Optimized 3D-FLAIR sequences to shorten the delay between intravenous administration of gadolinium and MRI acquisition in patients with Menière's disease.

OBJECTIVES: The aim of this study was to shorten the 4-h delay between the intravenous administration of gadolinium and MRI acquisition for hydrops evaluation using an optimized 3D-FLAIR sequence in patients with Menière's disease. METHODS: This was a single-center prospective study including 29 patients (58 ears), recruited between November 2020 and February 2021. All patients underwent a 3-T MRI with an optimized 3D-FLAIR sequence without contrast then at 1 h, 2 h, and 4 h after intravenous administration of gadobutrol. The signal intensity ratio was quantitatively assessed with the region of interest method. We also evaluated the volume of endolymphatic structures (saccule, utricle) then the presence of endolymphatic hydrops and blood-labyrinthine barrier impairment at each acquisition time. RESULTS: For all ears, the signal intensity ratio was significantly non-inferior at 2 h compared to 4 h, with a mean geometric signal intensity ratio at 0.83 (95% CI: 0.76 to 0.90, one-sided p < .001 for non-inferiority at -30% margin). Mean volume equivalence of saccule and utricle between 2 and 4 h was proven at a ± 0.20 standardized deviation equivalence margin. Intra-rater agreements (Cohen's kappa) were all greater than 0.90 for all endolymphatic hydrops location and blood-labyrinthine-barrier impairment between the 2- and 4-h assessments. CONCLUSIONS: We demonstrated that using an optimized 3D-FLAIR sequence we could shorten the acquisition from 4 to 2 h with a high reliability for the diagnosis of endolymphatic hydrops and blood-labyrinthine-barrier impairment. CLINICAL TRIAL REGISTRATION: Clinical trial no: 38RC15.173 KEY POINTS: • Magnetic resonance imaging with delayed 3D-FLAIR sequences allows the diagnosis of endolymphatic hydrops in patients with definite Menière's disease. • An optimized 3D-FLAIR sequence with a long TR of 16000 ms and a constant flip angle allows for reducing the delay between intravenous injection of gadobutrol and MRI acquisition from 4 to 2 h to diagnose endolymphatic hydrops. • Reducing this delay between intravenous injection and MRI acquisition could have implications for clinical practice for both patients and imaging departments.

Recurrent vestibulopathy: are cVEMP, oVEMP and inner ear MRI useful to distinguish patients with Menière's disease and vestibular migraine?

PURPOSE: The aim of this study was to assess the rate of endolymphatic hydrops (EH) on MRI and the rate of otolithic dysfunction with cVEMP and oVEMP, in patients with recurrent vertigo such as Menière's disease (MD), vestibular migraine (VM) and vestibular Menière's disease (vMD). METHODS: In this retrospective study, we performed 3D-FLAIR sequences with delayed acquisition in 20 MD, 20 VM and 20 vMD patients. Each subject was then assessed for the presence of EH on MRI. All patients underwent pure-tone audiometry, cVEMP and oVEMP. RESULTS: In MD patients, EH was observed in 18 (90%) out of 20 patients while EH was observed in only 1 MV (5%) and 1 vMD (5%) patients. We found significant differences between groups for the presence of EH on MRI (p = 0.001). MD patients had significant higher PTA level (p < 0.001) and oVEMP impairment than MV and vMD (p = 0.08 and p = 0.06, respectively). However, no significant differences were observed for cVEMP impairment, either asymmetric ratio (p = 0.36) and 1000/500 ratio (p = 0.20). CONCLUSIONS: Concerning cVEMP, we observed no significant differences between VM, vMD and MD. However, we observed higher oVEMP impairment, PTA level and EH on MRI in MD patients. We believe that MRI could be used to differentiate MD from VM patients with cochlear symptoms. However, in cases of migraine associated with recurrent vertigo and without cochlear symptoms, we believe that MRI is not a useful tool to differentiate between VM and vMD.

