Comparison of furosemide-loading cervical vestibular-evoked myogenic potentials with magnetic resonance imaging for the evaluation of endolymphatic hydrops

Abstract

Background

Furosemide-loading cervical vestibular-evoked myogenic potential (FVEMP), in which vestibular function is improved via diuretics-induced dehydration, can be used to estimate the presence of endolymphatic hydrops, one characteristic of Menière’s disease. Inner ear magnetic resonance imaging (MRI) can also reveal endolymphatic hydrops.

Aims/Objective: This study aimed to compare and confirm the usefulness of these two examination methods for the diagnosis of Menière’s disease.     

Electrophysiological measures of cochlear function in guinea pigs with long-term endolymphatic hydrops

Experimental endolymphatic hydrops was induced in guinea pigs by obliteration of the endolymphtic sac and duct. From 3 to 24 months after this operation, cochlear action potential (AP) audiograms and AP tuning curves were measured. The purpose of this study was to establish parallels, if any, between this supposed animal model of Menière's disease and the auditory symptoms of the disease in man. In some animals, low and middle frequency AP threshold elevations were observed whilst higher frequency regions maintained normal sensitivity. Other animals developed flat or very gradually sloping AP audiograms. These patterns are qualitatively similar to those found clinically in Menière's disease. AP tuning curves measured in frequency regions of threshold elevation indicated a deterioration of cochlear frequency selectivity; psychophysical and electrocochleographic studies demonstrate related changes in Menière's patients. One animal exhibited modifications in AP thresholds and tuning as a result of glycerol administration. These observations improve our confidence in the validity of this animal model for further studies of the pathophysiology of Menière's disease.     

Changes in endolymphatic hydrops in a patient with Meniere's disease observed using magnetic resonance imaging

We describe a case report of a patient with Meniere's disease whose changes in endolymphatic hydrops were observed using magnetic resonance imaging (MRI). Gadolinium was injected intratympanically through the tympanic membrane, and MRI scans performed with a 3-T MRI unit revealed endolymphatic hydrops inside the perilymphatic space filled with gadolinium. We evaluated the relationship between the image findings and hearing level. The correlation between the degree of endolymphatic hydrops observed by MRI and hearing level in patients with Meniere's disease offers a promising new method to study the progression of Meniere's disease.     

Delayed endolymphatic hydrops. Special emphasis on nystagmus associated with episodes and contribution of chemical labyrinthectomy

ObjectivesThe main objective was to describe spontaneous nystagmus characteristics during an episode of delayed endolymphatic hydrops (DEH), including an initial vertical upbeating nystagmus in one patient. The secondary objective was to highlight the contribution of chemical labyrinthectomy.MethodsEpisodic vertigo after a prolonged period of time of sensorineural hearing loss (profound or total) in one ear characterized ipsilateral DEH and was associated with the development of hearing loss in the opposite ear in contralateral DEH.ResultsTen patients met the criteria for DEH: 7 ipsilateral and 3 contralateral. Three (all ipsilateral DEH) were examined during a vertigo episode. Two patients had a typical horizontal-torsional nystagmus beating contralaterally to the hearing loss. One patient showed atypic initial vertical upbeating nystagmus with a slight torsional component, which secondarily became horizontal-torsional beating contralaterally to the hearing loss. Four patients had disabling vertigo with unilateral total deafness (ipsilateral DEH), successfully treated by 1-3 transtympanic gentamycin (Gentalline^®) injections.ConclusionNystagmus direction during vertigo episodes varies, and may initially present as vertical upbeating nystagmus, which, to our knowledge, has not been previously reported in DEH or Menière's disease. This nystagmus might reflect an inhibition of the superior semicircular canal (on the hearing-impaired side), suggesting incipient hydrops in this canal. Chemical labyrinthectomy is a simple and effective procedure in unilateral DEH, especially as the patient often suffers from total deafness.     

