Impact of Cochlear Implant on the Quality of Life in Post Lingual Deafened Adult Population in Tertiary Care Centre

Abstract

In India, 7–8% of the population is affected by post lingual deafness, which can lead to job dissatisfaction, depression, social withdrawal, and educational challenges. Despite the benefits, cochlear implantation in Northern India remains underutilized. This study examines the impact of cochlear implants on post lingual deafness, along with their etiology and indications. The study reviewed audiometric, clinical, and perioperative data of 50 adult patients (> 18 years) with bilateral post lingual severe to profound hearing loss, unresponsive to hearing aids, who underwent cochlear implantation between 2012 and 2024. Preoperative and postoperative demographic and audiometric data, operative details, postoperative therapy, and outcomes were assessed using hearing-specific quality of life measures (SSQ-12 and CIQOL-10 Global) and a subjective Likert scale of satisfaction. Outcomes were statistically compared. The cohort included 50 patients (31 male, 19 female), with a mean deafness onset age of 33.8 years and a mean duration of 4.48 years. About 48% had been deaf for less than four years. The VERIA technique was used in 86% of implantations, with no immediate postoperative complications. Later, 2% experienced moderate dizziness/vertigo and tinnitus. The mean SSQ-12 score was 63.96, and the mean CIQOL score was 53.29. Overall, 84% were satisfied with their post-implantation communication abilities. The VERIA technique is reliable for cochlear implantation in post lingually deaf adults. Cochlear implantation significantly improves the quality of life for these patients, enhancing their physical, mental, and social well-being.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-024-05110-y.

Introduction

India has about 7–8% post lingually deaf. Hearing is an important organ on which an individual's physical, mental and social well being depends. Poor hearing translates into job dissatisfaction, depression, social apathy, lack of job opportunities and poor educational attainments. In general, around 1⁄4th of cases of post lingual deafened patients have a genetic cause while a majority 3/4th have an acquired cause including Cochlear otosclerosis, Labyrinthitis ossificans, Elongated Vestibular Aqueduct syndrome, Meniere’s and viral labyrinthitis induced SSNHL. While Western countries have adopted hybrid implants for low-frequency hearing loss and tinnitus patients, in India, hearing aids are still considered a luxury by many. This limits the accessibility of implants to individuals with sufficient financial resources. In patients with severe to profound hearing loss cochlear implant outcomes depend on various factors including socioeconomic status, age of onset of deafness, duration of deafness, genetic, anatomical and post implantation training. Northern India suffers from twin disadvantages of a population suffering from lower socio economic status and lower literacy. Although cochlear implantation for prelingual deafness has been driven by public funding, access to implants for post-lingual deafness, which results in economic, personal, and social loss, is still not universally available. In this regard our study helps in evaluating the etiology, impact of cochlear implant on patients quality of life and also seeks to bring out the indications in adult post lingual population and the unique challenges associated with it.

Materials and Methods

An ambispective chart review was conducted in the Department of Neurotology in a tertiary care referral center. The study included adult patients (> 18 years) with bilateral post-lingual severe to profound hearing loss who did not get benefit from hearing aid, and who have undergone cochlear implantation from 2012 to 2024.

Data was collected from the cochlear implant clinic regarding demographic and clinical details including age, gender, socioeconomic, educational profile, etiology, radiological details, pre-operative behavioral and speech audiometry, brainstem auditory evoked response, duration of profound deafness, duration of hearing aid use before implant, implant model, processor technique surgical details, intraoperative, post opertaive complications, post operatively auditory verbal therapy (AVT) details, post-operative speech audiometry.

At the time of follow-up patient outcomes were assessed qualitatively using patient reported outcome measures using a hearing specific -quality of life (QOL) the Speech, spatial and quality of life -12 (SSQ-12) questionnaire [1] and a cochlear implant quality of life (CIQOL -10) Global questionnaire [2]. In addition, a subjective Likert scale of satisfaction in overall ability to hear and communicate was administered with regard to preop status. The result in 100 percentage points were then stratified into 4 groups very satisfied (> = 65), satisfied (> = 50 and < 65), not satisfied (30–49) and extremely dissatisfied (< 30) based on classification of feedback score.

Surgical Technique

Presurgical Evaluation

Prior to undertaking the implant, a rigorous review of radiology was done. In addition, vaccination was done. Patients with low IQ or neurological problems were excluded. Hearing aid trial was done for all patients including aided hearing aid audiograms.

