© Borgis - New Medicine 3/1999, s. 61-63
Elżbieta Reroń, Marek Modrzejewski, Katarzyna Zajdel, Piotr Muszyński
Analysis of aetiological factors in unilateral sudden hearing loss
Audiological Laboratory of the ENT Department, Jagiellonian University Hospital, Cracow
Head of Department: Prof. Eugeniusz Olszewski, M.D.
In the last decade in the ENT Department of the Jagiellonian University Hospital in Cracow, in 80 children aged 2 to 14 years, unilateral, usually sudden, severe hearing loss and deafness were diagnosed and treated.
The aim of this study is analysis of the potential aetiological factors responsible for sudden deafness on the basis of a detailed analysis of patient history, otolaryngological examinations, audiometric and pediatric tests.
In the material discussed, the fundamental aetiological factor in 35 children (43.8%) was a viral infection, such as epidemic parotitis, influenza, or German measles, as well as traumas of the skull and viral or bacterial meningitis.
In 31 children (38.75%) the aetiological factor remained unknown. In this group, in 7.5% of cases unilateral deafness was diagnosed accidentally, most often between the 7th and 10th year of age. The period of time which elapsed from the moment of occurrence of the symptoms of sudden deafness to the moment of its diagnosis and commencement of therapy was also taken into consideration.
Despite the fact that sensory-nervous sudden hearing loss of unknown aetiology was first described 138 years ago, this is still one of the controversial problems in otolaryngology.
According to Turmond and Amedee (16) and a number of other authors, sudden deafness means a hearing loss of at least 30dB for three consecutive frequencies occurring in a time period of less than three days. Hughes et al. (3) state that in the US there are 4000, and world-wide 15000, new cases of sudden deafness annually. According to Kog et al. (4), the incidence of unilateral sudden hearing loss in children amounts to approximately 0.1% and the aetiology of most of the cases remains unknown; neither children nor their parents can precisely determine the time of its appearance, especially when it is not accompanied by other symptoms, such as dizziness or tinnitus.
Analysing the risk factors of idiopathic sudden deafness, Nakashime et al. (6) concluded that fatigue and the influence of environmental factors, including diet, are essential in the aetiology of sudden hearing loss. Among various aetiological factors responsible for the pathomechanism of the disease, especially in adults, circulatory disorders are of primary importance (5, 9, 10, 11). On the other hand, Prirod et al. (10, 11) suggest that hypotension, especially in young children, is a fundamental factor in sudden deafness, and that in many cases after pharmacological regulation of vascular motor activity the hearing threshold easily returns to normal. The next most important factor causing sudden hearing loss is viral infection (1, 14, 18), especially epidemic parotitis (4, 12, 17). A number of cases have been reported of sudden deafness (both uni- and bilateral) in the asymptomatic course of mumps (4). This was confirmed by Okamato et al. (7) who examined the level of antibodies against epidemic parotitis in the serum of 131 patients with sudden deafness. Positive results obtained in 9 of them confirmed the relationship between sudden deafness and an asymptomatic course of mumps. Toxoplasmosis (13), disturbed iron metabolism (15) and measles (2) should also be taken into consideration as causes of sudden deafness. Nevertheless, in a great number of cases, the aetiology of idiopathic sudden hearing loss in children remains unknown (9, 8).
Aim of study
The aim of our study was evaluation of the influence of probable aetiological factors on the occurrence of unilateral hearing loss in children.
Material and methods
The study included 80 children aged 2 to 14 years hospitalized in the ENT Department of Jagiellonian University Hospital in Cracow in the last 10 years because of sudden unilateral hearing loss.
The assessment of the influence of the probable aetiological factors on unilateral deafness was carried out on the basis of:
1. Detailed history concerning the onset of deafness, concomitant diseases and symptoms, such as influenza, mumps, herpes, German measles, trauma of the head, tinnitus and dizziness, as well as other systemic diseases.
2. Physical examination including otolaryngological, pediatric and neurological examinations (when indicated).
3. Comprehensive audiological evaluation, that is, pure tone audiometry, registration of evoked otoaudiological emissions (EOAEs) and tympanometric tests.
Results and discussion
As Table 1 shows, sudden hearing loss in the studied group occurred in 37 girls (46.25%) and 43 boys (53.75%). In 42 cases sudden unilateral deafness affected the right ear (52.5%) and in 38 cases the left ear (47.75%).
Table 1. Morbidity rate of sudden hearing loss, taking into consideration sex, age and ear.
|Age||Sex||Ear||Sudden hearing loss|
| ||F||M||Right||Left||Nr. of cases||%|
Taking into consideration the aetiological factors responsible for sudden deafness in various age groups of the children examined, most often, that is in 25 cases (31.25%) the aetiological factor remained unknown. After adding cases of unilateral deafness revealed accidentally in children mainly between 7 and 10 years of age, the amount of deafness of unknown aetiology increases by another 6 children and amounts to 31 cases (38.75%).
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