Device Extrusion Research Articles

Otologics Fully Implantable Hearing System

To assess the safety of the Otologics fully implantable hearing system after 1 year of use in a Phase I clinical trial. Repeated-measures within-subjects design. Procedures were performed in a variety of facilities, including a university, military, and private hospital's ambulatory surgical center and outpatient clinical audiologic test facilities. Adult patients with bilateral moderate to severe sensorineural hearing loss. Surgical insertion of this prosthesis included an atticotomy to expose the incus, securing the transducer to the mastoid bone, attaching the transducer tip to the incus via insertion into a laser-drilled hole, and postauricular implantation of the microphone/battery/electronics capsule. Subjective patient benefit, aided sound field thresholds, and speech discrimination with the subject's own, appropriately fit, walk-in hearing aid(s) and the prosthesis were assessed. There were no pre-post-implant differences noted for bone conduction: slight differences were noted in the pre-post-implant air conduction results (p < 0.05). These differences were attributed to the healing process and reversed to almost preimplant assessment levels by the third-month evaluation. Pure-tone averages and monaural word recognition scores were slightly better for the walk-in-aided condition (p < 0.05), whereas the patient benefit scales favored the postoperative implant-aided conditions.Adverse effects of the implant were encountered on 14 occasions after the implantation of the 20 subjects. With the exception of partial device extrusions (that occurred later), all were rectified by the time of initial activation. At the 12-month data collection point, problems that had been encountered by subjects included 1) partial device extrusion (3 subjects), necessitating explantation in 2; 2) loss of external communication (2 subjects), resulting in 1 explantation; and 3) increased charging times beyond 1.5 hours (7), resulting in 3 explantations and 2 patients not using their device while awaiting explantation. Phase I trial results provide evidence that this fully implantable device can provide sound amplification to sensorineural hearing loss patients, with performance results similar to the patients' walk-in hearing aids.

Post-operative complications of cochlear implantation in adults and children: five years' experience in Maastricht

Although cochlear implantation is considered a safe method of rehabilitation for profoundly deaf individuals, a number of these patients suffer complications after surgery. To evaluate post-operative complications after cochlear implantation, a retrospective chart review was performed for 112 patients who had undergone implantation in the Maastricht Academic Hospital. Minor complications were defined as those that could be overcome by medical or audiological management. These occurred in 36 patients (32 per cent) and all were managed successfully. Major complications were defined as device extrusion and those requiring further surgery, and these were identified in four patients (3.6 per cent). These complications included wound infection and device failure mediated by middle-ear pathology. In cases of chronic otitis media, we recommend performance of cochlear implantation as a staged procedure. In order to reduce the post-operative incidence of acute otitis media, we recommend adenoidectomy, placement of ventilation tubes and early antibiotic treatment.

Intravitreal steroids in the management of macular oedema

The use of intravitreal corticosteroids in the management of macular oedema has recently gained widespread acceptance. New long-acting steroid preparations and methods of delivery have facilitated the use of these new modalities. This review describes the various types of macular oedema for which this therapeutic option is used and the results.

Histopathology of explanted AlphaCor due to keratoprosthesis extrusion

AlphaCor keratoprosthesis (KPro) is a new-concept poly (2-hydroxyethyl methacrylate) one-piece KPro that makes possible a two-step implantation technique easy to perform with a short learning curve. In literature an 18% incidence of AlphaCor removal due to melting complications is reported. The histopathology of corneal tissue removed during a re-operation while bearing an AlphaCor KPro has previously been described in the literature only in one report. Herein, the first histological features of an AlphaCor-corneal complex explanted because of KPro extrusion is described. The histopathology of the AlphaCor-corneal complex is characterized by mild inflammation in the corneal tissues, limited to the region surrounding the anteriorized and extruded part of the KPro. It is not possible to fully understand the mechanisms that trigger the device extrusion. One possible explanation could be a dislocation of the prosthesis in the corneal pocket due to the untied fixation stitch. Another explanation could be a foreign body reaction induced by KPro.

Bacterial Biofilm Formation on a Human Cochlear Implant

To report the characteristics of a bacterial biofilm from the surface of a cochlear implant. Bacterial biofilm formation on implanted devices causes intractable infections and device extrusions necessitating device removal, with loss of function. More information is needed about biofilm characteristics and interactions with the implant surface before better treatments can be designed. A retrospective case review was combined with a descriptive histological study of the surface of an otologic device. The receiver/stimulator device removed from a cochlear implant patient because of intractable infection and partial device extrusion was fixed and processed for microscopic examination. Its surface and the material present on its surface were analyzed using light and electron microscopy, focusing on surface texture, cell types, and bacteria species and extracellular polymeric substances present within the biofilm. Stereomicroscopic examination revealed extracellular polymeric substances, pinkish yellow in color, with spheres of uniform size scattered throughout, indicative of a biofilm containing Staphylococcus aureus. Biofilm density was greatest in depressions on the surface of the implant. Cross-sectional analysis revealed bacteria interspersed with polymorphonuclear leukocytes. Scanning electron microscopic examination demonstrated an amorphous layer of extracellular polymeric substances containing small filaments, bacteria, and inflammatory cells. Only Staphylococcus aureus was detected. Cochlear implant material can provide a surface for bacterial biofilm formation. Impressions can provide an environment conducive to biofilm establishment and growth, ultimately necessitating device removal, with loss of implant function. Biofilm characterization should aid in design of cochlear implant devices less susceptible to biofilm formation.

