**8. Treatment**

As the etiological factor is mostly not identifiable in SHL, its treatment is arranged in certain protocols. Several therapeutic modalities clinically different but similar in respect of main aspects have been developed. Systemic corticosteroids are beyond dispute the main therapeutic agents and they are also considered as the golden standard in the literature. Moreover, multiple medical agents can be used in the treatment. In patients, who did not respond or partially respond to the primary treatment, salvage treatment should be implemented. Although these treatments may change according to the patient and physician's algorithm, it should be initiated with the primary treatment. In SHL cases with identified etiology, treatment should be targeted to the underlying disorder. Hereinafter, the treatment protocols especially for the idiopathic SHL will be discussed.

#### **8.1. Medical treatment**

#### *8.1.1. Systemic corticosteroids*

They are currently the main therapeutic agents (**Figure 1B**). They should be included in the treatment protocols of SHL cases with unknown etiology. Although the mechanism of action of the corticosteroids considering the SHL pathogenesis is not fully elucidated, it is believed that they decrease the inflammation in the inner ear and accelerate the regeneration. An early initiation of the systemic corticosteroid therapy enables a relatively better respond to the treatment [66]. Wilson [66], in his randomized double-blind placebo-controlled study, showed clearly the positive effect of the corticosteroids on the SHL. The following numerous studies confirmed these findings. Although there are few studies in the literature reporting that corticosteroids are ineffective, we observed in our clinical practice, that they are highly effective and included them in our routine treatment protocol. Systemic corticosteroid therapy is a short-term treatment, which is initiated with a dose of 1 mg/kg and continued with a gradual dose reduction. This treatment with gradually declining dosage enables that the suppressed adrenal glands have enough time to produce steroids again. The SHL treatment guideline, which was published by the American Otolaryngology Academia in 2012, indicated the corticosteroids as the first-line therapy. It was stated that a dose of 1 mg/kg for approx. 10–14 days is sufficient for the treatment of SHL [67]. Systemic corticosteroids have diverse side effects. The most common side effects are acne, blurred vision, cataract or glaucoma, sleeping problems, hypertension, increased appetite, hypertrichosis, insomnia, immunosuppression, muscle weakness, irritability, uneasiness, osteoporosis, increase of insulin need in diabetic patients, diffuse edema due to the water and salt retention in kidneys, aseptic necrosis in the femur head. Steroids should be used carefully particularly in patients with comorbidity and in the pregnant and the risk-benefit of the therapy should be thoroughly evaluated. If in these patients corticosteroid use is risky, intratympanic corticosteroid injection should be considered in the primary treatment [68, 69].

#### *8.1.2. Antiviral agents*

suspected, levels of the relevant auto-antibodies; thyroid function tests, homocysteine, PT, APTT, INR or markers like specific factor levels, Elisa for HIV, HCV viruses, fasting blood sugar level, HbA1C, lipid profile, VDRL, RPR for syphilis, Lyme titration, serum iron levels can be checked. The control of all these parameters in each patient is not reasonable and also not always possible so that it is much more appropriate to make these analyses only in sus-

In SHL, unlike the laboratory examinations, a radiological examination should be definitely performed considering the differential diagnosis. Approximately in 1% of patients diagnosed with SHL, a tumor was identified in the cerebellopontine angle. Therefore, a contrast-enhanced, thin-sectioned temporal MRI must be carried out regarding the differential diagnosis and to determine the etiological factor. In MRI examination, we may observe a space-occupying mass lesion and also in SHL cases with vascular pattern, we may also observe hyperintensity in the pre-contrast examinations depending on the methemoglobin accumulated in the inner ear. In the presence of inflammation, hyperintensity might be observed in the 3D-flair sequence depending on the accumulation of the proteinous materials in the dense exudation [63]. Regarding the literature, the rate of the patients with MRI findings related to SHL was between 27 and 53% [64, 65]. In addition, MRI may also enable the identification of AICA

As the etiological factor is mostly not identifiable in SHL, its treatment is arranged in certain protocols. Several therapeutic modalities clinically different but similar in respect of main aspects have been developed. Systemic corticosteroids are beyond dispute the main therapeutic agents and they are also considered as the golden standard in the literature. Moreover, multiple medical agents can be used in the treatment. In patients, who did not respond or partially respond to the primary treatment, salvage treatment should be implemented. Although these treatments may change according to the patient and physician's algorithm, it should be initiated with the primary treatment. In SHL cases with identified etiology, treatment should be targeted to the underlying disorder. Hereinafter, the treatment protocols especially for the

They are currently the main therapeutic agents (**Figure 1B**). They should be included in the treatment protocols of SHL cases with unknown etiology. Although the mechanism of action of the corticosteroids considering the SHL pathogenesis is not fully elucidated, it is believed that they decrease the inflammation in the inner ear and accelerate the regeneration. An early initiation

pected etiological cases.

