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PubMedDate not supplied

[Effects of cochlear implant on the morphofunctional state of spiral ganglion neurocytes].

This paper discusses the effects of cochlear implantation on spiral ganglion neurocytes. It presents morphometric data and hearing measurements obtained from the treated animals. Cochlear implantation led to the death of some neurons and compensatory rearrangement of others. The number of the survivors was greater than that of degenerative cells. The functional variations were consistent with changes in the quality of spiral ganglion neurons and amplitude of the SSP EP peak at different postoperative intervals.

Animals↗

PubMed1997

Meningitis after cochlear implantation in Mondini malformation.

Although the potential for CSF leakage and subsequent meningitis after cochlear implantation in the malformed cochlea has been recognized, this complication has not been previously reported. We report a case of CSF otorhinorrhea and meningitis after minor head trauma developing 2 years after cochlear implantation in a child with Mondini malformation. Leakage of CSF was identified from the cochleostomy around the electrode of the implant, and this leak was sealed with a temporalis fascia and muscle plug. Although this complication appears to be rare, care must be taken to seal the cochleostomy in children with inner ear malformations at the initial surgery, and any episode of meningitis after surgery must be thoroughly investigated to rule out CSF leakage from the labyrinth.

Cerebrospinal Fluid Rhinorrhea↗

PubMed2005

Cochlear implant complications: utility of federal database in systematic analysis.

OBJECTIVES: To explore the suitability of the Manufacturer User Facility and Distributor Experience (MAUDE) database (which is maintained by the Food and Drug Administration and has a mandatory reporting requirement) for systemic analysis of cochlear implant complications and treatments and, in so doing, analyze trends in cochlear implant complications for 2 periods, 2002 and pre-1998. DATA SOURCES: All events from 2002 and from before 1998 were considered. Events and action taken were categorized and tabulated. DATA SYNTHESIS: Because there was no null hypothesis, statistical analysis (chi2) was only used in comparing the 2 time frames. CONCLUSIONS: Structural limitations of the database, in addition to disparate reporting quality, made systematic analysis difficult. It was noted that spontaneous device failure accounted for the greatest single number of adverse events for both 2002 and the pre-1998 period (267/654 [41%] and 74/129 [57%], respectively), confirming earlier studies. A statistically significant decrease in spontaneous device failure and a significant increase in infections from the pre-1998 period to 2002 was observed. Flap problems ranging from extrusion to infection that required explantation were less frequently reimplanted than other problems requiring explantation, such as device failure or trauma. We considered new directions, including close collaboration with the new MedSun reporting system and conclude that while a valuable resource for narrative data, the current structure of the MAUDE database is only modestly useful for analyzing trends in complications and cannot answer several crucial questions, including device type comparisons. We suggest changing the current report format to include patient age, duration of implant, presence of anatomical abnormalities, and details on spontaneous device failures.

Cochlear Implantation↗

PubMed1987

Pathology as it relates to ear surgery. VI. Cochlear implantation.

The surgical anatomy and pathology of the cochlea have been reviewed in relation to cochlear implant surgery. Animal experimentation, as well as human temporal bone studies, have shown that the implant electrodes were well tolerated by the cochlea. The possible chemical and mechanical trauma induced by the electrodes can be avoided by better choice of shape, size, length and material of the implants. Long-term electrical stimulation did not seem to cause any deleterious effects on the neuronal population of the cochlea. In the present state of the art, cochlear implantation seems justified in well chosen cases.

Child↗

PubMed2004

Degree of modiolar coiling, electrical thresholds, and speech perception after cochlear implantation.

OBJECTIVE: Perimodiolar electrode arrays were developed to improve stimulation of specific neural populations and to decrease power consumption. Postoperative radiographs suggest that some arrays are more tightly coiled than others. The purpose of this study was to evaluate whether the degree of modiolar coil correlates with electrical threshold and/or performance measures postimplantation with the Nucleus CI24RCS (Contour) device. STUDY DESIGN: Retrospective review. SETTING: Cochlear implant center and a tertiary care hospital. PATIENTS: Twenty-eight adult cochlear implant recipients with normal cochlear anatomy who underwent implantation with the Nucleus C124RCS perimodiolar electrode and are at least 1 year postimplantation. INTERVENTIONS: Therapeutic. MAIN OUTCOME MEASURES: Radiologic degree of perimodiolar electrode placement (determined by a computer algorithmic analysis) compared with electrical thresholds and standard speech perception outcome measures at 1 year postcochlear implantation. RESULTS: No significant correlations were found between the degree of modiolar coiling of the electrode array and electrical thresholds and speech perception outcome measures at 1 year postcochlear implantation. CONCLUSIONS: The degree of coiling of a modiolar hugging electrode array was not directly correlated with the level of electrical thresholds or postoperative speech perception outcome measures. Appearance of coil tightness on postoperative radiographs could reflect either differences in array placement or intrinsic variations in cochlear anatomy, and variations in speech perception performance can be influenced by other factors, including length of deafness.

