Deafness or hearing loss is the inability to perceive a sound stimulus. There are 3 types of hearing loss. A mechanical obstruction to the sound waves in the external or middle ear results in “Conductive” hearing loss. A defect in the cochlea (Sensory) or the eight cranial nerves and central auditory pathway (Neural) will result in a “Sensorineural” hearing loss. The term “Mixed” hearing loss is used when there are both conductive and sensorineural components. Sudden Sensorineural hearing loss (SSNHL) or Sudden deafness is defined as an unexplained, rapid sensorineural hearing loss of 30 dB or greater, over at least 3 contiguous frequencies occurring either all at once or within 72 hours. It can be unilateral or bilateral and is usually accompanied by Tinnitus (70%) or Vertigo (40%). The incidence of SSNHL is 11-77 per 1,00,000 population. The incidence also increases with age with 11 being the incidence below 18 years of age and increasing up to 77 for ages above 65 years.[1] Over the years, there have been extensive studies to assess the etiology and determine the management of sudden sensorineural hearing loss. However, there are still a lot of controversies surrounding the causative factors and appropriate treatment of these cases especially when a cause is not identified i.e., Idiopathic (ISSNHL). Our case series gives a comprehensive view about the different etiologies encountered in an office-based practice and the treatment protocol that can be ideally followed for the management of SSNHL.

A total of 20 patients who walked into our outpatient department between the years 2014-2016 were assessed. The details of each patient were entered into a proforma that included the following details: 1 Name, Age, Sex 2. Presenting symptoms (sudden onset hearing loss, giddiness and tinnitus) and duration of each. 3. Etiology - cold wind, noise exposure, ototoxic drug exposure, recent viral infection/ URTI, head injury, family history and comorbidities like dyslipidemia, hypertension, diabetes mellitus, thyroid disorders, ischemic heart diseases etc. 4. Details of hearing ability before the onset of symptoms- with/without prior supportive audiometry report. 5. Pure tone Audiometry report after development of presenting symptoms. 6. Clinical Examination findings 7. Investigation details 8. Treatment provided after obtaining valid and informed consent– Oral and intratympanic steroids with or without other supportive medications. 9. Pure tone Audiometry report obtained 10 days post treatment initiation. Investigations- Pure tone Audiometry at the first visit and 10 days after initiating treatment. Complete blood count, Thyroid profile, Lipid profile, ESR, markers for Autoimmune disease, FBS, PPBS and HbA1C. Magnetic resonance imaging with contrast was done only when the internal auditory canal was to be evaluated and cerebellopontine angle tumors were to be ruled out. Treatment- Each patient was treated with the following: 1. Tapering dose of oral steroids (prednisolone at 1mg/kg). Exclusion criteria to avoid oral steroids- a) Patients with uncontrolled Diabetes Mellitus b) Children below 10 years (Dexamethasone was given in this case) 2. Intratympanic steroid injection – Inj. Dexamethasone (0.5cc of 4mg/ml) was given either once in every 3 days or alternate days or daily for 5 doses. The patients who could not come on a daily basis were subjected to grommet insertion under LA and taught to instill the same medication on a daily basis for 5 doses. 3. Newly detected comorbidities were treated adequately. Medications for the other previously existing comorbidities were continued as usual. 4. Supportive medications like Ginko biloba, methylcobalamin and alpha lipoic acid were given along with the above medications. Exclusion criteria – 1. Patients who refused treatment or failed to complete the treatment course. 2. Patients who were unable to come for follow up. 3. Patients who presented with SNHL of more than 1 month duration. Statistical analysis: Data was entered into Microsoft excel data sheet and was analysed using SPSS 22 version software. Categorical data was represented in the form of Frequencies and proportions.