Functional MRI (fMRI) is used to assess the integrity and dominance of the auditory cortex by detecting neural activity changes through blood oxygenation level-dependent (BOLD) signals. Patients undergo auditory stimuli presentations (e.g., pure tones or speech) in a 3 Tesla MRI scanner, typically with a repetition time (TR) of 2–3 s and echo time (TE) of 30–40 ms. Activation maps are generated through statistical analysis, which highlights regions of the auditory cortex responding to the stimuli. Preprocessing steps include motion correction and spatial normalization. The presence or absence of activation reflects cortical integrity, while hemispheric dominance is determined by comparing the volume and intensity of activation in the left and right auditory cortices. A lateralization index may be calculated to assess whether the patient has left, right, or bilateral dominance. This information is valuable for tailoring rehabilitation strategies and predicting outcomes for patients with long-term auditory deprivation.

Surgical Technique

All patients were taken under general anesthesia in a HEPA filter equipped OT with double sterilized equipment and disposable drapes. Meticulous painting, draping was done with savlon and then betadine (3 paints). Preoperatively IV antibiotic Amoxiclav and Cefepime were given. We use primarily the Veria technique. The technique involved taking a C shaped incision near root of the zygoma starting from incisura terminalis and extending it over the squamous part of the temporal bone (Fig. 1). Skin and subcutaneous tissue were cut. The superiorly based Wurzburg flap was elevated. The bed of Implant was made using a template using a diamond drill. Initial drilling was done dry with little water to collect bone dust. After completing a suprameatal well was made to house the electrode (Fig. 2). Thereafter a channel was made using drill (Fig. 2) from suprameatal well to connect the bed. The tympanomeatal flap was elevated, chorda tympani and round window niche was identified. Then tunnel was made in the posterior canal wall via Trifon perforator 1.6 mm with guard set at 0.6 mm. Figure 2, the posterior canal was drilled so that the drill came out below the chorda tympani nerve such that it was in line with the round window niche. Then cochleostomy was done anterior inferior to the anterior pillar of the round window. In cases of hyper pneumatized mastoid after initial drilling of mastoid, posterior tympanotomy approach were also considered (Fig. 3).

Fig. 1.

Topographical marking of future modified end aural incision and implant bed

Fig. 2.

A–D Steps of Veria Technique: A Raising the Musculo-periosteal flap, B Suprameatal hollow, C Suprameatal tunnel, D Cochleostomy

Fig. 3.

A–E Various steps of posterior tympanotomy

Statistical Analysis

Descriptive statistics in the form of mean were used for demographic and socioeconomic data. Factors which affect the success of Cochlear implant will be categorized into continuous variables viz mean duration of hearing loss, age of hearing loss, mean number of hours of Auditory Visual therapy, duration of hearing aid use prior to implantation and Categorical variables such as type of speech processor, socio economic status. Continuous variables will be correlated with mean score of Hearing specific QOL instrument separately and in total to determine the correlation between the variables with the outcome using Pearson's correlations coefficient using SPSS.

Results

Clinical and Demographics

We included 50 patients in our study 31 male and 19 female. The study collected patients who had undergone Cochlear Implant from 2012 to 2024.The mean age of onset of hearing loss was 33.8 years. In our study except for 3 patients all were implanted with bilateral profound hearing loss the remaining 3 had bilateral severe hearing loss with no significant benefit from hearing aid. The associated conditions with hearing loss are shown in Table 1. The cochlea were normal in all patients and 2 had evidence of ossification. The mean duration between onset of profound hearing loss and implantation was 4.5 years with the mean age of implantation being 34 years. The type of implant and processor is shown in Tables 2 and 3. The economical profile of the patient being implanted reveals that most patients came for lower socioeconomic status (n = 42;84%). The educational status of patients revealed that 25% of patients were graduates and post graduates each while 29.2% were professionals.

Table 1.

Etiology of patients having severe to profound hearing loss

Etiology	Numbers of patients
Idiopathic hearing loss	23
Ototoxicity	6
Infective (Post COM)	5
Meniere's	5
Otosclerosis	2
Trauma	2
Enlarged vestibular aqueduct	2
Meningitis	1
Cochlear otosclerosis	1
IP II	1
Post viral	1
Labyrinthine ossificans	1

Table 2.

