Reoperations after cochlear implantation

During the 14-year history of cochlear implantation at Semmelweis University, 95 implantations were performed. There were 15 reoperations, and 2 patients had been operated 3 times. All of the reoperated patients received round window or intracochlear MedE1 devices. Successful reinsertion of the electrode was performed without significant difficulty, though in some cases osteoneogenesis was found in the round window or in the scala tympani. None of the patients suffered any inner ear abnormalities due to the first implant, and even the patient with a third implant in the same ear had excellent results and obtained better discrimination scores with the new device. In the authors' opinion, on the basis of the accumulated experience of nearly 100 implantations and 15 reoperations, replacement of the early generation extracochlear implants is most advisable and can be accomplished without adverse effects.     

Pneumocoele after cochlear implantation

Abstract

Objective and importance

Scalp pneumocoele is a rare complication of cochlear implantation surgery. We present the largest case series to date; consisting of four cases over 8 years from one centre. The presentation, diagnosis, and management of each case are reviewed. Previously unreported complications of pneumocoeles are highlighted.

Clinical presentation

Three of our four cases, consisting of two adults (aged 53 and 81 years) and one child (aged 26 months), developed scalp pneumocoeles within the first 3 months of implantation. Another child (aged 10) developed pneumocoele 7 years after surgery. The common diagnostic features include a soft, non-tender, fluctuant swelling over the receiver/stimulator package. In all cases, pneumocoeles were triggered by Valsalva's or Toynbee's manoeuvres. Complications include infection (case one) and reduction in cochlear implant (CI) function (cases three and four), secondary to displacement of the receiver/stimulator package or electrode displacement.

Intervention/technique

Diagnosis is made from clinical history and examination. Aspiration results in reduction of pneumocoeles. This is not necessary for smaller pneumocoeles as they may resolve spontaneously. Additional investigations may reveal complications of pneumocoeles, such as X-rays for implant displacement, and inflammatory marker to detect signs of infection. To prevent the recurrence of pneumocoeles, patients are advised to avoid Valsalva's or Toynbee's manoeuvres. There were no recurrences of pneumocoeles.

Conclusion

Post-cochlear implantation pneumocoeles can be associated with harmful complications such as infection and CI dysfunction. The mechanism of pneumocoele formation is discussed, and strategies for its prevention are examined.     

Tinnitus after cochlear implantation

Objective

The purpose of this study was to investigate properties of tinnitus which starts after cochlear implantation. Of the 17 adult patients in our cochlear implant group, four (23.5%) who had no pre-implantation tinnitus were eligible for the study.

Methods

Each patient was requested to complete a short questionnaire regarding his or her experience with tinnitus. Tinnitus match test was performed for each patient by using an Interacoustic Clinical Audiometer (model AC40; Assens, Denmark).

Results

Tinnitus match test revealed a tinnitus frequency of a 4 KHz for three and of a 6 KHz for one patient. Mean value of the loudness score was calculated as 17.5 dB SL.

Conclusions

The results of this study emphasize the importance of counseling patients regarding risks of tinnitus after cochlear implantation.     

Change of phonation control after cochlear implantation.

OBJECTIVE: To assess the influence of acquired auditory control on some voice parameters in deaf children and adults after cochlear implantation. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary referral center. PATIENTS: Twenty-nine prelingually deafened children and 11 postlingually deafened adults. INTERVENTIONS: The samples of a vowel /a/ were analyzed with an Multi-Dimensional Voice Program (Kay Elemetrics Corporation, Lincoln Park, NJ) before and 6 to 12 months after the cochlear implantation. MAIN OUTCOME MEASURES: The average fundamental frequency (F0), the short-term variation of F0 (JIT) and the amplitude (SH), the very long-term variation of F0 (vF0) and the amplitude (vAm), and the noise-to-harmonic ratio (NHR) were determined and compared for both age groups. The results of the acoustic analysis performed before the implantation were compared with the results after the implantation for children and adults. RESULTS: Significantly greater JIT, SH, vF0, and vAm were detected in the children than in the adults before and after the implantation. The prelingually deafened children significantly improved the control of their phonation after 6 to 12 months' use of the cochlear implant (JIT: p=0.014, SH: p=0.011, vF0: p=0.014, vAm: p=0.031). In the postlingually deafened adults, no significant improvement was found in any of the studied voice parameters after the implantation. F0 showed little or no change after the implantation in children and adults. CONCLUSION: As expected, the voice quality of the prelingually deafened children was significantly worse than that of the postlingually deafened adults. After cochlear implantation, the children significantly improved their short-term and long-term F0 and amplitude variability. In adults, no significant improvement was detected. We suppose that the improvement is a consequence not only of the acquired hearing control but also of the adaptation ability of neuromuscular phonation control and the maturing of these control mechanisms in children. In adults, better phonation quality in general and lesser improvement after the implantation can be the results of well-developed and stable phonation patterns.     

