Does meningitis after cochlear implantation remain a concern in 2011?

OBJECTIVE: There have been 283 cases of meningitis after cochlear implantation reported since 2002 to the CDC Database Manufacturer and User Facility Device Experience, resulting in 30 fatalities. This is the latest of a number of reports to track the continuing problem of meningitis occurring in cochlear implant users, mainly children. RESULTS: Although a number of these patients had received a device with a 2-piece electrode, the withdrawal of that particular device has not prevented further cases from occurring. There are many potential etiologic factors potentially involved in postimplantation bacterial meningitis; although some can be managed or eliminated, vaccination against the most prevalent causal organism, the streptococcus pneumoniae, seems to be a powerful tool against this uncommon but serious complication of cochlear implantation. CONCLUSION: Although up to 20 new cases of post-cochlear implantation meningitis continue to occur annually worldwide, considering the number of new devices implanted each year, it is expected that the incidence of this complication seems to be diminishing.

Longitudinal risk of meningitis after cochlear implantation associated with the use of the positioner.

OBJECTIVE: In 2002, the electrode combined with positioner was identified as a significant risk factor for postimplantation meningitis and was voluntarily discontinued by the manufacturer. The ongoing risk of meningitis with passage of time with the positioner remains unknown. The objective of this study was to determine the current risk of meningitis in patients implanted with the positioner. STUDY DESIGN: Data regarding the date of implantation, report of meningitis, and presence or absence of risk factors for meningitis (otitis media, inner ear malformation) were obtained from the clinical database maintained by the manufacturer. RESULTS: There were 8,329 devices implanted that may have used a positioner, yielding a cumulative postimplantation time of 74,976 patient-years. The incidence of meningitis during the 3-year spans of 1999 to 2001, 2002 to 2004, 2005 to 2007, and 2008 to 2010 was 33, 40, 11, and 2, respectively; the risk of meningitis in cases per patient-years has decreased significantly from 0.0044 at its peak in 2001 to 0.0011 in 2010. Only a single case of positioner-related meningitis 96 months or longer after implantation has been reported. More than 40% of children had otitis media within 1 week of developing meningitis; less than 10% had a history of meningitis or inner ear malformation. CONCLUSION: The risk of meningitis with the use of positioner is highest within the first 24 months after implantation and is frequently associated with otitis media. The risk of meningitis more than 96 months after implantation is significantly reduced. Thus, the prophylactic removal of the positioner is not recommended in patients who underwent implantation more than 8 years ago.

Current status of bacterial meningitis after cochlear implantation.

Meningitis after cochlear implantation continues to be a concern. Recent studies and anecdotal reports support the belief that intracochlear trauma, lack of appropriate immunizations, and a previously used dual-component electrode predispose patients to a higher rate of contracting meningitis. In addition, a history of meningitis, cochlear dysplasia, and certain variations of surgical technique such as the cochleostomy, very young age, immunocompromise, and the presence of neural prostheses such as shunts, are all potentially predisposing factors. Because many of these factors are beyond our control, there is likely to be an inevitable baseline incidence of meningitis, perhaps related to the underlying deafness, but by controlling other factors, we can hope to minimize the incidence. Despite the efforts of multiple individuals and organizations, there continue to be new cases of meningitis, including a small number of fatalities, each year. There is recent evidence that a sizeable percentage of children with implants have not been vaccinated as suggested by governmental agencies, otolaryngologic societies, implant manufacturers, and many cochlear implant centers. Clearly, efforts must be made to ensure age-appropriate vaccination for all cochlear implant recipients.

Retrosigmoid approach for acoustic tumor removal. 1992.

The retrosigmoid technique has evolved from the traditional suboccipital operation and, when combined with removal of the posterior wall of the internal auditory canal (IAC), affords a wide exposure of the cerebellopontine angle. This approach may be used for acoustic neuromas of all sizes, from intracanalicular, to more than 4 cm from the porus acusticus. Hearing preservation may be attempted and is generally successful in a substantial minority of cases. The facial nerve is readily visualized at the lateral end of the IAC and is at no greater risk than in the translabyrinthine operation. The authors use this approach for all hearing preservation surgery as well as for tumors of more than 3 cm, regardless of hearing.

Cochlear implantation in the neurofibromatosis type 2 patient: long-term follow-up.

