Single-stage surgery for implant placement: a retrospective study

Single-stage implant placement surgery offers patients a number of advantages. These include reduced cost and time commitments and greater comfort, function, and convenience. This article reports on the results of using a single-stage technique with 58 patients fitted with 240 implants. No implant failures were detected in any patients prior to the final attachment of a Dolder bar. Among the 27 patients and the 125 implants followed for a longer period of time, 99.2% exhibited no signs of implant mobility or pain. Indicators of gingival health and oral hygiene ranged in quality from acceptable to ideal.     

Stimulus-inadequate sensations in cochlear implant patients

From August 1984 to April 1987 the Department of Otolaryngology at the Medizinische Hochschule in Hannover implanted the NUCLEUS 22 channel cochlear implant system (CI) in their first 56 adults. Since implantation, 27 (51%) patients have described undesirable sensations from their implant. These were defined as stimulus-inadequate sensations (SIS) and were classified into three types: 1) pain-like sensations; 2) high-frequency sensations; and 3) non-stimulation. Twenty-three patients were radiographically investigated by polytomography. All of the intracochlear electrodes were visualised and a correlation between SIS and the radiological findings was established. It was found that i) SIS similar to pain are caused by electrical stimulation of the mucous membranes and periosteum of the tympanic cavity; ii) the high-frequency SIS seemed to be due to non-physiological electrical stimulation of the basal ganglion cells; and iii) the reason for non-stimulation is probably damaged electrodes and fibrosis around the electrode. Conventional tomography is the method of choice for estimating the number and configuration of intracochlear electrodes.     

Intonation of musical intervals by musical intervals by deaf subjects stimulated with single bipolar cochlear implant electrodes

Aqueous alcoholic mallow flower extracts were analyzed both by HPTLC-densitometry in the reflectance mode at 530 nm and by reversed-phase HPLC with gradient elution. For the mallow flower anthocyanins the best chromatographic resolution was obtained by HPLC, which revealed only two main compounds, confirmed by FAB-MS: malvidin 3,5-O-diglucoside (malvin) and malvidin 3-O-(6"-O-malonylglucoside)-5-O-glucoside. The HPTLC densitometric method on cellulose plates provides accuracy, reproducibility and selectivity for the quantitative analysis of the anthocyanins and this method was shown to be much more sensitive than the HPLC-DAD system, at 530 nm. Both methods give comparable quantitative results for total anthocyanins when applied to mallow flowers from two different sources: Italy and Albania.     

Modulation detection interference in cochlear implant subjects

The aim of this study was to determine whether detection thresholds for amplitude modulated signals on a single electrode were influenced by a masking modulation on a second electrode in cochlear implant users. Data were collected from four post-linguistically deafened subjects using the Cochlear Limited prosthesis. Investigated were the effects of the spatial separation between test and masker electrodes, 0 to 5 electrodes (0 to 3.75 mm), and the amount of masking modulation: 24%, 48%, 72%, and 96% above detection thresholds. Initially, modulation detection thresholds for stimulation on a single electrode without masking modulation were obtained for a set of six electrodes in the middle of the array. Modulation detection thresholds on a fixed test electrode were then obtained with unmodulated and modulated masking on a second electrode, which was one of the six electrodes in the initial study. In both studies, thresholds were measured for modulated pulse duration at the modulation frequencies of 10-200 Hz. In the first study, the shape of the detection thresholds as a function of modulation frequency, the temporal modulation transfer function, generally resembled a low-pass filter for two subjects. For the other two subjects, the functions were relatively flat across modulation frequencies. In the second study, unmodulated masking resulted in a small elevation in detection thresholds across electrodes. Modulation detection interference (MDI), the difference between thresholds for the modulated maskers and the unmodulated masker, was greater for larger amounts of masking modulation than for smaller amounts of masking modulation. For three of the four subjects, MDI was higher for smaller spatial separations between the two electrodes than for larger spatial separations suggesting that a portion of MDI may be due to overlap of neural excitation distributions produced by stimulation on two electrodes in close proximity on the array.     