Electrode failure and device failure in adult cochlear implantation

Abstract

Objectives

To determine the prevalence of cochlear implant electrode failure and the relationship with overall device failure.

Methods

Electrode status was analyzed in 322 functioning and in-use devices from 366 adult cochlear implant patients currently followed at our center. An additional 21 devices that had been explanted were also analyzed. Electrode failure was defined as unacceptably high impedance alone or in combination with aberrant percepts.

Results

At least one electrode had been turned off in 173 devices (54%). Most deactivated electrodes were the basal-most and had been turned off to improve sound quality. Of 437 deactivated electrodes, 33 were considered to have failed and were represented in 22 devices. These 22 devices are still in use (mean: 43.0 ± 29.8 months) without further electrode failures or device failure. There were no statistically significant differences in electrode failure rates among device manufacturers. There were 21 devices explanted of which 10 were due to device failure. One of five hard failures and two of three soft failures had deactivated electrodes prior to explantation. Two failures had no electrode data available.

Discussion

An inherent risk of cochlear implantation, as with all implanted electrical prostheses, is device failure. Failure of individual electrodes has been postulated to represent an early indicator of impending device failure. Our data demonstrate that electrode failure does not necessarily predict impending device failure. Although maps containing deactivated electrodes are fairly common, electrode failure as a reason for bypassing an electrode is rare and is often manageable with programming.     

Long-term complications after cochlear implantation

Objective

Cochlear implantation has become an effective treatment for many profoundly deaf patients. As with any surgical procedure, a proportion of patients suffer postoperative complications. The aim of this study was to analyze long-term postoperative complications in patients with cochlear implants with a view to improve clinical interventions and propose a consensus for reporting complications.

Methods

A total of 406 cases received cochlear implants between December 1985 and April 2007 at Tokyo Medical University (TMU) Hospital. We retrospectively reviewed case notes from 366 patients who had undergone cochlear implantation (215 adults and 151 children) after excluding 40 patients of re-implantation including 13 cases implanted initially at other hospitals. Life-threatening, major and minor complications were examined retrospectively.

Results

Major complications occurred following cochlear implantation in 32 patients (8.7%) who had received their initial implant at TMU Hospital. Revision surgery was required for 30 patients. The mean age at implantation was 33 years 6 months (range, 1 year 9 months to 83 years; median, 37 years). The main etiology of deafness was unknown or progressive (113, 52.6%) in adults and congenital (132, 87.4%) in children. The cause of deafness was meningitis in 41 cases (11.2%), and 26 cases (7.1%) were diagnosed with idiopathic sudden deafness.Flap-related problems (including middle ear infection and/or flap necrosis) developed in 13 cases (3.6%), with 12 cases (7 adults, 5 children) requiring re-implantation. Electrode slip-out occurred in 8 patients (7 adults, 1 child). All adult cases in whom electrodes slipped out underwent implantation before 1994, while the child (1 pediatric case) was operated in 2003. All cases required re-implantation and most cochlear implantations were performed using the modified split-bridge technique after 1997. Six patients (4 adults, 2 children) experienced device failure. Four patients experienced electrode problems. Non-surgical major complications included 1 patient with permanent facial nerve paralysis as a result of thermal injury in 1995.The total number of minor medical and surgical complications was 27, representing 7.4% of all operations.

Conclusion

Many cases of major complications, including electrode problems and facial paralysis, excluding traumatic device failure were considered avoidable by strict operative and postoperative procedures. Some cases of flap infection and traumatic device failure may not be able to be avoided completely, and every possible care should be taken by implant patients and others involved.     

Contralateral recovery of cochlear function after cochlear implantation

Significant recovery of sensorineural hearing loss in either ear after cochlear implantation (CI) is rare. We present the case of a 57-year-old lady with medically treated depression and a background of chronic suppurative otitis media (CSOM) in the non-implanted ear, who clearly fulfilled audiological criteria for CI. Two years post-implantation her CSOM in the non-implanted ear was addressed with blind sac closure of the ear. Post-operatively the hearing thresholds in this ear had improved to the extent that a bone-anchored hearing aid became a viable option. The literature is carefully reviewed to consider possible explanations of this phenomenon.     

