ORIGINAL ARTICLE
Year : 2020  |  Volume : 3 |  Issue : 1 |  Page : 3-7
DOI: https://doi.org/10.46319/RJMAHS.2020.v03i01.002

A study of sensorineural hearing loss in a tertiary care centre.
Sowmya Santhosh ^1*, Mohan M ², Jyothiswarup. R ³, Ashwini S Doddamani ^4
1 Post graduate student, ² Professor and HOD, ³ Professor, ⁴ Senior Resident, Department of ENT, Sri Siddhartha Medical College, Tumkur.
*Corresponding author:
Dr. Sowmya Santhosh, MBBS, post graduate student, department of ENT, Sri Siddhartha Medical Collge, Sri Siddhartha Academy of Higer Institution, Tumkur 572107, Karnataka. India.
E-mail: drsowmyambsanthosh@gmail.com
Abstract
Background: Sensorineural hearing loss(SNHL) is a common condition seen in an otology clinic. The causes for SNHL are chronic otitis media, Presbycusis, noise induced, ototoxic drug induced, idiopathic etc, There are various treatment modalities to treat them. Treatment outcomes are also different for all. Materials and Methods: A Prospective, observational single centre study was conducted in ENT OPD in which detailed history (onset, duration, associated symptoms of hearing loss), clinical examination followed by Pure tone audiometry was done. Hearing loss was calculated using Extended Fletcher’s Index. 35 patients received treatment depending on their diagnosis and followed up for three months with pure tone audiometry and then results were condition seen in an otology clinic. The causes for SNHL are chronic otitis media, Presbycusis, noise induced, ototoxic drug induced, idiopathic etc, There are various treatment modalities to treat them. Treatment outcomes are also  compared after one month and three months of treatment.  Results: Pre and post-treatment pure tone audiometry values were analyzed. Statistically significant differences in improvement was observed between younger and older age group, and also significant changes in outcome among the causes. Conclusion: ISSNHL is the most common cause of SNHL in the younger age group with a better result, and Presbycusis is the most common cause of SNHL in the older age group with worse outcome.
Keywords: Sensorineural hearing loss, Presbycusis, Ototoxicity, Ginkgo biloba extract, Extended Fletcher’s Index
Introduction
Hearing impairment is the most frequent sensory defect in humans. In 2018, the WHO estimated that there are 466 million people worldwide with a disabling hearing loss.[1] Hearing impairment of any degree results in substantial and long term implications in social and psychological aspects of human life in terms of social, emotional and physical well being. The prevalence and incidence rates of hearing loss in India are quite alarming, at 6.3%.[2] Hearing loss is classified as - Conductive, Sensorineural and Mixed hearing loss. 
            Sensorineural hearing loss (SNHL) results from lesions of the cochlea, VIIIth nerve or central auditory pathways. [3] Chronic otitis media is the leading cause of hearing loss. The other non suppurative causes which play an important role in sensorineural hearing loss are age related, noise induced, Ototoxic drug induced, Meniere’s disease, Head injury; Genetic causes including syndromic conditions like Ushers syndrome, Pendred syndrome, Systemic diseases like diabetes mellitus, hypertension, renal failure, and hypothyroidism; Neoplastic causes like Acoustic neuroma, cerebrovascular ischemia; Idiopathic and others like Cochlear otosclerosis. This study was done to identify different nonsuppurative causes for adult-onset SNHL, and to determine the outcome after treatment for those causes.
           Sudden Sensory Neural Hearing Loss (SSNHL) is the sensorineural hearing loss of 30 dB or more, over at least three contiguous audiometric frequencies, that develops over 72 hours or less. [4] Several factors have been postulated as aetiologies for Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL) like viral infections, vascular occlusion of cochlear arteries, autoimmune disorders. And at the same time, many treatment modalities are also proposed. Among them, widely used treatment is steroids- either systemic or intratympanic. 
            Age-related hearing loss is a progressive bilateral sensorineural hearing loss of mid to late adult-onset, where underlying causes have been excluded.[5] The term Noise-Induced Hearing Loss (NIHL) refers to an auditory acuity reduction as a consequence of excessive exposure to noise. The term ‘acoustic trauma’ describes the situation where a single exposure to an intense sound leads to an immediate hearing loss. [6] The term ototoxicity is the process by which several therapeutic drugs, certain environmental agents such as industrial solvents, and bacterial toxins cause damage to the peripheral end-organs of hearing and balance.[7]
            Hearing impairment is defined by the World Health Organization (WHO) as a hearing loss with a threshold greater than 25dB in one or both ears. The degrees of hearing loss is mild, moderate, severe and profound.[8]
             Pure Tone Audiometry (PTA) measures the auditory threshold of an individual. PTA results are good indicators of hearing impairment. It differentiates conductive, sensorineural and mixed hearing loss.
Materials and Methods
Patients aged more than 18 years of both genders attending Sri Siddhartha Medical College Hospital, audiologically diagnosed to have Sensorineural hearing loss studied for a period 12 months (June 2018 to May 2019) after obtaining written informed consent. Ethical committee clearance was obtained. Patients with suppurative middle ear diseases, congenital/hereditary disorders, autoimmune diseases, and postoperative SNHL were excluded. Sample size calculated using an appropriate formula taking into consideration of incidences of common causes like ISSNHL, Presbycusis. Patients selected by purposive sampling and subjected to detailed history taking and clinical examination. Hearing loss was measured with Pure tone audiometry, using Extended Fletcher Index. Haematological and radiological investigations done whenever necessary. Treatment was on depending on the cause; which included steroids as a mainstay, intravenous steroids for all patients with sudden onset hearing loss, oral steroids for patients who were not willing for admission. Intratympanic steroids along with oral Ginkgo biloba extract was given for those associated with comorbidities like Diabetes mellitus, hypertension and peptic ulcer. For patients with insidious onset hearing loss, Gingko Biloba extract is given alone as steroids was not proposed.
Table1: Showing distribution of treatment among study group.

