Labyrinthine enhancement on gadolinium-enhanced magnetic resonance imaging in sudden deafness and vertigo: correlation with audiologic and electronystagmographic studies

Pathophysiological analysis of idiopathic sudden sensorineural hearing loss by magnetic resonance imaging: A mini scoping review

Objective

To summarize the pathophysiological analysis of idiopathic sudden sensorineural hearing loss (ISSNHL) by magnetic resonance imaging (MRI), focusing on the findings of high signal or endolymphatic hydrops (EH) in the inner ear.

Methods

We summarize the published studies of our research group regarding the pathophysiological analysis of ISSNHL on MRI and review related clinical articles that have reported significantly high signal or the existence of EH in ears with ISSNHL.

Results

Pre-contrast high signal on MRI may indicate minor hemorrhage or increased permeability of surrounding vessels to the perilymph, whereas post-contrast high signal indicates breakdown of the blood-labyrinth barrier, in which irreversible changes would lead to poor prognosis. In some cases of ISSNHL, primary EH could be pre-existing and may be a risk factor for the onset of ISSNHL.

Conclusion

Analysis of ISSNHL by cutting-edge MRI evaluation could provide useful information for elucidating its pathophysiology and for predicting prognosis in this disease.

Hydropic Ear Disease: Correlation Between Audiovestibular Symptoms, Endolymphatic Hydrops and Blood-Labyrinth Barrier Impairment

Research Objective: To investigate the correlation between clinical features and MRI-confirmed endolymphatic hydrops (EH) and blood-labyrinth barrier (BLB) impairment. Study Design: Retrospective cross-sectional study. Setting: Vertigo referral center (Haga Teaching Hospital, The Hague, the Netherlands). Methods: We retrospectively analyzed all patients that underwent 4 h-delayed Gd-enhanced 3D FLAIR MRI at our institution from February 2017 to March 2019. Perilymphatic enhancement and the degree of cochlear and vestibular hydrops were assessed. The signal intensity ratio (SIR) was calculated by region of interest analysis. Correlations between MRI findings and clinical features were evaluated. Results: Two hundred and fifteen patients with MRI-proven endolymphatic hydrops (EH) were included (179 unilateral, 36 bilateral) with a mean age of 55.9 yrs and median disease duration of 4.3 yrs. Hydrops grade is significantly correlated with disease duration (P < 0.001), the severity of low- and high-frequency hearing loss (both P < 0.001), and the incidence of drop attacks (P = 0.001). Visually increased perilymphatic enhancement was present in 157 (87.7%) subjects with unilateral EH. SIR increases in correlation with hydrops grade (P < 0.001), but is not significantly correlated with the low or high Fletcher index (P = 0.344 and P = 0.178 respectively). No significant differences were found between the degree of EH or BLB impairment and vertigo, tinnitus or aural fullness. Conclusion: The degree of EH positively correlates with disease duration, hearing loss and the incidence of drop attacks. The BLB is impaired in association with EH grade, but without clear contribution to the severity of audiovestibular symptoms.

MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review

Objective: Capillaries within the inner ear form a semi-permeable barrier called the blood-labyrinth barrier that is less permeable than capillary barriers elsewhere within the human body. Dysfunction of the blood-labyrinth barrier has been proposed as a mechanism for several audio-vestibular disorders. There has been interest in using magnetic resonance imaging (MRI) with intravenous gadolinium-based contrast agents (GBCA) as a marker for the integrity of the blood labyrinth barrier in research and clinical settings. This scoping review evaluates the evidence for using intravenous gadolinium-enhanced MRI to assess the permeability of the blood-labyrinth barrier in healthy and diseased ears.

Methods: A systematic search was conducted of three databases: PubMed, EMBASE, CINAHL PLUS. Studies were included that used GBCA to study the inner ear and permeability of the blood-labyrinth barrier. Data was collected on MRI protocols used and inner ear enhancement patterns of healthy and diseased ears in both human and animal studies.

Results: The search yielded 14 studies in animals and 53 studies in humans. In healthy animal and human inner ears, contrast-enhanced MRI demonstrated gradual increase in inner ear signal intensity over time that was limited to the perilymph. Signal intensity peaked at 100 min in rodents and 4 h in humans. Compared to controls, patients with idiopathic sudden sensorineural hearing loss and otosclerosis had increased signal intensity both before and shortly after GBCA injection. In patients with Ménière's disease and vestibular schwannoma, studies reported increased signal at 4 h, compared to controls. Quality assessment of included studies determined that all the studies lacked sample size justification and many lacked adequate control groups or blinded assessors of MRI.

Conclusions: The included studies provided convincing evidence that gadolinium crosses the blood-labyrinth barrier in healthy ears and more rapidly in some diseased ears. The timing of increased signal differs by disease. There was a lack of evidence that these findings indicate general permeability of the blood-labyrinth barrier. Future studies with consistent and rigorous methods are needed to investigate the relationship between gadolinium uptake and assessments of inner ear function and to better determine whether signal enhancement indicates permeability for molecules other than gadolinium.

Prognostic Value of Early Magnetic Resonance Imaging Patterns in Sudden Hearing Loss

INTRODUCTION

Sudden sensorineural hearing loss (SSHL) is a relatively frequent disease, but a sensitive marker or a reliable test to identify the underlying cause is still unavailable. Neuroradiology appears to offer the most promising tools, especially magnetic resonance imaging (MRI). In a recent study from our group, we explored the ability of MRI to detect subtle changes in the inner ear compartments by means of a 3D-fluid-attenuated inversion recovery sequence, aiming at identifying 3 distinct MRI patterns (haemorrhagic, inflammatory, brain-labyrinth barrier breakdown). In the present study, we contrasted the MRI patterns at onset with relevant prognostic factors, with the audiological features of each patient's SSHL and with treatment outcomes.

