Cochlear Implant in Labyrinthitis Ossificans

Research Article

Austin J Otolaryngol. 2016; 3(2): 1075.

Cochlear Implant in Labyrinthitis Ossificans

Carvalho GM*, Lavor M, Beltrame Onuki LC, Paschoal JR, Bianchini WA and Guimares AC

Department of Ear, Nose, Throat and Head & Neck Surgery, Otology, Audiology and Implantable Ear Prostheses, So Paulo, Campinas University, UNICAMP, Brazil

*Corresponding author: Carvalho GM, Department of Ear, Nose, Throat and Head & Neck Surgery, Otology, Audiology and Implantable Ear Prostheses, So Paulo, Campinas University, UNICAMP, Brazil

Received: June 12, 2016; Accepted: August 19, 2016; Published: August 22, 2016


Introduction: Labyrinthitis ossificans is a pathologic ossification in the otic capsule due to an inflammatory or destructive process. The main causes are meningitis, trauma and otosclerosis. A Cochlear ossification result in sensorineural hearing loss, and its presence is associated with technical difficulties and poorer functional results. Advances in surgical techniques and bioengineering provided the development of special electrodes for this condition. This study aimed to evaluate the functional results with partial standard and double-array cochlear implantation in ossified cochlea and describe the performance using the device.

Methods: A retrospective and transversal analysis of data on demographic aspects, auditory performances and surgical findings was made. A transorbital radiograph was used to evaluate electrode migration and insertion depth and the position of the internal component. All patients who underwent either partial insertion of a standard electrode array or double-array electrode insertion for their cochlear implantation in a quaternary centre in the last five years were included.

Results: Eight patients (six adults and two children) were included. The cause of labyrinthitis ossificans was bacterial meningitis in six cases, Cogan’s syndrome in one patient and trauma in another patient. Most patients were implanted in adulthood and the average duration of deafness was 104.5 months. Displacement in the basal electrode was observed in one patient, who went through a new surgical procedure with successfully repositioning.

Discussion: Bacterial meningitis was the most common cause of cochlear ossification in the sample. In adult patients, meningitis acquired in childhood resulted in a longer deafness than in children, which may explain poorer auditory results.

Conclusion: Patients with ossified cochlea benefits significantly from double-array and compressed short array cochlear implantation.

Keywords: Cochlear implant; Labyrinthitis ossificans; Hearing loss


Labyrinthitis ossificans can be defined as a pathological ossification within the otic capsule in response to an inflammatory or destructive process. The main causes of cochlear ossification include meningitis, trauma, malignant infiltration, otosclerosis, tumors, ototoxicity or other infections affecting the internal ear [1,2]. Labyrinthitis ossificans is cause of sensorineural hearing loss of varying degrees and, when occurs bilaterally, there is an indication of cochlear implant in the failure of treatment with sound amplification therapy. Bacterial meningitis is a major cause of bilateral profound sensorineural hearing loss in children, with prevalence ranging from 60% to 90% [2-5].

Streptococcus pneumoniae is the etiologic agent most associated with high mortality and high risk of developing deafness [5-8].

Bacterial infection in the subarachnoid space, which usually reaches the cochlea by the cochlear aqueduct, may also occur via blood or the internal auditory canal. As a result, there is an ossification and partial or total of scala tympani obliteration of the basal turn of the cochlea in up to 80% of cases of labyrinthitis ossificans after meningitis [1,4,9,10].

The infection ascends from the basal turn to intracochlear structures, especially the organ of Corti, often causing profound and irreversible hearing loss [7].

It is known that the number of electrodes activated postoperatively is an essential factor for the presence of good audiological results. The presence of cochlear ossification hinders the full insertion of electrodes in conventional cochlear implants, resulting in a worse audiological result when compared with non-ossified cochleas [4,10].

Originally, the presence of labyrinthitis ossificans was considered a contraindication to the cochlear implant. The auditory brainstem implant can be considered an option for patients with cochlear malformations, including cochlear ossification. However, since this technique is still accompanied by high risk of complications and high morbidity, it is currently underused in these cases [2,9,11].

Advances in surgical techniques, better knowledge of the anatomy and development of specific electrodes have allowed more and more patients to become candidates for cochlear implants. Several techniques have been developed to obtain the largest possible number of electrodes implanted in totally ossified cochlea. However, these techniques allow only partial insertion, in addition to having a high rate of postoperative complications and do not preserve the anatomy of cochlea [2].

The cochlear implant with two beams of short electrodes (cochlear nucleus double array) was developed specifically for obliterated or/ with surgically inaccessible pars ascendens/2nd turn ossification of the cochleae and first used in 1995. This technique allows a greater number of electrodes implanted when compared with the technique of partial insertion, allowing better post operatory audiological results [2].