OBJECTIVE: To evaluate the long-term hearing outcomes of neurofibromatosis type 2 (NF2) patients with cochlear implants. METHODS: Retrospective analysis of cochlear implant performance in NF2 patients using open- and closed-set speech perception testing. RESULTS: Patients with NF2-associated bilateral vestibular schwannomas frequently become profoundly deaf. The aim of surgical resection should be to preserve serviceable hearing in at least one ear; however, this goal can be difficult to achieve. Frequently, tumor size or poor preoperative hearing status can require a surgical approach that leaves the patient with a profound, bilateral sensorineural hearing loss. If the cochlear nerve is preserved anatomically after vestibular schwannoma surgery, and if promontory stimulation confirms the functionality of the cochlear nerve, then cochlear implantation is an excellent option to restore hearing. We present six cochlear implant patients with NF2 who attained a significant improvement in open- and closed-set speech understanding with a mean follow-up of 7.9 (range: 5-13) years after surgery. In all but one case, the hearing results did not deteriorate over the follow-up period. CONCLUSION: Early surgical intervention for vestibular schwannomas in NF2 patients when the cochlear nerve can be spared is an important consideration to allow for possible cochlear implantation. A 6- to 8-week recovery period for the anatomically intact cochlear nerve may be necessary to obtain a positive promontory stimulation response following tumor resection and should be performed prior to cochlear implantation.

Revision cochlear implantation.

Reoperation on a patient with an indwelling cochlear implant is uncommon. When necessary, surgery is performed for explantation of an existing device with immediate or delayed reimplantation, or for scalp flap revision and receiver-stimulator repositioning in the case of infection or device migration. Rarely, revision surgery is performed to reintroduce intracochlear electrodes that may have partly or entirely extruded from the cochlea or were placed inappropriately. Successful revision cochlear implant surgery requires attention to certain surgical principles. Good outcomes, asa measured by speech perception tests, are common, but are not guaranteed. This article outlines the indications for revision cochlear implant surgery, the recommended surgical principles, and published outcomes from reimplantation.

Combined microtia and aural atresia: issues in cochlear implantation.

OBJECTIVES: This article presents the first report of cochlear implantation in a patient with congenital aural atresia, microtia, dysplastic cochlea and internal auditory canals, and bilateral profound sensorineural hearing loss (HL). This rare combination requires special management considerations. Preoperative issues include thorough evaluation of computed tomography and magnetic resonance imaging to determine favorable anatomy, cochlear implantation candidacy, and surgical planning. Intraoperative concerns include incision placement, surgical approach to the middle ear, and abnormal facial nerve anatomy. Postoperative use of a special headset combining a microphone and transmitter coil is required. STUDY DESIGN: Case report and literature review. METHODS: The patient's chart was reviewed for diagnostic studies, operative strategy, and postoperative auditory stimulation and testing. A literature review was performed. RESULTS: A 2-year-old male presented with bilateral aural atresia, microtia, and profound sensorineural HL. Imaging studies revealed multiple abnormalities of the cochlea, vestibule, and internal auditory canal, all of which were more favorable on the right side. An incision was designed to accommodate future microtia repair. The cochlear implant was placed without difficulty by way of a facial recess approach to the middle ear. Postoperative results include the detection of Ling sounds and voices in the environment as well as the ability to locate sounds. CONCLUSIONS: This is the first report of cochlear implantation in a patient with bilateral aural atresia, microtia, and profound sensorineural HL in conjunction with multiple inner ear abnormalities. Close collaboration among the otologist, neuroradiologist, and plastic surgeon is essential to coordinate surgical management and optimize cosmetic and functional outcomes in this unique population.

Auditory brainstem implantation in patients with neurofibromatosis type 2.

OBJECTIVES: Multichannel auditory brainstem implants (ABI) are currently indicated for patients with neurofibromatosis type II (NF2) and schwannomas involving the internal auditory canal (IAC) or cerebellopontine angle (CPA), regardless of hearing loss (HL). The implant is usually placed in the lateral recess of the fourth ventricle at the time of tumor resection to stimulate the cochlear nucleus. This study aims to review the surgical and audiologic outcomes in 18 patients implanted by our Skull Base Surgery Team from 1994 through 2003. STUDY DESIGN: A retrospective chart review of 18 patients with ABIs. METHODS: We evaluated demographic data including age at implantation, number of tumor resections before implantation, tumor size, surgical approach, and postoperative surgical complications. The ABI auditory results at 1 year were then evaluated for number of functioning electrodes and channels, hours per day of use, nonauditory side effect profile and hearing results. Audiologic data including Monosyllable, Spondee, Trochee test (MTS) Word and Stress scores, Northwestern University Children's Perception of Speech (NU-CHIPS), and auditory sensitivity are reported. RESULTS: No surgical complications caused by ABI implantation were revealed. A probe for lateral recess and cochlear nucleus localization was helpful in several patients. A range of auditory performance is reported, and two patients had no auditory perceptions. Electrode paddle migration occurred in two patients. Patient education and encouragement is very important to obtain maximum benefit. CONCLUSIONS: ABIs are safe, do not increase surgical morbidity, and allow most patients to experience improved communication as well as access to environmental sounds. Nonauditory side effects can be minimized by selecting proper stimulation patterns. The ABI continues to be an emerging field for hearing rehabilitation in patients who are deafened by NF2.