Glycerol pure tone audiometry and glycerol vestibular evoked myogenic potential: representing specific status of endolymphatic hydrops in the inner ear

This prospective study attempts to explore the effect of glycerol on vestibular evoked myogenic potential (VEMP) in patients with definite unilateral Meniere’s disease (MD) and to investigate whether the test reflects different pathologic states of endolymphatic hydrops (EH) in the inner ear by comparing the results of glycerol pure tone audiometry (PTA). Twenty-eight patients with definite unilateral MD were studied. As a control group, 11 patients with vestibular neuritis were selected. Sixteen ears of normal volunteers were enrolled to acquire normal range of the test. Each MD patient underwent glycerol testing measure with both conventional PTA and VEMP testing. Eleven vestibular neuritis patients also underwent glycerol-VEMP testing. The difference ratio was adopted to compare the changes in p1-n1 amplitude and latency of VEMP after the administration of glycerol (1.3 g/kg). Significant changes in the VEMP wave after the glycerol loading were seen in amplitude, but not in latency with MD patients. On the affected side, the amplitude of the p1-n1 biphasic wave significantly increased in 11 of 28 (39.3%) ears and decreased in 2 (7.1%) ears. On the unaffected side, 5 (17.9%) ears showed significant increase in amplitude. Significant changes in PTA were noted after administration of glycerol in 14 of 28 (50%) patients with MD. However, there was no statistically significant correlation between the test results. Glycerol administration had no significant effect on VEMP in patients with vestibular neuritis. The amplitude of VEMP in some patients with MD was increased, but the latency was not influenced by oral administration of glycerol. The severity of EH appears to vary in different parts of the inner ear. Glycerol-VEMP test results in patients with vestibular neuritis suggest that the VEMP reflects potential abnormality in the sacculocollic pathway, while glycerol-VEMP identifies the existence of EH in the saccule. VEMP and PTA after glycerol administration provide potential status of MD.     

Magnetic resonance imaging evaluation of endolymphatic hydrops andpost-operative findings in cases with otosclerosis

Conclusions: The presence of endolymphatic hydrops (EH) in the vestibule on magnetic resonance imaging (MRI) might be a high-risk factor for complications in cases that are candidates for stapes surgery.

Objective: Pre-operative detection of EH could be valuable in cases that are candidates for stapes surgery to prevent unpredictable complications following surgery. Pre-operative MRI findings and post-operative findings following stapes surgery were compared to evaluate the efficacy of such MRI evaluation for the management of cases with otosclerosis.

Subjects and methods: Sixteen cases who underwent pre-operative evaluation by 3T MRI performed 4?h after intravenous injection of gadolinium and stapes surgery for otosclerosis were recruited. Imaging data concerning the degree of EH in the vestibule and cochlea were compared with post-operative clinical findings for all cases.

Results: Mild EH in the cochlea or the vestibule was observed in eight ears and one ear, respectively, whereas one ear showed significant EH both in the cochlea and the vestibule. The post-operative course was uneventful in 12 of 14 cases with no EH in the vestibule, and the other two cases had a short period of dizziness, but two cases with EH in the vestibule had a long period of dizziness.     

Vestibular evoked myogenic potentials in patients with contralateral delayed endolymphatic hydrops

We studied vestibular evoked myogenic potentials (VEMPs) in nine patients with unilateral profound hearing loss followed by contralateral delayed hearing fluctuation and episodic vertigo. This condition has been called contralateral delayed endolymphatic hydrops. Five of nine ears with profound hearing loss (56%) showed an absence of VEMPs. One ear (11%) showed decreased responses, and three ears (33%) had normal responses. Of the ears with fluctuation of hearing, six (67%) showed an absence of responses, and three ears (33%) showed normal responses. In four patients we recorded VEMPs before and after oral administration of glycerol. Three hours after glycerol administration, two of four ears with fluctuating hearing loss showed the appearance of VEMPs although there was an absence of VEMPs before glycerol administration. These results suggested that saccular dysfunction could exist not only in the ears with profound hearing loss but also in ears with fluctuating hearing loss and that saccular endolymphatic hydrops could exist in the ears with fluctuating hearing loss. “Contralateral delayed endolymphatic hydrops” might be an appropriate term. Received: 22 March 2001 / Accepted: 11 July 2001     

