0.52-0.56). Pooling 7 studies (n = 511), the health-utility of profoundly deaf adults after cochlear implantation was 0.80 (95% CI, 0.78-0.82). This improvement of 0.26 in health-utility resulted in a cost-utility ratio of $12,787 per QALY. CONCLUSIONS: Profound deafness in adults results in a substantial health-utility loss. Over half of that loss is restored after cochlear implantation, yielding a cost-utility ratio of $12,787 per QALY. This figure compares favorably with medical and surgical interventions that are commonly covered by third-party payers in the United States today.     

Unanswered questions concerning the indication for cochlear implant

In a discussion of the function of cochlear implant (CI), the following criteria should be mentioned: (1) If possible, all deaf persons (including the prelingually deaf and children) should benefit from CI. (2) Since the number of patients with late deafness is doubtlessly decreasing with better prevention and medical care (elimination of ototoxic damage, decrease of iatrogenic deafness), the percentage distribution of the deaf will be displaced in favor of the prelingually deaf. At present, the ratio of cases of late deafness to those of prelingual deafness among our CI candidates is 1:3. (3) The objective of CI must be to provide the advantage of the procedure to children as early as possible. This means that under certain circumstances a technique that is as low in risks as possible and with a handy implement should already have been used in patients at the age of 3 to 4 years.     

Cochlear implants in the geriatric population: benefits outweigh risks.

Cochlear implantation has become widely accepted as an effective means of hearing rehabilitation in severely and profoundly deaf individuals. In the elderly, cochlear implantation involves a number of unique issues that can affect patient outcomes. These factors include age-related changes in the auditory system, prolonged durations of deafness, diminished communication abilities, and coexisting medical and psychosocial problems. In general, the results of cochlear implantation in the elderly have been comparable with those of younger adults. Perioperative attention to medical and surgical details allows for safe insertion and a minimum of postoperative complications. Patients older than 65 have obtained excellent results by both audiologic and quality-of-life measures.     

The Effect of Cochlear-Implant-Mediated Electrical Stimulation on Spiral Ganglion Cells in Congenitally Deaf White Cats

It has long been observed that loss of auditory receptor cells is associated with the progressive degeneration of spiral ganglion cells. Chronic electrical stimulation via cochlear implantation has been used in an attempt to slow the rate of degeneration in cats neonatally deafened by ototoxic agents but with mixed results. The present study examined this issue using white cats with a history of hereditary deafness as an alternative animal model. Nineteen cats provided new data for this study: four normal-hearing cats, seven congenitally deaf white cats, and eight congenitally deaf white cats with unilateral cochlear implants. Data from additional cats were collected from the literature. Electrical stimulation began at 3 to 4 or 6 to 7 months after birth, and cats received stimulation for approximately 7 h a day, 5 days a week for 12 weeks. Quantitative analysis of spiral ganglion cell counts, cell density, and cell body size showed no marked improvement between cochlear-implanted and congenitally deaf subjects. Average ganglion cell size from cochlear-implanted and congenitally deaf cats was statistically similar and smaller than that of normal-hearing cats. Cell density from cats with cochlear implants tended to decrease within the upper basal and middle cochlear turns in comparison to congenitally deaf cats but remained at congenitally deaf levels within the lower basal and apical cochlear turns. These results provide no evidence that chronic electrical stimulation enhances spiral ganglion cell survival, cell density, or cell size compared to that of unstimulated congenitally deaf cats. Regardless of ganglion neuron status, there is unambiguous restoration of auditory nerve synapses in the cochlear nucleus of these cats implanted at the earlier age.