Breaking a dogma: acute anti-inflammatory treatment alters both post-lesional functional recovery and endogenous adaptive plasticity mechanisms in a rodent model of acute peripheral vestibulopathy.

BACKGROUND: Due to their anti-inflammatory action, corticosteroids are the reference treatment for brain injuries and many inflammatory diseases. However, the benefits of acute corticotherapy are now being questioned, particularly in the case of acute peripheral vestibulopathies (APV), characterized by a vestibular syndrome composed of sustained spinning vertigo, spontaneous ocular nystagmus and oscillopsia, perceptual-cognitive, posturo-locomotor, and vegetative disorders. We assessed the effectiveness of acute corticotherapy, and the functional role of acute inflammation observed after sudden unilateral vestibular loss. METHODS: We used the rodent model of unilateral vestibular neurectomy, mimicking the syndrome observed in patients with APV. We treated the animals during the acute phase of the vestibular syndrome, either with placebo or methylprednisolone, an anti-inflammatory corticosteroid. At the cellular level, impacts of methylprednisolone on endogenous plasticity mechanisms were assessed through analysis of cell proliferation and survival, glial reactions, neuron's membrane excitability, and stress marker. At the behavioral level, vestibular and posturo-locomotor functions' recovery were assessed with appropriate qualitative and quantitative evaluations. RESULTS: We observed that acute treatment with methylprednisolone significantly decreases glial reactions, cell proliferation and survival. In addition, stress and excitability markers were significantly impacted by the treatment. Besides, vestibular syndrome's intensity was enhanced, and vestibular compensation delayed under acute methylprednisolone treatment. CONCLUSIONS: We show here, for the first time, that acute anti-inflammatory treatment alters the expression of the adaptive plasticity mechanisms in the deafferented vestibular nuclei and generates enhanced and prolonged vestibular and postural deficits. These results strongly suggest a beneficial role for acute endogenous neuroinflammation in vestibular compensation. They open the way to a change in dogma for the treatment and therapeutic management of vestibular patients.

MRI contribution for the detection of endolymphatic hydrops in patients with superior canal dehiscence syndrome.

PURPOSE: Patients with superior semicircular canal dehiscence syndrome, which can only be treated by surgery, present cochleo-vestibular symptoms related to a third-mobile window but also endolymphatic hydrops. Since cVEMP and oVEMP are disturbed by the presence of the dehiscence, the aim of the study is to assess the value of MRI for the diagnosis of endolymphatic hydrops in patients with superior semicircular canal dehiscence syndrome in comparison with cVEMP and oVEMP. METHODS: In this retrospective cohort study we enrolled 33 ears in 24 patients with superior semicircular dehiscence syndrome who underwent a 4-h delayed intravenous Gd-enhanced 3D-FLAIR MRI and pure tone audiometry, cVEMP and oVEMP. For each patient MRI images were evaluated by two radiologists who used a compartmental endolymphatic hydrops grading system in comparison with cVEMP and oVEMP. RESULTS: Endolymphatic hydrops was found on MRI in 9 out of 33 SCDS ears (27.3%). We found no significant correlation between the presence of endolymphatic hydrops on MRI and cVEMP and oVEMP (p = 0.36 and p = 0.7, respectively). However, there was a significant correlation between the presence of endolymphatic hydrops on MRI and the degree of sensorineural hearing loss, Air Conduction-Pure Tone Average level (p = 0.012) and Bone Conduction-Pure Tone Average level (p = 0.09), respectively. CONCLUSION: We demonstrated that EH might be observed in 27.3% of superior semicircular dehiscence syndrome ears. The role of inner ear MRI is important to detect endolymphatic hydrops, since cVEMP and oVEMP are disturbed by the presence of the dehiscence, because these patients could benefit from a medical treatment. LEVEL OF EVIDENCE: Level 3.

The vestibular aqueduct ossification on temporal bone CT: an old sign revisited to rule out the presence of endolymphatic hydrops in Menière's disease patients.