Continuous data was represented as mean and standard deviation. Paired t test is the test of significance for paired data such as Pre-treatment vs Post treatment for quantitative data. Graphical representation of data: MS Excel and MS word was used to obtain various types of graphs P value (Probability that the result is true) of <0.05 was considered as statistically significant after assuming all the rules of statistical tests. Statistical software: MS Excel, SPSS version 22 (IBM SPSS Statistics, Somers NY, USA) was used to analyse data Table I: Distribution of subjects according to Age, Sex Number Percentage Age in years Children(8-18 years) 1 5% Adults (19-55years) 10 50% Elderly (>55 years) 9 45% SEX Female 6 30% Male 14 70% Table II: Frequency distribution of subjects Symptoms, aetiology, side Number Percentage Symptoms Hearing loss 20 100% Tinnitus 8 40% Giddiness 3 15% Side Left 11 55% Right 9 45% Aetiology Noise exposure 1 5% Recent upper respiratory tract infection 1 5% Cold wind 1 5% Drug exposure 2 10% Idiopathic 1 5% comorbidities 13 65% Table III: Shows the percentage of people with uncontrolled comorbidities. Number Percentage Uncontrolled BP 2 15% Uncontrolled DM 4 31% Abnormal TSH 1 7% Dyslipidaemia (Uncontrolled) 4 31% Table IV: Distribution of hearing loss (according to degree of hearing loss). Hearing loss Number Percentage Mild (26-40 dB HL) 3 15% Moderate (41-55 dB HL) 5 25% Moderately Severe (56-70 dB HL) 5 25% Severe (71-90 dB HL) 6 30% Profound (>90 dB HL) 1 5% Table V: Comparison of the Pure tone audiometry reports (with reference to dB HL) pre-treatment and 10 days post-treatment. PTA Mean Std. Deviation P value Pre treatment 60.50 20.735 <0.001 Post treatment 21.665 8.7703 There was a statistically significant difference found between pre and post treatment with respect to PTA • Minimum improvement in PTA with treatment was 16.67% and Maximum was 86.67%. • Mean improvement was in PTA with treatment 61.2%.

Sudden sensorineural hearing loss is an otologic emergency and can be an alarming experience for the patient. It is characterized by a loss of at least 30dB over three frequencies occurring in a span of 3 days. The incidence of SSNHL is 11-77 per 1,00,000 population. Studies show that while men are more likely to develop hearing loss due to causes like noise exposure, there is no apparent gender predilection when it comes to sudden deafness.[4] In our case series we saw that 70% of the patients were males. The incidence also increases with age with 11(per 100,000) being the incidence below 18 years of age and increasing up to 77 (per 100,000) for ages above 65 years.[1]In our study, only 5% of the patients were children (aged below 18 years), 50% were adults (aged 19-55 years) and 45% were elderly (aged 55 years and above). There was not much of a difference in the side affected in our study with 55% of the patients having hearing loss in the left ear and 45% of the patients having hearing loss in the right ear. Tinnitus and vertigo (either spontaneous or isolated positional vertigo) very commonly accompany sudden deafness.[5] In this case around 40% of the patients presenting with sudden hearing loss had tinnitus and another 15% had associated vertigo as well. To diagnose sudden sensorineural hearing loss, there has to be at least 30 dB of hearing loss. Hearing loss can be categorized according to the severity. Mild (26-40 dB HL), Moderate (41-55 dB HL), Moderately severe (56-70 dB HL), Severe (71-90 dB HL) and Profound hearing loss (>90 dB HL). We had 15% of the patients presenting with mild hearing loss, 25% with moderate deafness, 25% with moderately severe hearing loss, 30% with severe hearing loss and 5% with profound hearing loss. It is also important to note that most of our patients presented to us within the first week of symptom onset and only 3 patients presented in the second week after symptom onset. We did not see any difference in the recovery rate with relation to the day of presentation. This could be because all of them presented within the first 15 days making it a difficult factor to analyze. It is well known that subjects seen earlier after onset of hearing loss show greater improvement, reflecting either the benefit of early treatment or the natural recovery rate.[6] A study by Na Sy, Kim MG et al conducted in 2014 showed that there were no differences in the sex predilection, side affected and degree of hearing loss between children and adults. However, the recovery rates of children with mild/moderately severe/profound hearing loss were much better when compared to adults.[2] The risk factors for idiopathic sudden sensorineural hearing loss (sudden deafness) include smoking, alcohol consumption, dietary habits, exposure to cold wind, barotrauma, environmental noise exposure, comorbidities (like thyroid disorders, diabetes mellitus, dyslipidaemias and hypertension), extreme stress, inadequate sleep, loss of appetite, fatigue, lack of nutritious diet and susceptibility to common cold.[3] A variety of disorders affecting the ear can cause SSNHL, but only about 10% of people diagnosed with SSNHL have an identifiable cause. The rest of the cases are Idiopathic (90%) Some of these conditions include: • Infections. • Head trauma. • Autoimmune diseases. • Exposure to certain drugs that treat cancer or severe infections. • Blood circulation problems. • Neurological disorders, such as multiple sclerosis. • Disorders of the inner ear, such as Ménière’s disease. In our case series we saw that 65% of the patients who presented with sudden sensorineural hearing loss had an associated previously existing or newly detected comorbidity and only 5% of the cases were truly idiopathic with no associated comorbidities. The comorbidities included Type II Diabetes Mellitus, Hypertension, Hypothyroidism and Dyslipidaemias. 15% of these patients had uncontrolled hypertension, 31% had uncontrolled type II DM and 7% had high TSH (Thyroid stimulating hormone) levels and another 31% had uncontrolled dyslipidaemias. A multivariate analysis conducted by Kathleen Bainbridge et al, showed that people with diabetes had significantly increased chances of hearing impairment in either ear, at all frequencies. This was also stronger among those people younger than age 60, and was independent of gender or chronic exposure to noise. The pathogenesis is that high blood glucose levels may damage the vessels in the stria vascularis and nerves impacting the biochemistry and neural innervation of the cochlea.