Advanced Imaging of the Vestibular Endolymphatic Space in Ménière's Disease

Contrast Enhancement of Cochlea after Direct Microneedle Intracochlear Injection of Gadodiamide through the Round Window Membrane with Minimal Dosage

RATIONALE AND OBJECTIVES

The potential of contrast-enhanced MRI for diagnosing endolymphatic hydrops is limited by long wait times following intravenous (IV) or intratympanic (IT) delivery, high contrast dosages, and inconsistent signal intensity enhancements. This study investigates microneedle-mediated intracochlear (IC) gadodiamide injection for consistent and efficient contrast delivery with minimal contrast dosage.

MATERIALS AND METHODS

A 100 µm diameter microneedle with 35 µm lumen was used to inject 1 µL of diluted gadodiamide (17.4 mM) into a guinea pig cochlea via the round window membrane. Serial MRI imaging was performed in a post-mortem animal using a 9.4 T small-animal MRI. Maximum intensity projections of MRI scans were generated to visualize diffusion of contrast within cochlea over time; mean intensities in defined regions of interest (ROIs) were calculated. Contrast diffusion time and intensity enhancements were determined.

RESULTS

Contrast was observed in the basal turn of scala tympani (ST) and scala vestibuli (SV) in the first MRI scan for all subjects which was acquired as early as 35 min after injection. Two-tailed paired t-tests confirmed that contrast reached the first two turns of ST and SV within 60 min, and the second half of third turns and apical turns of ST and SV within 90 min (p < 0.05). Intensity enhancements, defined as the percentage increase of the ROI mean intensity in the injection side compared to the contralateral side, exceeded 100% in the first turn and ranged from 12% to 32% in the third and apical turns of ST and SV at 90 min after injection.

CONCLUSIONS

IC gadodiamide enables controllable and efficient contrast delivery with significantly lower contrast dosage, making it a viable alternative for contrast-enhanced cochlear MRI.

The diagnostic performance of cochlear endolymphatic hydrops and perilymphatic enhancement in stratifying Ménière's disease probabilities: A meta-analysis of semi-quantitative MRI-based grading systems

BACKGROUND

The diagnosis of Meniere's Disease (MD) presents significant challenges due to its complex symptomatology and the absence of definitive biomarkers. Advancements in MRI technology have spotlighted endolymphatic hydrops (EH) as a key pathological marker, necessitating a reevaluation of its diagnostic utility amidst the need for standardized and validated MRI-based grading scales.

METHODS

Our meta-analysis scrutinized the diagnostic efficacy of semi-quantitative MRI-based cochlear endolymphatic hydrops (EH) and perilymphatic enhancement (PLE) grading systems in delineating clinically relevant discriminations: "Spotting" the shift from normal or asymptomatic ears to possible/probable MD (pMD), "Confirming" the progression to definite MD (dMD), and "Establishing" the presence of dMD. A thorough literature search up to October 2023 resulted in 35 pertinent studies, forming the basis of our analysis through a bivariate mixed-effects regression model.

RESULTS

Using criteria from the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) and Barany Society, across varying thresholds and disease probabilities; the Establishment model at an EH grade 1 threshold revealed a sensitivity of 85.4% and a specificity of 82.7%. Adjusting the threshold to EH grade 2 results in a sensitivity increase to 92.1% (CI: 85.9-95.7) and a specificity decrease to 70.6% (CI: 64.5-76.1), with a DOR of 28.056 (CI: 14.917-52.770). The Confirmation model yields a DOR of 5.216, indicating a lower diagnostic accuracy. The Spotting model demonstrates a sensitivity of 48.3% (CI: 34.8-62.1) and a specificity of 88.0% (CI: 77.8-93.9), with a DOR of 6.882. The normal ears subgroup demonstrated a notably high specificity of 89.7%, while employing Nakashima's criteria resulted in a reduced sensitivity of 74.9%, significantly diverging from other systems (p-value < 0.001). The PLE grading system showcased exceptional sensitivity of 98.4% (CI: 93.7-99.6, p-value < 0.001).