80 An Excursus into Hearing Loss

aneurysms and vertebrobasilar system anomalies.

**7.3. Radiology**

**8. Treatment**

idiopathic SHL will be discussed.

**8.1. Medical treatment**

*8.1.1. Systemic corticosteroids*

Antiviral agents were added to the treatment protocols in many clinics in respect of the findings related to the role of viruses in the etiology of SHL. Even though the responsible virus mostly cannot be isolated, they are used in combination with corticosteroids. Stookross created labyrinthitis with HSV-1 antigens in an experimental animal study and applied corticosteroids as monotherapy or in combination with acyclovir. He observed that the viral replication was suppressed in the 14th day of the treatment and discontinued the application. He concluded that acyclovir and corticosteroid combination provided better recovery compared to the corticosteroid monotherapy [70]. Park [71] conducted a study with 85 patients and administered a combination of steroid + antiviral + anticoagulant + stellar ganglion blockage to one group and corticosteroid monotherapy to another group. He observed better recovery in the combination group. In contrary, Westerlaken [72] conducted a placebo-controlled randomized study with 91 patients and administered acyclovir + corticosteroid combination in one group and corticosteroid alone in the other group. He concluded that antiviral agents did not provide additional benefit. Similarly, Tucci [73] concluded in his study conducted with 105 patients that the addition of valacyclovir to the corticosteroid therapy did not provide additional benefit and that antiviral treatment is ineffective in SHL. Antiviral agents like valacyclovir and famciclovir might be used instead acyclovir.

#### *8.1.3. Vasodilators and plasma expanders*

The goal of this treatment is to increase the blood perfusion in the inner ear and the oxygenation. In order to obtain this, either the arteries in the inner ear should be dilated or the viscosity of the blood should be decreased in order to increase its fluidity. Papaverine, histamine, and carbogen (mixture of 5% CO2 and 95% O2 ) were used for this purpose in the literature. In particular, agents such as histamine and papaverine have found effective as they reduced systemic vascular pressure [74]. Compared to these agents, carbogen treatment is more effective and provides a safer treatment option, which means that the oxygenation of the perilymph changes depending on the blood concentration of O2 and CO2 and systemic vascular resistance. Especially, the partial CO2 level in the peripheral blood is an important stimulator of the perilymphatic oxygenation. Kallinen demonstrated that carbogen treatment increased the perilymphatic oxygenation more than 100% O2 [75]. There are plenty of studies conducted with piracetam, prostaglandin E1, dextran (plasma expander) and various rheological agents. These agents are not used alone in the idiopathic SHL but added to the systemic corticosteroid therapy protocol as adjuvant agents [76].

in the recent years, was shown in different studies with control groups. Hyperbaric O<sup>2</sup>

We already mentioned that corticosteroids had a well-established efficacy in the treatment of SHL. In patients, in whom corticosteroids have limited use or efficacy, they may be administered intratympanically with different methods. Thus corticosteroids penetrate through the middle ear membranes to the inner ear and achieve high concentrations, which consequently increased the recovery rate [80]. ITS is a treatment method, which has an ongoing increase in popularity, minimizes the side effects of corticosteroids and enables achievement of therapeutic steroid concentrations with low doses. ITS is not only effective as a salvage therapy, but it also enables good results if it is combined with systemic corticosteroids during the primary treatment or administered as the primary treatment agent in patients, who cannot tolerate

therapy (HBO) is another salvage therapy method and investigated with a

decreased in the perilymph and cochlea in patients with SHL. Experimental studies have

and stimulates the cells. It decreases the platelet aggregation and increases the flexibility of the erythrocytes which positively affects the nutrition of the inner ear. Several recent studies demonstrated that the combined use of HBO therapy and corticosteroids or the use of HBO as a salvage therapy had positive effects on SHL [86–91]. The basic principle of the HBO therapy

in the inner ear with a controlled process. During the application of this procedure, the pos-

Surgical treatment can only be carried out in a subgroup of patients with a known etiology. Cases with membrane ruptures, intracochlear membrane ruptures, endolymphatic hydrops,

As SHL has a multifactorial etiology, the prognosis is variable. Considering all SHL cases, spontaneous regression rate is over 60%. In addition, some factors, which have positive or negative effects on the prognosis, have been described. Even though these factors do not change the treatment, they provide useful information about the course of the disease.

radicals should be taken into consideration.

with a 2–3 atm pressure in repeated doses and to increase the O2

intratympanic steroid treatment can be mentioned among these treatment principles.

large number of studies. The basic principle is to increase the partial O2

pressure in the inner ear supplies the needed O2

and acoustic neuroma can be treated with surgical interventions.

