[Delayed endolymphatic hydrops]

Delayed Endolymphatic Hydrops (DEH) is a disease entity that must be distinguished from idiopathic endolymphatic hydrops (Ménière's disease). Idiopathic hydrops is characterized by the following symptoms: 1) vertigo often accompanied by nausea and vomiting; 2) tinnitus; 3) hearing loss, usually fluctuating; and 4) sensation of pressure or fullness in the affected ear. Idiopathic hydrops most commonly occurs in middle-aged patients, usually between 30 and 50 years. It may involve one or both ears and usually exibits fluctuating hearing loss and episodic vertigo, although one symptom may precede the other by months or years. It is rare for Ménière's disease to present with a severe sensorineural hearing loss. Delayed Endolymphatic Hydrops was first described, under the name of "unilateral deafness with subsequent vertigo", by Wolfson and Lieberman and Nadol et al.; this was later confirmed by other authors. The disease is characterized by a profound sensorineural hearing loss in one ear, found to have been present in most cases from early childhood, due to an unknown cause, trauma or viral infections. After a prolonged period (usually many years) patients with DEH experience the onset of episodic vertigo from the deaf ear (Ipsilateral Delayed Endolymphatic Hydrops) or develop a fluctuating hearing loss and/or episodic vertigo in the opposite ear, previously with normal hearing (Controlateral Delayed Endolymphatic Hydrops). Vestibular symptoms are identical to those of Ménière's disease: in fact there is evidence that endolymphatic hydrops in the previously damaged ear or in the previously normal ear represents at least part of the labyrinthine pathology. Histopathology studies recently conducted on temporal bones of subjects affected with controlateral DEH show pathologic changes in the deaf ears similar to those found in viral labyrinthitis, whereas pathologic changes in the hearing ears resemble those known to occur in Ménière's disease. Medical treatment has not been found to be effective in patients with DEH, but it must be the first choice of treatment especially in controlateral forms of the disease. So far, surgical intervention has been demonstrated to give the best results; either conservative or more radical, depending on the type of DEH. Pharmacological labyrinthectomy with ototoxic drugs could be the therapy of choice in the future. In this paper we review the literature in order to summarize the clinical features and criteria for diagnosing DEH, we also report histopathologic findings and pathogenetic hypotheses formulated for this syndrome. Moreover, we discuss the best therapeutic approach for the ipsilateral and controlateral variants of DEH.