**Sudden Sensorineural Hearing Loss**

**Sudden Sensorineural Hearing Loss**

Harun Acıpayam, Hasan Emre Koçak and Mustafa Suphi Elbistanlı Mustafa Suphi Elbistanlı Additional information is available at the end of the chapter

Harun Acıpayam, Hasan Emre Koçak and

Additional information is available at the end of the chapter

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

#### **Abstract**

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70 An Excursus into Hearing Loss

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Sudden hearing loss (SHL) is a common disease in the daily practice of ear-nose-throat (ENT) and audiology clinics. It is usually defined as a sensorineural type hearing loss of 30 dB or greater in three contiguous frequencies. Although several factors were suggested for the etiology of SHL, in most of the cases, no cause could be detected and they were diagnosed as idiopathic cases. Although certain specific treatments might be applied in patients with known etiology, corticosteroids are the main component in the treatment of idiopathic SHL. Many experts and centers have developed different treatment protocols with similar approaches. SHL is considered as an emergency in ENT, as it may cause a permanent loss in hair cells, if it is not treated or the treatment is not initiated at the right time. For patients, who did not or partially benefit from the initial treatment, different salvage treatment protocols had been developed. As SHL severely affects the patient's quality of life, its diagnosis and treatment should be thoroughly deliberated.

DOI: 10.5772/intechopen.72219

**Keywords:** idiopathic hearing loss, salvage treatment, sudden deafness, sudden hearing loss, treatment

#### **1. Definition**

Sudden hearing loss (SHL) is an ear-nose-throat (ENT) emergency and as sensorineural hearing loss of 30 dB or greater in three contiguous audiometric frequencies occurring over 72 h. SHL was first described by Dekleyn in [1] (**Figure 1A**). Although the definition mentioned above involves the widely accepted diagnostic criteria of SHL, it actually develops within hours or minutes and is usually noticed by the patient early in the morning or during a telephone conversation. With an approach from a broader perspective, we may consider all identifiable and measurable hearing losses, which are noticed within minutes or within few days, as SHL. Patients usually visit an ENT specialist in a great panic, thinking they became deaf.

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

pathogenesis of SHL, can be classified into four main groups. Vascular factors, viral infec-

Sudden Sensorineural Hearing Loss

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

As it is well known, the cochlea is an end-organ perfused by the labyrinthine artery, which is a branch of the basilar artery and does not have collateral circulation [7]. The labyrinthine artery divides into two branches (vestibular and cochlear arteries) after entering through the internal acoustic meatus. The cochlear artery enters the cochlea after the division of its branch the vestibulocochlear artery [8]. Therefore, factors such as thrombi, emboli, atherosclerosis, vasospasm, and decreased blood flow may end up with vascular insufficiency and consequently a loss of function in the cochlea. A sudden interruption of the blood flow to the cochlea may induce the development of SHL, which will cause a complete restriction of the oxygen supply. The obstructions in the vertebrobasilar system may also cause SHL. Here, it should be noticed that a bilateral SHL emerges, in these cases, as the basilar artery, which is the only artery supplying that region. Kim et al. [9] detected a thrombus in the bilateral distal vertebral artery in a patient with bilateral SHL and observed improvement after the restoration of the circulation with a stent. In his experimental study, Perlman [10] stated that the occlusion of the internal auditory artery caused changes in the cochlea secondary to the ischemia and some of these changes were irreversible. The difference of this study from SHL patients is that the findings in SHL are reversible. In a recent study similar to these studies, Chung [11] found out a relation between increased arterial stiffness and SHL development and the response to the treatment and drew attention to the development of SHL with vascular causes. Subclinical

tions, autoimmune processes, and intracochlear membrane rupture.

atherosclerosis has also been reported in the literature, as a cause of SHL [12].

It is understandable that the temporary and permanent problems in the cochlear microcirculation may cause SHL depending on the damage in the cochlear hair cells [13]. Also, in cases of hypercoagulopathy, a possible intravascular obstruction may cause damage to the inner ear in the same way. Bernhard [14] investigated the effects of experimental hyperfibrinogenemia on the development of SHL and stated that although they did not respond to corticosteroids, intravenous defibrinogenation (ancrod) improved the process markedly. He suggested that defibrinogenation therapy should be considered in non-responding SHL patients. Similarly, the relation of SHL to the factors capable of intravenous obstruction such as sickle cell anemia, Waldenström's macroglobulinemia or contraceptive drugs have been reported in the literature [15]. Although, some studies have suggested that there is a relationship between Factor V Leiden mutation and SHL, it was shown with a meta-analysis that there is no clear relationship between these two pathologies [16]. It is clear that these diseases will not respond to corticosteroids and the main treatment should be targeted to the underlying cause. Cochlear damage may emerge due to the acute emboli after the cardiopulmonary bypass or non-otological, non-coronary operations and may result consequently in SHL [17]. Any obstruction due to any reason in the cochlear microcirculation will manifest itself with the symptoms corresponding to the level of the obstructed artery. For example, although hearing loss is the only finding in the presence of the cochlear artery obstructions, vestibular symptoms like vertigo and tinnitus will also emerge in the labyrinthine artery obstructions along with hearing loss.

**3.1. Vascular factors**

**Figure 1.** A: Sudden hearing loss sample audiogram. B: After treatment normal hearing level.

The physician, first of all, should calm the patient and then examine his/her medical condition, proceed immediately with the diagnostic procedures, identify—if possible—the etiology and initiate without delay the proper treatment.
