Introduction
Hearing impairment is one of the most frequent disabilities. It represents great risk to backwardness, communication, social development and also to auditory processing. Unilateral hearing loss and audiovestibular symptoms are common in the population and can be associated with Retrocochlear tumors such as Acoustic neuroma.
In Sensorineural hearing loss (SNHL) the pathology lies in vestibulo cochlear nerve (viii N), the inner ear, or central processing centers of the brain. Sensorineural hearing loss can be mild, moderate, severe or profound. The majority of the causes of sensorineural hearing loss are cochlear origin only, a few of cases are retro cochlear origin.
Sensorineural hearing loss (SNHL) is a complex disease influenced by interactions between multiple internal and external causative factors. Genetics and age-related hearing changes may predetermine a patient's hearing throughout their lifetime, and any potential hearing changes over time may be accelerated by numerous external factors.
The incidence of SSNHL has been estimated by Byl et al1 to range between 5 and 20 cases per 100,000 persons per year. Sudden sensorineural hearing loss is usually unilateral and can be associated with tinnitus and vertigo. In most cases the cause is not identified, although various infective, vascular, and immune causes have been proposed. A careful examination is needed to exclude life threatening or treatable causes such as vascular events and malignant diseases, and patients should be referred urgently for further assessment.
The complexity of the diagnostic evaluation and potential treatment options for SNHL has increased because of multiple considerations. There is a downward trend in the presenting age and an increasing severity of hearing loss in patients from first-world (industrialized) nations. Patterns of hearing loss have changed in relation to noise exposure because of various occupational hazards such as heavy industrial noise and firearms use in military and police occupations. Clinicians involved in the management of critically ill and complex medical patients are aware of the impact that pharmaceutical therapy for multisystem disease may have on hearing.
Since there is not much data available with differential diagnosis and management of unilateral sensorineural hearing loss with intact tympanic membrane to co-relate with other co-morbidities among Indian population. Most of the clinical studies done on hearing loss are involving both conductive and sensorineural hearing loss and are bilateral SNHL. There is a need for a clinical study to find the pattern of degree of hearing loss in different age group, sex and among patients suffering from co-morbidities such as Diabetes mellitus, Hypertension, Dyslipidemia, Smoking & Alcohol.
By doing this study we can identify the clinical manifestation and co morbid status of unilateral sensorineural hearing loss and associated symptoms and grading of hearing loss by different types
Materials and Methods
Study area
This is a cross-sectional, Hospital based study was carried out in ENT OPD of Apollo Hospital Chennai. The hospital caters not only to the population based in Chennai, but is also a tertiary referral center for the patients from other states like West Bengal, Assam and Arunachal Pradesh.
Inclusion criteria
All cases which are presented with unilateral sensorineural hearing loss aged above 18yrs who attended ENT OPD during the study period were included.
Sample size estimation
We have taken our hospital records as our base, Since there were no such studies available in the local set up. Which shows the prevalence of unilateral sensorineural hearing loss as 15% among the screened symptomatic ENT patients in the year October 2011 to September2012.
That percentage of patients presented with unilateral sensorineural hearing loss was 15% (0.15) [P]. The required sample size was estimated 50 with Z- 95% power with CI-1.96 and allowable error of 10%(0.1).
Methodology: Data collection technique and tools
All selected cases underwent a thorough history taking and ENT examination. A proper history was elicited from the patients, and a general and systemic examination was also carried out.
Pure tone audiogram and MRI scan of brain was carried out for all patients. The relevant cases underwent appropriate investigations like electronystagmogram, haematological tests like ESR, blood sugar levels, cholesterol, triglycerides and TSH levels.
The diagnosis was made eventually and the cases underwent appropriate surgical or medical management and the results were analyzed.
Methodology
Data collection technique and tools
Data validation and entry was done in MS Excel spread sheet. All the continuousvariables were assessed for the normality using Shapiro Wilk’s test. If the variablesfollow Gaussian distribution, they were expressed as mean+ standard deviationotherwise. All the categorical variables were expressed as either bypercentage or proportion.