Dexamethasone does not affect endolymphatic hydrops (EH) in patients with Meniere's disease within 24 h,and intratympanic administration of gadolinium plus dexamethasone simplifies high-quality imaging of EH using a novel protocol of 7 min

BackgroundIntratympanic administration of gadolinium chelate allows for a better visualization of endolymphatic hydrops (EH) using MRI than intravenous injection and was recently further improved to facilitate high-quality imaging of EH in 7 min. The aim of the present study was to simplify the intratympanic administration protocol by mixing gadolinium chelate with therapeutic dexamethasone and to evaluate the effects of this mixture on the visualization of EH in MRI.Materials and methodsIn an in vitro study, the potential impact of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on the stability of dexamethasone was evaluated by analyzing dynamic changes in dexamethasone with high-performance liquid chromatography (HPLC) after mixing with Gd-DTPA. Ten patients with definite Meniere's disease (MD) were recruited to study the potential interference of dexamethasone on MRI visualization of EH, and 49 patients with MD were recruited to evaluate the effect of intratympanic injection of Gd-DTPA mixed with dexamethasone on MRI of EH using a 3T MR machine and a novel heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery reconstructed using a magnitude plus zero-filled interpolation (hT₂FLAIR-MZFI) sequence.ResultsThe retention times and peak area of dexamethasone in HPLC were not modified by the addition of Gd-DTPA. EH grading in the cochlea and vestibule was not influenced in any ear by intratympanic injection of dexamethasone. Excellent inner ear images were obtained from all patients, and EHs with various grades were displayed. There were significant correlations between diagnosis and cochlear EH (p < 0.01, Spearman's Rho), between diagnosis and vestibular EH (p < 0.01, Spearman's Rho), and between cochlear and vestibular EH (p < 0.01, Spearman's Rho). The distribution of Gd-DTPA plus dexamethasone negatively correlated with the grade of vestibular EH. Injury of the endolymph-perilymph barrier was detected in one cochlea and three vestibules of 59 inner ears with MD.ConclusionsIntratympanic administration of Gd-DTPA plus dexamethasone yielded high-quality MRI images of EH in patients with MD using a novel 7-min protocol and simplified the clinical application. Intratympanic administration of Gd-DTPA plus dexamethasone might be used to test its therapeutic effect in future work.Level of evidence3.     

A perspective from magnetic resonance imaging findings of the inner ear: Relationships among cerebrospinal, ocular and inner ear fluids

Visualization of endolymphatic hydrops has been performed using magnetic resonance imaging (MRI) after intratympanic or intravenous gadolinium (Gd) injection. Our recent findings indicate that just as the prevalence of asymptomatic glaucoma is greater than that of symptomatic glaucoma, there are also many cases of asymptomatic endolymphatic hydrops. It is assumed that the asymptomatic endolymphatic hydrops that precedes Ménière's disease is found more frequently using MRI than with other techniques. Gd in the inner ear moves into the cerebrospinal fluid (CSF) via the internal auditory meatus. Gd enhancement is also recognized in the ocular fluid after the intravenous Gd administration. In this paper, the relationships between CSF, ocular fluid and inner ear fluid are reviewed. The central nervous system, eye and inner ear contain specialized extracellular fluids that are essential for maintaining their function: CSF, ocular fluid consisting of vitreous humor and aqueous humor, and inner ear fluid consisting of perilymph and endolymph. Abnormal accumulation of or pressure elevation in these fluids is associated with hydrocephalus, glaucoma and Ménière's disease, respectively. The dura mater and the arachnoid membrane of the optic nerve canal and inner ear meatus are very close to the eye and the inner ear, respectively. It has been reported that low CSF pressure is associated with glaucoma and endolymphatic hydrops. In glaucoma and Ménière's disease, nerve damage to ganglion cells rather than damage of the sensory cells is directly associated with progression of the disease. Retinal ganglion cells in glaucoma and spiral ganglion cells in Ménière's disease are targets of the abnormal accumulation of, or increased pressure in, the extracellular fluid, just as neurons are damaged in hydrocephalus. Studies on hydrocephalus, glaucoma and Ménière's disease as a group may deepen our understanding of each disease.     