OBJECTIVES: Menière's disease (MD) is associated with endolymphatic hydrops (EH), which is an accumulation of excessive endolymphatic fluid in the inner ear. However, using temporal bone CT, lower visualization rates of the vestibular aqueduct (VA) in these patients have also been reported. METHODS: In this retrospective single-center imaging study, we have included 25 healthy subjects and 47 patients having a definite, probable, or possible clinical diagnosis of MD that underwent temporal bone CT and inner ear MRI performed 4 h after contrast media administration. Two radiologists independently ranked the morphology of the VA in healthy subjects and in MD patients, using a three-level score (completely visible, discontinuous, and not visible). Each subject was then graded, based on both the VA's appearance and on EH presence. RESULTS: In healthy subjects, the VA was normal (grade 0) in 22/25 (88%) ears and discontinuous (grade I) in 3 healthy ears (12%). In the symptomatic ears of MD patients, we found 17/56 ears (30.3%) with VA grade 0, 15/56 ears (26.8%) with grade I, and 24/56 ears (42.8%) with grade II (p < 0.001). In MD patients, EH was observed in 46/94 ears (48.9%). A VA of grade 0 would eliminate the presence of EH with a negative predictive value of 88.6%, while a VA grade II would predict the presence of saccular hydrops with a positive predictive value of 93.1%. CONCLUSION: The evaluation by temporal bone CT of the VA can predict the presence of EH on MRI with a high positive predictive value. KEY POINTS: • The evaluation by temporal bone CT of the vestibular aqueduct can predict the presence of EH on MRI. • A vestibular aqueduct of grade 0 would eliminate the presence of EH on MRI with a negative predictive value of 88.6%. • A vestibular aqueduct grade II would predict the presence of endolymphatic hydrops on MRI with a positive predictive value of 93.1%.

Endolymphatic Hydrops Secondary to Spontaneous Intracranial Hypotension.

BACKGROUND: Spontaneous intracranial hypotension may be associated with neuro-otological symptoms that might mimic Menière's disease. CASE PRESENTATION: We report the case of a 53-year-old male presenting bi-frontal headache with recurrent spells of vertigo, left fluctuating hearing loss, and tinnitus. Dedicated brain and inner ear Magnetic Resonance Imaging, including a post-contrast 4 hours delayed FLAIR sequence, revealed typical signs of spontaneous intracranial hypotension associated with endolymphatic hydrops involving the left saccule and cochlea. CONCLUSIONS: Audio vestibular manifestations mimicking Menière's disease in spontaneous intracranial hypotension could be explained by endolymphatic hydrops, which can be detected using dedicated magnetic resonance imaging sequences.

Isolated enhancement of the superior semi-circular canal on inner ear MRI: acute vestibular syndrome or superior semi-circular canal dehiscence?

PURPOSE: Recently, it has been reported that patients with acute vestibular syndrome (AVS) could present a marked enhancement of the semi-circular canals, involving mostly the superior semi-circular canals on delayed inner ear MRI. METHODS: We reported one patient having AVS and another one having superior semi-circular canal dehiscence syndrome (SCDS) who underwent delayed inner ear MRI performed 4 h after contrast media administration. RESULTS: On delayed inner ear MRI, a marked enhancement of the superior semi-circular canal was observed in both patients. Although the clinical presentation is clearly not the same, the co-existence between these two disorders is possible. For this reason, in patients with AVS, the presence of a marked enhancement of the superior semi-circular canal should rule out the presence of a co-existing SCDS on temporal bone CT, particularly if the patient reported cochlear symptoms such as pulsatile tinnitus and/or autophony. CONCLUSION: To our knowledge, this is the first report showing this finding on delayed inner ear MRI in a patient with SCDS. In AVS patients, this radiological anomaly could be particularly disturbing and should rule out the presence of a co-existing SCDS.

Electrophysiological and inner ear MRI findings in patients with bilateral vestibulopathy.