METHODS

In this retrospective study, we enrolled 50 adult subjects (54.61 ± 18.26 years) with SSHL. They underwent an MRI within 72 h from admission, and 5 audiological evaluations: at admission, on the 5th day after the start of medical therapy, at the end of the first cycle of hyperbaric oxygen therapy, then 1 and 6 months later.

RESULTS

Abnormalities of the MRI signal and/or post-contrast enhancement asymmetry of the cochlea ("pattern+ MRI") correlated with worse audiological outcomes at 1 month, but the different MRI patterns were not correlated with any specific prognostic model, despite rigid protocol settings. However, a significant difference was found for low-tone SSHL, which were always "pattern" negative at MRI (p = 0.01), and for profound SSHL which demonstrated a pattern+ MRI in 80% (p = 0.04). At the onset of SSHL, a pattern+ MRI was found in 29/50 cases (58.0%) and was related with lesser degree of recovery of pure-tone average at 1 month and lesser chance to retain the hearing threshold benefit in the long term. Given the limited numbers of patients enrolled so far, the relative impact of comorbidities on each MRI pattern remains uncertain. At 6 months, we observed a trend of greater and more stable recovery (p = 0.023) and less frequent recurrence of SSHL in patients with a normal MRI.

CONCLUSIONS

The 3 observed MRI patterns did not correlate consistently with specific audio-vestibular features or any peculiar aspect of the patient's clinical history. Larger series of patients with SSHL are needed, possibly from multicentric studies.

Inflammation associated with noise-induced hearing loss

Inflammation is a complex biological response to harmful stimuli including infection, tissue damage, and toxins. Thus, it is not surprising that cochlear damage by noise includes an inflammatory component. One mechanism by which inflammation is generated by tissue damage is the activation of damage-associated molecular patterns (DAMPs). Many of the cellular receptors for DAMPS, including Toll-like receptors, NOD-like receptors, and DNA receptors, are also receptors for pathogens, and function in the innate immune system. DAMP receptors are known to be expressed by cochlear cells, and binding of molecules released by damaged cells to these receptors result in the activation of cell stress pathways. This leads to the generation of pro-inflammatory cytokines and chemokines that recruit pro-inflammatory leukocytes. Extensive evidence indicates pro-inflammatory cytokines including TNF alpha and interleukin 1 beta, and chemokines including CCL2, are induced in the cochlea after noise exposure. The recruitment of macrophages into the cochlea has also been demonstrated. These provide substrates for noise damage to be enhanced by inflammation. Evidence is provided by the effectiveness of anti-inflammatory drugs in ameliorating noise-induced hearing loss. Involvement of inflammation provides a wide variety of additional anti-inflammatory and pro-resolution agents as potential pharmacological interventions in noise-induced hearing loss.

Temporal bone MRI with 3D-FIESTA in the evaluation of facial and audiovestibular dysfunction

PURPOSE

To evaluate the clinical usefulness of magnetic resonance imaging (MRI) of the temporal bone using three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences in patients with facial and audiovestibular dysfunction.

METHODS

We retrospectively reviewed the MR images of 1263 patients who presented with hearing loss (n=429), peripheral facial palsy (n=96), tinnitus (n=341) or vertigo (n=397). There were 605 men and 658 women, with a mean age of 46.97±16.95 (SD) years (range: 2-83 years). Positive MRI findings that were responsible for clinical manifestations in individual patients were categorized according to the anatomic sites and etiologies of the lesions.

RESULTS

Positive MRI findings possibly responsible for clinical manifestations were found in 232/1263 (18.37%) patients, including 86/429 (20.05%) patients with hearing loss, 21/96 (21.88%) patients with facial palsy, 62/341 (18.18%) patients with tinnitus, and 63/397 (15.87%) patients with vertigo.

CONCLUSION

Although the use of MRI of the temporal bone using 3D-FIESTA shows positive findings in only 18.37% of patients, it provides important information in those with facial and audiovestibular dysfunction. However, for patients with normal MRI of the temporal bone, other etiological factors should be investigated in order to clarify or elucidate the cause of clinical manifestations.

Intratympanic Contrast in the Evaluation of Menière Disease: Understanding the Limits

BACKGROUND AND PURPOSE

Studies describing endolymphatic hydrops in Menière disease after off-label intratympanic gadolinium-based contrast have been limited by long acquisition times. We aimed to demonstrate the feasibility of post-intratympanic imaging on a 3T MR imaging system within a clinically tolerable acquisition time and to address potential pitfalls in acquisition or interpretation.

MATERIALS AND METHODS

FDA Investigational New Drug 115,342 and institutional review board approval were obtained for intratympanic injection of 8-fold diluted Gd-DTPA into the more symptomatic ear of 6 adults with Menière disease. 3T MR imaging was performed using a 3-inch surface coil before and up to 28 hours after injection using FLAIR to define the nonenhancing endolymphatic space within the enhancing perilymph. Variable FLAIR TI images were used to determine the impact of fluid-suppression on interpretation. Image quality was assessed for perilymphatic and extralabyrinthine contrast enhancement, definition of endolymphatic anatomy, and other anatomic variants or pathologic findings.