Outcome of rehabilitation of adult cochlear implant patients

Cochlear implantation is nowadays a well-accepted method of auditory rehabilitation in selected adults and children. We present rehabilitation data on 21 adult patients provided with the Nucleus CI22M.     

Educational placement of deaf children following cochlear implantation

The insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene has been postulated to be associated with CAD in some populations of European descent. As part of a study investigating metabolic and genetic factors in subjects with premature coronary artery disease (CAD), we examined the I/D polymorphism of the ACE gene in 134 subjects with premature CAD (105 men and 29 women, mean age 49 +/- 6 years) and 116 control subjects selected for health (71 men, 45 women; mean age 39 +/- 7 years). Both patients and controls were of French Canadian descent. As expected, significant differences were found between cases and controls with respect to age, plasma lipoprotein cholesterol, presence of smoking, diabetes and high blood pressure after correction for age. Multivariate analysis confirms the importance of age, HDL-C levels, smoking and apo B levels as determinants of CAD. Allele frequencies of the I and D polymorphism were 43.1% and 57.9% in controls, and 48.5% and 51.5% in CAD cases (chi 2 = 0.622, p = 0.430). No significant association between the I/D polymorphism and conventional cardiovascular risk factors, including plasma levels of lipids, lipoprotein cholesterol, diabetes or smoking, was found in cases or controls. Furthermore, the presence of the I/D polymorphism did not correlate with a history of hypertension or a family history of premature CAD in CAD patients. We conclude that, in our selected population, the I/D polymorphism of the ACE gene is not associated with CAD, conventional risk factors, or a family history of CAD. Although our sample size does not allow sufficient power to ascertain that the ACE I/D polymorphism is not associated with CAD, we do not recommend the routine measurement of the ACE polymorphism in our population to determine cardiovascular risk.     

Reconstruction of alveolar defects before implant placement

Guided bone regeneration and bone grafting have been used to reconstruct defective alveolar ridges in preparation for implant placement. This phase of implant treatment is critical to a successful overall result. Remarkable advances that have occurred in techniques and materials enable us to place and restore implants in cases where previously it was not feasible. Three case reports are presented to illustrate successful management of different alveolar defects.     

Studies of prosody perception by cochlear implant patients

Prosodic information is conveyed to normally-hearing listeners by variations in acoustic fundamental frequency, amplitude envelope, and duration of speech segments. This study measured cochlear implant patients' sensitivity to these parameters in electrically coded speech. The psychophysical discrimination of electric parameters used to code prosodic information, were examined, together with prosody perception using speech processing strategies which modified the contributions of these parameters. Patients were implanted with the Cochlear Limited prosthesis and used the MPEAK speech processing strategy. In the psychophysical studies, difference limens were measured for steady-state and time-varying stimuli, of different pulse rates and pulse durations, over a series of different stimulus durations. These limens were obtained using an adaptive procedure which converged on the 50 per cent correct point. In the prosody perception studies, performance was measured for the MPEAK strategy and for strategies which modified the contributions of pulse rate and pulse duration. Data were collected for five tests of prosodic contrasts. Difference limens for steady-state pulse rates were larger at higher rates (17 per cent at 400 pulses/s) than at lower rates (6 per cent at 100 pulses/s). For some patients, limens for the time-varying pulse rates were larger than those for the steady-state pulse rates while for the other patients, the limens were similar. Difference limens for pulse duration were 0.3 dB, corresponding to 4 per cent of the dynamic range, for steady-state stimuli and doubled in size for the time-varying stimuli. Prosody perception performance was generally poorer for the modified strategies than for the MPEAK strategy, suggesting that the removal of information coded by pulse rate and pulse duration reduced the perception of prosodic contrasts.     