All the categorical comparisons were done by ChiSquare test or Fisher Exacttest based on the number of observation. All the p values less than 0.05 were considered as statistically significant. All the analysis was carried out by using a statistical software SPSS version 11.
Results
Table 0
50 patients aged above 18 years with sensorineural hearing loss attending to ENT OPD at Apollo Hospital and Research Centre, Chennai from Oct 2012 - Sept 2013 were studied. Observations recorded in the study are described under the following heading.
Percentage of Grading of sensorineural hearing loss according to goodman
Out of 50 cases, 23(46%) patients were having profound SNHL, 8(16%) patients were having moderate SNHL, 6(12%) patients were having moderately severe SNHL and 2(4%) were having severe SNHL. Grading based on shape of audiogram low frequency loss 9(18%), high frequency loss 1(2%) and sloping 1(2%).Profound hearing loss was common in (46%) of cases followed by low frequency loss (18%) followed by moderate hearing loss (16%)
Age wise distribution of SNHL
Out of the 50 patients who presented with unilateral SNHL. 14(28%) patients were in the group less than 40yrs. Between 40-45yrs there were 3(6%) cases. 5(10%) patients were between 45-50yrs. Between 51-55yrs there were 13(26%) cases. >55yrs age 15(30%) patients were presented.
SNHL was common in age group more than >50yrs, together constitutes 56% of patients.
Sex wise distribution of grading of hearing loss
Table 3 Out of 50 patients 34 (64%) were males and 16(32%) were females. The male to female ratio was 2.12:1. Low frequency hearing loss and profound SNHL were common in males. Their was no statistically significant association with sex and distribution of grading of hearing loss with P value of 0.827.
Table 1
Comparison of grading of hearing loss with onset of SNHL P value-0.01
Fluctuating hearing loss was found in 13(26%) of cases, 88.9% of low frequency loss has got fluctuating hearing loss. Gradual onset was found in 26(56%) of cases, 65.2% of Profound SNHL has got gradual onset hearing loss. Sudden onset hearing loss found in 11(22%) of cases, 34.8% of profound SNHL has got sudden hearing loss, with P value <0.05. Which is statistically significant. Low frequency hearing cases more presents has fluctuating course and most of them were meniere's disease.
Table 2
Clinical symptoms with Sensory neural hearing loss
|
Clinical symptoms |
No of cases (%) |
|
Giddiness (vertigo) |
23 (46) |
|
Tinnitus |
31 (62) |
|
Ear discharge |
1 (2) |
|
Both vertigo and tinnitus |
3 (6) |
Table 3
Co relation of clinical symptoms with grading of hearing loss according to Goodman andClarkTable -8(A)-Giddiness P value -0.238
Giddiness was the presenting symptom in 43.6% of SNHL according to Goodman and Clark classification. 75% of moderate SNHL had got giddiness. 33.3% of moderately severe SNHL and 34.8% of profound SNHL had presented with giddiness. But this was not atavistically significant with P value of 0.238
Table 4
(B) Tinnitus P value- 0.076
Tinnitus was presenting symptom with 51.3% of SNHL according to Goodman and Clark classification. 87.5% of moderate SNHL had got tinnitus. 56.5% of profound SNHL had presented with tinnitus. But this was not statistically significant with P value of 0.076.
Table 5
(C)- Ear discharge P value- 0.87
Ear discharge was the presenting symptom with 2.6% of SNHL according to Goodman and Clark classification. 4.3% of profound SNHL had presented with ear discharge. But this was not statistically significant with P value of 0.87.
Table 6
Co relation of co-morbidities with grading of hearing loss according to Goodman and Clark
19(48.7%) of cases had no co-morbidities, 12(52.2%) of profound SNHL had no co-morbidities. Diabetes mellitus was presented in 11(28.2%), 26.1% of profound SNHL had diabetes mellitus. Hypertension and diabetes mellitus together was presented in 2(5.1%), 1 case had profound SNHL and another Moderate SNHL. Dyslipidemia was found in 2(5.1%), 1 case had profound SNHL and another Moderately severe SNHL. Hypothyroidism was found in 1(2.6%) of case in moderate SNHL. Diabetes mellitus and renal transplant together was found in 1(2.6%) of profound SNHL. Fatty liver was found in 1(2.6%) of severe SNHL.