PURPOSE: Bilateral vestibulopathy (BV) is an uncommon disorder and the etiology remained idiopathic in most cases. Delayed 3D-FLAIR sequences have provided new insights into various inner ear diseases, allowing the evaluation of the endolymphatic space and the permeability of the blood-labyrinthine barrier (BLB). The aim of this study was to assess both the morphology of the endolymphatic space and the permeability of the BLB in patients with BV as evaluated by delayed 3D-FLAIR sequences. METHODS: In this retrospective study, we performed 3D-FLAIR sequences 4 h after administering contrast media to 42 patients with BV. Two radiologists independently evaluated the morphology of the endolymphatic space (either vestibular atelectasis or endolymphatic hydrops) and the permeability of the BLB. RESULTS: Morphologic anomalies of the endolymphatic space and vestibular blood-labyrinthine barrier impairment were observed in 59.6% of patients with BV. Bilateral vestibular atelectasis (VA) was found in 21 patients (50%), involving only the utricle and all three ampullas while the saccule was always observed with no sign of collapse: idiopathic BV (n = 19), aminoglycoside administration (n = 1) and few days following abdominal surgery (n = 1). One patient had bilateral vestibular malformation. BLB impairment was observed in five patients (11.9%): paraneoplastic (n = 1), lymphoma (n = 1), autoimmune (n = 1), and vestibular "neuritis" (n = 2). Seventeen patients (40.4%) had normal MRI with no endolymphatic space anomaly or BLB impairment. CONCLUSION: Patients with BV presented with morphologic anomalies of the endolymphatic space or BLB impairment in 59.6% of patients.

Detection of intralabyrinthine abnormalities using post-contrast delayed 3D-FLAIR MRI sequences in patients with acute vestibular syndrome.

PURPOSE: 3D-FLAIR sequences with delayed acquisition after contrast medium injection have demonstrated new insights into blood-labyrinthine barrier (BLB) abnormalities in various diseases. The aim of this study was to assess the BLB in patients referred with unilateral acute vestibular syndrome (UAVS). MATERIALS AND METHODS: In this retrospective multicenter imaging study, we performed 3D-FLAIR and steady-state free precession (SSFP) sequences 4 h after contrast medium administration in 26 healthy volunteers and in 30 patients with UAVS. Two radiologists, blinded to the clinical data, independently assessed the asymmetrical enhancement of the labyrinthine structures and the vestibular nerve on 3D-FLAIR sequences, and the signal of the labyrinthine structures on SSFP sequences. Inter-reader agreement tests were performed. RESULTS: An asymmetrical enhancement of the semicircular canals was observed in 26 out of 30 ears (86.6%, p < 0.001) and never observed in healthy subjects. An asymmetrical enhancement of the vestibular nerve was never observed in either patients or healthy subjects. An asymmetrical enhancement of the cochlea was observed on the 3D-FLAIR sequence in 6 out of 30 ears only in the patients' group (20%, p = 0.03) and always associated with an enhancement of at least one semicircular canal. A low signal on SSFP sequences was observed only in 11 out of 30 symptomatic ears (36.7%, p < 0.001), involving the utricle in 7 ears and the superior semicircular canal in 4 ears. CONCLUSION: Patients with typical UAVS presented with semicircular canal enhancement on MRI, while an asymmetrical enhancement of the vestibular nerve was not displayed. TRIAL REGISTRATION: NCT02529475 KEY POINTS: • Patients with typical vestibular neuronitis presented with semicircular canal enhancement on MRI in 87% of cases. • An enhancement of the vestibular nerve was never displayed.

Author's reply to "Letter to the editor on the article: Saccular measurements in routine MRI can predict hydrops in Menière's disease by Simon F et al."