Cochlear implant candidacy and surgical considerations.

Numerous changes continue to occur in regard to cochlear implant candidacy. In general, these have been accompanied by concomitant and satisfactory changes in surgical techniques. Together, this has advanced the utility and safety of cochlear implantation. Most devices are now approved for use in patients with severe to profound rather the prior requirement of a bilateral profound loss. In addition, studies have begun utilizing short electrode arrays for shallow insertion in patients with considerable low frequency residual hearing. This technique will allow the recipient to continue to use acoustically amplified hearing for the low frequencies simultaneously with a cochlear implant for the high frequencies. New hardware, such as the behind-the-ear speech processors, require modification of existing implant surgery. Similarly, the new perimodiolar electrodes require special insertion techniques. Bilateral implantation clearly requires modification of the surgical techniques used for unilateral implantation. The surgery remains mostly the same, but takes almost twice as long, and requires some modification since at a certain point, when the first device is in contact with the body, the monopolar cautery may no longer be used. Research has already begun on the development of the totally implantable cochlear implant (TICI). This will clearly require a modification of the surgical technique currently used for the present semi-implantable devices. In addition to surgically burying the components of the present cochlear implant, we will also have to develop techniques for implanting a rechargeable power supply and a microphone for the TICI. The latter will be a challenge, since it must be placed where it is capable of great sensitivity, yet not exposed to interference or the risk of extrusion. The advances in design of, and indications for, cochlear implants have been matched by improvements in surgical techniques and decrease in complications. The resulting improvements in safety and efficacy have further encouraged the use of these devices. We anticipate further changes in the foreseeable future, for which there will likely be surgical problems to solve.

Meningitis in cochlear implant recipients: the North American experience.

INTRODUCTION: Until recently, postimplant meningitis was infrequently reported and felt to be uncommon. However, in the spring of 2002, there was a sudden increase in the number of reported cases of postimplantation meningitis in both Europe and North America. OBJECTIVE: Because complications of surgery often tend to be underreported, we decided to survey all cochlear implant centers in North America to determine the true incidence of postimplant meningitis and to learn more about the demographics and risk factors. STUDY DESIGN: We conducted a prospective study. A survey instrument was designed asking surgeons the number of implants performed and whether they had seen any cases of meningitis after implantation. If the answer was affirmative, they were asked to respond to a 20-point questionnaire. This instrument was sent to all 401 cochlear implant centers in North America. SETTING: Tertiary care referral centers. PATIENTS: We studied all patients having received cochlear implants in North America. MAIN OUTCOME MEASURES: Number of cases of postimplant meningitis, age of patients, device used, cochlear and temporal bone abnormalities, treatment, and outcomes. RESULTS: Meningitis is more common than previously thought. Risk factors included young age, cochlear dysplasia, temporal bone abnormalities, and the use of a two-part electrode system. This survey led to the involvement by the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention in a much more intensive analysis of a subset of the cases. CONCLUSIONS: Postimplant meningitis is related to patient, surgical, and device factors. By being aware of the risk factors involved, adhering to sound surgical principles such as packing of the cochleostomy with soft tissue, appropriately vaccinating patients, and eliminating any potentially traumatic electrode arrays, the incidence of meningitis should be significantly diminished.

Degree of modiolar coiling, electrical thresholds, and speech perception after cochlear implantation.

