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PubMed2002

Scala vestibuli cochlear implantation in patients with partially ossified cochleas.

Partial cochlear obstruction is a relatively common finding in candidates for cochlear implants and frequently involves the inferior segment of the scala tympani in the basal turn of the cochlea. In such patients, the scala vestibuli is often patent and offers an alternative site for implantation. The current report describes two patients with such partial obstruction of the inferior segment of the basal cochlear turn, caused in one case by systemic vasculitis (Takayasu's disease) and in the other by obliterative otosclerosis. A scala vestibuli implantation allowed for complete insertion of the electrode array. No problems were encountered during the surgical procedures and the good post-operative hearing and communicative outcomes achieved were similar to those reported in patients without cochlear ossification. The importance of accurate pre-operative radiological study of the inner ear is underscored, to disclose the presence and define the features of the cochlear ossification and ultimately to properly plan the surgical approach.

Adult↗
PubMed1988

Speech recognition by a deaf-blind multichannel cochlear implant patient.

A case study of the first deaf-blind patient implanted with a Nucleus 22 channel cochlear prosthesis is presented. The patient's preimplant evaluation data, using a powerful hearing aid and vibro-tactile device, are compared with results obtained 8 months postimplant. Preimplant testing indicated no consistent response to sound. Postimplant testing showed ability to comprehend some open set speech with hearing alone through the cochlear implant including ability to utilize the telephone without a code system. The postimplant data suggest potential benefit for other postlingually deaf-blind individuals from multichannel cochlear stimulation.

Blindness↗
PubMed1990

Promontory stimulation following labyrinthectomy: implications for cochlear implantation.

Transtympanic electric promontory stimulation is a psychoacoustic test used to assess residual acoustic neurons in profound sensorineural hearing loss. The test was performed in six patients who had previously undergone transmastoid (N = 5) or transcanal-oval window (N = 1) labyrinthectomy as a means of determining the feasibility of future cochlear implantation. Four patients had unilateral Meniere's disease, one had labyrinthitis, and one had delayed onset vertigo. All patients perceived a definite auditory sensation in the labyrinthectomized ear during stimulation. The results of threshold, dynamic range, and difference limen testing were similar to those obtained during preoperative stimulation of cochlear implant candidates (N = 12) who subsequently became successful users. There was no evidence of response degradations as the time following labyrinthectomy increased. The results of this study suggest the possibility of successful cochlear implantation following labyrinthectomy. Supporting histologic data are reviewed.

Acoustic Stimulation↗
PubMed2000

Effects of electrode location on speech recognition with the Nucleus-22 cochlear implant.

Speech recognition performance was measured as a function of electrode in two experiments with the Nucleus-22 cochlear implant using 4-electrode SPEAK speech processors. In experiment 1, the four stimulated electrode pairs were shifted in 0.75-mm steps over 3 mm in the apical-basal direction. In experiment 2, the four electrodes were closely spaced and positioned apically, medially, or basally. An additional condition spaced the four electrodes as widely as possible. In experiment 1, City University of New York sentence scores showed a significant decrease in performance as the electrodes were shifted basally; no other speech measures showed a significant change with electrode location. For experiment 2, all scores were the best with the processor that had the electrodes spaced as widely as possible. In both experiments, all 4-electrode SPEAK processors produced significantly poorer speech recognition than the subject's own 20-electrode processor. These results indicate that the location of electrodes is an important factor in implant performance.

Adult↗
PubMed1993

Auditory magnetic fields in cochlear-implant patients.

Neuromagnetic recordings were used to check if electrical stimulation of the auditory nerve in cochlear-implant patients activates cortical auditory areas in a similar manner as acoustic stimulation in normal hearing subjects or whether the excitation processes are different. The waveform of the evoked magnetic field complex elicited by electrical stimulation of the auditory nerve as well as the distribution of the magnetic responses over the head resemble that of auditory-evoked fields elicited by acoustic stimulation of normal subjects. The location and direction of the equivalent dipole are consistent with activation of the auditory cortex. Neuromagnetic recordings could be used in the future (i) to check activation of the auditory cortices in cochlear-implant patients; (ii) to gather information about the functional properties of this activity, and (iii) to study the integrity of central auditory pathways in totally deaf patients.

Auditory Cortex↗
PubMed2006

Some benefits and limitations of binaural cochlear implants and our ability to measure them.

