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PubMed2006

Flat-panel volume computed tomography for cochlear implant electrode array examination in isolated temporal bone specimens.

HYPOTHESIS: Flat-panel based volume computed tomography could improve cochlear implant electrode evaluation in comparison with multislice computed tomography. BACKGROUND: Flat-panel based volume computed tomography offers higher spatial resolution and less metal artifacts than multislice computed tomography. Both characteristics could improve the evaluation of challenging but important questions in cochlear implantation assessment, such as an exact imaging of cochlea, osseous spiral lamina, electrode array position, and single electrode contacts. These questions are not currently fully answered by multislice computed tomography. METHODS: Four isolated temporal bone specimens were scanned in a current multislice computed tomography scanner and in two experimental flat-panel based volume computed tomography scanners before and after cochlea implantation. To compare flat-panel based volume computed tomography and multislice computed tomography, four features were rated according to the following criteria: 1) visibility of the cochlea; 2) visibility of the osseous spiral lamina; 3) discernibility of individual electrode contacts; and 4) the ability to determine the electrode array position relative to scala tympani and scala vestibuli. Layer-by-layer microgrinding pictures were used as the ground truth for verification of imaging findings. RESULTS: Flat-panel based volume computed tomography was superior to multislice computed tomography in all four features rated. The cochlea and facial nerve canal were much better delineated in flat-panel based volume computed tomography. The osseous spiral lamina and single electrode contacts were only visible in flat-panel based volume computed tomography. Assessment of implant position with regard to the cochlear spaces was considerably improved by flat-panel based volume computed tomography. CONCLUSION: Cochlear implantation assessment could be improved by flat-panel based volume computed tomography and, therefore, would be highly beneficial for cochlea implantation research and for clinical evaluation. However, these first results were shown by scanning isolated temporal bone specimens; scanning whole human skull bases might be more challenging.

Artifacts↗
PubMed2003

Neuropsychological testing in the screening for cochlear implant candidacy.

OBJECTIVE: To demonstrate the utility of neuropsychological assessment in the screening process for pediatric cochlear implant candidacy. STUDY DESIGN: Prospective and ongoing evaluation of children with profound bilateral hearing loss using age-specific neuropsychological test batteries. METHODS: Eighteen children who met audiological criteria for cochlear implantation were evaluated by two age-specific neuropsychological tests. The Vineland Adaptive Behavior Scales survey assesses several domains of behavioral functions (communication, daily living skills, socialization, and gross motor skills). The Mullen Scales of Early Learning assess the child's visual perception, speech and language, and motor abilities. The Leiter International Performance Scale-Revised assesses intellectual ability. RESULTS: All patients underwent the Vineland Adaptive Behavior Scales survey. Overall scores were lower than normative means with a mean composite score in the 7th percentile. In addition, there was a strong inverse correlation between score and age of testing. Ten children were assessed using the Mullen Scales of Early Learning, and, again, there was a strong inverse correlation between score and age of testing. Intellectual ability was assessed in seven children using the Leiter International Performance Scale-Revised and was found to be lower than normative means with a mean score in the 13th percentile. CONCLUSIONS: Neuropsychological testing of profoundly deaf children provides a detailed and accurate assessment of the child's cognitive, behavioral, and motor functions. The profoundly deaf child does not develop at the same rate as normal children in cognitive and behavioral domains. Neuropsychological testing is a useful tool for screening for cochlear implant candidacy and has the potential to track changes before and after implantation.

Base Sequence↗
PubMed2003

Bilateral cochlear implantation in children.

AIMS: to determine the benefit of bilateral cochlear implantation in a child on speech and language development. METHOD: This child got her first implant, a Nucleus 24-system, on the right side at the age of 2.5 years. The left side was implanted at the age of 4.4 years with a Nucleus 24Contour-system. On the right side she's now wearing an Esprit 24-speechprocessor (SPR). On the left side she has a Sprint-SPR. M. goes to a mainstream school and receives Speech and Language therapy in a Speech and Hearing Rehab Centre. The etiology of her deafness was hyperbilirubinemia. Auditory capacity and speech recognition tests were performed for both ears separately and together. RESULTS: Aided thresholds give a PTA of 28 dBA with the first implant, 22 dBA with the second implant and with both implants we get a PTA of 23 dBA. Results for speech identification and recognition demonstrated an increased performance when both implants are used together. Speech and language development was equivalent to the mean of age 4.5. At the time of testing M. was 4.8 years. At this time the speech and language development show no delays with normal hearing children. CONCLUSIONS: bilateral cochlear implantation in children may have additional value for their speech and language development. Also, implantation may be considered when auditory neuropathy is likely.