*8.2.1. Intratympanic steroid therapy (ITS)*

systemic steroids [81–84].

Hyperbaric O2

is to apply 100% O2

sible damage of the free O2

**8.3. Surgical treatment**

**9. Prognosis**

partial O2

*8.2.2. Hyperbaric oxygen therapy*

demonstrated that HBO increased the partial O2

and

83

Sudden Sensorineural Hearing Loss

http://dx.doi.org/10.5772/intechopen.72219

pressure, which is

pressure

pressure in the inner ear [85]. The increased

even if the blood flow is decreased

#### *8.1.4. Diuretics*

If endolymphatic hydrops is responsible for SHL, diuretics may be used in the treatment. Besides this, they are not included in the standard treatment protocols.

#### *8.1.5. Magnesium*

Nageris [77] showed that corticosteroid and magnesium combination is more effective in SHL compared to the corticosteroid and placebo combination. Similarly, Gordin [78] determined also that magnesium treatment had positive effects on the recovery in SHL via antioxidant effects and recommended the addition of magnesium to the treatment regimes as an antioxidant.

#### *8.1.6. Low-density lipoprotein apheresis*

Low-density lipoproteins may cause the development of SHL, if their elevated concentrations increase the plasma viscosity. In a study with a large sample size, it was reported that the treatment with low-density lipoprotein apheresis and fibrinogen increased the recovery rate in SHL although the result was not statistically significant [79].

#### *8.1.7. Ozone therapy*

Ragab [92] conducted a study with 45 patients and reinjected the 100 ml blood, which he had taken from the patients and exposed to a 1:1 gas mixture of oxygen and ozone. After the implementation of this treatment protocol for a total of 10 sessions twice a week, he compared the ozone group with the placebo group. He concluded that a significant recovery was observed in the ozone group.

#### **8.2. Salvage therapies**

If known treatment protocols provided no or limited response in SHL patients, salvage treatments should be considered. The efficacy of the salvage treatments, which became popular in the recent years, was shown in different studies with control groups. Hyperbaric O<sup>2</sup> and intratympanic steroid treatment can be mentioned among these treatment principles.

#### *8.2.1. Intratympanic steroid therapy (ITS)*

of the blood should be decreased in order to increase its fluidity. Papaverine, histamine, and

particular, agents such as histamine and papaverine have found effective as they reduced systemic vascular pressure [74]. Compared to these agents, carbogen treatment is more effective and provides a safer treatment option, which means that the oxygenation of the perilymph

the perilymphatic oxygenation. Kallinen demonstrated that carbogen treatment increased the

with piracetam, prostaglandin E1, dextran (plasma expander) and various rheological agents. These agents are not used alone in the idiopathic SHL but added to the systemic corticosteroid

If endolymphatic hydrops is responsible for SHL, diuretics may be used in the treatment.

Nageris [77] showed that corticosteroid and magnesium combination is more effective in SHL compared to the corticosteroid and placebo combination. Similarly, Gordin [78] determined also that magnesium treatment had positive effects on the recovery in SHL via antioxidant effects and recommended the addition of magnesium to the treatment regimes as an

Low-density lipoproteins may cause the development of SHL, if their elevated concentrations increase the plasma viscosity. In a study with a large sample size, it was reported that the treatment with low-density lipoprotein apheresis and fibrinogen increased the recovery rate

Ragab [92] conducted a study with 45 patients and reinjected the 100 ml blood, which he had taken from the patients and exposed to a 1:1 gas mixture of oxygen and ozone. After the implementation of this treatment protocol for a total of 10 sessions twice a week, he compared the ozone group with the placebo group. He concluded that a significant recovery was

If known treatment protocols provided no or limited response in SHL patients, salvage treatments should be considered. The efficacy of the salvage treatments, which became popular

) were used for this purpose in the literature. In

[75]. There are plenty of studies conducted

and systemic vascular resis-

and CO2

level in the peripheral blood is an important stimulator of

and 95% O2

Besides this, they are not included in the standard treatment protocols.

in SHL although the result was not statistically significant [79].

changes depending on the blood concentration of O2

perilymphatic oxygenation more than 100% O2

therapy protocol as adjuvant agents [76].