Revision cochlear implant surgery utilizing the Advanced Bionics HiRes 90K implant

For revision surgical procedures, the HiRes 90K implantation technique was modified to ensure adequate device stability particularly in the presence of an excessively large implant receiver well/recessed bed. The recessed bed for implants such as the CII Bionic Ear is significantly larger and deeper than is required for the HiRes 90K device. When such implants are replaced with the HiRes 90K, there is the possibility of instability of the implant receiver if the device is placed in the oversize recessed bed. The HiRes 90K device was secured by revision of the anterior aspect of the receiver well and placement of sutures over the implant. Modification of the channel between the implant bed and the mastoid cavity was necessary to accommodate the electrode fantail. Revision of the cochleostomy was required to permit insertion of the electrode array. The HiRes 90K device has been consistently stabilized in an excessively large receiver well with this technique. There has been no evidence of device migration, extrusion, or malfunction. Complete intracochlear electrode array insertion was achieved at revision surgery.

The Infected or Exposed Breast Implant: Management and Treatment Strategies

Among the potential complications associated with the use of breast implants are the risks of periprosthetic infection and device extrusion. There is little published information about the effective management of these situations. Conservative recommendations include antibiotic therapy and removal of the implant until resolution of the infection or until the wound has healed. A retrospective review identified patients with periprosthetic infection or threatened or actual device exposure treated by the senior author. Twenty-four patients encompassing 26 affected prostheses were available for review and were classified into seven groups based on initial presentation as follows: group 1, mild infection (n = 8); group 2, severe infection (n = 4); group 3, threatened exposure without infection (n = 3); group 4, threatened exposure with mild infection (n = 3); group 5, threatened exposure with severe infection (n = 1); group 6, actual exposure without clinical infection (n = 5); and group 7, actual exposure with infection (n = 2). To salvage the prosthesis in these patients, various treatment strategies were utilized. All patients with a suspected infection or device exposure were started immediately on appropriate antibiotic therapy (oral antibiotics for mild infections and parenteral antibiotics for severe infections). Salvage methods included one or more of the following: antibiotic therapy, débridement, curettage, pulse lavage, capsulectomy, device exchange, primary closure, and/or flap coverage. Twenty (76.9 percent) of 26 threatened implants with infection or threatened or actual prosthesis exposure were salvaged after aggressive intervention. The presence of severe infection adversely affected the salvage rate in this series. A statistically significant difference exists among those patients without infection or with mild infection only (groups 1, 3, 4, and 6); successful salvage was achieved in 18 (94.7 percent) of 19 patients, whereas only two of seven of those implants with severe infection (groups 2, 5, and 7) were salvaged (p = 0.0017). Ten (90.9 percent) of 11 devices with threatened or actual exposure, not complicated by severe infection (groups 3, 4, and 6), were salvaged. Several treatment strategies were developed for periprosthetic infection and for threatened or actual implant exposure. Patients with infection were placed on oral or intravenous antibiotics; those who responded completely required no further treatment. For persistent mild infection or threatened or actual exposure, operative intervention was required, including some or all of the following steps: implant removal, pocket curettage, partial or total capsulectomy, débridement, site change, placement of a new implant, and/or flap coverage; the menu of options varied with the precise circumstances. No immediate salvage was attempted in five cases, due to either severe infection, nonresponding infection with gross purulence, marginal tissues, or lack of options for healthy tissue coverage. Based on the authors' experience, salvage attempts for periprosthetic infection and prosthesis exposure may be successful, except in cases of overwhelming infection or deficient soft-tissue coverage. Although an attempt at implant salvage may be offered to a patient, device removal and delayed reinsertion will always remain a more conservative and predictable option.

Long-term effects of cochlear implants in children.

