Michihiko Sone

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 Menieres 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.

Disorders of cochlear blood flow

The cochlea is principally supplied from the inner ear artery (labyrinthine artery), which is usually a branch of the anterior inferior cerebellar artery. Cochlear blood flow is a function of cochlear perfusion pressure, which is calculated as the difference between mean arterial blood pressure and inner ear fluid pressure. Many otologic disorders such as noise-induced hearing loss, endolymphatic hydrops and presbycusis are suspected of being related to alterations in cochlear blood flow. However, the human cochlea is not easily accessible for investigation because this delicate sensory organ is hidden deep in the temporal bone. In patients with sensorineural hearing loss, magnetic resonance imaging, laser-Doppler flowmetry and ultrasonography have been used to investigate the status of cochlear blood flow. There have been many reports of hearing loss that were considered to be caused by blood flow disturbance in the cochlea. However, direct evidence of blood flow disturbance in the cochlea is still lacking in most of the cases.

Grading of endolymphatic hydrops using magnetic resonance imaging

Conclusion: Grading of endolymphatic hydrops in the vestibule and the cochlea using magnetic resonance imaging (MRI) is proposed (2008 Nagoya scale). Objective: To standardize the evaluation of endolymphatic hydrops in both the vestibule and the cochlea using MRI. Patients and methods: The endolymphatic space was evaluated after intratympanic gadolinium injection using three-dimensional fluid attenuated (3D-FLAIR) MRI and three-dimensional real inversion recovery (3D-real IR) MRI. Results: A simple three-stage grading system was acceptable for hydrops in both the vestibule and the cochlea: none, mild, and significant. In the vestibule, the grading was determined by the ratio of the area of endolymphatic space to the vestibular fluid space (sum of the endolymphatic and perilymphatic spaces). Patients with no hydrops have a ratio of one-third or less, those with mild hydrops have between one-third and a half, and those with significant hydrops have a ratio of more than 50%. In the cochlea, patients classified as having no hydrops show no displacement of Reissners membrane; those with mild hydrops show displacement of Reissners membrane but the area of the endolymphatic space does not exceed the area of the scala vestibuli; and in those with significant hydrops the area of the endolymphatic space exceeds the area of the scala vestibuli.

Separate visualization of endolymphatic space, perilymphatic space and bone by a single pulse sequence; 3D-inversion recovery imaging utilizing real reconstruction after intratympanic Gd-DTPA administration at 3 Tesla

Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the perilymphatic space. Three-dimensional FLAIR can differentiate endolymphatic space from perilymphatic space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of perilymphatic space (positive value), endolymphatic space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing perilymphatic space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic space, perilymphatic space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

Individual Differences in the Permeability of the Round Window: Evaluating the Movement of Intratympanic Gadolinium Into the Inner Ear

Objective: Many recent studies have reported on intratympanic gentamicin therapy for the treatment of intractable Ménières disease. Intratympanic administration of steroids has also been used to treat sudden sensorineural hearing loss. These intratympanic drug therapies are based on the assumption that the drug administered intratympanically enters the inner ear through the round window membrane. We used magnetic resonance imaging (MRI) to evaluate whether and how intratympanically administered gadolinium (Gd) enters the inner ear. Methods: GD hydrate was injected intratympanically through the tympanic membrane using a 23-G needle into 61 ears of 55 patients with inner ear diseases. The injected Gd was diluted 8-fold in saline for injection into 58 ears and 16-fold for 3 ears. Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging was performed using a 3-Tesla MRI unit 1 day after the intratympanic injection. Results: In 53 of 61 ears, the Gd-containing inner ear was detected well as a high signal on 3D-FLAIR imaging. However, Gd was not visible in 2 ears with Ménières disease and in 1 ear with profound deafness. The concentration of Gd in the perilymph was lower in 4 ears with Ménières disease and 1 ear with delayed endolymphatic hydrops than after intratympanic administration of the 16-fold Gd dilution. Conclusion: Round window permeability was absent in 5% of ears, and 13% of ears had poor round window permeability. These results should be considered when planning intratympanic drug administration therapy to treat inner ear diseases.