RESULTS

The surface coil afforded 0.375 × 0.375 mm in-plane FLAIR resolution in <4 minutes 30 seconds, sufficient to perceive the nonenhancing spiral lamina, interscalar septa, and endolymphatic structures. Coronal views highlighted a potential interpretation pitfall of vestibular endolymphatic distention overestimation due to partial volume averaging. Varying FLAIR TI resulted in visible changes in the perception of the cochlear endolymphatic space. CSF enhancement was detectable at the internal auditory canal fundus on the injected side in half of the patients, which may confound interpretation.

CONCLUSIONS

Using a surface coil preserves high resolution within a clinically acceptable acquisition time. Pitfalls remain regarding the interpretation of these images and optimizing protocols across platforms in the absence of a clear internal reference for standardization.

Immune system of the inner ear as a novel therapeutic target for sensorineural hearing loss

Sensorineural hearing loss (SNHL) is a common clinical condition resulting from dysfunction in one or more parts in the auditory pathway between the inner ear and auditory cortex. Despite the prevalence of SNHL, little is known about its etiopathology, although several mechanisms have been postulated including ischemia, viral infection or reactivation, and microtrauma. Immune-mediated inner ear disease has been introduced and accepted as one SNHL pathophysiology; it responds to immunosuppressive therapy and is one of the few reversible forms of bilateral SNHL. The concept of immune-mediated inner ear disease is straightforward and comprehensible, but criteria for clinical diagnosis and the precise mechanism of hearing loss have not been determined. Moreover, the therapeutic mechanisms of corticosteroids are unclear, leading to several misconceptions by both clinicians and investigators concerning corticosteroid therapy. This review addresses our current understanding of the immune system in the inner ear and its involvement in the pathophysiology in SNHL. Treatment of SNHL, including immune-mediated inner ear disorder, will be discussed with a focus on the immune mechanism and immunocompetent cells as therapeutic targets. Finally, possible interventions modulating the immune system in the inner ear to repair the tissue organization and improve hearing in patients with SNHL will be discussed. Tissue macrophages in the inner ear appear to be a potential target for modulating the immune response in the inner ear in the pathophysiology of SNHL.

Sudden hearing loss with simultaneous posterior semicircular canal BPPV: possible etiology and clinical implications

OBJECTIVES

The objectives of this study were to describe the clinical course and outcome of patients with sudden sensorineural hearing loss (SSNHL) in conjunction with benign paroxysmal positional vertigo (BPPV), and hypothesize the possible pathophysiology of this entity.

STUDY DESIGN

Retrospective study of all patients with evidence of SSNHL with any type of BPPV between 2008 and 2012.

SETTINGS

Tertiary care university hospital.

SUBJECTS AND METHODS

Five patients aged 56 to 71 were diagnosed with unilateral profound SSNHL and BPPV. Neurotologic examination revealed an ipsilateral torsional, up-beating nystagmus on Dix-Hallpike exam. Severe or profound ipsilateral-sensorineural hearing loss was recognized on audiometry. The rest of the exam was normal; this was in keeping with the diagnosis of SSNHL with ipsilateral posterior semicircular canal BPPV.

RESULTS

All patients were treated with a modified Epley maneuver; oral steroids were administered for two weeks. In all cases vertigo resolved and the Dix-Hallpike exam became normal within several weeks. However, the hearing loss remained unchanged in two patients. Magnetic resonance imaging of the head was normal and ENG caloric test demonstrated mild ipsilateral canal paresis in two patients.

CONCLUSIONS

1. Patients with SSNHL and BPPV can have a variable clinical course and outcome. This entity may be quite common, but the diagnosis of BPPV can be missed if a complete neurological physical examination is not performed. 2. Arterial occlusions or selective multiple vascular or neural involvement may explain the pathophysiology of SSNHL with BPPV of the posterior semicircular canal.

Sudden sensorineural hearing loss: a review of diagnosis, treatment, and prognosis

Sudden sensorineural hearing loss (SSNHL) is commonly encountered in audiologic and otolaryngologic practice. SSNHL is most commonly defined as sensorineural hearing loss of 30 dB or greater over at least three contiguous audiometric frequencies occurring within a 72-hr period. Although the differential for SSNHL is vast, for the majority of patients an etiologic factor is not identified. Treatment for SSNHL of known etiology is directed toward that agent, with poor hearing outcomes characteristic for discoverable etiologies that cause inner ear hair cell loss. Steroid therapy is the current mainstay of treatment of idiopathic SSNHL in the United States. The prognosis for hearing recovery for idiopathic SSNHL is dependent on a number of factors including the severity of hearing loss, age, presence of vertigo, and shape of the audiogram.

Transport augmentation through the blood-inner ear barriers of guinea pigs treated with 3-nitropropionic acid and patients with acute hearing loss, visualized with 3.0 T MRI

OBJECTIVE

To visualize the permeability changes in the blood-inner ear barriers of guinea pigs with acute mitochondria dysfunction and in patients with acute hearing loss using contrast agent-enhanced MRI.

MATERIALS AND METHODS

An animal model of acute mitochondria dysfunction-induced hearing loss was created by introducing 3-nitropropionic acid (3-NP) intratympanically in guinea pigs. Vestibular disorder and hearing loss were evaluated. An MRI was performed at 2 h after either intravenous (IV) or intratympanic administration of dimeglumine gadopentetate (Gd-DTPA), using 3D fast-recovery fast spin-echo (FRFSE) and 3D fluid-attenuated inversion recovery (FLAIR) sequences. The inner ears of patients with acute hearing loss were imaged using a 3D-FLAIR sequence with a 3 T MRI machine at 2 h post-IV injection with Gd-DTPA at a routine dosage.