Speech-evoked cognitive P300 potentials in cochlear implant recipients

The cognitive P300 evoked potential was elicited by speech stimuli in successful cochlear implant recipients, and the resulting P300 morphology was remarkably similar to that of normal-hearing individuals. The P300 was elicited by the synthesized speech pair/da/and/di/ presented using an oddball paradigm to nine "good" Nucleus cochlear implant users and nine age-matched normal-hearing subjects (34-81 yr old). There were no significant differences in P300 amplitude and latency between the two groups. Moreover, the N1 and P2 potentials occurred at similar latencies in the two groups, although the N1 amplitude was significantly smaller in the cochlear implant users. The P300 was absent in one "poor" cochlear implant user. The results suggest that the P300 may serve as a useful tool for evaluating the cognitive aspects of auditory processing in cochlear implant recipients, and that it may aid in assessing the success of cochlear implantation.     

Changes in vowel quality in post-lingually deafened cochlear implant users

The present study addresses the effect of cochlear implantation on vowel production of 20 post-lingually deafened Dutch subjects. All subjects received the Nucleus 22 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 first and second formant frequencies were measured for eleven Dutch vowels (monophthongs only) in an h-vowel-t context. Twelve months post-implantation, the results showed an increase in the ranges of the first and second formant frequency covered by the respective vowels when the implant was switched on. The increase in the formant frequency range was most marked for some subjects with a relatively small formant range pre-implantation. Also, at 12 months post-implantation with the implant switched on we found a significant shift of the first and second formant frequency towards the normative values. Moreover, at this time the results showed significantly increased clustering of the respective vowels, suggesting an improvement in the ability to produce phonological contrasts between vowels. Clustering is defined as the ratio of the between-vowel variance of the first and second formant frequency and the within-vowel variance of three tokens of the same vowel.     

Design, maintenance and biomechanical considerations in implant placement

Successful treatment using implants involves careful consideration of fixture placement and prosthesis design if the biomechanical conditions are to be optimized. These parameters may be related to the implant/tissue interface at the individual fixture level, and thence to the relationship between the components of a prosthesis. The influence of the nature and magnitude of occlusal forces can also be significant and should be carefully assessed before placement.     

Predictive factors for speech perception in patients with cochlear implant

Cochlear implant therapy is an epoch-making advance in artificial sensory organ transplants, but the positive effects on speech perception vary. Quantification theory type I, a multivariate analysis, was used to determine predictive factors for speech perception in patients with cochlear implants. Fifty-one postlingual deaf adults (18 male and 33 female, mean age, 53.4, mean duration of deafness, 8.6 years) were tested for speech perception three or more months after a Nucleus 22 channels cochlear implant. The cause of deafness in nine patients was labyrinthitis, ototoxicity in five, meningitis in three and unknown in the remaining 34. Speech perception was measured by vowel, consonant and word recognition using a live voice, and monosyllable, word and sentence recognition using a videodisc. All tests were administered in a sound only condition. Results of the univariate analysis indicated that age at implantation was correlated with monosyllable recognition, and duration of deafness was correlated with live voice word recognition. Residual hearing and coding strategy were both correlated with all outcome measures. The multivariate analysis revealed that coding strategy, duration of deafness, residual hearing and the number of electrodes were significant predictors of live voice word recognition in that order.     

Prosthetic considerations in the fabrication of surgical stents for implant placement

The utilization of surgical stents/templates for implant placement is of significant importance to the success of the definitive prosthesis. However, major conceptual differences exist between surgical stents designed for implant-supported crowns and bridges and those designed for implant overdentures. In addition, various types of surgical stents exist within each group. In either case, optimizing the prosthetic result by customization of the stent should be a major consideration in the fabrication process. The design of the stent must account for several treatment conditions, including position of the implant, the tissue present, and the anticipated prosthesis. The teaching objective of this article is to present the prosthetic considerations in the fabrication and customization of surgical stents. The article compares the two groups and offers specific guidelines for the fabrication of surgical stents for the various types of restorations within each group.     

Video-assisted thoracoscopic placement of paravertebral catheters: a technique for postoperative analgesia for bilateral thoracoscopic surgery

Paravertebral catheters were placed bilaterally through a Tuohy needle under direct video control in a patient undergoing video-assisted thoracoscopic (VAT) surgery for recurrent, bilateral pneumothoraces. Postoperative analgesia was produced by infusing bupivacaine through the catheters. This provided good analgesia. VAT placement of paravertebral catheters is easily accomplished and may be a part of the surgical procedure.     

