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Biomedical subjects

A F Snik

Publications and source records attributed to A F Snik.

At least 37 records · Page 2Linked to original sources
PubMed1998

The influence of the concentration of volatile anesthetics on the stapedius reflex determined intraoperatively during cochlear implantation in children.

OBJECTIVE: The goal of this study was, first, to determine the effect of the concentrations of volatile anesthetics (halothane and isoflurane) on the intraoperative elicited electrical stapedius reflex threshold (ESRT) and, second, to evaluate the relation between the ESRTs and postoperative C-levels. STUDY DESIGN: This was a prospective clinical study in a single subject design. SETTING: The study was conducted at University Hospital Nijmegen, which is a tertiary care and cochlear implant center in The Netherlands. PATIENTS: The study population comprised 13 deaf children (6 males and 7 females) undergoing cochlear implantation. RESULTS: In most of the children, increasing the concentration of volatile anesthetic agent resulted in higher stapedius reflex threshold. After correction for this effect, a good relation was found between ESRT and C-level in all children, except for one. CONCLUSIONS: The outcome of this study supports the determination of intraoperative ESRTs for programming of the speech processor postsurgery.

Anesthetics, Inhalation↗
PubMed1997

The relation between age at the time of cochlear implantation and long-term speech perception abilities in congenitally deaf subjects.

The issue of whether an upper age limit should be set for cochlear implantation in congenitally deaf subjects has often been debated. To gain more insight, the speech perception abilities were analyzed of 12 congenitally deaf subjects whose age at the time of cochlear implantation ranged from 4 to 33 years. Subjects implanted during adulthood only showed progress during the first few months after the speech processor had been fitted and their long-term results were poor compared to those of children implanted early in life. This latter group showed steady improvement over the whole evaluation period. The present results support the notion that the earlier in life implantation is performed, the better the development of speech perception. Based on the progress-over-time profiles and data on actual daily use of the cochlear implant, it can be suggested that implantation of congenitally deaf subjects during or after puberty offers only limited benefit.

Adolescent↗
PubMed1997

Cochlear implantation: a review of the literature and the Nijmegen results.

The field of cochlear implantation is developing rapidly. In subjects with bilateral profound deafness who gain no benefit from conventional hearing aids the aim of cochlear implantation is to provide a means for them to receive auditory sensations. Throughout the world, most cochlear implant centres are still continuing their research efforts to improve the results with this technique. Although it is still difficult to predict how an individual will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, we review some recent papers and reports, and the results of the various Nijmegen cochlear implant studies. Data about subject selection, examinations, surgery and the outcome are discussed. Our results were in good agreement with those of other authors. It can be concluded once again that cochlear implantation is an effective treatment for postlingually deaf adults and children, and for prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

Adolescent↗
PubMed1997

Speech perception performance of children with a cochlear implant compared to that of children with conventional hearing aids. I. The "equivalent hearing loss" concept.

A new measure has been developed to quantify the speech perception performance of children with a cochlear implant (CI). The method summarizes the speech perception scores obtained on a battery of tests that ranges from very basal tasks up to open speech recognition. The overall performance of a child with a CI on the test battery at a certain time during follow-up is matched to that of a reference group of severely and profoundly hearing-impaired children with conventional hearing aids. This matching procedure results in the expression of the speech perception scores of a child with a CI as an "equivalent hearing loss" value. The equivalent hearing loss concept deals adequately with floor and ceiling effects which inevitably occur when a battery with such a large range of tests is used. To illustrate this, application of the procedure to three children with a CI showed that before implantation, while they were using conventional hearing aids, the equivalent hearing loss was above 120 dB hearing level (HL). At 3 years' follow-up the equivalent hearing loss improved to 70 dB HL in the two children with an aetiology of meningitis. This means that these children were performing as well as children in the reference group with a hearing loss of 70 dB HL. The child with congenital deafness showed minor improvements over time.

Child↗
PubMed1997

Speech perception performance of children with a cochlear implant compared to that of children with conventional hearing aids. II. Results of prelingually deaf children.

