Effect of experimentally induced otitis media on cochlear implants

Cochlear Implantation in Children with Otitis Media

One of the concerns during the cochlear implant candidacy process is the presence of chronic otitis media which could delay the implantation process. The aim of this study was to evaluate the surgical difficulties and the long-term complications in children with otitis media and to examine whether it is necessary to delay the implantation until the infection is resolved. The study used a comparative retrospective design based on chart review of all patients who received their implant(s) from January to December of 2012. A total of 200 patients were identified and were followed for 4 years post surgery. Patients were divided into three groups based on their history of otitis media (non-otitis media, chronic otitis media with effusion, and acute otitis media). Data included long-term complications, operative time and duration from first clinical visit to the time until implantation was received. None of study participants had long-term complications during the study period. The operative time was longer in the acute otitis media group with a difference of 45 min. The average delay in cochlear implantation due to the presence of otitis media in chronic group was more than 5 months. Pediatric patients with otitis media could be implanted in one stage safely and effectively.

Effect of otitis media with effusion on cochlear implant surgery: technical difficulties, post-operative complications and outcome

Objective:

This study evaluated the complications and outcomes of cochlear implantation in patients who had otitis media with effusion at the time of surgery.

Methods:

A retrospective chart review study was performed of 87 consecutive paediatric patients (age range 22 months to 10 years, mean 4.8 years) who underwent successful cochlear implantation, with follow-up periods of 5–6 years. All patients had unilateral implants, with eight on the left side. All devices were activated two weeks after implantation. The effect of the middle-ear condition on the procedure, post-operative complications and outcome were evaluated.

Results:

Unilateral ears of 17 otitis media with effusion patients were implanted with some surgical difficulties but no long-term post-operative complications.

Conclusion:

For children admitted for cochlear implantation who are subsequently found to have otitis media with effusion, surgeons should be aware of possible surgical difficulties. Greater intra-operative risks should be anticipated and more surgical time allowed for cochlear implantation in these patients.

Biomaterials in cochlear implants

The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces.

As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices.

This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development.

Cochlear implantation and management of chronic suppurative otitis media: single stage procedure?

In a series of 360 patients who underwent cochlear implantation at our center, four patients (five procedures) had cochlear implantation with obliteration of the mastoid cavity and management of cholesteatoma as a single-staged procedure. Three patients were bilaterally deaf secondary to CSOM and had bilateral mastoid cavities, and in one patient congenital cholesteatoma was identified during cochlear implantation. A mastoidectomy or revision mastoidectomy with obliteration of the mastoid cavity and cochlear implantation was performed as a single stage procedure. Cholesteatoma reoccurred in one patient 9 years after cochlear implantation. Surgical procedures, complications, follow-up and outcomes are discussed.

Cochlear implants in young children

The cochlear implant is best characterized as a device that provides access to the sound environment. The device enables the hearing pathway to respond to environmental and speech sounds, providing informational cues from the surroundings and from others that may escape visual detection. As the developmental effects of a profound hearing loss are multiple, cochlear implants have been applied to ever younger children in an attempt to promote a more normal level of developmental learning through audition. In deafness, transducer elements of the inner ear fail to trigger auditory nerve afferent nerves in the presence of sound input. However, large reserves of afferent fibers exist even in the auditory nerve of a profoundly deaf patient. Furthermore, these nerve fibers retain the ability to respond to prosthetic activation. Through developmental learning in the early, formative years, auditory centers of the brain appear capable of processing information from the implant to provide speech comprehension and oral language development. Multichannel implants have replaced original single channel designs. multichannel devices enable larger percentages of recipients to recognize the spoken word without visual cues because they provide spectral information in addition to temporal and intensity cues. Testing under conditions of auditory (implant)-only input reveals significant open-set speech understanding capabilities in more than 75% of children after three years of device use. The benefit provided by implants may vary with a number of conditions including: hearing history, age of deafness onset, age at implantation, etiology of deafness, linguistic abilities, and the presence of a motivated system of support of oral language development. Patient variables should be given individual consideration in judging candidacy for a cochlear implant and in planning rehabilitative and education services after surgery and activation of the device.

Cochlear implantation update

Cochlear implantation is recognized as a valuable intervention with important implications for the acquisition of speech perception and verbal language in children with severe to profound hearing impairment. Auditory rehabilitation, language intervention, and close coordination between parents, schools, and the implant center are necessary to maximize efficacy. Early identification of hearing loss, early hearing aid use and language intervention, and cochlear implantation by 2 years of age are positive predictors for language acquisition that can approach the levels of normal-hearing children. There are early indications that increased access to mainstream education and gains in quality of life are long-term benefits that render cochlear implantation a cost-effective intervention.

Cochlear implantation in the presence of chronic suppurative otitis media

Nine patients are presented who underwent cochlear implantation in the presence of chronic suppurative otitis media. Four had a simple tympanic membrane perforation, four had a pre-existing mastoid cavity and one had cholesteatoma in the ear chosen for implantation. Patients with a simple perforation had a staged procedure with myringoplasty followed by cochlear implantation after an interval of three months. Patients with cholesteatoma or with an unstable mastoid cavity were also staged. A mastoidectomy or revision mastoidectomy was performed with obliteration of the middle ear and mastoid using a superiorly pedicled temporalis muscle flap and blind sac closure of the external meatal skin. After a further six months a second stage procedure was performed to confirm that the middle-ear cleft was healthy and to insert the implant. Patients presenting with a stable mastoid cavity underwent obliteration of the cavity and implantation of the electrode as a one-staged procedure. To date there have been no serious problems such as graft breakdown, recurrence of disease or implant extrusion, and all patients are performing well.

Otitis media in children with cochlear implants

Fifty children who received a cochlear implant between 1991 and 1995 were evaluated for incidence of acute otitis media (AOM). Thirty-seven (74%) children had AOM before implantation and 8 (16%) after implantation. All children who had AOM after implantation had a history of AOM. A subgroup of 14 children required ventilating tubes for recurrent AOM before implantation. Five (35.7%) in this group had AOM after implantation. The incidence and severity of AOM decreased after implantation. All episodes of postimplant AOM were successfully treated with routine oral antibiotics, and no infectious complications occurred. A history of recurrent AOM should not inordinately delay cochlear implantation.

Cochlear implantation in children: labyrinthitis following pneumococcal otitis media in unimplanted and implanted cat cochleas

Pneumococcal otitis media is frequent in young children and could lead to labyrinthitis post-implantation. To assess the risk, and methods of minimizing it by a graft to the round window around the electrode entry point, we have used a cat animal model of pneumococcal otitis media. Twenty-one kittens were used in the study. Thirty-two cochleas were implanted when the kittens were 2 months of age. Fourteen cochleas were implanted without using a graft (12 were available for study); 9 had a fascial graft, and 9 a Gelfoam graft (7 were available for study). The implanted kittens had their bullae inoculated with Streptococcus pneumoniae 2 months after implantation and were sacrificed 1 week later. There were also 9 unimplanted control ears which were inoculated when the animals were 4 months of age. Labyrinthitis occurred in 44% of unimplanted control, 50% of implanted ungrafted, and 6% of implanted grafted (fascia and Gelfoam) cochleas. There was no statistically significant difference between the unimplanted control and the implanted cochleas (p < 0.05). There was, however, a difference between the implanted-ungrafted and implanted grafted cochleas, but not between the use of fascia and Gelfoam to graft the round window entry point. As a result, the data indicates that cochlear implantation does not increase the risk of labyrinthitis following pneumococcal otitis media, but it is desirable to use fascia as a graft to the round window around the electrode entry point.