We review new recognition and localization skills in patients using one or two cochlear implant(s). We observed one unilateral patient who showed localization performance above chance. We also provide evidence for binaural processing in bilateral cochlear implant patients, even when tested with speech from the front without noise. We unsuccessfully attempted to find correlations between localization and squelch, between these variables and pre-implant threshold differences, or these variables and post-implant recognition differences. We strongly believe that new tests are needed to examine the potential benefit of two implants. We describe three tests that we use to show a binaural advantage: cued recognition, movement direction, and recognition with multiple jammers.

Auditory Threshold↗
PubMedDate not supplied

Problems and issues in developing a cochlear implant programme for children.

This paper considers the implications for deaf children and their families of the establishment of a cochlear implant programme for children. The importance of recognizing that implantation affects the whole child and that a multidisciplinary whole-child approach is necessary is stressed. The elements of a cochlear implant support service for families with deaf children are described.

Child↗
PubMedDate not supplied

Vestibular function and cochlear implant.

The authors illustrate their personal experience relating to 32 patients, aged between 12 and 74 years, undergoing cochlear implant, in whom vestibular reflexes were evaluated before and after surgery. This series did not include cases of areflexia, but only 1 case of reduced vestibular reflexia consequently to surgery. In this case, owing to the probable intervention of central compensation processes, labyrinthine hyporeflexia never became clinically significant. These personal results enable the authors to affirm that preoperative vestibular reflexes do not offer elements able to influence the choice of the ear in which to perform the cochlear implant. In the series of patients reported by the authors, a cochleostomy by removal of the floor of the round window niche, following the suggestions of O'Leary et al., always headed the electrode implant. This contrivance may reduce or eliminate the negative effects on vestibular receptors indirectly caused by the consequent and inevitable alteration of perilymph pressure produced by the implant.

Adolescent↗
PubMed2006

Cochlear implantation in children with inner ear malformations.

OBJECTIVES: The aim of this study was to assess the outcomes of cochlear implantation in children with inner ear malformations (IEMs). METHODS: A retrospective review of 212 children who received implants from September 1994 to May 2004 was performed. Forty-six of them had radiologic evidence of IEMs. The preoperative evaluations, intraoperative findings, postoperative complications, and performance outcomes were analyzed. For the comparative analysis of performance outcomes, the children with IEMs were matched and compared with children with a normal inner ear who had received implants. Statistical analysis was performed with a repeated-measures analysis of variance. RESULTS: All of the children were studied with computed tomography and magnetic resonance imaging. Three-dimensional volume rendering of magnetic resonance images was performed in cases that were difficult to interpret because of structural complexity. The operative findings included aberrant facial nerves in 2 children and cerebrospinal fluid gushers in 22 children. Intraoperative fluoroscopic examination was performed to evaluate electrode placement. There were no serious postoperative complications. All children with IEMs achieved open-set speech perception abilities, except for the children with a narrow internal auditory canal (IAC), and showed progressive improvement of their speech perception abilities over time. There were no statistically significant differences in performance measured by the Common Phrases test between the 2 groups. Although the repeated-measures analysis of variance indicated that children with IEMs performed more poorly than those with a normal inner ear on the Phonetically Balanced Kindergarten test for phonemes, statistical significance was not found at 2 years after implantation. The children with a narrow IAC benefited from the implantation and used the device every day, although their speech perception abilities were limited. CONCLUSIONS: The results of the present study show that cochlear implantation can be performed relatively safely in deaf children with IEMs and that they receive considerable benefit from their implants. Substantial benefit can be expected from implantation in children with most kinds of IEMs, except for a narrow IAC, which is often associated with limited results.

Adolescent↗
PubMed2005

Cochlear implantation in a patient with eosinophilic otitis media.

Eosinophilic otitis media is an intractable middle ear disease with gelatinous mucoid fluid containing eosinophils associated with bronchial asthma and nasal allergy that sometimes induces deterioration of sensorineural hearing loss. Here, we report a case of eosinophilic otitis media in a 50-year-old woman who received a Nucleus 22 multi-channel cochlear implant in the right ear at the age of 42 years. She had received treatment for bronchial asthma, chronic sinusitis with nasal allergy and otitis media with effusion since the age of 30 years and had noted bilateral sudden deafness and vertigo at the age of 35 years. Preoperative CT and MRI showed cochlear ossification in the left ear, in which mastoidectomy was performed as treatment of eosinophilic otitis media. Long-term follow-up revealed that cochlear implant is indicated for deafness induced by eosinophilic otitis media, and an early decision for cochlear implant surgery is necessary. Steroid administration was remarkably useful in controlling eosinophilic otitis media in patients with bronchial asthma and chronic sinusitis with nasal allergy.