Adult↗

PubMed2003

Cochlear implant failure: imaging evaluation of the electrode course.

Cochlear implant (CI) is an electronic device used to rehabilitate patients with sensorineural hearing loss. The intent of this review is to demonstrate the normal position of the electrode on computed tomography (CT) and contrast this with various examples of the electrode malpositioning. Post-implantation CT is performed to localize the cause of implant failure in patients in which radiographs suggest an anomalous course of the electrode. A common cause of device failure is extrusion or malpositioning of the electrode. It is important for the radiologists to recognize this important aspect of device failure. Post-implant CT can help identify patients with malpositioned electrode in whom another attempt can be made by correctly re-implanting the electrode.

Cochlea↗

PubMed2002

The contribution of visual areas to speech comprehension: a PET study in cochlear implants patients and normal-hearing subjects.

Early visual cortex can be recruited by meaningful sounds in the absence of visual information. This occurs in particular in cochlear implant (CI) patients whose dependency on visual cues in speech comprehension is increased. Such cross-modal interaction mirrors the response of early auditory cortex to mouth movements (speech reading) and may reflect the natural expectancy of the visual counterpart of sounds, lip movements. Here we pursue the hypothesis that visual activations occur specifically in response to meaningful sounds. We performed PET in both CI patients and controls, while subjects listened either to their native language or to a completely unknown language. A recruitment of early visual cortex, the left posterior inferior temporal gyrus (ITG) and the left superior parietal cortex was observed in both groups. While no further activation occurred in the group of normal-hearing subjects, CI patients additionally recruited the right perirhinal/fusiform and mid-fusiform, the right temporo-occipito-parietal (TOP) junction and the left inferior prefrontal cortex (LIPF, Broca's area). This study confirms a participation of visual cortical areas in semantic processing of speech sounds. Observation of early visual activation in normal-hearing subjects shows that auditory-to-visual cross-modal effects can also be recruited under natural hearing conditions. In cochlear implant patients, speech activates the mid-fusiform gyrus in the vicinity of the so-called face area. This suggests that specific cross-modal interaction involving advanced stages in the visual processing hierarchy develops after cochlear implantation and may be the correlate of increased usage of lip-reading.

Auditory Cortex↗

PubMed2005

[The changes of fundamental frequency and formants of vowel in cochlear implant pre-lingual children of different age].

OBJECTIVE: To observe the changes of fundamental frequency and formants of vowel in cochlear implant pre-lingual children of different age and to provide the basis and direction for post-operative rehabilitation. To find the key period of language development from the aspect of phonetics and to illustrate the necessity of early implantation. METHOD: Nineteen pre-lingual cochlear implant children age from 3-13 who use 24 M or 24 Contour implant and Esprint speech processor participate the experiment. Voice analysis software was Vs99 which was explored by Beijing yangchen electronic technology corporation. Fundamental frequency and formants were abstracted from the sustained segment of vowel[a:]. RESULT: No significant difference of fundamental frequency was found between the age 4 group and normative group. Significant difference of fundamental frequency was found between the age 10 group and normative group (P < 0.05). No significant difference of formant 1 was found between the age 4 group and normative group. Significant difference of formant 1 was found between the age 10 group and normative group (P < 0.01). Formant 2 of the age 4 group was higher than the normative group, significantly. No significant difference of formant 2 was found between the age 10 group and normative group. No significant difference of the ratio of formant 1 to 2 was found between the age 4 group and normative group. Significant difference of the ratio of formant 1 to 2 was found between the age 10 group and normative group (P < 0.01). CONCLUSION: The phonation of the children from the age 4 to age 10 was obviously affected by age. This stage was the key stage for language development.

Adolescent↗

PubMed1999

Intracochlear schwannoma and cochlear implantation.

A case of intracochlear schwannoma in a 58-year-old candidate for cochlear implantation is described. The tumor was located in the basal turn of the cochlea and was discovered only during surgery. Computed tomography and magnetic resonance imaging obtained prior to surgery failed to detect the tumor. Intralabyrinthine schwannomas are rare tumors that grow either in the vestibule, as intravestibular schwannomas, or in the cochlea, as intracochlear schwannomas. Complete removal of this tumor was achieved through a posterior tympanotomy approach. Cochlear implantation, which resulted in good hearing, was successfully performed 3 years later.

Cochlear Implantation↗

PubMed1996

Within-subject comparison of speech perception benefits for congenitally deaf adolescents with an electrotactile speech processor and a cochlear implant.