CONCLUSION

Our meta-analysis supports a tailored diagnostic approach for MD, emphasizing the need for effective grading systems at each stage. For "Spotting," the model shows high specificity but requires improved sensitivity, suggesting additional criteria are needed. The "Confirming" stage highlights the need for refined, sensitive grading systems due to lower diagnostic accuracy. In the "Establishing" stage, an EH grade 1 threshold is effective, but grade 2 enhances sensitivity while reducing specificity, indicating a need for balance. The PLE grading system excels in sensitivity, making it highly reliable. High specificity in the normal ears subgroup confirms accurate non-pathological distinction, though Nakashima's criteria show reduced sensitivity, underscoring variability in grading systems. These findings advocate for a standardized, unified grading system balancing sensitivity and specificity across all MD stages to optimize diagnostics and clinical outcomes.

Delayed post gadolinium MRI descriptors for Meniere's disease: a systematic review and meta-analysis

OBJECTIVES

Delayed post-gadolinium magnetic resonance imaging (MRI) detects changes of endolymphatic hydrops (EH) within the inner ear in Meniere's disease (MD). A systematic review with meta-analysis was conducted to summarise the diagnostic performance of MRI descriptors across the range of MD clinical classifications.

MATERIALS AND METHODS

Case-controlled studies documenting the diagnostic performance of MRI descriptors in distinguishing MD ears from asymptomatic ears or ears with other audio-vestibular conditions were identified (MEDLINE, EMBASE, Web of Science, Scopus databases: updated 17/2/2022). Methodological quality was evaluated with Quality Assessment of Diagnostic Accuracy Studies version 2. Results were pooled using a bivariate random-effects model for evaluation of sensitivity, specificity and diagnostic odds ratio (DOR). Meta-regression evaluated sources of heterogeneity, and subgroup analysis for individual clinical classifications was performed.

RESULTS

The meta-analysis included 66 unique studies and 3073 ears with MD (mean age 40.2-67.2 years), evaluating 11 MRI descriptors. The combination of increased perilymphatic enhancement (PLE) and EH (3 studies, 122 MD ears) achieved the highest sensitivity (87% (95% CI: 79.92%)) whilst maintaining high specificity (91% (95% CI: 85.95%)). The diagnostic performance of "high grade cochlear EH" and "any EH" descriptors did not significantly differ between monosymptomatic cochlear MD and the latest reference standard for definite MD (p = 0.3; p = 0.09). Potential sources of bias were case-controlled design, unblinded observers and variable reference standard, whilst differing MRI techniques introduced heterogeneity.

CONCLUSIONS

The combination of increased PLE and EH optimised sensitivity and specificity for MD, whilst some MRI descriptors also performed well in diagnosing monosymptomatic cochlear MD.

KEY POINTS

• A meta-analysis of delayed post-gadolinium magnetic resonance imaging (MRI) for the diagnosis of Meniere's disease is reported for the first time and comprised 66 studies (3073 ears). • Increased enhancement of the perilymphatic space of the inner ear is shown to be a key MRI feature for the diagnosis of Meniere's disease. • MRI diagnosis of Meniere's disease can be usefully applied across a range of clinical classifications including patients with cochlear symptoms alone.

Bilateral Sensorineural Hearing Loss Related to a Skull Base Spontaneous Cerebrospinal Fluid Leak: A Case Report and Literature Review

Spontaneous intracranial hypotension (SIH) is a rare condition characterized by orthostatic headache, pulsatile tinnitus, vertigo, nausea, and fluctuating hearing loss; this latter seems to be due to the development of cochlear endolymphatic hydrops following negative cerebrospinal fluid (CSF) pressure transmitted to the perilymphatic space through a patent cochlear aqueduct. We here describe a case of bilateral progressive sensorineural hearing loss (SNHL) due to intracranial hypotension caused by an undiagnosed spontaneous CSF leak from a skull base defect in a middle-aged woman. To the best of our knowledge, this is the first report describing a SNHL in a patient affected by SIH secondary to sphenoidal CSF leak.

Automated Whole Cochlear T2 Signal Demonstrates Weak Correlation with Hearing Loss in Observed Vestibular Schwannoma

INTRODUCTION

We sought to evaluate the correlation between whole cochlear T2 signal changes obtained with a novel automated segmentation method and hearing levels, both at diagnosis and over time, in patients with observed vestibular schwannoma.

METHODS

This retrospective correlation study within an academic medical center neurotology practice evaluated 127 patients with vestibular schwannoma observed over time, each with ≥2 MRI scans (367 total) and ≥2 audiograms (472 total). 86 patients had T2-weighted sequences with sufficient resolution for cochlear signal analysis, yielding 348 unique timepoint intervals. The main outcome measure was correlation of the ipsilateral-to-contralateral ratio of whole cochlear T2 signal with hearing outcomes as measured by pure tone average (PTA) and word recognition score (WRS).