This is an answer to the Letter to the Editor regarding our previously published article « Saccular measurements in routine MRI can predict hydrops in Menière's disease ¼. We thank the authors for their interest in our article and their insightful comments. We would like to emphasise that our article was a preliminary study and to our knowledge the first published series establishing a correlation between measurements of saccular morphology in T2-weighed 3D CISS images and clinical definite Menière's disease. Therefore, we agree with the authors of the Letter that verifying reproducibility is paramount for the technique to be widely used. Further studies should be conducted to investigate the risk of artefacts reducing the reliability of saccular width measurements and to confirm the clinical implications. We recommend the use of saccular height measurements which have higher reliability. Also, the goal of the study was to present a possible radiological alternative to the more established methods of endolymphatic hydrops visualisation. If accessible, we agree that the latter techniques should be preferred, but we find that they are unfortunately too often unavailable in routine clinical practice to ENT physicians.

Saccular measurements in routine MRI can predict hydrops in Menière's disease.

Most patients with suspicion of hydrops do not have access to MRI with 3D reconstruction of the endolymphatic space. Our main objective was to show that measurements of the saccule on a non-enhanced 3D-T2 MRI could show hydrops and help diagnose Menière disease. We conducted a prospective study from 2015 to 2016 to compare consecutive patients consulting for Menière's disease to a control group (patients with unilateral non-hydrops disorders and contralateral healthy ears). They all received full auditory and vestibular testing. They also underwent a 3-Tesla 3D-T2 MRI using CISS sequence (0.4 mm thick slices), which were blindly evaluated by two independent neuroradiologists. The saccular height and width were measured in a coronal plane and Menière's disease patients' symptomatic ears were compared to asymptomatic and control ears. 36 patients with definite Menière's disease and 36 control patients were studied, including 42 symptomatic Menière, 30 asymptomatic Menière and 72 control ears. Saccular measurements were significantly different between symptomatic Menière ears compared to healthy ears (1.59 vs 1.32 mm, p < 0.001 for height; 1.13 vs 0.90 mm, p < 0.001 for width). Symptomatic and asymptomatic Menière ears' measurements were not significantly different (p = 0.307 and p = 0.109). Using ROC curve, we found cut-off values for saccular height 1.51 mm, Se = 63%, Sp = 95% and width 1.05 mm, Se = 41%, Sp = 95%. Routine 3D-T2 MRI, which patients must undergo for differential diagnosis, could help diagnose hydrops with high specificity using saccular measurements.

An Endoscopic Procedure for the Simultaneous Treatment of both Otosclerosis and Malleus Fixation.

To report the case of the simultaneous treatment of otosclerosis and malleus fixation through an entirely endoscopic transcanal approach. A targeted transcanalar epitympanotomy with annular bony ridge conservation was planned preoperatively, with 3D CT localization of the fixed part of the malleus head. The upper part of the malleus head and the superior ossified ligament of the malleus were drilled. A 0.6 mm stapedotomy was performed and a piston inserted. The patient's recovery was uneventful, with closure of the air-bone gap on her postoperative audiogram, associated with an overclosure in 500Hz, 1kHz, 2 kHz and 4 kHz. Laryngoscope, 134:2411-2414, 2024.

The Prognostic Value of Olfactory Dysfunction in Patients with COVID-19: The COVIDORA Study.

BACKGROUND: Among all studies describing COVID-19 clinical features during the first wave of the pandemic, only a few retrospective studies have assessed the correlation between olfac-tory dysfunction (OD) and the evolution of disease severity. The main aim was to assess whether OD is a predictive factor of COVID-19 severity based on the patient's medical management (outpa-tient care, standard hospital admission, and ICU admission). METHODS: A national, prospective, mul-ticenter cohort study was conducted in 20 public hospitals and a public center for COVID-19 screen-ing. During the first wave of the pandemic, from 6 April to 11 May 2020, all patients tested positive for COVID-19 confirmed by RT-PCR underwent two follow-up ENT consultations within 10 days of symptom onset. The main outcome measures were the evolution of medical management (out-patient care, standard hospital admission, and ICU admission) at diagnosis and along the clinical course of COVID-19 disease. RESULTS: Among 481 patients included, the prevalence of OD was 60.7%, and it affected mostly female patients (74.3%) under 65 years old (92.5%), with fewer comor-bidities than patients with normal olfactory function. Here, 99.3% (290/292) of patients with OD presented with non-severe COVID-19 disease. Patients reporting OD were significantly less hospi-talized than the ones managed as outpatients, in either a standard medical unit or an ICU. Conclu-sions: As regards the clinical course of COVID-19 disease, OD could predict a decreased risk of hospitalization during the first wave of the pandemic.