This study assessed speech perception benefits for three congenitally deaf adolescents who used an electrotactile speech processor (Tickle Talker(TM)) and subsequently went on to use a Nucleus Minisystem 22 cochlear implant. Both devices provided significant and comparable benefits for all children in the device plus lipreading condition. All children benefited from the additional information provided by either the Tickle Talker(TM) or the cochlear implant, and were able to perceive speech information with these devices that was not available through either aided residual hearing or lipreading. None of the three children were able to understand open-set words or sentences using either hearing aids alone or Tickle Talker(TM) alone, without the aid of lipreading. Two of the children showed significant open-set speech perception benefits while using their cochlear implant alone.

Adolescent↗

PubMedDate not supplied

Cochlear implants: an international perspective--Latin American countries and Spain.

A questionnaire to determine the status of cochlear implant programs was sent to 11 countries in Latin America and Spain. General data were collected based on the population of each country (1996), estimate of population with hearing disorders based on the 10 per cent figure of the World Health Organization. number of people with congenital or acquired sensorineural hearing loss, and candidates for implantation (children and adults). The survey reports the number of people from each country who have been implanted, the cost with respect to per capita annual income (PCAI), and how many people with respect to PCAI would cover the cost of a country's entire program. Also reported are the number who were implanted pre- or post-lingually and the estimate of future new candidates for implantation per year. In conclusion, the paper discusses the ethical and socio-economic issues for cochlear implantation in so-called third world developing countries.

Adolescent↗

PubMed1999

Evaluation of cochlear implantation in post-meningitic adults.

Meningitis is an important cause of deafness and in some studies has been associated with poorer outcomes in adult patients following cochlear implantation. Of the first 100 adults implanted under the Midland Cochlear Implant Programme, 28 were deafened as a result of meningitis. We compare our experience with these patients with patients with a non-meningitic aetiology. A degree of cochlear ossification was a more common finding in the meningitic group. In six cases (four meningitis, two non-meningitis) ossification was encountered only during surgery, not being apparent on pre-operative radiology. The average scores achieved on auditory tests by the meningitic group were similar to those achieved by non-meningitic patients. At nine months, using only the implant, users were able to identify 54 per cent of common environmental sounds, achieved an average score of 30 words per minute on connected discourse tracking and identified an average of 42 per cent of words correctly in BKB sentences. Poorer outcomes were more commonly associated with cochlear ossification. In patients with cognitive and neurological sequelae, benefits with the implant were not always apparent in the early months, however, with intensive therapy these patients can obtain measurable sustained benefit from their implant.

Adult↗

PubMed1998

[Development and clinical testing of a non-magnetic cochlear implant. Preliminary experimental studies and surgical concept. Results in the first 10 patients].

BACKGROUND: To ensure good transmission of electromagnetic signals from the speech processor to the internal cochlear stimulator (ICS) in cochlear implants, exact alignment of the external transmitter coil over the receiver coil of the ICS is necessary. Usually this is achieved by two magnets: one implanted within the ICS, the other one integrated into the transmitter coil of the external headset. Although this principle works, there are some serious problems with the implanted magnet. The most serious of these is that it renders MRI studies potentially hazardous or impossible, or at least compromises image quality. METHOD AND RESULTS: We developed a method to eliminate the magnet. The method requires varying the implantation technique and using a special headset. The technique is easy to perform, and the headset is suitable for series production. Experience with our first patients revealed the coil alignment to be remarkably stable, even more than in patients with a cochlear implant equipped with a magnet. Results of the first ten patients are presented. DISCUSSION: Aside from eliminating the magnet, we attempted to optimize the acoustic properties of the headset. This resulted in design changes such as repositioning the microphone. Further improvements such as integration of telephone coils and special sockets to connect peripheral appliances can easily be implemented in our special headset.

Adult↗

PubMed1993

[Intracochlear placement of cochlear implant electrodes in soft surgery technique].

It is commonly accepted that the intracochlear placement of the cochlear implant electrode is potentially damaging to the hearing rests which may exist. Consequently, cochlear implants have been recommended for totally deaf ears only. The question has been raised whether or not it is possible to preserve residual hearing during intracochlear implantation through extremely careful surgical techniques. Experience has shown, that the cochleotomy of the scala tympani anterior to the round window niche, careful preservation of the fibrine endost layer and the use of Healon are amongst the surgical procedures described which may assist in retaining the rest function of the inner ear. These observations which are discussed in detail suggest that the experienced surgeon can effect preservation of residual hearing for patients who cannot derive significant benefits from conventional acoustic amplifiers.

Adult↗

PubMed1993

Cochlear implantation in the congenitally malformed ear.

A child with a congenital hearing loss and auricular malformations was evaluated for cochlear implantation. Preoperative radiologic studies demonstrated a common cavity cochlear malformation and a contralateral narrow internal auditory canal. Intraoperative findings included an aberrantly coursing facial nerve, preventing routine placement of the electrode array. The surgical approach was consequently modified and the cochlea was accessed through a malformed semicircular canal. Cochlear implantation can be performed safely and effectively in children with congenitally malformed ears.