A possible mechanism of the formation of endolymphatic hydrops and its associated inner ear disorders

The pathology of Meniere’s disease (MD) is well established to be endolymphatic hydrops. However, the mechanism underlying deafness and vertigo of MD or idiopathic endolymphatic hydrops is still unknown. In order to evaluate the pathogenesis of deafness and vertigo in MD, it seems to be rational to investigate the interrelationship between hydrops and inner ear disorders using animals with experimentally-induced endolymphatic hydrops. In spite of intense efforts by many researchers, the mechanism of vertiginous attack has been unexplained, because animals with experimental hydrops usually did not show vertiginous attack.Recently, there are two reports to succeed to evoke vertiginous attack in animals with experimental hydrops. In the present paper were first surveyed past proposals about underlying mechanism of the development of hydrops and inner ear disorders associated with hydrops, and were discussed the pathogenetic mechanism of vertiginous attack in hydrops. In conclusion, abrupt development of hydrops was thought to play a pivotal role in the onset of vertiginous seizure.     

Dexamethasone does not affect endolymphatic hydrops (EH) in patients with Meniere's disease within 24 h,and intratympanic administration of gadolinium plus dexamethasone simplifies high-quality imaging of EH using a novel protocol of 7 min

BackgroundIntratympanic administration of gadolinium chelate allows for a better visualization of endolymphatic hydrops (EH) using MRI than intravenous injection and was recently further improved to facilitate high-quality imaging of EH in 7 min. The aim of the present study was to simplify the intratympanic administration protocol by mixing gadolinium chelate with therapeutic dexamethasone and to evaluate the effects of this mixture on the visualization of EH in MRI.Materials and methodsIn an in vitro study, the potential impact of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on the stability of dexamethasone was evaluated by analyzing dynamic changes in dexamethasone with high-performance liquid chromatography (HPLC) after mixing with Gd-DTPA. Ten patients with definite Meniere''s disease (MD) were recruited to study the potential interference of dexamethasone on MRI visualization of EH, and 49 patients with MD were recruited to evaluate the effect of intratympanic injection of Gd-DTPA mixed with dexamethasone on MRI of EH using a 3T MR machine and a novel heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery reconstructed using a magnitude plus zero-filled interpolation (hT₂FLAIR-MZFI) sequence.ResultsThe retention times and peak area of dexamethasone in HPLC were not modified by the addition of Gd-DTPA. EH grading in the cochlea and vestibule was not influenced in any ear by intratympanic injection of dexamethasone. Excellent inner ear images were obtained from all patients, and EHs with various grades were displayed. There were significant correlations between diagnosis and cochlear EH (p < 0.01, Spearman''s Rho), between diagnosis and vestibular EH (p < 0.01, Spearman''s Rho), and between cochlear and vestibular EH (p < 0.01, Spearman''s Rho). The distribution of Gd-DTPA plus dexamethasone negatively correlated with the grade of vestibular EH. Injury of the endolymph-perilymph barrier was detected in one cochlea and three vestibules of 59 inner ears with MD.ConclusionsIntratympanic administration of Gd-DTPA plus dexamethasone yielded high-quality MRI images of EH in patients with MD using a novel 7-min protocol and simplified the clinical application. Intratympanic administration of Gd-DTPA plus dexamethasone might be used to test its therapeutic effect in future work.Level of evidence3.     

内耳钆造影MRI技术的原理与临床应用进展

目的内耳钆造影磁共振成像（magnetic resonance imaging,MRI）技术为目前诊断多种内耳疾病提供了新方法,甚至有望成为某些内耳疾病诊断的金标准。本文基于国内外鼓室钆造影技术的发展现状,归纳了钆造影的多种给药方式、临床应用、评估方法及各自的优点和缺点,并与传统方式进行了对比,总结了内耳钆造影MRI技术目前的研究现状,同时对其未来的发展趋势进行展望。     

Prognostic evaluation of electrocochleography in idiopathic sudden sensorineural hearing loss