Otosclerosis: audiometric results and quality of life after stapedectomy with interposition or CO2 laser-calibrated stapedotomy without interposition.

BACKGROUND: The surgical treatment of otosclerosis consists of the replacement of the stapes using a piston. AIMS/OBJECTIVES: The objective of this study is to assess the audiometric results and quality of life (QOL) of patients who underwent surgery for otosclerosis by stapedectomy with fascia interposition (STIP) or by stapedotomy using CO2 laser (SLaser) without fascia interposition. MATERIAL AND METHODS: Ninety-one patients operated on for otosclerosis by STIP (40 patients) and by SLaser (51 patients) were included. Audiometric results were graphically displayed using the Amsterdam Hearing Evaluation Plot and were compared to the Common Otology Database (COD) comprising 660 patients. The patients' QOL was assessed with an otological validated survey. The significance level was p < .05. RESULTS: There was no significant difference in hearing improvement between SLaser and STIP-operated patients. There was no significant difference between our results and that of COD. QOL was significantly improved (+3.5/10) postoperatively for both STIP and SLaser in both social and professional fields. CONCLUSIONS AND SIGNIFICANCE: By comparing QOL and hearing gain of STIP and SLaser, our results suggest that both surgical techniques are a safe and successful treatment for otosclerotic stapes fixation. Further studies aiming at comparing larger series may confirm and refine these results.

Local budesonide therapy in the management of persistent hyposmia in suspected non-severe COVID-19 patients: Results of a randomized controlled trial.

OBJECTIVES: Consequences of COVID-19 on olfactory functions remained unclear during the pandemic. We assessed the efficacy of local budesonide in addition to olfactory rehabilitation when managing non-severe COVID-19 patients with persistent hyposmia. METHODS: A multicentric, randomized, superiority trial was conducted (ClinicalTrials.gov NCT04361474). The experimental group (EG) received budesonide and physiological saline nasal irrigations administered via three syringes of 20 ml in each nasal cavity in the morning and evening for 30 days. The control group (CG) received a similar protocol without budesonide. Patients were included if they were >18 years old, with a SARS-CoV-2 infection and presenting an isolated hyposmia persisting 30 days after symptom onset. The primary endpoint was the percentage of patients with improvement of more than two points on the ODORATEST score after 30 days of treatment. RESULTS: In total, 123 patients were included and randomized (EG: 62 vs CG: 61). Two patients from the EG met the primary endpoint with no statistical difference between the two groups (P = 0.5). CONCLUSION: To our knowledge, this is the first study evaluating local budesonide for COVID-19 related hyposmia treatment even though previous trials were performed with other local corticosteroids. Local budesonide efficacy was not demonstrated for persistent hyposmia related to COVID-19.

Infliximab for the Treatment of Inflammatory Labyrinthitis: A Retrospective Cohort Study.