Table 7
Analysis of Duration and investigation of SNHL
The mean age of presentation of SNHL is 48.5yrs and SD of 12.98 with 2 SD deviation, the age group is (61.48-35.52). Duration of SNHL at the time of presentation mean-854.06hrs (35.4 days).
Table 8
Analysis of Investigations with SNHL
Statistical analyses were carried out using Kruskal Wallis test. The mean values of ESR, Cholesterol, Triglycerides and TSH among different degree of SNHL were found out to be similar. The P value was being >.05 was not statistically significant.
Table 9
Co relation of ENG with grading of hearing loss
ENG was done in 35 of cases of which it is abnormal in 30 cases, Left Hypo active labyrinth in 17(48.6%), Right hypo active labyrinth 13(37.1%). Left hypoactive labyrinth patients has more of low frequency loss (66.7%). Right hypoactive labyrinth patients has more of profound hearing loss (53.8%). It was not statistically significant as P value >0.05.
Analysis of MRI for diagnosis of SNHL
MRI was done in all 50 cases with unilateral SNHL, in 4 cases it found to be abnormal and they were left mastoid opacity with eroded ossicles, Right CP angle lesion, Right Acoustic neuroma and Dominant left vertebral artery, bilateral fetal origin of post cerebral arteries.
Table 10
Etiologies of Unilateral SNHL
Etiologies of unilateral SNHL were follows Meniere's disease in 14 (28%) followed by Metabolic in 12(24%) of cases, Sudden SNHL in 11(22%) of cases, idiopathic in 10 (20%) of cases, Acoustic neuroma in 2 (4%) of cases and Left COM, squamosal disease in 1 (2%) of cases.
Discussion
This study was carried out in Apollo Hospital and Research Centre, Chennai from Oct 2012 - Sept 2013 .The cases which presented with unilateral sensorineural hearing loss to OPD were taken into the study. During the study, it was found, 50 cases were presented with unilateral SNHL during the study period. It constitutes 15% of cases screened. SNHL was one of the important otologic emergency presenting to ENT OPD.
In our study common age group of presentation of unilateral SNHL was more than 55yrs which constitutes 30% of cases, followed by <40yrs with 28% and between 50-55yrs 26%. Mean age of presentation of unilateral SNHL was 48.54yrs (SD = 12.89, Range =18-74yrs) in our study. Steven D. Rauch et al2 study showed sudden sensorineural hearing loss typically occurs between 43 years and 53 years of age, with equal sex distribution. In Shaia and Sheehy study3 which included 1220 cases three quarter of patients were over the age of 40yrs. In our study, out of 50 patients 34(64%) were males and 16(32%) were females. The male to female ratio was 2.12:1. In other studies Tiong TS et al4 and Yimtae K, et al5 showed females are commonly affected.
Grading of hearing loss according to Goodman and Clark, among the cases presented as follows 23(46%) patients were having profound SNHL, 8(16%) patients were having moderate SNHL, 6(12%) patients were having moderately severe SNHL and 2(4%) were having severe SNHL. Grading based on shape of audiogram high frequency loss 9(18%), low frequency loss 1(2%) and sloping 1(2%).
In our study the presenting complaints were tinnitus 31(62%), vertigo (giddiness) 23(46%), both vertigo and tinnitus 3(6%) and ear discharge 1(2%). In our study of the 50 patients, 14 patient had diabetes mellitus of which 2 had hypertension and one was post renal transplant patient. One with dyslipidemia and one with hypothyroidism. Other causes were GERD, epistaxis and fatty liver
Side of lesion of SNHL
The involvement of side of SNHL in our study is as follows Left side 30 (60) and right side 20 (40), left side more involvement. Similar result found in Tiong TS et al4 study conducted in Singapore with left side 30(56.6%) and right side 23(43.4%).
