Operative Challenges in Doing Cochlear Implant in an Ossified Cochlea, is it Worth it? Case Report and Reviewing the Literature

Farid Alzhrani

doi:10.4103/1319-8491.273924

CLINICAL CASE

Year : 2018 | Volume : 20 | Issue : 2 | Page : 68-73

Operative Challenges in Doing Cochlear Implant in an Ossified Cochlea, is it Worth it? Case Report and Reviewing the Literature

Farid Alzhrani
King Abdullah Ear Specialist Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia

Date of Web Publication

23-Dec-2019

Correspondence Address:
Farid Alzhrani
King Abdullah Ear Specialist Center, College of Medicine, PO Box 245 Riyadh 11411
Saudi Arabia

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-8491.273924

Abstract

Objectives: To present an unusual way of cochlear implant electrode insertion and discuss the audiological as well as the speech outcome.
Study Design: Case report.
Method: Will be reviewing a file of a deaf patient who underwent retrograde insertion of cochlear implant array. Once the audiological and speech findings are evaluated then the literature for similar cases and alternative techniques will be discussed.
Results: A case of a 24-year-old male patient that underwent cochlear implantation due to post meningitis deafness. Considering an ossified cochlea a cochlear implant array was inserted in a retrograde manner from the apex toward the basal turn of the cochlea. There was neither an intraoperative nor postoperative complication. The post implantation audiological outcome was comparable with those subjects who have no ossification in the cochlea. The patient started to use a mobile phone 4 months post- op. 76% speech discrimination score at 60 dB has been achieved within 5 months post implantation.
Conclusion: The apical cochleostomy with descending cochlear implant array insertion is an efficient procedure that has very good postoperative results.

Keywords: ossified cochlea, post-meningitis deafness, cochlear implantation

How to cite this article:
Alzhrani F. Operative Challenges in Doing Cochlear Implant in an Ossified Cochlea, is it Worth it? Case Report and Reviewing the Literature. Saudi J Otorhinolaryngol Head Neck Surg 2018;20:68-73

How to cite this URL:
Alzhrani F. Operative Challenges in Doing Cochlear Implant in an Ossified Cochlea, is it Worth it? Case Report and Reviewing the Literature. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2018 [cited 2023 Jan 31];20:68-73. Available from: https://www.sjohns.org/text.asp?2018/20/2/68/273924

Introduction

Post meningitis deafness is one of the challenging situations. The cochlear ossification is a common finding in patients where total deafness is caused by meningitis and labyrinthitis ^[1]. Formerly, ossification was considered as a contraindication to cochlear implantation ^[2]. This belief was based on the damage caused to the spiral ganglion cells by ossification would be too great to result in any significant auditory precept ^[2]. Advanced drill-out procedure ^[3] and specifically designed CI electrodes like compressed ^[4]or double/ split arrays ^[5])have been proposed to allow cochlear implantation in these difficult cases.

The aim of all those different techniques is to maximize the number of intra-cochlear electrodes, which is believed to correlate with better hearing outcome ^[6]. Another technique has been also described to achieve this aim, in which the electrode array will be implanted directly into the middle or apical turns of the cochlea. The array can be placed inside the cochlea with either an ascending or a descending orientation ^[7]. In our case an apical cochleostomy with retrograde (descending orientation) array insertion has been done. This technique was described first by Montandon et al.^[8]. In those cases reverse speech processor programming should be undertaken.

Material and Methods

We have reviewed the preoperative as well as the postoperative audiological and radiological investigation of a patient with post-meningitis deafness. We also reported the procedure technique which was used with the intraoperative audiological measurement. Then the postoperative speech results and hearing benefit were discussed. Our paper is also supported by literature review. This study was approved by the local Institutional Review Board (IRB).

Results

We are presenting a case of post meningitis deafness that had an ossified cochlea. A 24- year-old male patient who was complaining of bilateral deafness for 9 years presented to our otology clinic for evaluation and advice. He suddenly lost his hearing after meningitis. The patient denied any history of trauma or chronic illnesses. The family history was negative for hearing loss. He had six months trial of hearing aids without benefit.

Audiological Findings

The pure tone audiogram (PTA) showed bilateral profound sensorineural hearing loss (SNHL). Otoacoustic emissions were negative bilaterally. Tympanogram showed type A graph [Figure 1]. An aided PTA showed bilateral severe hearing range at 250Hz slopping to no response. ABR also was done and showed no reproducible waves even at 95dB presentation level.

