Cochlear implantation in obstructed cochleas: the effect of the degree of obstruction on the number of activated electrodes and the amount of postoperative speech perception

Tight modiolar proximity and feasibility of slim modiolar cochlear implant electrode array insertion in diverse etiologies of hearing loss

PURPOSE

To report on our experience with the slim modiolar electrode (SME) especially focusing on the wide range of etiologies including inner ear anomalies, tumors, ossifications, and even revision surgeries.

METHODS

All the cochlear implantation cases performed from June 2018 to September 2019 by a single surgeon was prospectively recruited. The molecular/radiological etiology of hearing loss, intraoperative outcomes, and radiographic studies of cases where the SME was implanted was reviewed to evaluate compatibility of SME for the wide range of etiologies. For cases where SME replaced the other electrode as a revision, audiologic assessment was also made.

RESULTS

Among the 99 ears implanted during the study period, the SME was successfully implanted in 86 ears. These SME cases comprised inner ear anomaly/cochear nerve deficiency (n = 21) including cochlear hypoplasia type IV with the modiolus, intracochlear schwannoma (n = 1), far advanced otosclerosis (n = 1) and 7 revision cases. The SME was successfully used in 7 revision surgeries to replace the existing electrode. Shorter spiral diameter and decreased intracochlear position index for SME was found compared with their previous electrodes. Four out of the 6 patients who received revision implantation showed better speech perception after their surgeries.

CONCLUSION

The SME can be implanted in any cases unless the integrity of the modiolus is totally compromised. Due to its slim design and tight modiolar-hugging feature, good functional outcome can also be anticipated. Additionally, it is suitable for revision surgeries possibly allowing better hearing outcomes which may be attributed to its closer proximity to the modiolus.

Revision cochlear implantation using a double array device in the post-meningitis ossified cochlea

PURPOSE

To describe the surgical technique and outcome in a series of patients who underwent revision cochlear implantation using a double array or split electrode device. All patients developed ossified cochleae due to meningitis and were functioning poorly with the previous implant.

METHODS

Four patients between the ages of 4-15 years underwent revision with five double-array cochlear implant devices. One patient underwent bilateral revision surgery. All patients had previous meningitis with CT and MRI imaging studies that demonstrated completely ossified cochleae. The time interval range between the disease and the initial cochlear implantation and was 4 months to 3 years. The patient's data were retrospectively analyzed with emphasis on the surgical technique, the number of electrodes inserted, and the number of active electrodes at follow-up. In addition, pre and post-revision surgery function was compared.

RESULTS

The revision surgery was carried out 2-11 years after the initial surgery. Two tunnels, basal and apical, were drilled in the ossified cochlea. In each of the tunnels, 5 to 11 electrodes were inserted. While the number of active electrodes before revision was 0-5, after revision with the double array, it was increased to 8-12, resulting in improved auditory and speech function.

CONCLUSION

Revision cochlear implantation with a double array implant using the two tunnel technique can increase the number of active electrodes. This leads to a better outcome in post-meningitis children with completely ossified cochleae and a poor functioning previous device.

High-resolution 3-D T2-weighted imaging in the diagnosis of labyrinthitis ossificans: emphasis on subtle cochlear involvement

BACKGROUND

Meningitis is the most common cause of acquired sensorineural hearing loss (SNHL) in children. Labyrinthitis ossificans develops in a significant number of patients with meningitis-related SNHL. Reduced T2 signal on MRI within the membranous labyrinth is often noted in the fibrous and ossifying stages of labyrinthitis ossificans.

OBJECTIVE

The purpose of this study is to demonstrate the distribution and extent of involvement of the cochlea in children being evaluated for labyrinthitis ossificans; using high-resolution 3-D T2-weighted imaging, and to evaluate for subtle involvement of the scala tympani within the basal turn of the cochlea.

MATERIALS AND METHODS

A retrospective review from 2002 to 2012 was performed using a cochlear implant database and PACS search function. Twenty-four patients were found to have MR findings consistent with labyrinthitis ossificans, 13 previously reported. Axial 3-D T2-weighted sequences were obtained in all patients. The presence of abnormal decreased T2 signal within the scala tympani and vestibuli of the cochlea was noted and graded according to the extent. The electronic medical record was reviewed for audiometry and risk factors as well as correlative operative findings.

RESULTS

The average age at imaging was 4.2 years. M:F ratio = 5:1. Eighty-eight percent (21/24) of patients had bilateral SNHL. The most common risk factor for labyrinthitis ossificans was meningitis (19/24 or 79%). Eighteen (75%) patients had a history of bacterial meningitis. The mean age for the onset of labyrinthitis was 1.2 years with an average of 2.2-year interval to imaging. Nineteen patients (79%) underwent placement of a cochlear implant. Cochlear obstruction was documented in 83% (40/48) of the ears. Lower grade (1) cochlear obstruction was present in 14 ears and limited to the scala tympani. Statistical analysis was performed correlating MRI imaging and surgical findings.

CONCLUSION

Subtle, isolated involvement of the scala tympani within the proximal basal turn is a common finding in labyrinthitis ossificans and history typical for meningitis is not uniformly present. The extent of cochlear obstruction is important and has surgical implications.

Cochlear implantation in patients with prelingual hearing loss

CONCLUSION

The average age at the time of cochlear implantation is progressively being reduced. While cochlear obstruction and perilymph/cerebello-spinal fluid gusher were found in some cases, preoperative MRI and CT scans were predictive of such occurrences. The preoperative developmental quotient in the Cognitive-Adaptive Area was strongly correlated to the postoperative development in the Language-Social Area.

OBJECTIVE

To summarize the background, implant devices, intraoperative findings, and postoperative developmental quotients of prelingually deafened patients who underwent cochlear implantation.

METHODS

We conducted a retrospective chart review of 134 prelingually deafened cochlear implant recipients.

RESULTS

The median age at implantation was 3 years and 5 months. Most patients were born deaf without any known etiologies. In most cases, the transmastoid facial recess approach was utilized. Cochlear obstruction was identified in four patients, all of whom lost their hearing as a result of meningitis. Perilymph/cerebello-spinal fluid gusher was observed in six patients with inner ear anomalies. The preoperative developmental quotient for the Cognitive-Adaptive Area showed significant correlation with the postoperative developmental quotient in the Language-Social Area with a correlation coefficient of 0.71.