A Ten Year Follow-up Study on Unilateral Deafness in Children and Estimation of the Occurrence Rate of Delayed Endolymphatic Hydrops

Abstract

We made a follow-up study on 41 patients with unilateral profound hearing loss discovered in childhood. All consulted our clinic for hearing loss.Mean age is 16.4 years old at present, and they have been suffering from unilateral deafness for 10.0 years on average. The cause of the hearing loss was mumps in 10, head trauma in 2, rubella in 1 and juvenile unilateral hearing loss of unknown etiology in 28.Among 41 patients, 22 had experienced some kind of dizziness or vertigo, and we could perform vestibular examinations on 16 of them. Canal paresis on the deafened side was observed in 6/16 (38%). Clinical diagnosis for dizziness or vertigo of the 16 cases was orthostatic dysfunction in 11 and ipsilateral delayed endolymphatic hydrops (DEH) in 4. In the 4 cases of DEH, the result of the Schellong test was positive in 3. Dysfunction of the autonomic nervous system may have some relation to the occurrence of DEH. We diagnosed DEH by the clinical symptoms and the furosemide test (Futaki, et al: 1975).In this study on patients with unilateral deafness discovered in childhood, we found that about 10% (4/41, 9.8%) of them developed symptoms of DEH by their middle teens. In 1986 we reported 30 cases of DEH; in 24 of these cases, profound hearing loss was discovered in childhood. Among these 24 cases, 15 developed symptoms of DEH later than 16 years of age. So we estimated that the final occurrence rate of DEH in the population of unilateral deafness discovered in childhood is around 25%.We emphasize that a very intensive follow-up study is necessary in determining the occurrence rate of DEH.