The frequency of childhood deafness is estimated at 1:1,000 and at least half of these cases are genetic. Recently, mutations in the GJB2 gene have been found in a great number of familial and sporadic cases of congenital deafness in Caucasians. The most common mutation (70%) is the frameshift mutation of a single guanine in position 35 (35delG). More than 20 mutations in the GJB2 gene are associated with DFNB1, a prevalent type of autosomal recessive non-syndromic neurosensory deafness. Last year we initiated a systematic screening programme to evaluate the causes of deafness in the population of prelingually deaf children who are referred to our cochlear implant programme. All of the deaf children and their parents undergo a comprehensive medical review, directed to identify causes of acquired deafness and manifestations of syndromic hearing impairment. DNA is extracted from the blood of all of the children. The technique AS-PCR (allele-specific polymerase chain reaction) is used for the identification of the mutation 35delG. Screening for other GJB2 gene mutations is carried out by single-strand conformation polymorphisms (SSCP). Our results on the identification of DFNB1 will be presented, as well as a discussion on the implications of an aetiological diagnosis in cochlear implantation.     

Visualization of endolymphatic hydrops in patients with Meniere's disease

OBJECTIVE: Recently, there have been many reports of intratympanic gentamicin therapy for the treatment of intractable Meniere's disease. Intratympanic administration of steroids has also been used to treat sudden sensorineural hearing loss. We attempted to visualize how the intratympanically administered drug enters the inner ear. METHODS: Gadolinium hydrate diluted eightfold with saline was injected intratympanically through the tympanic membrane using a 23 G needle in nine patients with inner ear diseases. With a 3 Tesla magnetic resonance imaging (MRI) unit, three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging was performed. RESULTS: 3D-FLAIR MRI clearly revealed that the gadolinium entered the perilymphatic space and delineated the perilymphatic and endolymphatic spaces of the inner ear. In patients with endolymphatic hydrops, the perilymphatic space surrounding the endolymph was small or had disappeared. Gadolinium appeared first in the scala tympani of the basal turn of the cochlea and the perilymphatic space of the vestibule. One day after the intratympanic injection of gadolinium, the gadolinium was observed in almost all parts of the perilymph. Six days after the intratympanic injection, the gadolinium had almost disappeared from the inner ear. CONCLUSION: We reported the first visualization of endolymphatic hydrops in patients with Meniere's disease. The relationship between the image of the endolymphatic space and functional tests, such as electrocochleography and vestibular-evoked myogenic potential, must be examined in the near future. It is important for the development of intratympanic drug therapies for inner-ear diseases to investigate how the drugs enter and leave the inner ear.     

The effect of glycerol on the guinea-pig hydropic ear

The aim of this paper was to investigate the effect of glycerol on experimental endolymphatic hydrops in guinea-pigs. The right endolymphatic sac and duct were obliterated through an extradural posterior fossa approach. Some animals received a 3 g/kg dose of glycerol for a period of 7 days, whereas others received the same dose for 30 days. The activity of glycerol was studied by investigating the volumetric changes in the scala media determined with a computerized planimeter. Glycerol induced a significant reduction of the hydrops showing its effectiveness and suggesting a strial metabolic response.     

Endolymphatic sac surgery: analysis of 100 operations*

One hundred endolymphatic mastoid shunt operations in 89 patients with classical Menière's disease were analysed. The disease was bilateral in 18 patients (20%). The patients were carefully pre-selected by a comprehensive protocol of audiovestibular and metabolic investigations. All patients had definite electrophysiological evidence of endolymphatic hydrops with an enhanced negative summating potential on transtympanic electrocochleography. The surgical results were analysed both by the original American Academy of Ophthalmology and Otolaryngology Guidelines (AAOO, 1972) and the more recent modifications of the American Academy of Otolaryngology, Head and Neck Surgery (AA-HNS, 1985). Control of the vertigo was achieved in 81% of the patients overall, in 88% of the patients with unilateral disease and in 63% of the patients with bilateral disease. A significant hearing improvement was obtained in 19% of patients, no change in 55% and hearing became worse in 26%. Tinnitus improved in 38% of patients, was unchanged in 52% and became worse in 10%. Disability was assessed and there was no disability in 44% of the patients post-operatively, some degree of disability in 48% but only 8% were severely disabled and unable to sustain gainful employment.