Delayed endolymphatic hydrops as a clinical entity.

Delayed endolymphatic hydrops (DEH) is a clinical entity that can be differentiated from Ménière's disease and is typically observed in patients who have been suffering from longstanding unilateral profound inner-ear hearing loss. DEH probably is caused by delayed atrophy or fibrous obliteration of the endolymphatic resorptive system of the membranous labyrinth. The time that elapses between the occurrence of hearing loss and the onset of DEH can range from 1 to 74 years. The most common cause of hearing loss preceding DEH is juvenile-onset unilateral profound deafness (early childhood unilateral profound sensorineural hearing loss of unknown etiology), followed by labyrinthitis from various causes and physical and acoustic traumas to the inner ear. Two types of DEH exist: the ipsilateral type, in which the ear with profound hearing loss suffers progressive endolymphatic hydrops, and the contralateral type, in which the formation of progressive endolymphatic hydrops takes place in the ear opposite to the previously deafened ear. The incidence of the ipsilateral type is higher than that of the contralateral type, and the contralateral type is more common in older patients. When recurrent episodic vertigo cannot be remedied through conservative treatment, labyrinthectomy and vestibular neurectomy on the deaf ear are curative for ipsilateral DEH. However, no such surgical treatment is available for the contralateral type.

Familial unilateral deafness and delayed endolymphatic hydrops.

Delayed endolymphatic hydrops (DEH) is a unique disorder characterized by fluctuating otologic symptoms in the setting of preexisting unilateral deafness. The symptoms include aural fullness, fluctuating hearing, and/or episodes of vertigo similar to those observed in Meniere disease and may occur ipsilateral or contralateral to the previously deafened ear. In most reported cases, the unilateral deafness has been a profound sensorineural hearing loss with a sudden onset that has been variously attributed to bacterial or viral labyrinthitis, acoustic or cranial trauma, otosclerosis, and congenital CMV infection. Familial occurrence of the syndrome has not previously been reported in the literature. In this report, we describe two possible familial instances of delayed DEH. These patients raise the possibility that genetic factors may sometimes be the cause of this unusual syndrome.

Head-shaking nystagmus: its significance in neurology

To examine HSN, horizontal HST should be performed routinely, supplemented by vertical HST when a central lesion is suspected. HSN with more than four distinct consecutive beats is generally pathological, especially when observed using Frenzel's glasses in a dark room. However, HSN may be physiologial only when the patient's vision is completely blocked, such if the patient's eyes are closed. Horizontal HSN suggests the exsistence of an imbalance between right and left in the vestibular system, and it may have either a peripheral or a central origin. On the other hand, a distinct vertical (usualy down beating) HSN strongly suggests the existence of a central lesion. HSN usually appears in a monophasic or biphasic pattern. The pattern which appears in case of peripheral vestibular disorder (PVD) depends mainly on the stage of recovery. PII nystagmus of biphasic HSN is usually weaker in terms of nystagmus intensity, but tends to lost longer than PI in PVD. PII that is a strong or stronger than PI may suggest a central origin. In long-lasting PVD, HSN beats toward the normal ear in about 75 per cent of monophasic cases and in more than 85 per cent of biphasic cases in PI. Usually, a patient with biphasic HSN of this type is already in the recovery stage. In many cases with long-lastins PVD, both spontaneous nystagmus (SPN) and HSN reverse their nystagmus directions during the course recovery in the following order: SPN toward the impaired ear (irritative nystagmus), SPN toward the normal ear, (paretic nystagmus) monophasic HSN toward the normal ear, biphasic HSN in PI toward the normal ear, monophasic HSN toward the impaired ear, and finally SPN toward the impaired ear (recovery nystagmus). In patients with long-lasting PVD, who show monophasic nystagmus toward the impaired side, the function of the impaired labyrinth is usually recovering (reverse-type monophasic HSN). This type of HSN can also be observed in cases of Meniere's disease. Biphasic HSN in which the nystagmus in PI beats toward the impaired ear (reverse-type biphasic HSN) is rarely encoutered in cases of long-lasting PVD. In cases of Meneire's discase, on the other hand, this type of biphasic HSN is relative ly common and amounts, when added to cases of monophasic HSN toward the impaired ear, to about 30 per cent of all cases. The monoexistence of CP is highly probale (95 per cent), when HSN is not present. On the other hand, whether CP is present cannot be determined when HSN is positive.