Sudden sensorineural hearing loss

Summary

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. About half of patients completely recover, usually in about 2 weeks. Many treatments are used, including corticosteroids, antiviral drugs, and vasoactive and oxygen-based treatments. Although no treatment is proven, we recommend a short course of oral high-dose corticosteroids. There is much to learn about pathogenesis of sudden sensorineural hearing loss, and more clinical trials are needed to establish evidence-based management.

Introduction

Hearing loss is common, affecting about a fifth of the population in the UK, and can be defined by site of disease, severity, audiometric configuration, and method of onset.¹ In adults, progressive late onset sensorineural hearing loss (so-called presbyacusis) is the most common presentation and is often associated with a genetic predisposition, exposure to excessive noise, or age-related pathological changes. Sudden sensorineural hearing loss—described by De Kleyn in 1944,² and defined as hearing loss of at least 30 dB in three sequential frequencies in the standard pure-tone audiogram over 3 days or less³—is less common than is late onset loss. National surveys4, 5, 6 have estimated the incidence of sudden sensorineural hearing loss at between five and 30 cases per 100 000 per year. However, a study⁷ from Germany has shown an incidence as high as 160 cases per 100 000 per year.

Rapidly progressive sensorineural hearing loss, which develops over weeks to months, has also been described.⁸ However, these patients often initially present with a sudden sensorineural hearing loss, followed by a rapid progression or additional sudden drops in hearing. Sudden and rapidly progressive sensorineural hearing loss have many common features and possible causes, and we suggest that they should be investigated and managed in a similar way.

Patients with sudden sensorineural hearing loss often delay seeking medical attention, or might present to a range of specialties, including primary care, otolaryngology, audiovestibular medicine, and internal medicine. In primary care and non-specialist departments, patients can be inappropriately reassured, without investigation, in the mistaken view that the loss is attributable to middle-ear dysfunction secondary to upper respiratory tract infection.

Detailed investigation will show a specific cause in about 10% of patients.⁹ The term idiopathic sudden sensorineural hearing loss is often used to describe the remainder of patients. An important, but poorly recognised, cause of sudden sensorineural hearing loss is immune-mediated inner-ear disorders, including both organ-specific inner-ear disease and systemic autoimmune disorders. The condition is also associated with posterior circulation events, coagulation disorders, neoplasms, demyelinating disease, and various infections. Therefore, investigation for systemic disorders should be done for all patients. Published work on this topic is confusing, and approaches to diagnosis and management vary widely.¹⁰ This Seminar presents a practical framework for assessment and management of this disorder.