In a previous paper, a method was introduced to transform the results obtained by children with a cochlear implant (CI) on a battery of speech perception tests into an overall value, the "equivalent hearing loss" value. This was achieved by matching the speech perception test scores with those of a reference group of children with conventional hearing aids and hearing loss ranging from 50 to 130 dB hearing level (HL). The equivalent hearing loss values of 16 prelingually deaf children with a CI were plotted as a function of time. There was considerable spread in the rate of progress made by the children in terms of the equivalent hearing loss values. The variables studied, age at onset of deafness/duration of deafness (in the present study, these two factors were indistinguishable) and the communication mode used at the children's school, accounted for 64% of the variance in speech perception performance. A plateau in the performance of the better performers was found which seemed to be caused by the level of hearing (the aided thresholds) with the CI.

Age of Onset↗
PubMed1997

Fitting hearing aids in children with severe hearing loss.

Because of limited initial data about the hearing loss of children and the difficulties in getting an optimal prescription, every fitting has to incorporate a procedure verifying or validating the final fitting. Fitting hearing aids should be focused on optimal speech recognition, even in children with very severe or profound hearing loss. When the MTS test is used, it is possible to optimize the gain and frequency response that gives the best possible prospects for speech recognition. The abilities for speech perception are a function of the PTA. For a hearing loss exceeding about 110 dB there are hardly any possibilities for adequate speech perception with hearing aids. Also, training on basal sound identification abilities shows no improvements. This is in contrast to hearing aid users with PTA between 90 and 110 dB.

Child, Preschool↗
PubMed1997

Long-term speech perception in children with cochlear implants compared with children with conventional hearing aids.

OBJECTIVE: To determine the speech perception of children with cochlear implants. SUBJECTS AND METHODS: Speech perception results of seven children with cochlear implants (excellent performers), who showed stable speech recognition scores in the long term, were compared with those of severely hearing-impaired children with conventional hearing aids (reference group). The groups of children were matched according to their mean free-field aided thresholds. RESULTS: The results of the open-set word recognition test were comparable in the two groups. CONCLUSION: If we consider the results of the hearing aid users as the gold standard, the results suggest that speech recognition in selected children with a cochlear implant is close to optimal.

Audiometry, Pure-Tone↗
PubMed1997

Speech perception performance of congenitally deaf patients with a cochlear implant: the effect of age at implantation.

The relation between age at cochlear implantation and long-term open-set speech recognition was studied in a group of nine congenitally deaf children. The age at cochlear implant surgery ranged from 4 to 13 years. The results showed that there was a tendency toward poorer results in the children implanted at a relatively older age. However, the results also indicated that an upper limit for age at implantation cannot yet be defined in these children.

Adolescent↗
PubMed1996

The relation between electric auditory brain stem and cognitive responses and speech perception in cochlear implant users.

Electrically evoked brainstem responses (EABR) and event-related cortical potentials were recorded in seven postlingually deaf adults who were experienced users of a Nucleus multichannel cochlear implant. The patients were divided into two subgroups: good performers and moderate performers. Poor EABR were found in two of the moderate performers. The latencies and amplitudes of the cortical N1 P2 complex in the good performers were within the same range as those of subjects with normal hearing, but were deviant in the group of moderate performers. This may indicate disturbed cochleotopical organization of the auditory cortex in the latter group. P300 measurements in the good performers showed normal latencies, whereas in the moderate performers they were prolonged. The results suggest that the outcomes of electrophysiological measurements to assess the integrity of a patient's auditory neural system on a brainstem and a cortical level, are related to the patient's performance with the cochlear implant.

Adult↗
PubMed1996

Detection of the binaural interaction component in the auditory brainstem response.