Tinnitus modifications after cochlear implantation

Tinnitus can be defined as a phantom sensation in the absence of an external sound. In our study, we evaluated the effect of cochlear implant on tinnitus evolution. Among adult, postlingually deaf patients who underwent cochlear implantation at our clinic, we selected 20 subjects with pre-implantation tinnitus (group A) and 10 subjects without pre-implantation tinnitus (group B). Pre- and post-surgery tinnitus was assessed through two questionnaires: the first one dealing with tinnitus characteristics and psychosocial impact, and the second one represented by THI, an internationally validated score of evaluation of the effects of tinnitus on patient’s emotions and activities of daily living. None of the patients belonging to group B developed tinnitus after surgery. As for group A, 40% of patients declared suppression of tinnitus, 30% attenuation of tinnitus after surgery, 25% reported tinnitus was unchanged and 5% reported worsening of tinnitus. In the nine patients with bilateral tinnitus (45%), after implantation tinnitus disappeared from both sides in four patients and attenuated bilaterally in four patients. A comparison between pre- and post-implantation THI scores showed decreased score in 65% of cases, unchanged score in 30% and increased score in 5%. The beneficial effect of cochlear implant on tinnitus, reported by a majority of patients, could be due to acoustic masking, to direct electrical stimulation of the acoustic nerve, and above all to a possible cochlear implantation dependent reorganization of the central auditory pathways and associative cerebral areas. In the light of these results, the authors propose (1) to include tinnitus in the selection criteria of which ear to implant; (2) to consider implantation eligibility for patients with bilateral severe hearing loss associated with severe tinnitus; and (3) to inform patients about the small risk of post-operative tinnitus worsening.     

Professional occupation after cochlear implantation

The aims of this study were to verify whether cochlear implants helped profoundly deaf adults to maintain or even to develop their professional occupations, and to identify other elements that may contribute to or, on the contrary, impede such patients' professional success. All adult patients received a questionnaire concerning their professional activities before and after implantation. Demographic data, health information, hearing performance and degree of satisfaction with the implant were also considered. Sixty-seven adults had been implanted, with three different devices, since 1985. At the time of implantation, 34 had been professionally active. After implantation, 29 had remained professionally active, four of whom reported positive developments in their careers. Five patients had become professionally inactive. Those patients who had previously been professionally inactive remained so. There had been no difference in performance, either between different types of cochlear implants or between professionally active or inactive patients. The implanted patients had kept their jobs and many of them had developed their professional skills. In spite of this, cochlear implants may still be perceived as proving insufficiently satisfactory hearing to enable professionally inactive patients to reintegrate and to facilitate further learning or career developments.     

Language outcomes after cochlear implantation

This article presents a focused review of language, speech, and comprehension outcomes in children with cochlear implants. Language acquisition with early-age implants and later-age implants are discussed, along with literacy and comprehension skills. A wide range of language outcomes is possible for children with cochlear implants, but many can achieve listening and spoken language skills at the same rate as their hearing peers. Appropriate auditory rehabilitation and parental guidance is vital for the development of listening and spoken language skills.     

Conservation of residual acoustic hearing after cochlear implantation.

OBJECTIVE: This study was designed to test the hypothesis that partial hearing conservation is attainable after cochlear implantation with a long perimodiolar electrode. Surgical strategies for hearing conservation during cochlear implantation are described. STUDY DESIGN: Prospective, single-subject, repeated-measures design. SETTING: Academic tertiary care center. PATIENTS: Twenty-eight severely to profoundly hearing-impaired adult cochlear implant recipients who had some measurable hearing preoperatively. INTERVENTION: Cochlear implantation using Nucleus Freedom Contour Advance electrode. MAIN OUTCOME MEASURES: Preimplant and postimplant pure-tone thresholds and speech recognition scores were obtained to determine the incidence and degree of conserved hearing at a mean interval of 9 (+/-3.9) months. RESULTS: Thirty-two percent of subjects experienced complete conservation of hearing (0- to 10-dB loss), and 57% experienced partial conservation of hearing (>11 dB) after implantation. However, open-set speech recognition was partially conserved in only one subject. Cochlear implant performance was not better in patients with conservation of residual hearing. CONCLUSION: Conservation of pure-tone hearing was possible in 89% of implanted patients; however, residual speech perception was not conserved with this long perimodiolar electrode. A ceiling effect tends to inflate the prevalence of hearing conservation in implantation studies of severely to profoundly hearing-impaired patients.     

Migration of the ball electrode after cochlear implantation.