RESULTS

Guinea pigs treated with 3-NP showed severe hearing loss and vestibular dysfunction. MR imaging with a 3D-FLAIR sequence at 2 h post-IV injection of Gd-DTPA was an optimal method for visualizing transport augmentation through the blood-inner ear barriers. Apoptosis appeared in the stria vascularis and Reissner's membrane of cochleae treated with 3NP. Similar MRI changes were observed in patients with SSHL and Ménière's disease 2 h post-IV injection with Gd-DTPA using the 3D-FLAIR sequence.

CONCLUSION

Variations of Gd-DTPA transport through the blood-inner ear barriers induced by mitochondria toxin was visualized in guinea pigs using a clinical 3.0 T machine. IV injection of Gd-DTPA with 2 h of waiting time and imaging with 3D-FLAIR are optimal methods. The MRI observation of the inner ear in the animal model was translatable to patients with acute hearing loss, using an IV injection of Gd-DTPA at the routine dosage.

Magnetic resonance imaging of the inner ear in Meniere's disease

Recent magnetic resonance imaging (MRI) techniques have made it possible to examine the compartments of the cochlea using gadolidium-chelate (GdC) as a contrast agent. As GdC loads into the perilymph space without entering the endolymph in healthy inner ears, the technique provides possibilities to visualize the different cochlear compartments and evaluate the integrity of the inner ear barriers. This critical review presents the recent advancements in the inner ear MRI technology, contrast agent application and the correlated ototoxicity study, and the uptake dynamics of GdC in the inner ear. GdC causes inflammation of the mucosa of the middle ear, but there are no reports or evidence of toxicity-related changes in vivo either in animals or in humans. Intravenously administered GdC reached the guinea pig cochlea about 10 minutes after administration and loaded the scala tympani and scala vestibuli with the peak at 60 minutes. However, the perilymphatic loading peak was 80 to 100 minutes in mice after intravenous administration of GdC. In healthy animals the scala media did not load GdC. In mice in which GdC was administered topically onto the round window, loading of the cochlea peaked at 4 hours, at which time it reached the apex. The initial portions of the organ to be filled were the basal turn of the cochlea and vestibule. In animal models with endolymphatic hydrops (EH), bulging of the Reissner's membrane was observed as deficit of GdC in the scala vestibuli. Histologically the degree of bulging correlated with the MR images. In animals with immune reaction-induced EH, MRI showed that EH could be limited to restricted regions of the inner ear, and in the same inner ear both EH and leakage of GdC into the scala media were visualized. More than 100 inner ear MRI scans have been performed to date in humans. Loading of GdC followed the pattern seen in animals, but the time frame was different. In intravenous delivery of double-dose GdC, the inner ear compartments were visualized after 4 hours. The uptake pattern of GdC in the perilymph of humans between 2 hours and 7 hours after local delivery needs to be clarified. In almost all patients with probable or suspected Ménière's disease, EH was verified. Specific algorithms with a 12-pole coil using fluid attenuation inversion recovery sequences are recommended for initial imaging in humans.

MRI manifestation of novel superparamagnetic iron oxide nanoparticles in the rat inner ear

AIM

Superparamagnetic iron oxide nanoparticles hierarchically coated with oleic acid and Pluronic F127 copolymers (POA@SPION) have shown exceptional T2 contrast enhancement. The aim of the present work was to investigate the MRI manifestation of POA@SPION in the inner ear.

MATERIALS & METHODS

A total of 26 male Wister rats were selected for testing POA@SPION administered through intracochlear, intratympanic and intravenous routes. MRI was performed with a 4.7 T MR scanner.

RESULTS & CONCLUSION

POA@SPION can be introduced into the perilymph space, after which it becomes widely distributed and can demonstrate the integrity of the perilymph-endolymph barrier. Positive highlighting of the endolymph compartment against the darkened perilymph was visualized for the first time. POA@SPION passed through the middle-inner ear barriers in only small amounts, but stayed in the perilymph for 3 days. They did not traverse the blood-perilymph barrier or blood-endolymph barrier. The inner ear distribution of POA@SPION was confirmed by histology. POA@SPION is a promising T2 negative contrast agent.

Imaging analysis in cases with inflammation-induced sensorineural hearing loss

CONCLUSION

3D-FLAIR imaging is sensitive to inflammatory inner ear disturbances and may be a useful method in investigating the severity of inner ear disturbance in cases of inflammation-induced SNHL.

OBJECTIVE

To evaluate the usefulness of the three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) sequence in investigating different etiology of inner ear disturbances in cases with inflammation-induced acute sensorineural hearing loss (SNHL).

PATIENTS AND METHODS

Five cases with inflammation-induced acute SNHL by different conditions are included in this study: acute meningitis, acute otitis media, and Wegener granulomatosis. Imaging analysis was performed using a three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) sequence, and correlation between clinical symptoms and FLAIR abnormalities was evaluated.

RESULTS

In the affected ears in all cases, 3D-FLAIR revealed high pre-contrast signal and increased signal in the cochlea after the administration of gadolinium. Enhancement was still observed in the inner ear after several months with continuing nystagmus in those cases induced by meningitis and severe otitis media. In a case with Wegener granulomatosis, increased signal in the post-contrast images was stronger on the side of the cochlea with the worse hearing level.

Visualization of inner ear disorders with MRI in vivo: from animal models to human application

CONCLUSION

The inner ear membranous permeability and leakiness and endolymphatic hydrops can be visualized using gadolinium-enhanced MRI in both rodents and man. Intratympanic administration of contrast agent gives greater perilymphatic loading of gadolinium.

OBJECTIVES

Visualization of different types of inner ear dysfunction in MRI with intravenous or intratympanic administration of contrast agent.