Type of implants

Standard	29
Concerto 2 medium	11
Synchrony 2 medium	2
Flex 28	1
Foam 19	1
Cochlear nucleus	6

Table 3.

Type of speech processors

Opus 1	3
Opus 2	26
Rondo	9
Rondo 2	4
Rondo 3	1
Sonnet 2	1
Sonnet	3
CP802	3

The Implantations were done by Veria technique in 43/50(86%) and subtotal petrosectomy in 4/50 (8%) and by posterior tympanotomy in 3/50 (6%). Posterior tympanotomy was selected due to hyper pneumatization of the mastoid while subtotal petrosectomy was done in patients with recurrence squamosal disease. Insertion of electrodes was done by anterior cochleostomy in 34/50(68%) and anterior inferior cochleostomy in 11(22%) patients while round window insertion was done in 4/50(8%) patients and anterosuperior insertion was done in 1% Cases. Insertion was determined by the rotation of cochlea and angle of hook region which was studied preoperatively. Post insertion the NRT responses revealed that at least 12 electrodes gave responses in 96% patients while 10 and 8 electrodes in 2% (n = 1) patients each. Our patients did not encounter any intra operative or postoperative complications of surgical site infections, flap failure and trauma to implanted device. Postoperatively only later adverse effects of Dizziness/Vertigo and Tinnitus moderately bothersome in 2% of cases. In addition, overall satisfaction measured on a Likert scale revealed that 52% (n = 26) were extremely satisfied with their post implantation communication abilities and 32% (n = 16) were satisfied while 3 patients were not satisfied with their outcomes.

Quality of Life Assessment

Post operative outcome assessment done by using hearing specific QOL measure SSQ12 (Table 1 supplementary) and CIQOL-10 Global. Table 4 reveals that mean SSQ 12 score of our series was 63.96 ± 11.87(SD). The mean improvement as per CI QOL -10 global was 53.29 ± 8.24. We used Pearson's correlation coefficient to compare the duration of deafness with SSQ 12. The result of the Pearson’s correlation showed that there was a low, negative correlation between SSQ score and Duration of Deafness (r = −0.14, p = 0.343). 48% of patients (n = 24) had duration of deafness less than 4 years. The correlation between total and duration of deafness was not statistically significant.

Table 4.

Lip reading and comparison with speech perception

	Test statistic	Std. error	Std. Test statistic	p	Adj. p
10. Identification of sound—LIP READ BEFORE IMPLANT	89.4	11.01	8.12	< .001	< .001
11. Quality and naturalness—LIP READ BEFORE IMPLANT	97.54	11.01	8.86	< .001	< .001
12. Listening Effort—LIP READ BEFORE IMPLANT	95.06	11.01	8.63	< .001	< .001

Adj. p: Values adjusted with Bonferroni correction

Pearson’s test was also applied to ascertain the correlation between age of implantation with SSQ -12 score which returned a score of 0.614 indicating no correlation with a p value of < 0.05 for significance. Lip reading has been earlier considered to be a factor which may lead to a poor outcome by theorists in this regard. Our study outcomes with satisfactory mean SSQ scores reveal that lip reading may indeed facilitate the process of post implantation speech processing. Dunn-Bonferroni-Tests application (Table 4) comparing preoperative lip reading with identification of sound, quality and naturalness and listening effort reveal a statistically significant difference indicating the positive impact of lip reading on post cochlear implant outcomes.

Discussion

Post lingual hearing loss varies from region to region with gross estimates in India varying from between 7 and 8% [3]. Hearing loss in adults has been considered to be the third most prevalent chronic medical disorder [4]. It is well known that severe hearing impairment is associated with dementia and cognitive impairment due to increased use of top down neurocognitive mechanisms in hearing in a form of vicious cycle [5–10]. In addition, post lingual deafness leads to depression, anxiety added upon by a vicious cycle initiated by economic losses as lack of educational and economic opportunities triggered by lack of hearing.

There are but a few studies elaborating upon the etiology of Post lingual hearing loss in India. However most studies in international literature cite progressive hearing loss progressing from childhood in around 80% cases, sudden sensorineural hearing loss (10%) followed by meningitis (6%), trauma (2%) and ototoxic drugs (2%) as causes of hearing loss [11, 12].