Since 1987, when the use of multichannel cochlear implants was initiated in children, candidacy has expanded; many thousands of children have received these devices, and results have revealed a wide range of performance. However, few long-term studies exist on a large population of these children. There have been concerns expressed that cochlear implant function might degrade over time, that devices and electrodes might migrate and extrude in the growing child, or that there might even be a deleterious effect of long-term stimulation of the cochlear nerve. The purpose of this study was to explore the long-term effects of implantation as a function of performance over time, reimplantation, and educational factors. We studied 81 children who received implants at a major academic medical center and were followed for 5 to 13 years. Results revealed significant gains in speech perception, use of oral language, and ability to function in a mainstream environment. There was no decrease in performance over time and no significant incidence of device or electrode migration or extrusion, and device failure did not cause a deterioration in long-term outcome. Multichannel cochlear implants in children provide perception, linguistic, and educational advantages, which are not adversely affected by long-term electrical stimulation.

Cochlear reimplantation: surgical techniques and functional results.

The most common indication for cochlear reimplantation is device failure. Other, less frequent indications consist of "upgrades" (e.g., single to multichannel), infection, and flap breakdown. Although the percentage of failures has decreased over time, an occasional patient requires reimplantation because of device malfunction. The varying designs of internal receiver/stimulators and electrode arrays mandate an examination of the nature and effects of reimplantation for the individual designs. The purpose of the current study was to investigate the reimplantation of several implant designs and to determine whether differences in surgical technique, anatomical findings, and postoperative performance exist. Retrospective chart review. The subjects were 33 of 618 severely to profoundly deaf adults and children who had implantation at the New York University Medical Center (New York, NY) between February 1984 and December 2000. The subjects had previously had implantation with either a single-channel 3M/House (House Ear Institute, Los Angeles, CA) or 3M/Vienna (Technical University of Vienna, Vienna, Austria) device or with one of the multichannel Clarion (Advanced Bionics, Sylmar, CA), Ineraid (Smith & Nephew Richards, TN), or Nucleus (including the Contour) devices (Cochlear Corp., Englewood, CO) before reimplantation. Length of use before reimplantation ranged from 1 month to 13 years and included traumatic and atraumatic (electronic) failures, as well as device extrusion or infection. Results indicated that postoperative performance was either equal to or better than scores before failure. None of the devices explanted caused damage that precluded the implantation of the same or an upgraded device. These findings support the efficacy and safety of internal implant designs as related to the maintenance of a functional cochlea for the purpose of reimplantation. Cochlear reimplantation can be performed safely and without decrement to performance. The number of implanted electrodes at reinsertion were either the same or greater in all cases.

Clarion cochlear implants: surgical implications.

The surgical aspects of 34 Clarion cochlear implants, positioned during a five-year period on 31 profoundly-deaf subjects as primary (11 children, 20 adults) and revision surgery (one child, three adults) were taken into consideration. Intra- and post-operative complications related to the specific structure of this device were considered along with the benefits obtained by update of the hardware and surgical approach. A smaller thickness of the internal receiver as well as the shifting from a retro-auricular/sub-temporal (RA-ST) to an endaural-retromastoid (EA-RM) approach have contributed to a dramatic drop in post-operative complications, such as skin defect or device extrusion. Special care should, however, be taken when cochlear implantation is planned in ears with chronic otitis or its surgical sequelae. From the two revised cases (hardware failure, electrode displacement) in whom re-implantation in the same side was performed, it has been demonstrated that the helicoidal shape of the electrode carrier is not inducing any additional trauma to the cochlear structure.

Cochlear implant in the child under two years of age: Skull growth, otitis media, and selection

Early cochlear implantation is desirable to effect maximal development of receptive and expressive language. Factors to consider in implanting before the age of 2 years include anatomic considerations, temporal bone growth and device extrusion or migration, the sequela of otitis media, and the accuracy of early diagnosis. Clinical experience and laboratory data indicate that cochlear implantation before the age of 2 years is possible. (Otolaryngol Head Neck Surg 1997;117:217-9.)

Multi-unit recording from regenerated bullfrog eighth nerve using implantable silicon-substrate microelectrodes

Multi-microelectrode silicon devices were developed for extracellular recording from multiple axons in regenerated eighth cranial nerves of American bullfrogs. Each includes a photolithographically defined array of holes and adjacent metal microelectrodes. A device is implanted within a transected eighth nerve; regenerating fibers grow through the holes en route to the brainstem. Multiple spike trains were recorded from two animals at up to 21 weeks after implantation. Single units were tracked for over 8 h. Some responded to sound with tuning typical of fibers innervating the amphibian and basilar papillae. Units of vestibular origin also were recorded. Action potentials were 30–140 μV P-P amid noise of 5–10 μV RMS, an adequate signal-to-noise ratio for spike detection and sorting. Histology confirmed that bundles of myelinated fibers grew through holes near electrodes that recorded activity. The implantation success rate was low, due to surgical morbidity, device extrusion, and lack of nerve regeneration through some devices. Future designs will address these issues and incorporate transistor amplifiers on devices to increase signal-to-noise ratios. The potential of implanted silicon devices to simultaneously record from many axons offers an opportunity for multicellular studies of auditory, vestibular and seismic signal processing in the vertebrate inner ear.