Child, Preschool↗
PubMed1997

Cochlear implant in the child under two years of age: skull growth, otitis media, and selection.

Early cochlear implantation is desirable to effect maximal development of receptive and expressive language. Factors to consider in implanting before the age of 2 years include anatomic considerations, temporal bone growth and device extrusion or migration, the sequela of otitis media, and the accuracy of early diagnosis. Clinical experience and laboratory data indicate that cochlear implantation before the age of 2 years is possible.

Age Factors↗
PubMed2000

Speech, vocabulary, and the education of children using cochlear implants: oral or total communication?

This study examines the relationship between the teaching method, oral or total communication, used at children's schools and children's consonant-production accuracy and vocabulary development over time. Children who participated in the study (N = 147) demonstrated profound sensorineural hearing loss and had used cochlear implants for between 6 months and 10 years. Educational programs that used an oral communication (OC) approach focused on the development of spoken language, whereas educational programs that used a total communication (TC) approach focused on the development of language using both signed and spoken language. Using Hierarchical Linear Modeling (HLM) we compared the consonant-production accuracy, receptive spoken vocabulary, and expressive spoken and/or signed vocabulary skills, over time, of children who were enrolled in schools that used either OC or TC approaches, while controlling for a number of variables. These variables included age at implantation, preoperative aided speech detection thresholds, type of cochlear implant device used, and whether a complete or incomplete active electrode array was implanted. The results of this study indicated that as they used their implants the children demonstrated improved consonant-production accuracy and expressive and receptive vocabulary over time, regardless of whether their school employed a TC or OC teaching method. Furthermore, there appeared to be a complex relationship among children's performance with the cochlear implant, age at implantation, and communication/teaching strategy employed by the school. Controlling for all variables, children in OC programs demonstrated, on average, superior consonant-production accuracy, with significantly greater rates of improvement in consonant-production accuracy scores over time compared to children in TC programs. However, there was no significant difference between OC and TC groups in performance or rate of growth in consonant-production accuracy when children received their implants before the age of 5 years. There was no significant difference between the OC and TC groups in receptive spoken vocabulary scores or in rate of improvement over time. However, children in the TC group achieved significantly higher receptive spoken vocabulary scores than children in the OC group if they received their implant before the age of 5 years. The TC group demonstrated superior scores and rates of growth on the expressive vocabulary measure (spoken and/or signed) when compared to the OC group if they received their implants during their preschool or early elementary school years. There was no significant difference if the children received their implants during middle elementary school. Regardless of whether children were in the OC or TC group, children who received their implants during preschool demonstrated stronger performance, on average, on all measures over time than children who received their implants during their elementary school years. The results of this study suggest that children may benefit from using cochlear implants regardless of the communication strategy/teaching approach employed by their school program and that other considerations, such as the age at which children receive implants, are more important. Implications and future research needs are discussed.

Child Language↗
PubMed2005

Impact to the head increases cochlear implant reimplantation rate in children.

OBJECTIVE: To describe the outcome of cochlear implantation in children and to discuss the cause and management of cochlear reimplantation. STUDY DESIGN: Retrospective chart review. METHODS: The medical records of 110 patients younger than 18 years of age, who underwent cochlear implantation at the Department of ORL, Head and Neck Surgery, of the University of Kiel, Germany, were reviewed for demographics, complications, and history of revision surgery. The patients had previously had implantation with either Nucleus (including the Contour) devices or MED-EL devices. RESULTS: Length of use before cochlear explanation ranged from 4 days to 3.9 years. Reimplantation was caused by traumatic device failure, wrong electrode insertion and infection of implanted area. Results indicated a reimplantation rate of 5.4% in children compared to 0.8% in adults, mostly resulting from the greater risk of children receiving an impact to the head. Postoperative performance data showed no decrease in scores taken before failure. CONCLUSIONS: Though young children who are developing their motor skills are probably at greater risk of a cochlear reimplantation resulting from device failure following head trauma, surgical revision with reimplantation can be performed safely and without decrement to performance.