Abnormalities, Multiple↗

PubMed2000

Modeling spoken word recognition performance by pediatric cochlear implant users using feature identification.

OBJECTIVE: Computational simulations were carried out to evaluate the appropriateness of several psycholinguistic theories of spoken word recognition for children who use cochlear implants. These models also investigate the interrelations of commonly used measures of closed-set and open-set tests of speech perception. DESIGN: A software simulation of phoneme recognition performance was developed that uses feature identification scores as input. Two simulations of lexical access were developed. In one, early phoneme decisions are used in a lexical search to find the best matching candidate. In the second, phoneme decisions are made only when lexical access occurs. Simulated phoneme and word identification performance was then applied to behavioral data from the Phonetically Balanced Kindergarten test and Lexical Neighborhood Test of open-set word recognition. Simulations of performance were evaluated for children with prelingual sensorineural hearing loss who use cochlear implants with the MPEAK or SPEAK coding strategies. RESULTS: Open-set word recognition performance can be successfully predicted using feature identification scores. In addition, we observed no qualitative differences in performance between children using MPEAK and SPEAK, suggesting that both groups of children process spoken words similarly despite differences in input. Word recognition ability was best predicted in the model in which phoneme decisions were delayed until lexical access. CONCLUSIONS: Closed-set feature identification and open-set word recognition focus on different, but related, levels of language processing. Additional insight for clinical intervention may be achieved by collecting both types of data. The most successful model of performance is consistent with current psycholinguistic theories of spoken word recognition. Thus it appears that the cognitive process of spoken word recognition is fundamentally the same for pediatric cochlear implant users and children and adults with normal hearing.

Case-Control Studies↗

PubMed2002

Contribution of speech rate to speech perception in multichannel cochlear implant users.

This study describes the effect of speech rate (fast, 11 syllables per second; medium, 9 syllables per second; slow, 6 syllables per second) on speech perception in 10 cochlear implant users. The speech perception performance was evaluated on the basis of the percentage score of syllables that were correctly recalled in sentences composed of 4 to 6 words. The percentage scores at the fast, medium, and slow speech rates were 15.7%, 39.0%, and 56.0%, respectively. The effect of speech rate slowing was significant (p < .0001). Variations in the effect of speech rate slowing were observed in the cochlear implant users. The improvement of speech perception by speech rate slowing was significantly (p < .005) related to the word test score and the score at the fast speech rate. The results reveal that the rate of speech is an important factor in improving the speech perception of cochlear implant users.

Cochlear Implants↗

PubMed2002

Neurophysiology of cochlear implant users I: effects of stimulus current level and electrode site on the electrical ABR, MLR, and N1-P2 response.

OBJECTIVE: As the need for objective measures with cochlear implant users increases, it is critical to understand how electrical potentials behave when stimulus parameters are systematically varied. The purpose of this study was to record and evaluate the effects of implanted electrode site and stimulus current level on latency, amplitude, and threshold measures of electrically evoked auditory potentials, representing brainstem and cortical levels of the auditory system. DESIGN: The electrical auditory brainstem response (EABR), electrical auditory middle latency response (EAMLR), and the electrical late auditory response (ELAR) were recorded from the same experimental subjects, 11 adult Clarion cochlear implant users. The Waves II, III, and V of the EABR, the Na-Pa complex of the EAMLR and the N1-P2 complex of the ELAR were investigated relative to electrode site (along the intra-cochlear electrode array) and stimulus current level. Evoked potential measures were examined for statistical significance using analysis of variance (ANOVA) for repeated measures. RESULTS: For the EABR, Wave V latency was significantly longer for the basal electrode (7) compared with the mid (4) and apical (1) electrodes. For the EAMLR and ELAR, there were no significant differences in latency by electrode site. For all subjects and each of the evoked potentials, the apical electrodes tended to have the largest amplitude and the basal electrodes the smallest amplitude, although amplitude differences did not reach statistical significance. In general, decreases in stimulus current level resulted in statistically significant decreases in the amplitude of Wave V, Na-Pa and N1-P2. The evoked potential thresholds for Wave V, Na-Pa, and N1-P2 were significantly higher for the basal Electrode 7 than for Electrodes 4 and 1. CONCLUSIONS: Electrophysiologic responses of Waves II, III, and V of the EABR, Na-Pa of the EAMLR, and N1-P2 of the ELAR were characterized as functions of current level and electrode site. Data from this study may serve as a normative reference for expected latency, amplitude and threshold values for the recording of electrically evoked auditory brainstem and cortical potentials. Responses recorded from cochlear implant users show many similar patterns, yet important distinctions, compared with auditory potentials elicited with acoustic signals.

Adult↗