Onset of hearing loss
The following are the onset of presentation in our study with, Fluctuating hearing loss was found in 13(26%), Gradual onset was found in 26(52%), Sudden onset hearing loss found in 11(22%) of cases.5
88.9% of low frequency loss has got fluctuating hearing loss. 62.5% of Profound SNHL has got gradual onset hearing loss. 34.8% of profound SNHL has got sudden hearing loss, with P value <0.05. Which is statistically significant.
Duration of SNHL at the time of presentation
In our study mean duration symptoms of unilateral of SNHL at the time of presentation is 854.06hrs (35.5 days).
In Flavia Alencar de Barros et al6 study only four patients (20%) sought our services after the tenth day: one (5%) between days 11 and 20 with a profound level of initial loss; one (5%) between days 21 and 30 with a severe initial loss; and two (10%) after more than 31 days, of whom one had moderate loss and the other had severe loss.
Clinical symptoms with unilateral Sensory neural hearing loss
In our study the presenting complaints were tinnitus 31(62%), vertigo (giddiness) 23(46%), both vertigo and tinnitus 3 (6%) and ear discharge 1(2%).
In Tiong TS et al4 study the main presenting symptoms were deafness (40 patients), tinnitus(38), and vertigo(12).
In Flavia Alencar de Barros et al6 study seven patients (35%) had exclusively associated with tinnitus; three (15%) showed tinnitus plus ear blockage; five (25%) showed tinnitus plus vertigo; one (5%) showed tinnitus plus vertigo plus ear blockage; one (5%) showed ear blockage and three (15%) showed only hearing loss. Given these results, the most common symptom associated with the hearing loss was tinnitus, which appeared in 16 patients (80%). Similar to Tiong TS et al4 and Flavia Alencar de Barros et al6 studies in our study also tinnitus was the common presenting symptoms along with hearing loss.
Association of clinical symptoms with grading of hearing loss according to Goodman and Clark classification. Giddiness was the presenting symptom in 43.6% of SNHL, Tinnitus was presenting symptom with 51.3% of SNHL, Ear discharge was the presenting symptom with 2.6% of SNHL. But its association with grading of hearing loss is not statistically significant.
Co-morbidities associated with SNHL
In our study of the 50 patients, 14 patient had diabetes mellitus of which 2 had hypertension and one was post renal transplant patient. One with dyslipidemia and one with hypothyroidism. Other causes were GERD, epistaxis and fatty liver.
In Tiong TS et al4 study out of 50 patient, 16 patients were found to have associated conditions of diabetes mellitus, seven with hypertension, and 12 with hyperlipidaemia.
Chamyal P C et al 7 found hearing loss mild to moderate and was detected in 40% of diabetes.
In our study diabetes mellitus was associated in 14(26.1%) of cases of which 2 cases associated with hypertension and one with post renal transplant. Onset of hearing loss was gradual in 10(71.4%) of cases, and 57.1% of cases had profound hearing loss. Diabetes mellitus was associated with gradual onset profound hearing loss at presentation.
ENG with grading of hearing loss
ENG was done in 35 of cases of which it is abnormal in 30 cases , Left Hypo active labyrinth in 17(48.6%) of which 10 cases were menieres disease, Right hypo active labyrinth 13(37.1%) of which 4 cases of each metabolic and sudden SNHL, 3 cases were menieres disease.
Left hypoactive labyrinth patients has more of low frequency loss (66.7%). Right hypoactive labyrinth patients has more of profound hearing loss (53.8%) but it was not statistically significant.
Etiologies of Unilateral SNHL
In our study following are the etiologies found for unilateral SNHL, Meniere's disease in 14 (28%) followed by Metabolic in 12 (24%) of cases, Sudden SNHL in 11(22%) of cases, idiopathic in 10 (20%) of cases, Acoustic neuroma in 2 (4%) of cases and Left COM,squamosal disease in 1 (2%) of cases.
