OTORRHINOLARYNGOLOGY

CHRISTIANE RIBEIRO ANIAS

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Sudden Deafness



Introduction

Sudden Deafness can be defined as a sensorineural hearing loss that develops over a period of hours or a few days. The severity of the hearing loss may vary from mild to total loss of perception of the most intense sound. The loss of hearing may be permanent, or the hearing may spontaneously return to normal or near normal. It is usually unilateral but it can be bilateral in about 4% of the cases.

Although it has a small incidence, it is very important to know how to deal with this disease which is a medical emergency.

Etiology

Acoustic Neurinoma - About 15% of patients with this disease will present with sudden sensorineural hearing loss as their initial symptom. It is due to a compression of vestibulocochlear nerve in the inner.
Noise - The exposition to acute acoustic trauma (gunfire injures and explosion for instance ) can cause severe and sudden hearing loss. The cause is partly a direct and mechanical one, due to bleeding and partly an indirect metabolic effect on the microcirculation causing partially reversible damage to the sensory cells of the organ of corti.
Perilymph fistula - There is little doubt that perilymph fistula ( either spontaneous or following surgery, barotrauma or acoustic trauma ) can cause sudden deafness. Nevertheless, this is an area of significant controversy because of the lack of firm criteria for its diagnosis, including intraoperative observation.
Vascular causes - Vasoespasm, thrombosis, embolism, hemorrhage into the inner ear, hypercoagulation are frequently mentioned as common causes of sudden deafness, but the evidence for this point of view is lacking.

Others causes of sudden deafness are bacterial meningitis, labirinthitis due to bacterial invasion of the inner ear, syphilis, trauma, ototoxic drugs and metabolic disorders.

Clinical Manifestation

The deafness may begin instantaneously and, when the onset is so sudden, it may be accompanied by the sensation of a loud sound in the affected ear. More often the hearing loss develops over the course of an hour, a day or several days. The loss of hearing is usually unilateral. The percentage of patients with bilateral involvement is about 4%.

About 70% of patients with sudden deafness has tinnitus of varying degrees sometime during their illness and about 40% have mild or transient vertigo with nausea and vomiting.

Diagnostic Tests

Audiometry shows a unilateral sensorineural deafness. Computed tomography of the temporal bone is indicated to avoid overlooking mastoiditis, primary cholesteatoma, acoustic neuroma and spondylosis deformans. Blood studies of value should include a complete blood count and serologic test for syphilis.

Natural History and Prognosis

Approximately one third of patients have a return of normal hearing, one third are left with moderate hearing loss and one third have total loss of useful hearing.

Once recovery of hearing begins, it is likely to take place very rapidly in a matter of few days. Even when severe initially, the vertigo tends to subside within one week and, as a general rule, all vestibular symptoms clear spontaneously within 6 weeks.

Treatment

The frequently spontaneous recovery of hearing to normal or near normal makes evaluation of any form of therapy for sudden deafness very difficult.

When possible the etiologic treatment is ideal: treat syphilis, treat perilymph fistula, remove acoustic neuroma. But in majority of the cases the treatment is inespecific. The therapy currently advocated includes:

  • vasodilatadors, anticoagulantion, reduction of the viscosity of the blood - They are based on the theory of vascular causes of sudden deafness.
  • corticosteroids - based on the anti- inflammatory effects of these agents in viral infection.
  • vitamins - the rationale for the vitamins therapy is not clear.
  • sedation
  • bed rest

    Rehabilitation

    Young patients who don’t recover from unilateral sudden deafness, should have preferential seating in the classroom .Children and adults must acquaint with their inability to localize the source of sound and must truly stop, look and listen, when crossing the street.

    Bibliography

    1) BECKER W, NAUMANN H.H, PFLALTZ C.R - Ear, Nose and Throat Diseases 2nd edition 1994 pages145-146.
    2) AGUIAR F.A.B, AGUIAR F.A.B -Surdez Súbita -Diagnóstico e tratamento-A propósito de um caso. J.B.M, volume 68 jan/fev 1995 pages 56-58.
    3)HUNGRIA H. - Otorrinolaringologia 6a edição 1991 pages 395-400.
    4) PIRES M.T.B - Erazo manual de urgências em pronto Socorro 4a edição 1993 pages 377-379.
    5) TIERNEY L.M, MCPHEE S.J, PAPADAKIS M.A - Current Medical Diagnosis and Treatment 35th edition 1996 page190.
    6) PAPARELLA M.M, SHUMRICK D.A,Otolaryngology 1991 3rd edition volume II pages 1619-1627.

    Acknowlogments to Cláudia Maria Valete, Otorrynolaryngologic Doctor at Federal University of Rio de Janeiro, for her helpful review of this article.

    If you have suggestions or comments send an e-mail to Christiane Ribeiro Anias

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