A recent Japanese study investigated genetic causes of post-lingual deafness. While GJB2 is the most common cause of non-syndromic hearing loss in prelingual children, genetic causes are only identified in 40% of adult cases. The study found genetic factors in 35.8% of post-lingual CI/EAS patients, with CDH23 (9%) being the most common gene, followed by MYO7A, TMPRSS3, and others. It also identified various rare causative genes and mitochondrial mutations. Compared to prelingual cases, more dominant and mitochondrial genes are involved in post-lingual deafness, and the study suggested that CI outcomes may be better for cochlear-related causes. The most common causative gene was CDH23 (9%), followed by MYO7A (4%), TMPRSS3 (4%), MYO15A (2%), DFNB31 (1%), ACTG1 (2%), DFNA5 (1%), MYO6 (1%), and CRYM (1%). In the post lingual CI/EAS patients, mitochondrial 3243A > G (1%) and 1555A > G mutation (2%) were also found to be involved [12]. Though, we did not directly analyze genetic factors. We found no maternal or paternal history suggestive of genetic etiology. Presumably our cases had no genetic factors related to intrinsic cochlear proteins.

The outcome of Cochlear implant also depends on other prognostic factors. Predictive factors as per various studies include cochlear anatomy, duration of deafness, ipsilateral and contralateral residual hearing, social and educational status, age of implantation, duration of deafness and on etiology [13–16]. Duration of deafness has been identified as an important prognostic factor in adult cochlear implantation. Several studies have identified shorter duration of deafness with higher performance post implant based on biological basis of deprivation leading to deterioration of auditory structures Balkany et al. have recommended not to implant the deprived ear if duration of deafness is more than 10 years [17, 18]. In our cohort the mean duration of deafness pre implant was 4.48 years with maximum duration of deafness being 10 years and minimum duration of deafness being 1 year with no significant correlation with outcomes (p value of 0.343). In addition, we did f MRI for patients above 4 years of deprivation to analyze whether the auditory cortex is being stimulated. The decision to implant was taken after f MRI results.

An important factor in deciding the success of implantation in prelingual patients is the duration of auditory verbal therapy (AVT). In prelingual patients the focus of therapy is speech acquisition. In adult post lingual therapy is more focused on sound recognition with the user aiming to develop speech recognition by reading and self talk. Lip reading which has been regarded as playing a role in predicting the outcome of cochlear implants is in this regard lip reading has been traditionally considered to be a hindrance. However it has now emerged that auditory deprivation is the source of cross modal neuroplasticity manifesting in heightened vision and lip reading. In this regard various authors have hypothesized that due to competitive resource use Post CI patients with lip reading may be worse off. There is another group with the hypothesis that these patients who lip read may in fact be better off due to cooperation manifesting as synergy between visual and auditory data processing despite reorganization [19, 20].

Most of our patients who lip read continue to do so however most lip readers have learned to use their Cochlear implant and as per SSQ-12 with a mean score of 5.16, 5.32, 5.28 for the questions of Identification of sound, quality and naturalness and listening effort can be interpreted as satisfactory as per the SSQ-12 norms. Pre Implant auditory deprivation has been considered to be a significant factor modulating the impact of cochlear implantation in post lingual patients. In our series 10 patients had a history of use of hearing aid and most did not use hearing aids reliably. In this regard we consider that lip reading was a significant factor which facilitated better outcomes post implant due to cross modal facilitation. However, a separate study is required to assess the nature of cross talk.

Conclusion

We conclude that VERIA technique in adult post lingual implant is a safe technique in adult cochlear implantation and the outcome of adult post lingual implantation. There is no correlation between age of deafness and outcome. Cochlear implantation in the adult post lingual population can significantly improve the quality of life of these patients physically, mentally and socially in particular their sense of self efficacy leading to overall a positive attitude towards life.

Supplementary Information

Below is the link to the electronic supplementary material.

Author Contributions

All authors made substantial contribution to this paper and all the authors have approved the version to be published.

Funding

No funds, grants, or other support was received.

Data Availability

Data will be provided at reasonable request to the corresponding author.

Declarations

Conflicts of interest

The authors have no conflicts of interest to declare that are relevant to the content of this article.

Ethical Approval

This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the institution ethics committee.

Consent to Participate

Informed consent was obtained from all individual participants included in the study.

Consent for Publication

The participants have consented to the submission of the case details for publication.