The vestibular sedative was given for all patients with giddiness i.e. cinnarizine 75mg OD for one week. 
Follow up was done after 5days, 15days, one month, three months after treatment in OPD with Pure tone audiometry. The collected data was entered in the Excel sheet and analyzed using statistical package for social sciences (SPSS) version 18.0.  Descriptive and Inferential statistical analysis was carried out, Student t-test, one way ANOVA test, pearson chi square tests were used. Suggested significant p value (< 0.05).
Results
We have included 35 patients of sensorineural hearing loss, with 18(51.4%) females and 17(48.6%) males, and mean age at presentation was 42.76 years. Among them, 17 patients had bilateral involvement, and slight left ear preponderance was noted with 11(31.4%) patients involving the left ear and 7(20%) patients involving the right ear. 88.5% of patients presented with reduced hearing, 77% with tinnitus, 22.8% with giddiness. The diagnosed causes, include Presbycusis in 9 patients, ISSNHL in 12 patients, Ototoxicity in 3 patients, Noice induced hearing loss in 2 patients; Meniere’s disease, Cerebrovascular ischemia, Post-infection, Post-traumatic, Head injury, Presbycusis with Diabetes mellitus in one patient each. Presbycusis with hypertension in 2, Presbycusis with Noise in 1 patient. Among these 51.4% had sudden onset hearing loss and 48.6% had insidious onset hearing loss. ISSNHL was seen in 10 patients in age <45 years, one patient aged >45 years whereas Presbycusis viewed in 10 patients aged >45 years. 
Table 2 shows average PTA values for different age groups at the time of presentation, one month after treatment and three months after treatment. The average improvement decreases as age progress from 21.73dB in 18-30years aged patients to 4dB in >60years aged patients, the difference being statistically significant (p value of <0.001).

Table 2: Showing improvement in different etiologies.

In this study, among 11 patients of age 18-30years, 9 patients had good recovery with more than 15dB improvement in PTA, 2(18.2%) had poor recovery with less than15dB improvement in PTA and among patients aged more than 60 years all had poor improvement. 

Table 3: Showing distribution of hearing loss according to age.

11 patients in the age group of 18-30 years, presented with average PTA of 59.5dB, after three months average PTA was 38.8dB with improvement of 20.7dB. Among 7 patients of the age group of more than 60 years, average PTA at presentation was 46.08dB, after three months 41.7dB with improvement of 4.3dB, the difference is statistically significant (p value of <0.001).

Table 4-:Showing improvement in PTA from the time of presentation to 1 month an 3 months after treatment.

Table 5 shows PTA values for two major etiologies at the time of presentation, one month after treatment and three months after treatment, the average improvement for ISSNHL was 24.13dB whereas for Presbycusis it was 2.93dB, which is significant statistically (p<0.01).

Table 5: Showing improvement in PTA values according to cause

Ŧ Based on t-test; ¥Based on repeated measurement ANOVA;
Discussion
Study showed highest number of patients had presbycusis (37.14%) followed by ISSNHL(34.2%). CVI, Head injury, Meniere's disease, infection, post-traumatic were other etiologies identified which was similar to Kumar et al study.[13] considering the patients age, ISSNHL was the most common etiology in younger age group and presbycusis will remain as the most common cause in older age group. Mean hearing loss of ISSNHL at the time of presentation was 62.2dB; The maximum number (48.6%) were in the moderate hearing loss group. A study conducted by Kyu Ho Lee et al. in 2015 on 122 patients also observed mean PTA of 62.84dB in one of the groups studied.[14] Symptoms wise 31 patients had reduced hearing, 27 along with tinnitus, 6 patients along with both tinnitus and giddiness, 4 presented with only tinnitus. Our study out of 17 sudden sensorineural hearing loss, 14 showed good recovery(72%) similar to a study conducted by Zadeh et al on 51 patients showed improvement in 37 patients (73%).[15] Our data showed that there was a statistically significant difference in the average PTA measured between one month and 3-month post-treatment( p <0.001), which indicates that there is a need for long term treatment.
Conclusion
           ISSNHL is the most common etiology of SNHL in the younger and presbycusis among aged. There is a significant difference in improvement between one and 3 months. Hence, long term treatment given for better outcome. Gender, vertigo, tinnitus and laterality does not play a significant role in recovery. The treatment outcome is better for younger patients and ISSNHL than for elderly patients and Presbycusis.
           
Limitations of the study: There are no control group, small sample size, and short follow up; therefore there is a need for study with a large group.
Acknowledgements:Nil
Financial support and sponsorship:Nil
Conflict of interest:Nil
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