RESULTS

Whole cochlear T2 signal ratios did not show a correlation with hearing levels at diagnosis. Change in signal ratio over time showed weak correlation with changes in PTA, but not WRS, over time. Cochlear signal ratio did not precede changes in hearing but did follow changes in both PTA and WRS.

CONCLUSION

Whole cochlear T2 signal ratios were weakly correlated with changes in hearing in patients with observed vestibular schwannoma. The technology of automated segmentation and signal processing holds promise for future evaluation of clinical entities causing cochlear signal changes.

Endolymphatic Hydrops Magnet Resonance Imaging in Ménière's Disease Patients after Cochlea Implantation

INTRODUCTION

Cochlear implantation in patients with Ménière's disease (MD) is the treatment of choice in cases of functional deafness. Additional vertigo control is of central importance in this group of patients. Endolymphatic hydrops (ELH) is the pathophysiological correlate of MD and can be evaluated by magnet resonance imaging (MRI). Bilateral MD occurs in 10-33% and can be the reason for a postoperative persisting or newly occurring vertigo in this group. Recent developments in the field of implant magnets and experience in MRI sequences allow the diagnostic performance of MRI in cochlear implantees to be evaluated. The aim of the present study was to evaluate the possibility of MRI as a visual diagnostic tool for endolymphatic hydrops in cochlear implantees.

MATERIAL AND METHODS

This was a retrospective study including three cochlear implantees (age: 61-76 years, one female, two male) suffering from MD who, postoperatively, had a recurrence of vertigo with Ménière's-like symptoms. An MRI was performed for the evaluation of ELH (ELH-MRI). MRI observation was performed by a 4 h iv. delayed Gad 3 D Flair sequence.

RESULTS

In all cases, the ipsilateral implant magnet artifact covered the vestibulum, the semicircular canals and the cochlea. The contralateral vestibulum, the semicircular canal and the cochlea were fully observable, and a classification of the ELH-MRI could be performed.

CONCLUSION

ELH-MRI scanning allows for the detection of contralateral labyrinthine endolymphatic hydrops and is a tool for the postoperative evaluation of vertigo in cochlear implantees.

Potential nanotechnology-based diagnostic and therapeutic approaches for Meniere's disease

Meniere's disease (MD) is a progressive inner ear disorder involving recurrent and prolonged episodes or attacks of vertigo with associated symptoms, resulting in a significantly reduced quality of life for sufferers. In most cases, MD starts in one ear; however, in one-third of patients, the disorder progresses to the other ear. Unfortunately, the etiology of the disease is unknown, making the development of effective treatments difficult. Nanomaterials, including nanoparticles (NPs) and nanocarriers, offer an array of novel diagnostic and therapeutic applications related to MD. NPs have specific features such as biocompatibility, biochemical stability, targetability, and enhanced visualization using imaging tools. This paper provides a comprehensive and critical review of recent advancements in nanotechnology-based diagnostic and therapeutic approaches for MD. Furthermore, the crucial challenges adversely affecting the use of nanoparticles to treat middle ear disorders are investigated. Finally, this paper provides recommendations and future directions for improving the performances of nanomaterials on theragnostic applications of MD.

Ménière's disease: new guidelines, subtypes, imaging, and more

PURPOSE OF REVIEW

This article reviews recent developments in Ménière's disease including etiologic, diagnostic, and therapeutic investigations that have changed the landscape for medical providers. These updates shed light onto the complex nature of Ménière's disease and generate additional means to provide optimal care to patients.

RECENT FINDINGS

Given the multifactorial cause of Ménière's disease, five subtypes of Ménière's disease have recently been proposed. A knowledge of these subtypes will aid in the development of an appropriate treatment algorithm. Although newer treatments have not been developed, stepwise treatment algorithms have been proposed and can improve patient care. New MRI modalities and serum testing hold promise as clinical clues and biomarkers.

SUMMARY

As these updated diagnostic criteria are used, Ménière's disease can be identified and treated more precisely. This will in turn allow for future randomized controlled studies to improve the quality of treatment options available. Future imaging, vestibular testing, and the potential for serum biomarkers may illuminate additional diagnostic criteria, only furthering the improvement in clinical care.