Intensity discrimination and auditory brainstem responses in cochlear implant and normal-hearing listeners

Intensity-discrimination limens (IDLs) and auditory brainstem responses (ABRs) were measured as a function of stimulus intensity in 6 cochlear implant (CI) and 8 normal-hearing (NH) listeners. Pulse-train stimuli were delivered electrically to the auditory nerve in CI listeners and acoustically in NH listeners. In CI listeners, the IDLs expressed as Weber fractions decreased monotonically with increasing intensity. In NH listeners, a nonmonotonic IDL function showing a peak a midintensities was observed. ABR wave amplitudes increased regularly with intensity only in CI listeners. Results support the notion that the slight decrease in Weber's fractions with increasing sound intensity--generally referred to as "the near-miss to Weber's law"--is subtended by retrocochlear processes, whereas the increase in Weber's fractions at midlevels--known as "the severe departure from Weber's law"--originates in cochlear mechanisms.     

Complications of motility peg placement for the hydroxyapatite orbital implant

PURPOSE: The hydroxyapatite implant is an ocular motility implant designed to provide natural movement of the artificial eye. The movement of the prosthesis is maximized when the implant is coupled to the prosthesis via a peg. The purpose of this study is to determine the complications of the hydroxyapatite motility peg and the factors related to those complications. DESIGN: Retrospective review of 47 cases over 5 years. METHODS: A retrospective review was performed on all cases of hydroxyapatite motility peg placement. The technique of hydroxyapatite and peg placement, follow-up details, and complications of the peg were recorded. RESULTS: The complications of peg placement included peg extrusion in 26% (12 of 47), nonspecific conjunctivitis in 6% (3 of 47), audible click in 6% (3 of 47), temporary excessive conjunctival edema in 4% (2 of 47), and temporary excessive postoperative pain in 4% (2 of 47). There were no cases of infection, persistent pain, persistent edema, or discharge at peg site. The median time interval from peg placement to extrusion was 16 months (range, 1-52 months). The only statistically significant factor related to peg extrusion was age over 50 years (P = 0.04). There was a trend toward peg extrusion with use of a nonsleeved peg (versus sleeved peg) (P = 0.10). The extrusion rate was 32% (12 of 38) for nonsleeved pegs and 0% (0 of 9) for sleeved pegs. Factors unrelated to peg extrusion were patient sex, prior ocular surgery or radiotherapy, presence of giant papillary conjunctivitis, time interval from enucleation to peg placement, and degree of implant vascularization on magnetic resonance imaging. Of the 12 nonsleeved pegs that extruded, a sleeved peg system was subsequently successfully placed in 5 patients, a nonsleeved peg in 1 patient, and 6 patients remained without a peg system. CONCLUSIONS: Hydroxyapatite motility pegs have relatively few complications except for extrusion. The rate of extrusion can be minimized by employing a sleeved peg rather than a nonsleeved peg system.     

Electrode discrimination and speech recognition in postlingually deafened adult cochlear implant subjects