Whereas a greater number of implanted electrodes imply the best audiological responses, early detection of cochlear ossification is essential to surgical success. Imaging diagnosis can be done by CT scans or high resolution MRI with good accuracy. The process of cochlear ossification in meningitis starts in the first weeks after infection and can take months for the formation of compact bone [8].

It was observed that CT has limitations for identification of early stages of cochlear ossification in the basal turn, being surpassed by MRI, which is able to identify the stage of fibrosis of the perilymphatic space, prior to ossification [4].

Thus, there is controversy regarding the time of implantation in these patients: some authors advocate the use of sound amplification therapy at least one year before the cochlear implant; others argue that the implant should be performed as early as possible, due to the risk of complete ossification and partial insertion of electrodes [12].

This study aimed to evaluate patients undergoing double array or compressed partial insertion type cochlear implant due to cochlear ossification and describe the outcomes using the device. For this purpose, the following aspects were considered: audiological performance, the type of device, duration of deafness preimplantation and the rate of postoperative complications.


Retrospective, cross-sectional study based on analysis of data from patients with profound sensorineural hearing loss due to labyrinthitis ossificans. Patients underwent unilateral cochlear implant (compressed or double array), between 2009 and 2013, in the reference service.

The following aspects were considered: etiology of cochlear ossification, preoperative audiological evaluation and imaging, age at implantation, time between the onset of cochlear disease and surgery and complication rate. Preoperative evaluation using computed tomography and magnetic resonance imaging was performed to demonstrate the degree of cochlear ossification.

Postoperatively, transorbital radiographs were performed to evaluate the position and possible migration of internal component, as well as its electrode.

The surgical decision to use the compressed array versus the double array was by random and was followed interchangeably between these two models.

Inclusion criteria

Inclusion criteria were: sensorineural hearing loss (severe/ profound), normal otoscopy, absence of middle ear disease, absence of acoustic reflex, absence in ABR waves and imaging (MRI / CT) showing the presence of the cochlear nerve and excluding retro cochlear disturbances.

Hearing aids were used in all subjects before treatment and when no benefits were showed it was indicated the cochlear implants (have sensorineural bilateral hearing loss with little or no benefit from HA - less than 40% of auditory discrimination in monosyllables), have puretone thresholds =80 dB hearing loss, have had stable hearing loss for at least the past two years, and lastly pass a psychological examination ensuring they had realistic expectations about the potential benefits of receiving a cochlear implant. All subjects underwent Pure Tone Audiometry (PTA) and speech tests, pre- and postoperatively.

All patients who did not complete these criteria were excluded from the study.

Audiological evaluation

Audiological tests were performed including impedanciometry, speech and pure tone audiometry. The tests were performed using an audiometer AC30-SD25, calibrated according to ISO 389 standards / 64.

For ABR, which were repeated at least two times, we used the device AT-235 (Interacoustics).

The classification of hearing impairment by audiometry was through stratification in mild, moderate, severe or profound hearing loss [13].

Speech perception tests

Preoperatively, all subjects took a speech perception test the same day as their implantation. We used a speech perception sentence test based on one developed by [14] from several English language tests [14]. Subjects did the test with their hearing aids on, in a quiet place.

Postoperatively, all subjects repeated the speech perception test at least one year of CI experience. Tests were done in subject’s bestaided condition: CI-only. The same audiologist conducted all the pre and postoperative tests.

Subjective ratings

Likert scale was applied in the pre operative and also in the postoperative time. In the pre operative time it was applied in the day before the surgery. When the subjects did their postoperative speech tests they were asked to rate the quality of their experience with CI over the past year on a Likert scale scored 0 to 10. A score of 0 indicated the user regretted the intervention, would not recommend it to others, and felt he/she had been better off in the past with their hearing aids. A score of 10 indicated the user was completely satisfied with the intervention and would strongly recommend it.

Statistical analysis

The data were analyzed using descriptive analysis, with production of means, medians, standard deviation tabs.

Chi-Square was used to compare the groups of our sample. Spearman analysis and Mann- Whitney tests was also performed.

The confidence Interval was of 95% and p-value <0.05 was considered significant.

Ethical considerations

This study was previously approved by the Research Ethics Committee of the Faculty of Medical Sciences of the University of Campinas on June of 2014, with the ID 30981814.1.0000.5404.


We collected data from eight patients, six adults and two childrens. The average age of the sample was 31 years. The main cause of the cochlear ossification was meningitis, observed in six patients, one patient had Cogan’s syndrome and another patient had previous trauma (Table 1). All patients underwent cochlear implant between December 2009 and April 2013 in a quaternary service. The average duration of deafness was 104.5 months. Four of these patients, one child and three adults underwent cochlear implantation using double array and in the other four patients was used the short compressed.