Asthma↗
PubMed2005

A temporal bone study of insertion trauma and intracochlear position of cochlear implant electrodes. II: Comparison of Spiral Clarion and HiFocus II electrodes.

In recent years, several new designs of cochlear implant electrodes have been introduced clinically with the goal of optimizing perimodiolar placement of stimulation sites. Previous studies suggest that perimodiolar electrodes may increase both the efficiency and performance of a cochlear implant. This is the second of two studies designed to examine the positioning of electrodes and the occurrence of insertion-related injury with these newer designs and to directly compare two perimodiolar electrodes to their predecessors. In our previous report we compared the Nucleus banded electrode with the Nucleus Contour perimodiolar electrode. In the present study, using the same protocol, we examine the Spiral Clarion electrode and its successor, the HiFocus II electrode with attached positioner. Eight Spiral Clarion arrays and 20 HiFocus II electrodes with positioners were inserted into human cadaver temporal bones. Following insertion, the specimens were embedded in acrylic resin, cut in quarters with a diamond saw and polished. Insertion depth, proximity to the modiolus and trauma were evaluated in X-ray images and light microscopy. The newer electrode was consistently positioned closer to the modiolus than the previous device whereas the angular depth of insertion measured for the two electrodes was similar. The incidence of trauma was minimal when either electrode was inserted to a depth of less than 400 degrees . However, severe trauma was observed in every case in which the HiFocus II with positioner was inserted beyond 400 degrees and in some cases in which the Spiral Clarion was inserted beyond 400 degrees . To evaluate the possible role of electrode size in the trauma observed we modeled both devices relative to the dimensions of the scala tympani. We found that the fully inserted HiFocus II electrode with positioner was larger than the scala tympani in approximately 70% of temporal bones measured. The results suggest that both the Clarion spiral and HiFocus II with positioner can be inserted with minimal trauma, but in many cases not to the maximum depth allowed by the design.

Cadaver↗
PubMed2003

Cortical responses to cochlear implant stimulation: channel interactions.

This study examined the interactions between electrical stimuli presented through two channels of a cochlear implant. Experiments were conducted in anesthetized guinea pigs. Multiunit spike activity recorded from the auditory cortex reflected the cumulative effects of electric field interactions in the cochlea as well as any neural interactions along the ascending auditory pathway. The cochlea was stimulated electrically through a 6-electrode intracochlear array. The stimulus on each channel was a single 80- micro s/phase biphasic pulse. Channel interactions were quantified as changes in the thresholds for elevation of cortical spike rates. Experimental parameters were interchannel temporal offset (0 to +/-2000 micro s), interelectrode cochlear spacing (1.5 or 2.25 mm), electrode configuration (monopolar, bipolar, or tripolar), and relative polarity between channels (same or inverted). In most conditions, presentation of a subthreshold pulse on one channel reduced the threshold for a pulse on a second channel. Threshold shifts were greatest for simultaneous pulses, but appreciable threshold reductions could persist for temporal offsets up to 640 micro s. Channel interactions varied strongly with electrode configuration: threshold shifts increased in magnitude in the order tripolar, bipolar, monopolar. Channel interactions were greater for closer electrode spacing. The results have implications for design of speech processors for cochlear implants.

Animals↗
PubMed2001

Development of functional electrical stimulators utilizing cochlear implant technology.

In 1983, R. Davis proposed the development of a functional electrical stimulator, based on multi-channel cochlear implant technology, for the restoration of function in spinal cord injured paraplegic subjects. In 1984, the US Veteran Administration funded the initial investigations including animal experiments and purchase of a FES stimulator based on the Nucleus 22 cochlear implant. In 1987, the US Food and Drug Administration approved an Investigational Device Exemption (IDE# G870142) for this FES project. In 1991, the first stimulator was implanted in a 21-year old male paraplegic subject (complete thoracic spinal cord lesion at level #10), who was subsequently able to stand and to perform one-handed tasks for up to 1h. In 1996-1997 development started on a new multi-function FES system. In 1998, a stimulator was implanted in a 35-year-old male paraplegic subject (complete thoracic spinal cord lesion at level #10). After 8 months of use providing multiple functions including bladder voiding, the implant's internal antenna wire broke. A modified implant (FES 24-B) is due to be implanted in July 2001.