OBJECTIVE: Perimodiolar electrode arrays were developed to improve stimulation of specific neural populations and to decrease power consumption. Postoperative radiographs suggest that some arrays are more tightly coiled than others. The purpose of this study was to evaluate whether the degree of modiolar coil correlates with electrical threshold and/or performance measures postimplantation with the Nucleus CI24RCS (Contour) device. STUDY DESIGN: Retrospective review. SETTING: Cochlear implant center and a tertiary care hospital. PATIENTS: Twenty-eight adult cochlear implant recipients with normal cochlear anatomy who underwent implantation with the Nucleus C124RCS perimodiolar electrode and are at least 1 year postimplantation. INTERVENTIONS: Therapeutic. MAIN OUTCOME MEASURES: Radiologic degree of perimodiolar electrode placement (determined by a computer algorithmic analysis) compared with electrical thresholds and standard speech perception outcome measures at 1 year postcochlear implantation. RESULTS: No significant correlations were found between the degree of modiolar coiling of the electrode array and electrical thresholds and speech perception outcome measures at 1 year postcochlear implantation. CONCLUSIONS: The degree of coiling of a modiolar hugging electrode array was not directly correlated with the level of electrical thresholds or postoperative speech perception outcome measures. Appearance of coil tightness on postoperative radiographs could reflect either differences in array placement or intrinsic variations in cochlear anatomy, and variations in speech perception performance can be influenced by other factors, including length of deafness.

Prevention and management of cerebrospinal fluid leak following vestibular schwannoma surgery.

OBJECTIVES/HYPOTHESIS: Postoperative cerebrospinal fluid (CSF) leak is reported in 2% to 30% of cases following vestibular schwannoma surgery. The authors' current surgical techniques for translabyrinthine, retrosigmoid transmeatal, and middle cranial fossa approaches have evolved from analysis of their prior experience in an effort to minimize their complication rate. The authors evaluated the efficacy of their current surgical technique in decreasing the postoperative CSF leak rate. STUDY DESIGN: Retrospective review. METHODS: The vestibular schwannoma database from the New York University Medical Center (New York, NY) neurotological service was reviewed. Data were extracted for type of approach, tumor size, and CSF leak rate. Liberal leak criteria were used. Surgical techniques and management of CSF leak were reviewed. RESULTS: Data from 215 patients who had surgery from 1995 to 2000 manifested a 6.6% CSF leak rate for primary surgeries. This compared favorably with the authors' 17% overall CSF leak rate in 555 total primary surgeries performed between 1979 and 1995. Translabyrinthine closure was performed with dural sutures used as a sling across the posterior fossa dura and abdominal fat placed as a series of corks through the sutures. Abdominal fat was used to obliterate the mastoid cavity in conjunction with aditus and mastoid obliteration. Attention must be paid to soft tissue obliteration of potentially open air cell tracts. Retrosigmoid transmeatal closure was performed with a soft tissue graft in the internal auditory canal drill-out held in position by a "saloon-door" dural flap. Bone wax was used to block perimeatal cells in all cases. Watertight dural closure was achieved with a sutured temporalis fascia graft. Abdominal fat obliteration of the mastoidectomy cavity was performed with an additional firm pressure from the "Palva" periosteal flap. Middle cranial fossa closure was performed with attention to potential air cell tracts of the internal auditory canal drill-out, as well as abdominal fat graft, tissue glue, and bone wax. Fibrin glue was used in all approaches to temporarily secure fat in situ. Management of CSF leaks starts with nonoperative measures including bed rest, oversewing of incisional wounds, and placement of a lumbar subarachnoid spinal fluid diversion drain. If these conservative measures fail, repeat exploration is necessary and is directed at identifying and corking the cell or cells (usually perimeatal or perilabyrinthine) opening directly into the posterior fossa. CONCLUSION: Evolution in surgical techniques, with particular attention to exposed air cell tracts, abdominal fat graft, and Palva periosteal flap for closure, has had a significant effect in decreasing the author's CSF leak rate after vestibular schwannoma surgery. Conservative management was successful in approximately 50% of cases. Repeat exploration, when needed, was directed at blocking the air cell tract (usually perimeatal or perilabyrinthine) responsible for the CSF leak.

Fluoroscopically assisted cochlear implantation.

HYPOTHESIS: Real-time intraoperative fluoroscopy is a useful adjunct to cochlear implantation in selected cases. The advantages include the avoidance of complications such as extracochlear array placement, intrameatal array insertion, and avoidance of significant bending or kinking. This is particularly useful when implanting a severely abnormal cochlea. BACKGROUND: The technique was initially developed for laboratory study of electrode prototypes in cadaver temporal bones to evaluate insertion dynamics and mechanisms of intracochlear trauma. The technique was subsequently adapted for use in live surgeries. METHODS: Live surgeries were performed using fluoroscopic guidance on nine patients. RESULTS: Five patients were implanted with the Nucleus 24 RCS during preclinical trials. Two patients with severe cochlear malformations were implanted with a Nucleus CI24M straight array. Two patients with severe cochlear ossification were implanted with the Nucleus CI24 double array. Appropriate insertions were achieved without electrode damage in all cases. CONCLUSIONS: Intraoperative fluoroscopy is a useful adjunct to cochlear implantation, which can be performed with minimum risk to the patient and operating room staff if the outlined precautions are taken. Intraoperative fluoroscopy is indicated in cases where the intracochlear behavior of the electrode array cannot be predicted, a condition encountered when implanting new electrode designs, cases with severely malformed inner ears, or cases of severe intraluminal obstruction requiring a double-array insertion.

