Nobuyuki Katahira

3D-FLAIR MRI findings in patients with low-tone sudden deafness.

Abstract Conclusion: The findings suggest that alterations in the composition of inner ear fluid play important roles in the development of low-tone sudden deafness (LTSD). High-intensity signals on three-dimensional fluid attenuated inversion recovery (3D-FLAIR) may reflect an increased concentration of protein in the inner ear due to the increased permeability of blood vessels. Disordered blood flow in the inner ear is associated with an increased permeability of the blood–labyrinth barrier. Therefore, the disordered blood flow in the cochlea may be closely related to the pathophysiological mechanisms of LTSD. Objectives: The 3D-FLAIR sequence has been used to detect alterations in the composition of inner ear fluid. The purpose of this study was to report imaging findings in cases of LTSD. Methods: 3D-FLAIR magnetic resonance imaging was performed in five women with nonrecurrent-type LTSD. Results: Three of the five patients (60%) showed high-intensity signals in the cochlear basal turn on precontrast 3D-FLAIR. Postcontrast enhancement was not prominent in any patient. In patient 1, the cochlea of the unaffected side showed high-intensity signals. No patients had such signals in the vestibulae or the semicircular canals.

Diluted gadoteridol (ProHance®) causes mild ototoxicity in cochlear outer hair cells

Abstract Conclusion: Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear outer hair cells (OHCs). Objectives: Visualization of endolymphatic hydrops is done by intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol. Methods: Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Morphological changes in isolated cochlear OHCs were observed after application of gadoteridol and GdCl3. Results: At the highest frequency (F2 = 12 000 Hz), DPOAE level was significantly (p < 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) of OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared with 1/8 diluted gadoteridol. Morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared with 1/8 diluted gadoteridol (p < 0.05). Morphological damage was observed at a high rate (8/10 cells, 80%) after application of GdCl3.

Red blood cell distribution width predicts prognosis in idiopathic sudden sensorineural hearing loss

Abstract Conclusion: Red cell distribution width (RDW) can predict outcome in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). Further studies are required to clarify the potential pathophysiological explanations for these findings. Objectives: RDW is one of the parameters reported in a complete blood count, and is elevated in direct proportion to variation in red cell size (anisocytosis). High RDW values are strongly associated with poor clinical outcomes in various diseases, including inflammatory and thrombotic diseases. To identify a prognostic biomarker that better predicts outcomes after ISSNHL, the association between RDW values at hospitalization and prognosis in patients with ISSNHL was assessed. Method: This study measured RDW and performed hearing assessments in 89 consecutive patients with ISSNHL. Patients were then divided into two groups (‘recovered’ and ‘unrecovered’), according to their response to the treatment, and further analysis undertaken. Results: Mean RDW was significantly higher in the unrecovered group (13.2% ± 1.0% compared with 12.7% ± 0.7% in the recovered group, p = 0.031). After adjusting for potentially confounding factors in a binary logistic regression model, only RDW was associated with recovery from ISSNHL (odds ratio = 2.33, 95% confidence interval = 1.20–4.51, p = 0.012).

Soybean β-Conglycinin Prevents Age-Related Hearing Impairment

Obesity-related complications are associated with the development of age-related hearing impairment. β-Conglycinin (β-CG), one of the main storage proteins in soy, offers multiple health benefits, including anti-obesity and anti-atherosclerotic effects. Here, to elucidate the potential therapeutic application of β-CG, we investigated the effect of β-CG on age-related hearing impairment. Male wild-type mice (age 6 months) were randomly divided into β-CG-fed and control groups. Six months later, the body weight was significantly lower in β-CG-fed mice than in the controls. Consumption of β-CG rescued the hearing impairment observed in control mice. Cochlear blood flow also increased in β-CG-fed mice, as did the expression of eNOS in the stria vascularis (SV), which protects vasculature. β-CG consumption also ameliorated oxidative status as assessed by 4-HNE staining. In the SV, lipofuscin granules of marginal cells and vacuolar degeneration of microvascular pericytes were decreased in β-CG-fed mice, as shown by transmission electron microscopy. β-CG consumption prevented loss of spiral ganglion cells and reduced the frequencies of lipofuscin granules, nuclear invaginations, and myelin vacuolation. Our observations indicate that β-CG ameliorates age-related hearing impairment by preserving cochlear blood flow and suppressing oxidative stress.

Investigation of the ototoxicity of gadoteridol (ProHance) and gadodiamide (Omniscan) in mice.

Abstract Conclusion: In the mouse, when a tympanic perforation is present, gadoteridol does not seem to cause ototoxicity. Gadodiamide may cause mild ototoxicity other than toxicity to the outer hair cells of the cochlea. Objectives: Endolymphatic hydrops have been visualized through intra-tympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, reports on the safety of GBCAs are limited. This study aimed to assess ototoxicity of gadoteridol and gadodiamide. Method: In a prospective, randomized, controlled trial, myringotomies in the left ear were performed in 20 male C57 BL/6 mice. After testing the baseline auditory brainstem response (ABR) (range = 8–32 kHz), the test solution (gadoteridol, gadodiamide, saline, or cisplatin) was injected into the left ear. ABR testing was repeated 14 days after test solution application. In morphological experiments, images of post-mortem surface preparations were assessed for cochlear hair cell status. Results: At 14 days following gadoteridol application, there was no significant change in ABR thresholds at 8, 16, or 32 kHz. Gadodiamide application caused a significant change in the ABR threshold at 8 kHz. Apparent cochlear hair cell loss was not observed in the surface preparation after gadoteridol or gadodiamide application.

Usefulness of 3D-FLAIR MRI to Detect Inner Ear Abnormalities in Patients with Sudden SNHL:

Objectives: Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) has been used to detect alterations in the composition of the inner ear fluid. We aimed to investigate an association between the hearing level and the signal intensity of pre- and postcontrast 3D-FLAIR MRI in patients with sudden-onset sensorineural hearing loss (SNHL). Methods: 3D-FLAIR MRI was performed in 18 patients with sudden-onset SNHL: 12 patients with mild-to-moderate SNHL (baseline hearing levels, ≤ 60 dB) and 6 patients with severe-to-profound SNHL (baseline hearing levels >60 dB). Results: High-intensity signals in the inner ear were observed in 2 of 6 patients (33%) with severe-to-profound SNHL but not in those with mild-to-moderate SNHL (P < .05). Signals were observed on MRI scans 6 or 18 days after SNHL onset. Conclusions: Our results indicate that 3D-FLAIR MRI is not a useful tool for detecting inner ear abnormalities in patients with mild SNHL.

Diluted Gadoteridol Causes Mild Ototoxicity in Cochlear Outer Hair Cells

Objectives: Recently, visualization of endolymphatic hydrops has been achieved through intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, the effects of gadoteridol (ProHance®) on inner ear cells are not yet understood. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol. Methods: Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of a 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Moreover, morphological changes of isolated cochlear outer hair cells (OHCs) were observed after application of gadoteridol and GdCl3. Results: At the highest frequency (F2 = 12000 Hz), DPOAE level was significantly (P < 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared to 1/8 diluted gadoteridol (P < 0.05). Moreover, morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared to 1/8 diluted gadoteridol (P < 0.05). Morphological damages were shown at high rate (8/10 cells, 80%) after application of GdCl3. Conclusions: Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear OHCs.