Adult↗
PubMed1987

Cochlear patency problems in cochlear implantation.

Sensory deafness may be associated with partial or total obliteration of the cochlear scalae. Before undertaking cochlear implant surgery, a preoperative assessment of cochlear patency with high-resolution computed tomography (CT) is indicated. To determine the accuracy of pre-implant CT, a review of the radiographic and surgical findings in 36 implanted ears was performed. An abnormal CT scan was found to be a reliable predictor of compromised cochlear patency at operation. These findings help the surgeon to select the side most favorable for implantation and to anticipate problems that may be encountered during device insertion. A normal pre-implant CT scan, however, does not exclude the possibility of compromised cochlear patency. A 46% false negative rate was encountered, presumably because subtle degrees of osseous or fibrous obliteration of the cochlea are beyond the resolution by current generation CT scanners. In our opinion, the radiographic finding of cochlear ossification is not a contraindication to an attempt at cochlear implantation. The only assured way of determining the extent of cochlear patency is by performing an "exploratory cochleostomy" with fenestration of the basal cochlear turn. Drilling anteriorly through an ossified basal scala tympani will often expose an adequate lumen and permit insertion of even a long multichannel electrode into a partially ossified cochlea. Nevertheless, it is essential that the implant team be prepared with devices appropriate for whatever existing or surgically created lumen may be available.

Cochlea↗
PubMed2001

Cochlear implantation in children with large vestibular aqueduct syndrome and a review of the syndrome.

OBJECTIVE: Children with Large Vestibular Aqueduct Syndrome (LVAS) frequently develop speech and language skills prior to deterioration of their hearing. Operations designed to halt the progression of hearing loss have largely failed so the question of Cochlear Implantation in these children has arisen. It had been suggested that there would be technical difficulties in implanting these patients and, therefore, there had been an initial reluctance to proceed to implantation. The aim of the present paper is to assess surgical and functional outcomes in implanted children with LVAS and review the related literature. MATERIAL AND METHODS: From the 170 children assessed by MRI in the Nottingham Paediatric Cochlear Implant Programme, seven (4%) were identified as having LVAS. Four of these children were implanted and had at least 12 months follow up. Two of the children are on the waiting list for implantation and one child was not implanted because of absence of the cochlear nerve. Operative findings, complications and outcome measures were recorded. The auditory skills of the children were assessed before implantation and 1 year following implantation. A literature search was done to identify other series with experience in implanting children with LVAS. RESULTS: Full insertion of the electrode array was achieved in all our cases. After cochleostomy two patients experienced a mild CSF leak that was easily controlled by the muscle graft. On the first day post-operation two patients were nauseous and one had an episode of vomiting, however, all were discharged within 24 h of surgery. Initial outcome measures at 12 months post-implantation were encouraging showing significant progress in children's auditory skills. CONCLUSIONS: The results of the present study and the review of the literature suggest that LVAS is not a contraindication to implantation as initial concerns about severe perilymph leaks and surgical complications have proved to be unfounded. The post-operative progress of these children in listening skills also suggest that these children are suitable for cochlear implantation

Auditory Threshold↗
PubMed2000

Changes in stimulation levels over time in nucleus 22 cochlear implant users.

The purpose of this study was to evaluate changes that occur over time in the electrical stimulation levels of cochlear implant users. A retrospective review of program summaries for 26 postlingually deafened adult Nucleus cochlear implant users was completed. Program summaries were used to assess changes in electrical stimulation at threshold (T) and maximum comfort (C) levels. Comparisons were made at intervals including the subject's initial stimulation and 2-week, 3-month, 6-month, 1-year, and most recent programming sessions. Five patients had 5 years or more of implant use; 8 patients had 3 to 5 years or more of implant use; and the remainder had been using their implant for 2 to 3 years. No patient with less than 2 years of implant use was included. Results indicated that changes in stimulation levels occur gradually over time. Although the changes in stimulation levels from one programming session to the next were not significant, the changes in current requirements for both T and C levels were found to be significant when we compared the 6-month and most recent programming intervals.

Adult↗