MATERIALS AND METHODS

In the animal study, gadolinium was administered intravenously or intratympanically and imaged with 4.7 T MRI. In man, gadolinium was delivered intratympanically and studied with 1.5 T or 3 T MRI.

RESULTS

In the animals, intravenous delivery of gadolinium demonstrated uptake in the perilymph of normal inner ears. The cochlear modiolus appeared to be a critical site for the secretion of perilymph and the location of fluid communication between the perilymphatic scalae. Intense noise exposure and immune reaction caused cochlear injury and accelerated gadolinium passage through the blood-perilymph and blood-endolymph barriers. In man, perilymphatic uptake of gadolinium was only observed in the impaired inner ear when administered intravenously. However, the signal-to-noise ratio of images was improved when gadolinium was delivered intratympanically. MRI demonstrated endolymphatic hydrops in both animal models and patients with Meniere's disease.

Inner ear and facial nerve complications of acute otitis media, including vertigo

Acute otitis media is one of the most common diagnoses made in children in the United States. Intracranial and extracranial (intratemporal) complications have greatly decreased in the antibiotic era, but still remain a challenge when they arise. This article addresses two intratemporal complications with significant associated morbidity: facial nerve paralysis/paresis, and labyrinthitis. Epidemiology, pathology, clinical diagnosis, and treatment options are discussed, focusing on an evidence-based approach to diagnosis and management. In addition, the future of treatment and current questions regarding otitis media are briefly discussed.

Cochlear modiolus and lateral semicircular canal in sudden deafness

CONCLUSION

This study demonstrated that precise analysis shows that the inner ear shape in sudden deafness (SD) is different from that in controls in that the fluid-filled area of SD labyrinths is significantly larger than that of controls. Reduced cochlear modiolus area and inner area of the lateral semicircular canal (LSCC) may be associated with insufficient maturation of the inner ear.

OBJECTIVE

The aim of this study was to quantify the morphologies of the cochlea and LSCC using magnetic resonance imaging (MRI) and to evaluate their relationships with clinical symptoms in SD.

SUBJECTS AND METHODS

Twenty-six unilateral SD patients with vertigo, 26 unilateral SD patients without vertigo and a matched control group without hearing loss were studied. The areas of cochlear modioli and LSCCs were traced on the MRI console and compared between SD patients with or without vertigo and control subjects. The ratio of the LSCC fluid-filled area to the total LSCC area was used to index the degree of dysplasia.

RESULTS

The cochlear modiolus area was significantly less in SD ears (4.1+/-0.2 mm2) than in controls (4.3+/-0.4 mm2). The LSCC inner area was significantly less in SD ears (6.9+/-1.7 mm2) than in controls (9.1+/-1.8 mm2). These results suggest that the fluid-filled area of SD labyrinths is significantly larger than controls. Morphology did not differ between affected and contralateral sides or between ears with or without vertigo in SD patients.

Ressonância magnética em surdez súbita

A surdez súbita é um sintoma cuja etiologia nem sempre é elucidada mesmo dispondo-se de toda propedêutica atual. Neste estudo avaliaremos as alterações encontradas em ressonância magnética de pacientes portadores de surdez súbita. FORMA DE ESTUDO: coorte transversal. MATERIAL E MÉTODO: Estudo prospectivo com realização de RM em 49 dos 61 pacientes com surdez súbita atendidos no pronto socorro de Otorrinolaringologia do Hospital São Paulo, no período de abril de 2001 a maio de 2003. Doze pacientes abandonaram ou não foram submetidos à ressonância magnética por outros motivos. RESULTADOS: 23 (46,9%) pacientes apresentaram alterações à ressonância magnética. Foram encontrados dois tumores sugestivos de meningioma e três schwannomas do oitavo par craniano. Lesões subcorticais e periventriculares esparsas e hiperintensas em FLAIR foram encontradas em 13 pacientes. Cinco (21,7%) pacientes apresentaram alterações periféricas. CONCLUSÃO: A surdez súbita deve ser abordada como um sintoma comum a diferentes doenças. A presença de tumores do ângulo pontocerebelar em 10,2% dos nossos casos, entre outras causas tratáveis, justifica o uso da ressonância magnética com contraste tanto para o estudo do sistema auditivo periférico quanto para o estudo das vias auditivas centrais, incluindo o cérebro.

Magnetic resonance imaging in sudden deafness

The etiology of sudden deafness can remain undetermined despite extensive investigation. This study addresses the value of magnetic resonance imaging in the analysis of sudden deafness patients. Study design: transversal cohort. Material and Method: In a prospective study, 49 patients attended at otolaryngology emergency room of Federal University of Sao Paulo - Escola Paulista de Medicina, from April 2001 to May 2003, were submitted to magnetic resonance imaging. Results: Magnetic Resonance abnormalities were seen in 23 (46.9%) patients and revealed two tumors suggestive of meningioma, three vestibular schwannomas, thirteen microangiopathic changes of the brain and five (21.7%) pathological conditions of the labyrinth. Conclusion: Sudden deafness should be approached as a symptom common to different diseases. The presence of cerebellopontine angle tumors in 10.2% of our cases, among other treatable causes, justifies the recommendation of gadolinium-enhanced magnetic resonance use, not only to study the auditory peripheral pathway, but to study the whole auditory pathway including the brain.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

Magnetic Resonance Imaging Findings in the Auditory Pathway of Patients With Sudden Deafness

OBJECTIVES

The objectives of this study were to evaluate magnetic resonance imaging (MRI) findings of patients with sudden sensorineural hearing loss (SSNHL) and to grade the findings based on their clinical importance.