Chau JK et al 8 conducted a metaanlysis showed etiologies for patients suffering sudden sensorineural hearing loss included idiopathic (71.0%), infectious disease (12.8%), otologic disease (4.7%), trauma (4.2%), vascular or hematologic (2.8%), neoplastic (2.3%), and other causes (2.2%).
Koc A et al 9 did a literature survey of recent studies found etiology for SNHL were viral inflammation, vascular diseases, allergic reaction, rupture of intralabyrinthine membranes, and autoimmune diseases.
Approximately 1% of cases of sudden sensorineural hearing loss are due to “retro- cochlear” disorders that may be related to vestibular schwannoma, demyelinating disease, or stroke.3 Another 10 to 15% are due to another identifiable cause, such as Meniere’s disease, trauma, autoimmune disease, syphilis, Lyme disease, or perilym- phatic fistula.The remainder are idiopathic and almost exclusively unilateral.
Conclusions
Sensorineural hearing loss is one of the important clinical presentation to ENT opd. The prevalence of unilateral sensorineural hearing loss is 15%.
Common age group of presentation of unilateral SNHL is more than 55yrs (30%) and males were commonly affected ratio of 2.12:1.
Profound sensorineural hearing loss is the common grade of hearing loss in age group more than 40yrs.
The common side of lesion of unilateral SNHL was left side (60%
Most common clinical symptoms which presented with SNHL was tinnitus (62%
Most common type of onset of SNHL was gradual onset of hearing loss (52%
Diabetes mellitus was most common Co morbidities associated with SNHL
Common etiologies of unilateral sensorineural hearing loss were Meniere's disease in 14 (28%) followed by Metabolic in 12(24%) of cases, Sudden SNHL in 11(22%) of cases, idiopathic in 10 (20%).
Most of the cases were managed by reassurance (52%). Other cases were manged by medical management in done 18(36%) of cases, surgical management was doe in 3(6%) and hearing aid was prescribed in 3(6%) of cases.
Summary
50 cases of unilateral sensorineural hearing loss aged above 18yrs who attended ENT opd of Apollo Hospital Chennai were reviewed.
In these cases, grading of hearing loss, onset , clinical feature , co morbidities, investigation , diagnosis and management were studied.
Unilateral sensorineural hearing loss was presented in 15% of the cases screened during this period.
Grading of hearing loss which common was profound SNHL (46%) followed by low frequency loss (18%) and moderate SNHL (16%). Profound hearing loss was common in all age group above 40yrs, low frequency hearing loss was common in age less than 40yrs.
Gradual onset of hearing loss (52%) was common followed by fluctuating hearing loss (26%). Sudden onset hearing loss was 22%. 65.2% of profound SNHL has got gradual onset hearing loss. Low frequency hearing cases presents has fluctuating onset and most of them were meniere's disease.
Clinical symptoms which was commonly presented with SNHL was tinnitus (62%). Vertigo was presented in 46%.
Co-morbidities associated with SNHL were Diabetes mellitus, hypertension, hyperlipidemia and hyperthyroidism. Diabetes mellitus was common 14 cases of which 2 cases with hypertension and 1 with renal transplant.
Diabetes mellitus was associated in 14 (26.1%) of cases. Onset of hearing loss was gradual in 10(71.4%) of cases, and 57.1% of cases had profound hearing loss. Diabetes mellitus was associated with gradual onset profound hearing loss at presentation.
Etiologies of unilateral sensorineural hearing loss were follows Meniere's disease in 14(28%) followed by Metabolic in 12(24%) of cases, Sudden SNHL in 11(22%) of cases, idiopathic in 10(20%) of cases, Acoustic neuroma in 2(4%) of cases and Left COM, squamosal disease in 1(2%) of cases.
Meniere's disease 9(100%) of cases presented as low frequency loss was. Which is statistically significant with p value <0.05.
Metabolic causes found in 12(24%) of cases of which 7 cases of profound SNHL, 3 cases of moderately severe and 2 cases of moderate SNHL.
Sudden SNHL was found in 11(22%) of cases, of which 8 cases were profound SNHL, 2 cases are moderately severe and 1 case was severe SNHL.