Adolescent↗
PubMed1999

The magnetless Clarion cochlear implant in a patient with neurofibromatosis 2.

We present our experience using the Clarion magnetless multichannel cochlear implant with a woman profoundly deafened following bilateral acoustic neuromata as a consequence of neurofibromatosis 2 (NF2). The right neuroma had been previously removed without an attempt at neural preservation. On the left, however, a posterior fossa approach had been taken with the aim of preserving hearing. Although the left cochlear nerve appeared to be undamaged at the end of the operation, no hearing thresholds could be elicited on post-operative audiometry, because of damage either to the cochlear nerve or to the blood supply to the cochlea. Round window electrical stimulation subsequently produced a perception of sound, confirming that the cochlear nerve was capable of functioning and that a cochlear implant would be effective. Because she would need regular magnetic resonance imaging (MRI) to monitor existing and future NF2 lesions, it was decided to use a magnetless Clarion implant, which has been shown to be MRI compatible. We report our experience of using the device in this case and discuss some of the issues related to the provision of cochlear implants to patients with NF2.

Adult↗
PubMedDate not supplied

Effect of cochlear implantation on voice fundamental frequency in post-lingually deafened adults.

The present study addresses the effect of cochlear implantation on the voice fundamental frequency at which 20 post-lingually deafened Dutch subjects utter speech materials. All subjects received the Nucleus 22 cochlear implant (3 WSP and 17 MSP processors). Speech recordings were made pre-implantation and three and twelve months post-implantation with the implant switched on and off. The fundamental frequency (f0) was sampled while reading a text. The pre-implantation results show that in some subjects, f0 was too high compared with the range in f0 of normally-hearing subjects. Post-implantation, with the implant switched on, we found that the abnormally high f0 values pre-implantation changed toward the normative values. In addition, post-implantation we found that the range over which f0 varied within a subject while reading the text, the f0 sway, decreased for most subjects who, pre-implantation, had their f0 sway outside the normative ranges, the normative range being defined as the interval between the mean plus/minus one standard deviation of the f0 sway found for normally-hearing subjects. Voice fundamental frequency of post-lingually deafened adults is characterized by large interindividual variability in the pre-implantation f0 values. This large interindividual variability is found also in the effect of cochlear implantation on f0.

Adult↗
PubMedDate not supplied

[Cochlear implant application with postlingually deaf patients].

Through last several decades, cochlear implant has been fully recognized for treatment of profound hearing loss. Modern technology development enabled unimagined possibilities in technical qualities of the device, as well as development of usable coding strategies, which led to extraordinary results of patient rehabilitation. It is well known that postlingually deaf implanted patients show better results than prelingually deaf implanted patients. This is to be understood, concerning the fact of matured hearing paths and centers of CNS, presence of developed speech in patients postlingually deaf, contrary to prelingually deaf patients in whom the development of hearing paths and centers is yet to be established only after cochlear implantation. Accordingly, this is a case report of male adult patient B.D. who was implanted because of complete deafness following the application of gentamicin. The results of implantation were excellent and fully justified the choice of the patient for CI application.

Adult↗
PubMed1994

Low-pass filtering in amplitude modulation detection associated with vowel and consonant identification in subjects with cochlear implants.

Temporal auditory analysis of acoustic events in various frequency channels is influenced by the ability to detect amplitude modulations which for normal hearing involves low-pass filtering with a cutoff frequency around 100 Hz and a rejection slope of about 10 dB per decade. These characteristics were established in previous studies measuring modulation transfer functions. For cochlear implant subjects, the delivery of detailed amplitude modulation information has been recently shown to result in very significant improvements in speech understanding. Several previous studies on cochlear implant subjects have reported capacities for temporal resolution rather equivalent to those of normally hearing subjects but with some notable individual differences. Recently two studies on some cochlear implant subjects indicated modulation transfer functions often quite similar to those of normal hearing but exhibiting marked individual differences in shape and absolute sensitivity. The present study compared amplitude modulation detection and phonetic recognition in a group of cochlear implant subjects to determine the extent to which the two tasks are correlated. Nine individuals who had been implanted with an Ineraid device and who demonstrated open speech understanding ranging from excellent to poor were chosen and tested in the present study. For each subject modulation transfer functions were measured at the most apical electrode and phonetic recognition of isolated vowels and intervocalic consonants was assessed. Results showed a strong correlation between the depth of high-frequency rejection in modulation transfer functions and success in vowel and consonant intelligibility. These results emphasize the importance of temporal speech features and offer perspectives for customizing signal processing in cochlear implants.