STUDY DESIGN

A prospective clinical study.

SETTING

A tertiary referral center (university hospital).

PATIENTS

MRI findings of 82 consecutive patients with SSNHL fulfilling the inclusion criteria.

MAIN OUTCOME MEASURES

We studied 1.0-T MR images that were analyzed by one experienced neuroradiologist.

RESULTS

Of the six cases (7%) in which clearly hearing loss was obviously associated with the observed pathology, four patients had an acoustic neuroma in the internal auditory canal or cerebellopontine angle, one patient had changes at the level of pons, and one patient had an obliterated internal carotid artery. Of the six other patients (7%) in which MRI revealed changes that suggest a possible etiology to hearing loss, two patients showed a demyelinating process and four patients showed blood vessel abnormalities such as caroticocavernous fistula, abnormally locating vertebral or basilar artery, and a venous angioma.

CONCLUSIONS

Enhanced MR imaging seems to be a useful examination in patients with SSNHL. The aim should not be only to exclude specific retrocochlear etiologies, but by appropriate techniques, MRI could reveal both peripheral and central abnormalities.

3D MRI of the in vivo vestibulo-cochlea labyrinth during Gd-DTPA-BMA uptake

The morphology, time-course and volume of the in vivo uptake of the T1 contrast agent gadolinium (Gd) in the perilymphatic vestibulo-cochlea labyrinth, including the utricle, saccule, semicircular canals and scalae of the guinea pig inner ear were analyzed as Fourier transform signal intensity enhancement levels by 3D MRI at 4.7 T. The uptake of Gd as a function of time in the perilymphatic space of the vestibular labyrinth was shown by ANOVA and PLSD post hoc tests to be significantly less (p < 0.05) than that of the scala tympani of the cochlea 10, 30, 60 and 90 min after i.v. injection. Experimentally induced fistulae resulted in MRI detected morphological and quantitative alterations in Gd concentration in the perilymphatic labyrinthine space. The findings demonstrate that Gd-enhanced 3D MRI of the perilymphatic space may be used to examine the morphology, kinetics and intravenous substance delivery in the in vivo mammalian vestibulo-cochlea labyrinth.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

The usefulness of MR imaging of the temporal bone in the evaluation of patients with facial and audiovestibular dysfunction

OBJECTIVE

To evaluate the clinical utility of MR imaging of the temporal bone in patients with facial and audiovestibular dysfunction with particular emphasis on the importance of contrast enhancement.

MATERIALS AND METHODS

We retrospectively reviewed the MR images of 179 patients [72 men, 107 women; average age, 44 (range, 1-77) years] who presented with peripheral facial palsy (n=15), audiometrically proven sensorineural hearing loss (n=104), vertigo (n=109), or tinnitus (n=92). Positive MR imaging findings possibly responsible for the patients' clinical manifestations were categorized according to the anatomic sites and presumed etiologies of the lesions. We also assessed the utility of contrast-enhanced MR imaging by analyzing its contribution to the demonstration of lesions which would otherwise not have been apparent. All MR images were interpreted by two neuroradiologists, who reached their conclusions by consensus.

RESULTS

MR images demonstrated positive findings, thought to account for the presenting symptoms, in 78 (44%) of 179 patients, including 15 (100%) of 15 with peripheral facial palsy, 43 (41%) of 104 with sensorineural hearing loss, 40 (37%) of 109 with vertigo, and 39 (42%) of 92 with tinnitus. Thirty (38%) of those 78 patients had lesions that could be confidently recognized only at contrast-enhanced MR imaging.

CONCLUSION

Even though its use led to positive findings in less than half of these patients, MR imaging of the temporal bone is a useful diagnostic procedure in the evaluation of those with facial and audiovestibular dysfunction. Because it was only at contrast-enhanced MR imaging that a significant number of patients showed positive imaging findings which explained their clinical manifestations, the use of contrast material is highly recommended.

Imaging evaluation of sensorineural hearing loss

The imaging evaluation of patients with sensorineural hearing loss (SNHL) focuses on the acoustic pathways from the cochlea to the auditory cortex. Magnetic resonance imaging (MRI) is the modality of choice for most patients with SNHL, though computed tomography (CT) also plays an important role in the evaluation of bony changes and in patients for whom MRI is contraindicated. Conventional enhanced MRI is the most commonly used technique in this clinical setting. High-resolution fast spin-echo T2 MRI is an adjunctive technique that provides exquisite evaluation of the cerebellopontine angle (CPA), internal auditory canal (IAC), cranial nerves, and membranous labyrinth, and plays a significant role in the diagnosis and surgical evaluation of SNHL. Categories of lesions that cause SNHL include brain lesions involving central auditory pathways; neoplasms of the CPA and IAC, the most common being schwannoma; other neoplastic, congenital, and cystic masses of the CPA and IAC; congenital anomalies of the inner ear; intrinsic cochlear nerve defects, inflammatory processes of the inner ear; and temporal bone trauma.

Magnetic resonance imaging results in patients with central electronystagmography findings

The objective of this study was to determine the findings on magnetic resonance imaging (MRI) in patients identified as having central vestibular abnormalities on electronystagmography (ENG) testing, to discuss the issue of 'gold standard' in the investigation of central oculo-vestibular system diseases and to present a model for understanding this area. A retrospective review of the case notes of patients (n = 23) found to have central ENG findings at vestibular assessment and for whom MRI scanning data was available was undertaken. Each patient underwent a full ENG evaluation, including gaze, ocular-motor and caloric testing, and MRI. Only seven of the patients with central ENG findings had abnormal MRI scans. Thus, the incidence of the identification of structural abnormality on MRI in patients with central ENG findings is low. These investigations are complementary in the investigation of balance disorder patients.

