**7. Diagnosis**

Atherosclerotic disorders Previous cardiopulmonary surgeries

Arteriovenous malformations Acoustic trauma

Erythrocyte Deformities **Neoplastic Causes Infection** Acoustic Schwannoma Viral Causes Multiple Myeloma Herpes viridea family (HSV Type 1, 2; VZV, CMV, EBV) Metastatic tumors

Mumps Meningeal carcinomatosis

HIV **Endocrine Causes** Influenza family Hypothyroidism Enteroviridea family Iron deficiency anemia Adenovirus Diabetes mellitus Human Spumaretrovirus **Toxic Causes** Bacteria-Parasite Aminoglycosides

*Toxoplasma gondii* Iron-containing drugs *Mycoplasma* spp. ACE inhibitors *Cryptococcus* spp. Loop Diuretics *Meningococci* Cisplatin *Enterobacteriae* Aspirin

**Autoimmune Causes** Chemotherapeutic agents

Ulcerative Colitis Narcotic analgesics SLE Benzodiazepines Small vessel vasculitis **Neurological Causes** Cogan syndrome Multiple Sclerosis Antiphospholipid Antibody Syndrome **Psychiatric Causes**

Autoimmune inner ear disease Phosphodiesterase Type-5 inhibitors

Sarcoidosis Histrionic (somatoform) deafness Endolymphatic hydrops **İdiosyncrasy** (most common cause)

*Treponema pallidum* Gold *Borrelia burgdorferi* Quinine

Crohn's Disease Heroin

**Table 1.** Etiology of sudden hearing loss.

Aneurysm

78 An Excursus into Hearing Loss

Rubella Rubeola

#### **7.1. Audiology**

The audiological examination is the most important process regarding the diagnosis. Puretone audiometry may enable a definitive diagnosis and also provide information about the severity of the hearing loss and the type of the audiological curve with additional data related to both differential diagnosis and prognosis. In addition to the pure-tone audiometry, tympanometric examination, acoustic reflex, speech audiometry may support the diagnosis. Such additional tests are not always needed. They are only recommended if there is a clinical necessity. In patients who cannot comply with the audiometry process ABR might be useful for the diagnosis. A definitive diagnosis of SHL can be made, if a hearing loss of 30 dB or greater is observed in three contiguous frequencies.

#### **7.2. Laboratory analysis**

As several different causes were suggested in respect of SHL etiology, the necessity of routine laboratory examination is still disputable regarding the diagnosis. The general consensus is that laboratory examination should be carried out only for the suspected etiological factors. If a viral involvement is suspected, viral antigen titration; if an autoimmune mechanism is 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 suspected etiological cases.

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

Sudden Sensorineural Hearing Loss

81

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

corticosteroid injection should be considered in the primary treatment [68, 69].

valacyclovir and famciclovir might be used instead acyclovir.

*8.1.3. Vasodilators and plasma expanders*

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

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

*8.1.2. Antiviral agents*

#### **7.3. Radiology**

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 aneurysms and vertebrobasilar system anomalies.