Adult↗
PubMedDate not supplied

Cochlear implantation after acoustic tumour resection in neurofibromatosis type 2: impact of intra- and postoperative neural response telemetry monitoring.

The present paper reports about a 16-year-old male with neurofibromatosis type 2 (NF-2) of the Wishart type with bilateral deafness who had undergone cochlear implantation after resection of the acoustic neuroma (AN) of the same side. Neural response telemetry (NRT) recordings are essential in those patients during cochlear implantation where no stapedial reflexes can be electrically elicited due to the resection of the AN. In the present case, amplitude growth function and a type II pattern of the NRT waveforms could be well established. The comparison of the N(1) response intra-operatively and after 2 years showed a decline in latency by 50% and an increase in absolute amplitude by 10 times at the same current level of electrical stimulation. This improved auditory nerve transduction suggested a change to a 'faster' encoding strategy to improve speech understanding. The change from SPEAK to ACE 18 months after the operation led to an increase in the open-set sentence recognition test from 52 to 88%. Thus, NRT recordings monitor the intra-operative success of electrode placement and help to assess the integrity of the auditory pathway. Moreover, they can reliably be used in programming the speech processor postoperatively as objective tool. In patients with NF-2, the restoration of hearing can be successfully achieved in several ways. The indications for hearing implants (auditory brain stem and cochlear implants) should be carefully considered with respect to the remaining, functional integrity of the auditory nerve and the technical possibilities to monitor the success of these procedures.

Action Potentials↗
PubMed1991

Medical imaging in cochlear implant candidates.

A retrospective study of preoperative radiographic surveys obtained in 85 cochlear implant patients was performed. A total of 90 cochlear implant patients were seen at our institution during the last 10 years. In three, the implant was placed at another institution. In two otosclerosis patients, no preimplant radiographic examination was obtained. Meningitis was the cause of deafness in 45 of 90 patients (50 percent); 28 of 40 pediatric age group patients (70 percent), and in 17 of 50 adult patients (34 percent). Thirty-three of 45 postmeningitis patients (73 percent) showed characteristic radiographic signs of sclerosing labyrinthitis or labyrinthitis ossificans. These signs were present in only one other patient who was deaf with unknown cause. Deformity of the inner ear sufficient to explain congenital deafness was noted in three cases; one Mondini deformity and two obliterated base of the cochlea (modiolus). Three otosclerosis patients who had preimplant radiographs, and one congenital syphilis patient showed classic radiographic signs of their respective diseases. Obliteration or stenosis of the round and/or the oval windows were observed in 26 cases drawn from all major etiologic groups. State-of-the-art high resolution, thin-section CT can demonstrate subtle changes that may be the only clue to the cause of deafness. MRI promises to be a useful technique to follow meningitis patients with membraneous labyrinth changes progressing to sclerosing labyrinthitis.

Adolescent↗
PubMed2001

Cochlear implants in five cases of auditory neuropathy: postoperative findings and progress.

OBJECTIVES: To review our experiences with some of the preoperative and postoperative findings in five children who were diagnosed with auditory neuropathy and were provided with cochlear implants. We describe changes in auditory function, which enabled these children to have significant improvement in their hearing and communication skills. STUDY DESIGN: Pre- and postoperatively, these children received complete medical examinations at Mayo Clinic, including related consultations in audiology, pediatrics, neurology, medical genetics, otolaryngology, psychology, speech pathology, and radiology. METHODS: These children typically had additional medical and audiological examinations at more than one medical center. The hearing assessments of these children included appropriate behavioral audiometric techniques, objective measures of middle ear function, acoustic reflex studies, transient (TOAE) or distortion product (DPOAE) otoacoustic emissions, auditory brainstem responses (ABR), and, in some cases, transtympanic electrocochleography (ECoG). After placement of the internal cochlear implant devices (Nucleus CI24), intraoperatively we measured electrode impedances, visually detected electrical stapedius reflexes (VESR) and neural response telemetry (NRT). These intraoperative objective measures were used to help program the speech processor for each child. Postoperatively, each child has had regular follow-up to assure complete healing of the surgical incision, to assess their general medical conditions, and for speech processor programming. Their hearing and communication skills have been assessed on a regular basis. Postoperatively, we have also repeated electrode impedance measurements, NRT measurements, otoacoustic emissions, and electrical auditory brainstem responses (EABR). We now have 1 year or more follow-up information on the five children. RESULTS: The five children implanted at Mayo Clinic Rochester have not had any postoperative medical or cochlear implant device complications. All of the children have shown significant improvements in their sound detection, speech perception abilities and communication skills. All of the children have shown evidence of good NRT results. All but case D (who was not tested) showed evidence of good postoperative EABR results. Otoacoustic emissions typically remained in the non-operated ear but, as expected, they are now absent in the operated ear. CONCLUSION: Our experiences with cochlear implantation for children diagnosed with auditory neuropathy have been very positive. The five children we have implanted have not had any complications postoperatively, and each child has shown improved listening and communication skills that have enabled each child to take advantage of different communication and educational options.