Magnetic resonance imaging for evaluation of otic labyrinth pathology

The auditory (cochlear) labyrinth, the cochlea, holds the hearing sensory receptors. The vestibular labyrinth contains the sensory receptors for balance, which lie in the three semicircular canals and in the otolithic organs (the saccule and utricle). Pure tone audiometry and brain stem evoked audiometry can help to differentiate a peripheral cochlear disorder from central lesion. The type of nystagmus, severity of postural instability, and neurological evaluation can help to differentiate a peripheral vestibular disorder from a central vestibular lesion. The decision whether to perform an appropriate imaging such as brain imaging versus labyrinthine imaging depends on the clinical and paraclinical information provided to the radiologist by the neurotologist, neurologist, or other clinicians. The magnetic resonance imaging characteristics of peripheral cochlear and vestibular lesions are the main focus of this article.

Magnetic resonance imaging of the internal auditory canal

Magnetic resonance imaging (MRI) is presently the study of choice for assessment of the internal auditory canal (IAC). MRI provides excellent assessment of the IAC and the bony changes occurring in the canal walls, and it provides excellent demonstration of the content of the canal. Pathological processes arising within the IAC are well visualized by various MR sequences. The possibility of demonstrating masses as small as 2 mm has propelled MRI into the leading role for diagnosis of vestibular schwannoma. Unfortunately, the high cost of MR has been a limiting factor in its use as a screening test for patients with sensorineural hearing loss (SNHL) of unknown origin. Auditory brain stem response has been widely used as a screening procedure, but this test fails to recognize small lesions and cannot be used whenever hearing loss is severe. In this article, we will discuss our approach to assessment of the IAC in patients with retrocochlear SNHL or vestibular symptoms of central origin, review the pathological processes involving the IAC walls or arising within the canal, emphasizing the appropriate MRI sequences used for diagnosis.

Cogan's syndrome: an oculo-audiovestibular disease

Typical Cogan's syndrome is a rare disease of young adults consisting of flares of interstitial keratitis and sudden onset of Ménière-like attacks (nausea, vomiting, tinnitus, vertigo and hearing loss). Life-threatening aortic insufficiency develops in 10% of reported cases. Atypical Cogan's syndrome (audiovestibular dysfunction with other types of inflammatory eye disease) is associated with vasculitis in 20% of cases and has a less favourable prognosis than typical Cogan's syndrome.

Magnetic resonance imaging assessment of labyrinthine pathology

Membranous labyrinth pathologies are quite rare. They were until recently difficult to demonstrate by imaging technics, CT being the modality of choice. Our purpose was to stress the interest of MR examination for investigating patients complaining of vertigo, tinnitus, and profound sensorineural hearing loss. Normal anatomy as well as the main pathologically encountered changes are illustrated.

Current concepts in the diagnosis and treatment of sudden sensorineural hearing loss

Sudden hearing loss (SHL) has been a controversial topic in the literature for the past several decades. Although much theoretical work has been done regarding its diagnosis and treatment, no useful practical guidelines exist for application to current patient management. Many authors have discussed the various treatment protocols available to treat this entity, but only a handful of dated, clinical studies supporting these treatments are available. More recent studies applying treatment protocols including vasodilators, plasma expanders, anti-coagulants, and carbogen inhalations have shown no improvement over the rate of spontaneous recovery without therapy. Except in cases of therapy directed toward known predisposing factors, there is insufficient evidence in the literature to support medical treatment for SHL, although steroid therapy appears to be useful in selected patients. Our own review of 14 patients with SHL is presented. A standard diagnostic and therapeutic approach based on a comprehensive review of the literature is described that can be applied to most patients presenting with SHL.

Ramsay Hunt syndrome mimicking acoustic neuroma on MRI

The authors present a case of Ramsay Hunt syndrome in whish the MRI appearance mimicked that of an intracanalicular acoustic neuroma.

Significance of auditory brain stem response and gadolinium-enhanced magnetic resonance imaging for idiopathic sudden sensorineural hearing loss

Previous studies tried to correlate prognosis and response to oral corticosteroids in patients with idiopathic sudden sensorineural hearing loss to such factors as the age of the patient, presence of vertigo, shape of the audiogram, or severity of the hearing loss. However, temporal bone histopathologic evidence shows that idiopathic sudden sensorineural hearing loss may be caused by cochleitis or cochlear nerve neuritis. Herein we report results of a retrospective study of 96 consecutive patients with idiopathic sudden sensorineural hearing loss who were evaluated with auditory brain stem responses and gadolinium-enhanced magnetic resonance imaging. Results of the auditory brain stem response and magnetic resonance imaging were correlated with hearing outcome. Follow-up was available for 65 patients: 14 with abnormal and 51 with normal auditory brain stem responses. The overall rate of hearing recovery or improvement was 65% in the normal auditory brain stem response group compared with 43% in the abnormal auditory brain stem response group (p = 0.07). Among the 38 patients treated with a tapering course of oral corticosteroids, the recovery or improvement rate was 83% for those with normal auditory brain stem responses and 56% for those with abnormal auditory brain stem responses (p < 0.05). Of the 27 patients who did not receive steroid therapy, the improvement rate was 41% in those with normal auditory brain stem responses and 20% in those with abnormal auditory brain stem responses (p = 0.09). Magnetic resonance imaging with gadolinium was obtained on all 14 patients with abnormal auditory brain stem responses but on none with normal auditory brain stem responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced MRI in patients with vestibular neuronitis

Recent advances in magnetic resonance imaging (MRI) have demonstrated facial nerve enhancement in facial nerve palsy and cochlea enhancement in sudden deafness. However, no report has described the findings of enhanced MRI in vestibular neuronitis. Eight cases of vestibular neuronitis were studied with enhanced MRI. We did not detect any enhanced lesions of the vestibular nerve or ganglion. So far, as the present conditions of MRI are concerned, it is difficult to detect any enhancement in the vestibular nerve and ganglion. Further study will be required to evaluate the suitability of MRI for vestibular neuronitis.