[7] According to Nagahar K et al, high pressure in the vascular system in patients with hypertension may cause inner ear haemorrhage, which may lead to progressive or sudden hearing loss.[8] A study by I. Klien et al showed that hypothyroidism can affect the level of blood lipid to promote coronary atherosclerosis, cause high coagulation state, fibrous protein decomposition damage, abnormal function of platelet and endothelial function disorder, increase the peripheral vascular resistance, cause endothelial dependent vasodilation damage, change the arterial smooth muscle structure and hemodynamic changes which can indirectly lead to hearing loss.[9] There is some evidence that dyslipidaemia may be a risk factor for SSNHL. The pathology behind it could be the initiation of an inflammatory or stressful response in the inner ear. There is also evidence that correction of the dyslipidaemia can be more effective while treating patients with SSNHL who have this particular comorbidity.[10] Management of patients presenting with sudden onset hearing loss includes a detailed history and clinical examination followed by elaborate laboratory tests to identify a cause. There are several treatment options that have been suggested for sudden deafness. But, the high chances of a possible spontaneous recovery and lack of understanding of the various aetiologies make it difficult to narrow down the ideal mode of treatment for a case of sudden deafness. Every patient in our study went through a detailed clinical evaluation which included a thorough history, general physical examination, systemic examination, an otoscopic examination of the ear, tuning fork tests and an audiometric evaluation (pure tone audiometry) in the clinic. This was followed by a set of laboratory investigations like complete blood count, coagulation profile, lipid profile, thyroid profile and blood sugar profile. Serological tests for infection and radiological tests like MRI brain were considered only when indicated. Laboratory blood tests like complete blood counts, coagulation profile, serum electrolytes, erythrocyte sedimentation rate are not recommended as per the American academy of otorhinolaryngology and head and neck surgery (AAO-HNS) clinical practice guidelines.[11] The decision to perform Serological tests for infectious causes should be directed by clinical and epidemiological scenarios. However, an autoimmune workup and metabolic panel work up for diabetes, dyslipidaemia and thyroid dysfunction is reasonable to look for specific aetiology and the metabolic risk factors management. TREATMENT There are several treatment options available for sudden sensorineural hearing loss. Systemic corticosteroids are the most common first line medicines used in these cases despite there being very limited documented evidence supporting the same.[11]It can be given either orally (Prednisolone 1mg/kg tapering dose) or as an intravenous pulse therapy with 300mg Prednisolone for 3 days. Both have been found to be equally efficacious. [12] Intratympanic steroids have several advantages like targeted drug delivery, lesser quantity of drug required, lesser systemic absorption and fewer complications. The various methods of intratympanic drug delivery include intratympanic injection, placement of grommet tube for drug instillation, placement of absorbable sponge in round window niche and placement of Silverstein micro-wick and round window micro catheter for sustained drug delivery. Intratympanic injections remain the most convenient and commonly used method. This mode of treatment can be used as a primary/adjuvant therapy and there have been several studies that have tested out the efficacy of giving the intratympanic steroid injections/systemic steroids alone vs giving the two together.[14] Hyperbaric oxygen therapy aims to improve the oxygen supply to the ischemic vasculature in the cochlea. While there are a few case studies supporting this form of therapy, there are also a few that are against it (in terms of availability, cost constraints, side effects, no significant statistical benefits) and hence must be used with caution.[11] A myriad of other therapies has been used to treat ISSNHL (Idiopathic SSNHL) including antivirals, volume expanders, vasodilators and vasoactive substances, thrombolytics, antioxidants, histamines, magnesium, diuretics, intravenous diatrizoate and herbal remedies. Lack of the right evidence is the main reason why these modalities are not supported in literature.[13]

In our practice, each patient was treated with the following: 1. Pure tone audiometry recorded on day 1. 2. Tapering dose of oral steroids (prednisolone at 1mg/kg). Exclusion criteria to avoid oral steroids- a) Patients with uncontrolled Diabetes Mellitus b) Children below 10 years (Dexamethasone was given in this case) 3. Intratympanic steroid injection – Inj. Dexamethasone (4mg/ml) was given either once in every 3 days or alternate days or daily for 5 doses. The patients who could not come on a daily basis were subjected to grommet insertion under LA and taught to instill the same medication on a daily basis for 5 doses. 4. Newly detected comorbidities were treated adequately. Medications for the other previously existing comorbidities were continued as usual. 5. Supportive medications like Ginko biloba, methyl cobalamin and alpha lipoic acid were given along with the above medications. Patient’s improvement was assessed with a Pure tone audiometry on the 10th day after initiation of therapy. We have found a statistically significant difference between pre and post treatment (combination of oral steroid with intratympanic steroid injections) with respect to PTA (p value <0.001). Minimum improvement in PTA with treatment was 16.67% and Maximum was 86.67%.Mean improvement in PTA with treatment was 61.2%. Therefore, this treatment combination of tapering dose of oral steroids with 5 doses intratympanic steroid injections can be considered as the ideal mode of therapy to combat the elusive sudden sensorineural hearing loss in an office-based practice while avoiding hospital admissions, minimizing side effects and other costly treatment options.