Second oral language capabilities in children with cochlear implants.

OBJECTIVE: The development of oral language in children with a cochlear implant is dependent on numerous factors. Although baseline achievements have been established, ceiling attainment levels have yet to be explored. One indicator of a higher capability level is the ability of children with implants to learn to communicate orally using a second language. The purpose of this research was to explore 1) the feasibility of children with cochlear implants developing oral fluency in a second language and 2) the factors that affect the development. STUDY DESIGN: Retrospective study of children fulfilling the criteria. SETTING: University medical center. PATIENTS: Eighteen profoundly hearing-impaired children who were reported to be bilingual. INTERVENTION: Cochlear implantation at age 5 or younger. MAIN OUTCOME MEASURES: The subjects were evaluated using standard speech perception and receptive and expressive language measures. RESULTS: The data revealed the ability of some pediatric cochlear implant recipients to develop competency in a second spoken language in addition to their primary language. Equally as important is the fact that the majority showed age-appropriate receptive and/or expressive language abilities in their primary language commensurate with normal-hearing children. CONCLUSION: High levels of achievement including the learning of a second spoken language are possible after implantation in the pediatric population. Variables include speech perception postimplantation, the linguistic environment, type of intervention, and educational placement.

Long-term effects of cochlear implants in children.

OBJECTIVE: 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. STUDY DESIGN AND SETTING: We studied 81 children who received implants at a major academic medical center and were followed for 5 to 13 years. RESULTS: 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. CONCLUSIONS: Multichannel cochlear implants in children provide perception, linguistic, and educational advantages, which are not adversely affected by long-term electrical stimulation.

Delayed implantation in congenitally deaf children and adults.

OBJECTIVE: To determine the efficacy of cochlear implants with current processing strategies in children and adults with long-term congenital deafness, and to determine whether the growth of auditory perceptual skills in these patients is similar to the data reported for patients who have undergone implantation with earlier devices and coding strategies. STUDY DESIGN: A prospective study of children and adults fulfilling the study inclusion criteria. SETTING: University medical center. PATIENTS: Thirty-five congenitally deaf children who received implants after the age of 8 years and 14 congenitally deaf adults who received implants as adults participated in this study. Length of device use ranged from 6 months to 3 years. MAIN OUTCOME MEASURES: Open set phoneme, word recognition tests, and sentence recognition tests were administered in quiet and noise auditory only conditions preoperatively and postoperatively. Changes in test scores were examined by paired t tests, and differences between groups were compared by Student's t tests. Spearman correlation coefficients were calculated to identify associations between scores and subject characteristics. A two-sided alpha of less than 0.05 was considered statistically significant. RESULTS: The results indicated significant improvement in open set speech perception skills in the children after implantation; the adults demonstrated improved mean scores on both word and sentence recognition. A shorter length of deafness correlated with better postoperative performance, but all subjects continued to improve over time. The improvement in test scores was similar between the devices, and no significant differences were detected between the different processing strategies. CONCLUSION: Children and adults with long-term congenital deafness can obtain considerable open set speech understanding after implantation. Length of deafness (age at implantation), length of device use, and mode of communication contribute to outcome.

Surgical technique for the Nucleus Contour cochlear implant.

This paper deals with the Nucleus C124R (CS) (Contour) cochlear Implant: its characteristics, differences compared with the previous generation of devices, the perimodiolar electrode, and the surgical technique used for safe insertion. We also discuss the rationale behind perimodiolar electrodes in general, as well as the results of laboratory studies validating the design and safety of this particular electrode array. The differences in surgical technique between this device and prior Nucleus cochlear implants are as follows: the incision and the size of the well, or recess, for the electronics are smaller; the cochleostomy is larger; the posterior portion is placed in a subpericranial pocket, not tied down, before electrode insertion; and the insertion process itself is quite different, due to the nature of the electrode, its size, shape, and stylet. The technique described is that used by one experienced cochlear implant center, and reflect the authors' practice. Clearly, there are other possible variations on this theme, which may be equally satisfactory in other hands. Most surgeons find this device to be easier to place than previous generations: complications to date have been uncommon.