Value of Gd-DTPA-enhanced MR imaging of the labyrinth in patients with sudden hearing loss

Recent reports describe labyrinthine enhancement on MRI as a highly specific sign of labyrinthine disease. This paper reports 44 patients with unilateral sensorineural hearing loss (SNHL) and laboratory evidence of cochlear damage investigated with Gd-enhanced MR imaging. Enhancement of the cochlea was observed in only one patient with a lesion at the fundus of the internal auditory canal (IAC) that extended into the cochlea after Gd-DTPA administration. In one more patient, MR imaging demonstrated large vestibular aqueducts as underlying cause for his hearing loss, but no enhancement of the labyrinth was observed. No abnormal signal intensity on precontrast MR scans nor pathologic enhancement of the membranous labyrinth were identified in the other 42 patients. Gd-enhanced MR imaging appears to be insensitive in demonstrating labyrinthine disease and normal examination findings in a patient with sudden SNHL cannot exclude damage at the cochlear level.

Case report: prolonged contrast enhancement of the inner ear on magnetic resonance imaging in Ramsay Hunt syndrome

There have been recent reports of enhancement of the inner ear in acute labyrinthitis on gadolinium enhanced magnetic resonance imaging (MRI). However, none has described persistence of enhancement beyond 6 weeks. We report a case of Ramsay Hunt syndrome with labyrinthitis, sensorineural hearing loss and facial nerve palsy in which marked enhancement of the inner ear structures was observed on MRI 6 months after the onset of symptoms. Enhancement on delayed or repeated imaging after a period of months does not exclude labyrinthitis from the differential diagnosis of the small intracanalicular acoustic neuroma, and care should be taken not to confuse them.

Dizziness in childhood

There is a scant literature regarding vestibular evaluation of children with complaints of dizziness or vertigo. Considerable time and effort are expended on the problem and prevention of hearing loss in children, yet we often ignore concurrent or subsequent vestibular disorders. This neglect could be due to several factors, perhaps the most common being the fact that vertiginous crises in childhood are often attributed to problems of behavior or incoordination. In this article, we offer an approach to the dizzy child based on presenting symptoms. We discuss features of the history, examination, and laboratory evaluation key to determining the cause of dizziness. Finally, we discuss management, which varies according to the diagnosis.

Magnetic resonance examination of the inner ear and cerebellopontine angle in patients with vertigo and/or abnormal findings at vestibular testing

The inner ears of 167 patients with vertigo and/or abnormal findings at vestibular testing were studied using magnetic resonance (MR). Pathology potentially explaining vertigo was found in 54 patients, and was detected in the posterior fossa (28%), the internal auditory canal (28%) and the membranous labyrinth (44%). The overall percentage of pathology and the percentage of pathology found in the membranous labyrinth was high and was probably influenced by the referral pattern in our hospital where high resolution MR of the inner ear (three dimensional Fourier transformation-constructive interference in steady state sequence; 3DFT-CISS sequence) is available. Unenhanced, and especially gadolinium (Gd)-enhanced T1-weighted spin-echo images, are needed to detect most of the pathology inside the internal auditory canal, and some of the lesions inside the membranous labyrinth. 3DFT-CISS images are the only images that can show fibrous obliteration of the intralabyrinthine fluid spaces, and are therefore necessary to recognise most of the intralabyrinthine pathology. Finally, T2-weighted spin-echo images are best suited to demonstrate cerebellar or brain stem infarction. An additional MR-angiography sequence (three dimensional Fourier transformation-fast imaging with steady precession; 3DFT-FISP) is used when vascular compression of the cochleovestibular nerve is suspected. MR is the method of choice to look for pathology in patients with vertigo, and allows detection of pathology that remains invisible with other imaging techniques. However, well adapted sequences are needed to detect these lesions.

Magnetic resonance imaging in patients with sudden deafness

Although many theories on the etiology of sudden deafness have been proposed, the main pathological focus remains uncertain. In this study, MR examinations were performed on patients with unilateral sudden deafness to study the relationship between MRI findings and response to treatments, i.e. amidotrizoate, steroid, or both. In 7 out of 30 cases, the cochlea and/or the vestibule showed higher signal intensity on proton density and T2-weighted images on the diseased side (MRI positive cases). These findings suggest changes in the chemical composition of the perilymph and/or the endolymph, since proton density and T2-weighted images reflect water content. It appears that MRI positive sudden deafness is more difficult to cure even with the use of amidotrizoate or steroid than MRI negative sudden deafness. Amidotrizoate seems to be more effective in MRI negative sudden deafness. MRI would help us to further classify the etiology of sudden deafness.

Eosinophilic granuloma of the head and neck: CT and MRI features in three cases

We report the radiological findings and more specifically the MRI features in three typical cases of Langerhans' cell histiocytosis of the head and neck. All three cases were of solitary eosinophilic granuloma of bone: two mandibular and one temporal bone lesion. Reports on the MRI features of head and neck eosinophilic granulomas are rare.