This study investigated the relationship between electrode discrimination and speech recognition in 11 postlingually deafened adult cochlear implant subjects who were implanted with the Nucleus/Cochlear Corporation multichannel device. The discriminability of each electrode included in a subject's clinical map was measured using adaptive and fixed-level discrimination tasks. Considerable variability in electrode discriminability was observed across subjects. Two subjects could discriminate all electrodes, and discrimination performance by the remaining nine subjects varied from near perfect to very poor. In these nine subjects, the results obtained from the discrimination tasks were used to create a map that contained only discriminable electrodes, and subjects' performance on speech recognition tasks using this experimental map was measured. Four different speech recognition tests were administered: a nine-choice closed-set medial vowel recognition task, a 14-choice closed-set medial consonant recognition task, the NU6 Monosyllabic Words Test [T. W. Tillman and T. Carhart, Tech. Rep. No. SAM-TR-66-55, USAF School of Aerospace Medicine, Brooks Air Force Base, Texas (1966)] scored for both words and phonemes correct, and the Central Institute for the Deaf (CID) Everyday Sentences test [H. Davis and S. R. Silverman, Hearing and Deafness (Holt, Rinehart, and Winston, New York, 1978)]. Seven of the nine subjects tested with the experimental map showed significant improvement on at least one speech recognition measure, even though the experimental map contained fewer electrodes than the original map. Three subjects' scores improved significantly on the CID Everyday Sentences test, three subjects' scores improved significantly on the NU6 Monosyllabic Words test, and five subjects' scores improved significantly on the NU6 Monosyllabic Words test scored for phonemes correct. None of the subjects' scores improved significantly on either the vowel or consonant tests. No significant correlation was observed between electrode discrimination ability and speech recognition scores or between electrode discrimination ability and improvement in speech recognition scores when programmed with the experimental map. The results of this study suggest that electrode discrimination tasks may be used to improve speech recognition of some cochlear implant subjects, and that each electrode site does not necessarily provide perceptually distinct information.     

Indications for middle ear obliteration within the scope of cochlear implant management

BACKGROUND: Cochlear implants have gained worldwide acceptance as a reliable method of rehabilitation of profoundly hearing-impaired patients. Due to thorough patient selection major postoperative complications rarely occur and are flap related in most cases. Deafness can develop during chronic suppurative otitis media, either coincidentally or secondary to the medical treatment; normally this condition is regarded as a contraindication for cochlear implantation. In cases with a mastoid cavity after surgical treatment for cholesteatoma, the electrode covered only by the epithelial lining will likely become exposed or extruded. Therefore we suggest the obliteration of the middle ear cleft with abdominal fat and the blindsac closure of the external ear canal before cochlear implantation in these conditions. PATIENTS: The average age of our 12 patients was 48 years, whereas the youngest was 2 1/2 years of age. Due to chronic inflammatory ear disease. 11 patients had a mastoid cavity on both ears. Eight patients had a cholesteatoma, the chronic bone destroying process in the temporal bone of two female patients was considered as a fibroinflammatory pseudotumor. The child had a congenital deafness in both ears with a Mondini dysplasia in CT scan. She had already developed two episodes of pneumococcal meningitis which was caused by a defect in the stapes footplate through which a liquor-filled cystic sac herniated in the middle ear. Because of a massive liquorrhoea after opening of the sac, we decided to obliterate the middle ear cleft after successful insertion of the electrode array. RESULTS: All active electrodes of 10 Nucleus implants (Cochlear) and two Clarion devices (Advanced Bionics Corp.) were successfully inserted in the cochlea of the 12 patients. After an average follow-up of 15 months, a temporary facial palsy in one patient and an insufficient closure of a retroauricular fistula over the mastoid cavity in two cases were observed as postoperative complications. One patient with a fibroinflammatory pseudotumor developed a massive inflammatory reaction in the implanted ear two months after cochlear implantation, which could not be controlled by conservative treatment. The implant had to be removed and local conditions settled after administration of immunosuppressive treatment with cyclophosphamide. The patient received a new implant seven months ago. CONCLUSIONS: Implantation of a foreign body in a potentially infected space which communicates intracranially means a surgical challenge which can be managed by obliteration of the middle ear after subtotal petrosectomy with abdominal wall fat combined with a reliable closure of the external ear canal. In case of massive inflammation we would prefer a two-stage procedure.     

Further experience with a straight, vertical incision for placement of cochlear implants

Experience with a straight, vertical incision for cochlear implantation in 168 patients of all ages is reported and comparison made with previous experience using a 'C' shaped incision in 173 patients with regard to complications encountered. With the straight incision the only complication was a wound infection which settled in one week; this is in contrast to the 'C' shaped incision, which was associated with a number of serious complications. The straight incision also compared favourably with the other incisions commonly used for cochlear implantation and appears to offer advantages over them.