OBJECTIVE: To review the postoperative radiographic investigations of patients implanted with a cochlear implant. STUDY DESIGN: Retrospective case series. PATIENTS: Thirty-nine patients (22-77 yrs old) implanted for sensorineural deafness in the cochlear implants program of the Academic Medical Center of Amsterdam. INTERVENTION: Cochlear implantation with Cochlear Nucleus 24 Contour and Cochlear Nucleus Freedom (Cochlear Corp., Lane Cove, New South Wales, Australia) implant. RESULTS: This retrospective analysis of the postoperative computed tomographic scans showed that, in a large number of the implantations, the external ball electrode of the cochlear implant migrated from the insertion place toward the magnet of the receiver/stimulator unit of the implant. It seems that this migration of the external ball electrode does not influence the function of the cochlear implant and the result of the hearing rehabilitation in the short term. CONCLUSION: Because of the magnetic field of the receiver/stimulator unit of the cochlear implant and the magnet of the external transmitting coil of the speech processor, it seems to be possible that the extracochlear ball electrode can migrate in the space between the temporal bone and the temporal muscle during the postoperative healing phase. The importance of our observation is still not clear.     

Cortical activation shortly after cochlear implantation

We evaluated the cortical activations in postlingually deaf cochlear implant (CI) users in the early period (0-2 months) of CI usage. The subjects were 8 early CI users and 8 normal subjects. With tone burst stimuli (1 kHz) delivered to the right side, strong and broad activation of the ipsilateral (right) primary auditory cortex with 2 peaks and weaker activation of the contralateral (left) temporal lobe were observed in early CI users, in a clear contrast with the normal subjects in whom activation was observed in a small area of the contralateral (left) primary cortex. With word stimuli, activation of the superior frontomedian cortex presumably including the supplementary motor area and the neighboring cingulate gyri was observed in early CI users, which was absent in normal subjects. The activation in the immediate association cortices near the primary area was lower in early CI users, while the periphery of the association cortex seemed to be more mobilized.     

Trends in rehabilitation after cochlear implantation

Although postimplant rehabilitation is generally considered to be an important aspect of a cochlear implant program, the literature reports widely varying practices in the implementation of such programs. The National Institutes of Health consensus statement on cochlear implantation (May 1988), while recognizing that aural rehabilitation facilitates maximal use of the implant, offers no specific guidelines or recommendations. A questionnaire survey was made of over 200 otolaryngologists to determine current practices in a variety of aspects of their cochlear implant programs. Results were obtained from a total of more than 1400 patients, including adults, adolescents, and children. Rehabilitation is an integral part of the cochlear implant program in the vast majority of active programs surveyed. General aspects of cochlear implant programs, as well as those of rehabilitation programs in particular, are discussed.     

Facial nerve stimulation after cochlear implantation

OBJECTIVES: This study was designed to compare the incidence and nature of facial nerve stimulation (FNS) in patients receiving cochlear implants (CI) manufactured by Cochlear Corporation, Advanced Bionics Corporation, and MedEl. STUDY DESIGN: Retrospective chart review at a tertiary referral center. METHODS: The charts of 600 patients who received CIs from 1993 to 2003 with at least 1 year of follow-up were reviewed for significant FNS (FNS on at least 1 channel at functional stimulation levels). Data collected included age, sex, etiology of deafness, device type, electrode, FNS onset after initial stimulation, number and location of electrode contacts causing FNS, and loudness level at which FSN occurred. Nucleus straight and perimodiolar electrodes were also compared. RESULTS: Thirty-nine of 600 (6.5%) patients had FNS on at least one channel, (MedEl 3 of 43 [7.0%], Nucleus 29 of 440 [6.6%], and Clarion 7 of 117 [6.0%]). The incidence of FNS in Nucleus perimodiolar electrodes (16 of 250 [6.4%]) was similar to straight electrodes (13 of 190 (6.8%]), as was the mean number of electrodes causing FNS per patient (11 vs. 12). However, straight electrodes caused stimulation at significantly softer perceived loudness levels than perimodiolar electrodes (P < .0001). CONCLUSIONS: In this large series of CI FNS, the overall incidence of FNS is consistent with previous reports. All devices had a similar incidence of FNS, but perimodiolar electrodes produced FNS only at significantly higher loudness levels than straight electrodes, making them preferable for patients at risk for FNS receiving Nucleus devices.     

Foreign body reaction after cochlear implantation

Cochlear implantation is a widely accepted, safe procedure for patients with severe to profound sensorineuronal hearing loss. While complications are rare, revision surgeries are required for complications like device failure, misplaced electrode, flap necrosis, and wound infection. Foreign body reaction is a rare complication following cochlear implantation. We experienced a case of foreign body reaction after cochlear implantation treated by device removal. Foreign body reaction has to be considered as one of several causes in cochlear implantation cases that show symptoms mimicking recurrent wound infection or delayed extrusion. We report a case of foreign body reaction with a literature review.