Inflammatory labyrinthitis is defined as a fluctuant vestibulo-cochlear syndrome associated with an impairment of the blood-labyrinthine barrier (BLB) on delayed FLAIR MRI sequences. Systemic and intratympanic corticosteroids are the gold standard treatment but their effect is frequently insufficient. The objective is here to determine whether infliximab could be of value in the treatment of bilateral inflammatory labyrinthitis. A retrospective monocentric study was conducted between January 2013 and December 2021. All patients included in the study were affected with a bilateral vestibulo-cochlear syndrome associated with bilateral blood-labyrinthine barrier impairment. Patients were administered infliximab at the dose of 5 mg/kg every 6 weeks for 6 months. Audiometry, MRI with delayed FLAIR sequences on the labyrinth, and corticosteroid doses still required were assessed both before and after treatment with infliximab was completed. Pure-tone average (PTA) was the primary outcome. The secondary outcomes were the speech recognition threshold (SRT), the Dizziness Handicap Inventory (DHI) score, and the corticosteroid (CS) dose. A total of nine patients including five men and four women were enrolled in the study. Thirteen ears were analyzed. After a 6-month period of treatment, the mean PTA (54 ± 24 db versus 66 ± 22 db; p = 0.027), SRT (54 ± 37 db versus 66 ± 32 db; p = 0.041) and DHI score (27 ± 15 versus 9 ± 2; p = 0.032) significantly improved. After the 6-month treatment period, the mean CS dose decreased from 38 ± 33 to 6 ± 5 mg/day (p = 0.003). We conclude that infliximab substantially improves the vestibulo-cochlear function in patients with bilateral inflammatory labyrinthitis and could be of value in corticosteroid-dependent cases.

Cognitive and balance functions of astronauts after spaceflight are comparable to those of individuals with bilateral vestibulopathy.

Introduction: This study compares the balance control and cognitive responses of subjects with bilateral vestibulopathy (BVP) to those of astronauts immediately after they return from long-duration spaceflight on board the International Space Station. Methods: Twenty-eight astronauts and thirty subjects with BVP performed five tests using the same procedures: sit-to-stand, walk-and-turn, tandem walk, duration judgment, and reaction time. Results: Compared to the astronauts' preflight responses, the BVP subjects' responses were impaired in all five tests. However, the BVP subjects' performance during the walk-and-turn and the tandem walk tests were comparable to the astronauts' performance on the day they returned from space. Moreover, the BVP subjects' time perception and reaction time were comparable to those of the astronauts during spaceflight. The BVP subjects performed the sit-to-stand test at a level that fell between the astronauts' performance on the day of landing and 1 day later. Discussion: These results indicate that the alterations in dynamic balance control, time perception, and reaction time that astronauts experience after spaceflight are likely driven by central vestibular adaptations. Vestibular and somatosensory training in orbit and vestibular rehabilitation after spaceflight could be effective countermeasures for mitigating these post-flight performance decrements.

Increased signal intensity with delayed post contrast 3D-FLAIR MRI sequence using constant flip angle and long repetition time for inner ear evaluation.

PURPOSE: The purpose of this study was to compare the degree of perilymphatic enhancement between 4 hour post-contrast constant flip angle three-dimensional fluid attenuated inversion recovery (3D-FLAIR) images obtained with short repetition time (TR) and those obtained with long TR. MATERIALS AND METHODS: This single-center, prospective study included patients who underwent MRI of the inner ear with heavily T2-weighted sequence, 3D-FLAIR sequence with a "short" TR of 10,000 ms (s3D-FLAIR) and with a "long" TR of 16,000 ms (l3D-FLAIR). Signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) obtained with s3D-FLAIR and l3D-FLAIR were quantitatively assessed using region of interest (ROI) method and compared. The morphology of the endolymphatic space on both sequences was also evaluated. RESULTS: From March 2020 to July 2020, 20 consecutive patients were enrolled (9 women and 11 men; mean age, 52.1 ± 14.5 [SD] years; age range: 29-75 years). On l3D-FLAIR images, mean SIR (21.1 ± 8.8 [SD]; range: 7.6-46.1) was significantly greater than that on s3D-FLAIR images (15.7 ± 6.7 [SD]; range: 5.9-33.4) (P < 0.01). On l3D-FLAIR images, mean CNR (17 ± 8.5 [SD]; range: 2-40) was significantly greater than that on s3D-FLAIR images (12 ± 6.3 [SD]; range: 3.2-29.8) (P < 0.01). Kappa value for inter-rater agreement for endolymphatic hydrops, vestibular atelectasis and perilymphatic fistula were 0.93 (95% CI: 0.74-1), 1 (95% CI: 0.85-1) and 1 (95% CI: 0.85-1) respectively. CONCLUSION: This study demonstrates that the sensitivity of 3D-FLAIR sequences to low concentration gadolinium in the perilymphatic space is improved by elongation of the TR, with SIR and CNR increased by +34.4% and +41.3% respectively.