Audiometry, Evoked Response↗
PubMed2000

[Cochlear implantation and auditory feedback].

The aim of the present study was to evaluate the short term effect of cochlear implantation on the fundamental frequency and the articulation of 13 patients. This investigation objectives for the first time the changes of fundamental frequency and articulation in cochlear implant patients. All postlingual deaf patients were provided with a Combi 40+ cochlear implant. Voice recording was performed pre- and three months post-implantation. The voice data was analyzed using the "X-Tool" software. The results show that 38% of the patients had a significant (p < 0.05) decrease of F0 mean three months after implantation. A postoperative decrease of F0 towards the normal range was observed generally in all patients. Spectographs pre- and post-implantation showed that the articulation improved already 3 months after partial restoration of auditory feedback. A large variability of F0 was noticed among the deaf subjects, but no correlation to the duration of deafness could be established.

Adolescent↗
PubMed1994

Speech perception after multichannel cochlear implantation in the pediatric patient.

Clinical trials to evaluate multichannel cochlear implantation in children ages 2 to 17 years began in late 1986, with pre-market approval granted in 1990. To date, 870 children in the United States have received the Nucleus 22-channel device. Performance on measures of speech perception in 30 children who have used the Nucleus cochlear implant for a minimum of 6 months is presented and discussed in terms of the predictive value of patient biographic variables. Age at implantation and age to deafness onset were positively correlated with test performance for pre- and perilinguistically deafened subjects.

Adolescent↗
PubMed1988

[Cochlear implant for children? Possibilities--risks--prerequisites].

The development of scientific, technical, medical and psychological knowledge of human hearing and communication has reached a point where it seems possible to liberate totally deaf patients from their acoustic isolation. For some of them there is now reasonable hope that, to a certain degree, hearing and speech may be restored by the use of a cochlear implant. The cochlear implant is a device which directly stimulates the auditory nerve via electrical stimuli and in doing so mimics the function of the auditory system transmitting sound information to the central hearing pathways. It is expected that the human brain is able to "read" this message and, for example, to understand speech. But there are very special risks regarding implantation in children which are reviewed and discussed. Preconditions that have to be met to ethically, justify this experiment are stated, aiming at achieving maximum benefit for the child.

Audiometry, Evoked Response↗
PubMed2002

Speech dynamic range and its effect on cochlear implant performance.

This study examines optimal conversions of speech sounds to audible electric currents in cochlear-implant listeners. The speech dynamic range was measured for 20 consonants and 12 vowels spoken by five female and five male talkers. Even when the maximal root-mean-square (rms) level was normalized for all phoneme tokens, both broadband and narrow-band acoustic analyses showed an approximately 50-dB distribution of speech envelope levels. Phoneme recognition was also obtained in ten CLARION implant users as a function of the input dynamic range from 10 to 80 dB in 10-dB steps. Acoustic amplitudes within a specified input dynamic range were logarithmically mapped into the 10-20-dB range of electric stimulation typically found in cochlear-implant users. Consistent with acoustic data, the perceptual data showed that a 50-60-dB input dynamic range produced optimal speech recognition in these implant users. The present results indicate that speech dynamic range is much greater than the commonly assumed 30-dB range. A new amplitude mapping strategy, based on envelope distribution differences between consonants and vowels, is proposed to optimize acoustic-to-electric mapping of speech sounds. This new strategy will use a logarithmic map for low-frequency channels and a more compressive map for high-frequency channels, and may improve overall speech recognition for cochlear-implant users.

Adult↗