Figure 1: Preoperative Audiological Results Showed Bilateral Profound Sensorineural Hearing Loss with Absence of Otoacoustic Emissions.

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Radiological Findings [Figure 2]:

Figure 2: Preoperative Radiological Work Up.

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Computed tomography of the temporal bone revealed cochlea on both sides with sclerotic changes of the lateral semicircular canals. The magnetic resonance showed lack of visualization of the normal T2 signal intensity of the anterior limb of the superior semicircular canal and the lateral semicircular canal. It also showed normal size, configuration and decrease signal intensity of bilateral inner ear structures including cochlea, vestibule.

Surgical findings:

Based on the clinical history, audiological and radiological findings, we advised the patient to have a cochlear implant to restore his hearing. The patient underwent a cochlear implant surgery using a standard mastoidectomy facial recess technique. However, we could not intraoperatively find a clear round window so we tried to open the basal turn of the cochlea but unfortunately we could not find any lumen neither scala tympani nor vestibuli. So we have decided to do anterior tympanotomy through the same incision to get wide view to the inner ear. After full exposure the incus was removed. Then a cochleostomy into the second turn of the cochlea, about 1 mm inferior to the cochleariform process and 2 mm anterior to the oval window was done. A full insertion of nucleus contour advance electrode in a retrograde manner towards the basal turn was achieved. The intraoperative audiological measurements (impedance / NRT) were within normal limit.

Postoperative findings:

Postoperatively the patient had no complication. His x-ray as well as CT temporal bone [Figure 3] were done. It showed that the electrode is curving within the cochlea with its tip projecting over the middle to basal turns of the right cochlea. The postoperative fitting was done 4 weeks after surgery and it showed usual findings. The first post-operative speech rehabilitation session revealed that the patient was able to detect speech sounds with minimal discrimination. He was very delighted with his cochlear implant.

Figure 3: Postoperative Computer Tomography and X-Ray Showing the Intracochlear Position of the Cochlear Electrode in a Retrograde Manner.

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a common cause of acquired profound SNHL in children. It has also a high incidence (15% to 30%) of cochlear ossification^[1]. Durisin et al.^[9] reported that the incidence of labyrinthitis ossificans in profoundly deafened patients by meningitis is 322% in children and 36% in adults. Bilateral assymetric ossification occurred in most cases. As early as 4 weeks post meningitis, labyrinthineossification was documented on high resolution computed tomographic scan.They found a significant increment of the rate of osteoneogenesis over time after meningitis. Cochlear ossification can Five months later, the patient started to communicate using his mobile phone. He underwent full audiological evaluation for the right ear with cochlear implant [Figure 4], which showed excellent results. The aided PTA was almost within normal limit. The speech reception threshold was 20dB. And the patient achieved 76% speech discrimination score at 60dB.

Figure 4: The Postoperative Audiological Assessment Showed a Normal Aided Pure Tone Audiogram on Right Side, SRT of 20Db and SDS of 76% At 60Db.

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Discussion

The technique which was used in our case is apical cochleostomy with retrograde electrode insertion. This technique was first described by Montandonet al.^[8]. The term apical cochleostomy does not seem to be accurate as Pascal S. et al. ^[7] found that cochleostomy site was in the middle and not in the apical turn in about 5/8 implanted ears. However, the exact location of the apical cochleostomy seems to be more of academic interest than of importance for the functional outcome. We do not have documented infection in our patient but we think it is Meningogenic labyrinthitis. It is start very early and surge over time with unpredictable speed^[9]. In our case the patient was presented to our clinic 9 years after the attack of meningitis which was too late.

To allow cochlear implantation in these difficult cases different techniques have been proposed. Gantz et al.^[10] described drill-out procedures, where a trough around the modiolus should be removed. This technique necessitates a canal wall down mastoidectomy with closure of the Eustachian tube ^{More Details} and external auditory canal. Rauch et al. ^[11] found that patients who underwent total drill out procedures showed poor performance.

An alternative technique is drilling the basal turn and partial insertion of the cochlear implant electrode or using compressed arrays ^[4]. This technique can be done through the standard approach for cochlear implant (mastoidectomy-facial recess). Another technique is similar to the previous one with drilling another window into the middle turn of the cochlea and using double/split arrays ^[5].Roland et al. found that the double array allows more usable electrodes than the partially inserted cochlear implant^[12].