*8.1.6. Low-density lipoprotein apheresis*

carbogen (mixture of 5% CO2

82 An Excursus into Hearing Loss

tance. Especially, the partial CO2

*8.1.4. Diuretics*

*8.1.5. Magnesium*

antioxidant.

*8.1.7. Ozone therapy*

observed in the ozone group.

**8.2. Salvage therapies**

We already mentioned that corticosteroids had a well-established efficacy in the treatment of SHL. In patients, in whom corticosteroids have limited use or efficacy, they may be administered intratympanically with different methods. Thus corticosteroids penetrate through the middle ear membranes to the inner ear and achieve high concentrations, which consequently increased the recovery rate [80]. ITS is a treatment method, which has an ongoing increase in popularity, minimizes the side effects of corticosteroids and enables achievement of therapeutic steroid concentrations with low doses. ITS is not only effective as a salvage therapy, but it also enables good results if it is combined with systemic corticosteroids during the primary treatment or administered as the primary treatment agent in patients, who cannot tolerate systemic steroids [81–84].

#### *8.2.2. Hyperbaric oxygen therapy*

Hyperbaric O2 therapy (HBO) is another salvage therapy method and investigated with a large number of studies. The basic principle is to increase the partial O2 pressure, which is decreased in the perilymph and cochlea in patients with SHL. Experimental studies have demonstrated that HBO increased the partial O2 pressure in the inner ear [85]. The increased partial O2 pressure in the inner ear supplies the needed O2 even if the blood flow is decreased and stimulates the cells. It decreases the platelet aggregation and increases the flexibility of the erythrocytes which positively affects the nutrition of the inner ear. Several recent studies demonstrated that the combined use of HBO therapy and corticosteroids or the use of HBO as a salvage therapy had positive effects on SHL [86–91]. The basic principle of the HBO therapy is to apply 100% O2 with a 2–3 atm pressure in repeated doses and to increase the O2 pressure in the inner ear with a controlled process. During the application of this procedure, the possible damage of the free O2 radicals should be taken into consideration.

#### **8.3. Surgical treatment**

Surgical treatment can only be carried out in a subgroup of patients with a known etiology. Cases with membrane ruptures, intracochlear membrane ruptures, endolymphatic hydrops, and acoustic neuroma can be treated with surgical interventions.

### **9. Prognosis**

As SHL has a multifactorial etiology, the prognosis is variable. Considering all SHL cases, spontaneous regression rate is over 60%. In addition, some factors, which have positive or negative effects on the prognosis, have been described. Even though these factors do not change the treatment, they provide useful information about the course of the disease.

The most important criterion is the time between the emergence of the symptoms and the initiation of the treatment. The prognosis is much better in patients started treatment early. Another factor is the age of the patient. An age less than 15 or greater than 65 years indicates a bad prognosis. The prognosis worsens with the severity of the hearing loss. Although the prognosis is relatively better in the low-frequency hearing loss compared to the highfrequency hearing loss, an ascendant type audiometric curve promises a better prognosis than the descendant type audiometric curve. The presence of vertigo and nystagmus, which shows that vestibular system is also affected, is a sign of bad prognosis. In contrary, tinnitus indicates a good prognosis in SHL, because tinnitus is considered as a sign that the hair cells in the inner ear are not completely destroyed. Bilateral SHL has a relatively worse prognosis. Increased sedimentation rate and an increase in the high sensitive CRP levels are related to the severity of the inflammation and thus to the bad prognosis. In SHL, recovery can be observed within 6 months to 1 year, it is wise to arrange the pre-rehabilitation follow-up plan according to this duration. In SHL patients, who did not show any recovery after 1 year, hearing rehabilitation can be planned upon the patient's request and according to the severity of the hearing loss.

**Author details**

Harun Acıpayam<sup>1</sup>

İstanbul, Turkey

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\*Address all correspondence to: harunacipayam@gmail.com

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and Mustafa Suphi Elbistanlı<sup>2</sup>

Sudden Sensorineural Hearing Loss

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### **10. Conclusion**

As we have seen, SHL preserves its darkness as an enigma of ENT world. There are several already-published and a large number of ongoing studies on the etiology and treatment of SHL in the literature. Although certain diagnosis and treatment algorithms developed for SHL are already available, they cannot be implemented in all SHL cases. If corticosteroids cannot deliver sufficient results, there are not much treatment choices. Further studies for a full elucidation of the physiopathology, etiology, and treatment of SHL are required.

### **Abbreviations**