MRI characteristics of intralabyrinthine schwannoma on post-contrast 4 h-delayed 3D-FLAIR imaging.

PURPOSE: The purpose of this study was to describe the MRI characteristics of intralabyrinthine schwannoma (ILS) on post contrast three-dimensional (3D) fluid-attenuation-inversion-recovery (FLAIR) images obtained four hours after intravenous administration of a gadolinium-based contrast agent (4h-3D-FLAIR). MATERIALS AND METHODS: This IRB-approved retrospective multi-center study included patients presenting with typical ILS from January 2016 to October 2020. All medical charts were systematically collected. All MRI examinations, including 4h-3D-FLAIR images, were reviewed by two board-certified neuroradiologists. Main outcome measures were location, signal intensity and associated anomalies of ILS. RESULTS: Twenty-seven out of 8730 patients (0.31%) referred for the investigation of a cochleovestibular disorder had a final diagnosis of ILS. There were 13 men and 14 women with a mean age of 52 ± 17 (SD) years (age range: 20-86 years). The most common clinical presentation was unilateral progressive sensorineural hearing loss (16/27; 59%). All ILS were unilateral and 15 (15/27; 55%) were intracochlear. All ILS presented as a hypointense filling defect within the labyrinth on T2-weighted images that enhanced on post-contrast T1-weighted images. On 4h-3D-FLAIR images, all ILS presented as a hypointense filling defect, associated with diffuse perilymphatic hyperintensity. Two patients (2/27; 7%) presented with ipsilateral endolymphatic hydrops. CONCLUSION: ILS displays consistent features on post-contrast 4h-3D-FLAIR images. ILS should not be confused with endolymphatic hydrops and requires a systematic analysis of the corresponding T2-weighted images.

Navigation strategies in patients with vestibular loss tested in a virtual reality T-maze.

During navigation, humans mainly rely on egocentric and allocentric spatial strategies, two different frames of reference working together to build a coherent representation of the environment. Spatial memory deficits during navigation have been repeatedly reported in patients with vestibular disorders. However, little is known about how vestibular disorders can change the use of spatial navigation strategies. Here, we used a new reverse T-maze paradigm in virtual reality to explore whether vestibular loss specifically modifies the use of egocentric or allocentric spatial strategies in patients with unilateral (n = 23) and bilateral (n = 23) vestibular loss compared to healthy volunteers (n = 23) matched for age, sex and education level. Results showed that the odds of selecting and using a specific strategy in the T-maze were significantly reduced in both unilateral and bilateral vestibular loss. An exploratory analysis suggests that only right vestibular loss decreased the odds of adopting a spatial strategy, indicating an asymmetry of vestibular functions. When considering patients who used strategies to navigate, we observed that a bilateral vestibular loss reduced the odds to use an allocentric strategy, whereas a unilateral vestibular loss decreased the odds to use an egocentric strategy. Age was significantly associated with an overall lower chance to adopt a navigation strategy and, more specifically, with a decrease in the odds of using an allocentric strategy. We did not observe any sex difference in the ability to select and use a specific navigation strategy. Findings are discussed in light of previous studies on visuo-spatial abilities and studies of vestibulo-hippocampal interactions in peripheral vestibular disorders. We discuss the potential impact of the history of the disease (chronic stage in patients with a bilateral vestibulopathy vs. subacute stage in patients with a unilateral vestibular loss), of hearing impairment and non-specific attentional deficits in patients with vestibular disorders.