Our patient achieved good result with cochlear implant. Although, the outcomes of cochlear implantation in ossified cochleae are variable. Rotteveel et al.^[13] concluded that the patients with complete insertion of electrode array have more benefits than patients with partial insertion. Also Beiter et al. ^[14] & Nichani et al. ^[15] reported that patients with incomplete insertion are benefiting from an implant. On the other hand, poor speech perception in the majority of the cases of partial insertion has been reported by Cohen and Waltzman^[16].

The presented surgical strategy is not complicated comparing to the use of double arrays and drill-out post meningitis have better auditory and language performance.

The cochlear implant outcome post-meningitis is less predictable than in congenitally deaf patients[15]5). The proper CI placement, the depth of electrode insertion, as well as the type and severity of additional neurologic sequelae of meningitis are important factors which play an important role in predicting the cochlear implant outcome.Damage to the cochlear spiral ganglia caused by meningitis, may result in failure of the neuronal response even in cases with uneventful electrode insertions (1).

An alternative technique is drilling the basal turn and partial insertion of the cochlear implant electrode or using compressed arrays ^[4]. This technique can be done through the standard approach for cochlear procedures^[7]. The retrograde insertion has goodresults, with speech perception scores almost similar to that reported for double arrays,however it is less complicated. In cases of apical retrograde insertion, the monosyllabic word recognition scores were reported to be between 25.8% and 41.7 %( 7). While for double arrays 21%, 22% and 57% have been reported in different articles [5,7.17]). Alsothis technique showed satisfactory long-term results^[7].

The use of postoperative high-resolution temporal bone computer tomography to fully understand the intra-cochlear array position is crucial and accordingly programming the speech processor can be adjusted^[7]. Nichani et al.^[15]conclude that cochlear implant is beneficial for most patients with profound sensorineural hearing loss after meningitis. Durisin et al.^[18]looked at the relation between the performance of implantees deafened by meningitis and the duration of deafness. They found thatpatients implanted within 6 months implant (mastoidectomy-facial recess). Another technique is similar to the previous one with drilling another window into the middle turn of the cochlea and using double/split arrays ^[5].Roland et al. found that the double array allows more usable electrodes than the partially inserted cochlear implant^[12]. Our patient achieved good result with cochlear implant. Although, the outcomes of cochlear implantation in ossified cochleae are variable. Rotteveel et al.^[13] concluded that the patients with complete insertion of electrode array have more benefits than patients with partial insertion. Also Beiter et al. ^[14] & Nichani et al. ^[15] reported that patients with incomplete insertion are benefiting from an implant. On the other hand, poor speech perception in the majority of the cases of partial insertion has been reported by Cohen and Waltzman^[16].

The presented surgical strategy is not complicated comparing to the use of double arrays and drill-out procedures^[7]. The retrograde insertion has goodresults, with speech perception scores almost similar to that reported for double arrays,however it is less complicated. In cases of apical retrograde insertion, the monosyllabic word recognition scores were reported to be between 25.8% and 41.7 %( 7). While for double arrays 21%, 22% and 57% have been reported in different articles [5,7.17]). Alsothis technique showed satisfactory long-term results^[7].

The use of postoperative high-resolution temporal bone computer tomography to fully understand the intra-cochlear array position is crucial and accordingly programming the speech processor can be adjusted^[7]. Nichani et al.^[15]conclude that cochlear implant is beneficial for most patients with profound sensorineural hearing loss after meningitis. Durisin et al.^[18]looked at the relation between the performance of implantees deafened by meningitis and the duration of deafness. They found thatpatients implanted within 6 months post meningitis have better auditory and language performance.

The cochlear implant outcome post-meningitis is less predictable than in congenitally deaf patients[ 15]5). The proper CI placement, the depth of electrode insertion, as well as the type and severity of additional neurologic sequelae of meningitis are important factors which play an important role in predicting the cochlear implant outcome.Damage to the cochlear spiral ganglia caused by meningitis, may result in failure of the neuronal response even in cases with uneventful electrode insertions (1).

Conclusion

The retrograde insertion of the cochlear implant is an efficient procedure for those with ossified cochlear basal turn. The postoperative results were pretty good as well.

Conflict of Interest: No Financial disclosure: Compliance with Ethical Standards There are no funders to report for this submission

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