In humans, the binaural interaction at the brainstem level has been studied for over 15 years. The binaural interaction component (BIC) is obtained by subtracting the summed auditory brainstem response (ABR) in the monaural stimulus mode from the ABR obtained in the binaural stimulus mode. By nature of this subtraction process, the signal-to-noise ratio of the difference waveform is poor, requiring an objective detection criterion to decide whether a significant BIC is present. In this study, the effectiveness of two analysis methods was compared. The first method is the "3 SD' method, which is based on a signal-to-noise evaluation. The second method is a template matching method, in which templates are derived from normal hearing subjects' responses and individual responses are cross-correlated with these templates. The templates were allowed to shift over a range of -0.8 to 0.8 ms in search of the maximum correlation coefficient. Thirty-nine subjects with normal hearing and five patients with a unilateral profound hearing loss participated in the study. ABRs were obtained with rarefaction and condensation clicks at a rate of 15/s and a level of 70 dB nHL. Latencies of the ABR waves I, III and V for all normal hearing subjects and for the normal ear of the patients were within the normal range. The efficiencies of both methods, defined as the number of normal hearing adults with a significant BIC plus the number of patients without a significant BIC divided by the total number of subjects, were determined. The results show that the "3 SD' method is superior to the template matching method: the efficiencies were 95% and 70% respectively, when responses to rarefaction and condensation clicks were taken together. With the "3 SD' method, a significant BIC is demonstrated in almost all normal hearing subjects (97%). However, the "3 SD' method also falsely indicated a significant BIC in one patient. These results suggest that the BIC may have clinical value in studying binaural interaction in humans.

Adolescent↗
PubMed1996

Stapedius reflex measurements during surgery for cochlear implantation in children.

Electrically evoked stapedius reflex measurements were obtained in 19 children during surgery for cochlear implantation. They all received the Nucleus device. Stapedius reflexes could be elicited in all the children with congenital deafness but not in all the children with an etiology of meningitis. The intraoperative stapedius reflex thresholds were compared with postoperative values obtained after fitting of the speech processor and with the children's long-term behavioral most comfortable levels (C-levels). The intraoperative reflex thresholds were considerably higher than the postoperative reflex thresholds (44 "stimulus level steps" on the average), which could in part be ascribed to the influence of anesthetics used during surgery. It was concluded that, especially in children with an etiology of meningitis, the intraoperative stapedius reflex threshold (even after corrections for the concentration of the volatile anesthetics used) was a weak predictor of the C-level.

Adolescent↗
PubMed1996

Carriers of the Usher syndrome type IB: is audiometric identification possible?

Some studies in the past have shown that carriers of genes for recessive deafness cannot be identified by standard audiometry. However, remarkable results with regard to the identification of heterozygotes have been reported using Békésy audiometry and Audioscan audiometry. In the present study, nine obligate carriers from five families with the Usher syndrome type IB were examined. Methods that reflect the function of the cochlea, including pure-tone audiometry, Audioscan audiometry, and otoacoustic emission measurements were used to detect (subtle) audiometric manifestations of heterozygosity. Abnormalities in hearing sensitivity were found in some obligate carriers but to the same extent in some of the controls. No statistically significant differences were found in the presence of audiometric abnormalities between carriers and controls. Additional audiologic measurements indicated that if hearing loss was present in Usher type IB carriers, it was presumably of cochlear origin. It is concluded that carriers of the Usher syndrome type IB cannot be identified properly via standard audiometric methods.

Adult↗
PubMed1995

Patients' opinions of bone-anchored vs conventional hearing aids.

OBJECTIVE: To evaluate patients' opinions of the bone-anchored hearing aid (BAHA) compared with a conventional hearing aid. DESIGN: Prospective study with two questionnaires. Questionnaire A consisted of questions that compared patients' previous hearing aid with the BAHA. Questionnaire B consisted of questions about the patients' experiences with the hearing aids. PATIENTS: Sixty-five consecutive patients who had used conventional hearing aids. SETTING: Tertiary referral center. INTERVENTION: A percutaneous titanium implant in the temporal bone for the BAHA. MAIN OUTCOME MEASURE: Qualitative descriptive results of questionnaire A and difference scores from questionnaire B comparing conventional hearing aids and the BAHA. RESULTS: Patients favored the BAHA to the conventional bone-conduction hearing aid. Patients with BAHA reported a significant improvement in speech recognition in quiet and in noise, in sound quality, and in comfort (P < .01). The results with the BAHA compared with the air-conduction hearing aid were ambiguous for speech recognition, but all the patients reported a decrease in ear infections. CONCLUSION: The BAHA is a good alternative for the conventional bone-conduction hearing aid if a patient can no longer use an air-conduction hearing aid.