Imaging of Endolymphatic and Perilymphatic Fluid at 3T After Intratympanic Administration of Gadolinium-Diethylene-Triamine Pentaacetic Acid

SUMMARY: By optimizing the inversion time of a 3D inversion-recovery turbo spin-echo sequence at 3T, we obtained separate images of endolymphatic and perilymphatic space 24 hours after intratympanic administration of gadolinium contrast material. In patients with Ménière disease, endolymphatic hydrops were detected not only in the cochlea but also in the vestibule. Fusion of the 2 types of images visualized the entire fluid space of the labyrinth and the spatial relationship of the 2 spaces.

Endolymphatic hydrops revealed by intravenous gadolinium injection in patients with Ménière's disease

CONCLUSION Visualization of endolymphatic hydrops became possible after intravenous gadolinium (Gd) injection in patients with Ménières disease. OBJECTIVE To visualize endolymphatic hydrops after intravenous Gd injection. METHODS Gd (gadoteridol; 0.2 mmol/kg) was injected intravenously in three patients with unilateral Ménières disease. We performed three-dimensional fluid attenuated inversion recovery (3D-FLAIR) and three-dimensional real inversion recovery (3D-real IR) magnetic resonance imaging (MRI) 4 h after the injection using a 3-Tesla MRI unit. We used a 32-channel array coil to obtain a high signal-to-noise ratio. RESULTS Endolymphatic hydrops was observed in the ears of patients with Ménières disease. However, Gd concentration in the perilymph was lower compared with that obtained after intratympanic Gd injection.

Endolymphatic hydrops and blood-labyrinth barrier in Ménière's disease.

Abstract Conclusions: The blood–labyrinth barrier is impaired in association with the hydrops grade in Ménières disease. Objectives: To investigate the relationship between endolymphatic hydrops and the clinical characteristics of patients with Ménières disease revealed by 3 T magnetic resonance imaging (MRI). Methods: A double dose of gadoteridol (Gd; 0.2 mmol/kg) was injected intravenously in 12 patients with Ménières disease. We performed three-dimensional fluid attenuated inversion recovery MRI and three-dimensional real inversion recovery MRI 4 h later using a 3 T MRI unit. Ten patients had unilateral and two had bilateral Ménières disease. Results: Fourteen ears with Ménières disease showed intense Gd contrast on MRI compared with that in the 10 asymptomatic contralateral ears of patients with unilateral Ménières disease (1.12 ± 0.36 vs 0.82 ± 0.15). The hydrops grade was correlated significantly with the contrast effect. The 14 ears with Ménières disease had endolymphatic hydrops. Of the 10 contralateral ears of patients with unilateral Ménières disease, 2 had endolymphatic hydrops in the cochlea and 6 had endolymphatic hydrops in the vestibule.

Relationship between the Degree of Endolymphatic Hydrops and Electrocochleography

The purpose of this study was to evaluate the relationship between the endolymphatic space image obtained using magnetic resonance imaging (MRI) and the results of electrocochleography. Electrocochleography recordings were obtained from 25 ears of 24 patients, who underwent MRI 1 day after the intratympanic injection of gadolinium diethylenetriamine pentaacetic acid bismethylamide. The average summating potential to action potential (SP/AP) ratio in patients with significant endolymphatic hydrops in the cochlea was 54 ± 17%. However, in some patients who had significant endolymphatic hydrops in the cochlea, the SP/AP ratio was not enlarged. This may imply that elevation of the SP/AP ratio is related to not only the degree of endolymphatic hydrops but also to the persistence of hydrops.

Relationship between endolymphatic hydrops and vestibular-evoked myogenic potential

Abstract Conclusion: Vestibular-evoked myogenic potential (VEMP) can be used to examine endolymphatic hydrops, especially in the vestibule. Objective: To investigate the relationship between the degree of endolymphatic hydrops revealed by magnetic resonance imaging (MRI) and VEMP. Methods: Gadolinium diluted with saline was injected intratympanically in 49 ears (40 patients). One day after the injection, the endolymphatic space in the vestibule and the cochlea was visualized by 3 Tesla MRI. A VEMP test was done, and VEMP was judged as absent when the VEMP was within the noise level. Results: VEMP was present in 21 ears and absent in 28 ears. Endolymphatic hydrops was significantly associated with the disappearance of VEMP. Endolymphatic hydrops in the vestibule had a stronger effect than endolymphatic hydrops in the cochlea. Five patients with extremely large vestibular hydrops showed no response of VEMP.