1. Thomas H Alexander , Jeffrey P Harris.Incidence of sudden sensorineural hearing loss. Otol Neurotol. 2013 Dec;34(9):1586-9. doi: 10.1097 2. Na Sy, Kim MG et al; Comparison of sudden deafness in adults and children. Clinical and Experimental Otorhinolaryngology, 01 Aug 2014, 7(3):165-169 DOI: 10.3342/ceo.2014.7.3.165 3. T Nakashima , T Tanabe, N Yanagita, K Wakai, Y Ohno. Risk factors for sudden deafness: a case-control study. Auris Nasus Larynx. 1997 Jul;24(3):265-70. doi: 10.1016/s0385-8146(96)00024-7. 4. Dass Arjun, Goel Neha, Singhal Surinder K, Kapoor Ravi. Sudden Sensorineural Hearing LossPrognostic Factors. Iran J Otorhinolaryngol. 2015 Sep; 27(82): 355–359. 5. Fetterman BL, Saunders JE, Luxford WM. Prognosis and treatment of sudden sensorineural hearing loss. Am J Otol. 1996;17(4):529–36. 6. Byl F. Sudden hearing loss: Eight years-experience and suggested prognostic table. Laryngoscope. 1984;94(5):647–66. 7. Bainbridge KE, Hoffman HJ, Cowie CC. Diabetes and hearing impairment in the United States: Audiometric evidence from the National Health and Nutrition Examination Survey, 1999-2004. Ann Intern Med. July 2008;149(1):1-10. 8. Nagahar K, Fisch U, Yagi N. Perilymph oxygenation in sudden and progressive sensorineural hearing loss. Acta Otolaryngol. 1983;96:57–68. doi: 10.3109/00016488309132875. 9.I. Klein, K. Jamaa. Thyroid hormone and the cardiovascular system. N Engl J Med, 344 (2001), pp. 501-509 10. Cadoni G, Scorpecci A, Cianfrone F, Giannantonio S, Paludetti G, Lippa S. (2010) Serum fatty acids and cardiovascular risk factors in sudden sensorineural hearing loss: a case-control study. Ann Otol Rhinol Laryngol 119: 82–88. 11. Stachler R.J., Chandrasekhar S.S., Archer S.M., Rosenfeld R.M., Schwartz S.R., Barrs D.M., Brown S.R., Fife T.D., Ford P., Ganiats T.G., Hollingsworth D.B., Lewandowski C.A., Montano J.J., Saunders J.E., Tucci D.L., Valente M., Warren B.E., Yaremchuk K.L., Robertson P.J., American Academy of Otolaryngology-Head and Neck Surgery Clinical practice guideline: sudden hearing loss. Otolaryngol. Head Neck Surg. 2012;146: S1–S35. doi: 10.1177/0194599812436449. 12. Westerlaken B.O., de Kleine E., van der Laan B., Albers F. The treatment of idiopathic sudden sensorineural hearing loss using pulse therapy: a prospective, randomized, double-blind clinical trial. The Laryngoscope. 2007;117:684–690. 13. Conlin A.E., Parnes L.S. Treatment of sudden sensorineural hearing loss: I. A systematic review. Arch. Otolaryngol. Head Neck Surg. 2007;133:573–581. doi: 10.1001/archotol.133.6.573. 14. Anup Singh, David Victor Kumar Irugu. Sudden sensorineural hearing loss – A contemporary review of management issues. J Otol. 2020 Jun; 15(2): 67–73.Published online 2019 Jul 30. doi: 10.1016/j.joto.2019.07.001