Audiometry, Speech↗
PubMed1995

Bone-anchored hearing aids in patients with sensorineural hearing loss and persistent otitis externa.

Recently, a new bone-conduction hearing aid has become available which can be connected percutaneously to the skull: the bone-anchored hearing aid or BAHA. Several clinical trials have shown its efficacy in patients with a conductive or mixed hearing loss. A second group of potential candidates are patients who suffer from an almost instantaneous skin reaction to any kind of earmould. Three such patients with a predominant sensorineural hearing loss were fitted with a BAHA. The aided free-field thresholds proved to be poor compared with the desired values using prescriptive rules. Speech recognition measured objectively (with tests) and subjectively (with a questionnaire) was comparable or better than with conventional bone-conduction hearing aids. Two patients were using their BAHA all day, whereas the third patient was only using it for a few hours per day. Although it did not produce optimal results, the BAHA seems to be the best solution for these patients.

Adolescent↗
PubMed1995

Otoacoustic emission measurements in evaluation of the immediate effect of ventilation tube insertion in children.

It is generally acknowledged that hearing assessment is needed before and after possible surgical intervention in children with otitis media with effusion. The conventional method in young children is visual reinforcement audiometry, which requires much time and cooperation from the child. The assessment of otoacoustic emissions may be an alternative, as it is proven to be rapid, easy, and objective as a screening procedure. We studied the applicability of click-evoked otoacoustic emissions to assess hearing acuity in children with otitis media with effusion who were scheduled for ventilation tube insertion. To avoid cooperation problems, the measurements were performed in the operating room immediately before and after ventilation tube insertion with the child under general anesthesia. None of the ears tested (n = 29) showed any increase in otoacoustic emissions when preoperative and postoperative levels were compared. At follow-up visits, however, 80% of the tested ears did. The acute outcome may be best explained by assuming that the surgical manipulations themselves were responsible, either through their fatiguing effects on the outer hair cells caused by the suctioning noise, or through their mechanical effects on the middle ear processes that govern reverse transmission from the cochlea to the outer ear canal. We conclude that it is not worthwhile to measure otoacoustic emissions directly after ventilation tube insertion to assess the effect on hearing acuity, although they may be valuable in the outpatient setting.

Adolescent↗
PubMed1995

Hearing-aid fitting in profoundly hearing-impaired children. Comparison of prescription rules.

Generally, the performance of a hearing-impaired child with his or her hearing aids is the major criterion in selection programmes for cochlear implantation. Thereto, it has to be considered whether the hearing-aid fitting is optimal. For this purpose, methods which prescribe hearing-aid gain are valuable, especially in young preverbal children. Three of these methods were evaluated by comparing the calculated and measured gain as a function of frequency in a selected group of profoundly hearing-impaired children (n = 16), all of whom were successful users of hearing aids. Fair agreement was found for the modified NAL rule applicable in profoundly hearing-impaired subjects and the DSL method (desired sensation level method).

Adolescent↗
PubMed1995

Measured and calculated insertion gains in young children.

The insertion gain measured in 34 children of up to 6 years of age with symmetrical sensorineural hearing loss, who were fitted successfully with binaural hearing aids, was compared in retrospect to the calculated insertion gain using two different prescriptive methods: the half-gain rule (HGR) and the desired sensation level method (DSL). The measured and calculated values were in fair agreement with the results of both of the prescription methods. The desired saturated sound pressure levels calculated using the DSL method and those measured on a 2-cc coupler were in fair agreement.

Audiometry↗