Enhanced MRI in patients with vestibular neuronitis

Four-hour-delayed 3D-FLAIR MRIs in patients with acute unilateral peripheral vestibulopathy

OBJECTIVE

Conventionally, MRI aids in differentiating acute unilateral peripheral vestibulopathy/vestibular neuritis (AUPV/VN) from mimickers. Meanwhile, the diagnostic utility of MRIs dedicated to the inner ear remains to be elucidated for diagnosing AUPV/VN.

METHODS

We prospectively recruited 53 patients with AUPV/VN (mean age ± SD = 60 ± 15 years, 29 men). Initial MRIs were performed with a standard protocol, and an additional axial 3D-fluid-attenuated inversion recovery (3D-FLAIR) sequence was obtained 4 h after intravenous injection of gadoterate meglumine. Abnormal enhancement was defined as a signal intensity that exceeded the mean + 2SD value on the healthy side. The findings of neurotologic evaluation and MRIs were compared.

RESULTS

Overall, the inter-rater agreement for gadolinium enhancement was 0.886 (Cohen's kappa coefficient). Enhancement was observed in 26 patients (49%), most frequently in the vestibule (n = 20), followed by the anterior (n = 12), horizontal (HC, n = 8), posterior canal (n = 5), and superior (n = 3) and inferior (n = 1) vestibular nerves. In multivariable logistic regression analysis, the enhancement was associated with decreased HC gain in video head-impulse tests (p = 0.036), increased interaural difference in ocular vestibular-evoked myogenic potentials (p = 0.001), and a longer onset-to-MRI time span (p = 0.024). The sensitivity and specificity were 92.3% and 81.5%, respectively, with an area under the curve of 0.90 for predicting gadolinium enhancement.

INTERPRETATION

Robust gadolinium enhancement was observed on 4-hour-delayed 3D-FLAIR images in nearly half of the patients with AUPV/VN, with a good correlation with the results of neurotologic evaluation. The positivity may be determined by the extent of vestibular deficit, timing of imaging acquisition, and possibly by the underlying etiology causing AUPV/VN. MRIs may aid in delineating the involved structures in AUPV/VN.

Unilateral decrease in inner ear signal in fluid-attenuated inversion recovery sequences in previously suspected canine idiopathic vestibular syndrome

The aetiology of canine idiopathic vestibular syndrome (IVS) remains unclear. In human medicine, characteristic magnetic resonance imaging (MRI) techniques are used to demonstrate differences in endolymph composition between affected and unaffected inner ears. The purpose of this study was to determine whether similar MRI techniques could help to detect changes in the inner ears of canine IVS patients. Medical records from two veterinary referral clinics were reviewed retrospectively. Dogs were included if they had a diagnosis of IVS, obvious lateralisation of clinical signs, and an MRI of the vestibular system. A region of interest (ROI) was manually outlined by defining the anatomical area of the inner ear in T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. In order to calculate the ratio of FLAIR suppression of each ear, the mean grey value of the ROI was determined in both sequences. If a unilateral decrease in suppression was identified, it was compared with the direction of clinical signs. In total, 80 dogs were included in the study. There was a significantly lower degree of suppression on the affected compared to the unaffected side (0.8886 vs. 0.9348, respectively; P = 0.0021). In 92.5% of cases, there was agreement between the most suppressed side on MRI and the direction of clinical signs. This study provides preliminary evidence about the appearance of endolymph on MRI of dogs with IVS. Further studies are needed to investigate associations between the severity of MRI changes and prognosis.

Histology and neuroanatomy suggest a unified mechanism to explain the distribution of lesion patterns in acute vestibular neuropathy

Human temporal bone studies have described the distribution of afferent fibers from each of the five organelles in the labyrinth. Data from vestibular tests in patients with vestibular neuritis can be abnormal in almost any pattern. We propose a unified explanation for these patterns, based on histological and neuroanatomical factors.

Reduced Balance Restoration Capacities Following Unilateral Vestibular Insult in Elderly Mice

Acute vestibular syndrome (AVS) is characterized by severe posturo-locomotor and vestibulo-oculomotor impairment and accompanies several types of peripheral vestibulopathies (PVP). We know very little about its etiology, how its various symptoms are expressed and how it evolves with age. Robust repair capabilities of primary vestibular synapses have recently been shown to restore behavioral functionality. In this study, we used a mouse model of an excitotoxically induced unilateral vestibular lesion to compare the ability to restore balance and posture between old and young adult mice. We compared the temporal evolution of the evoked vestibular syndrome using a battery of behavioral tests to follow the evolution of postural-locomotor alterations and equilibrium. For the first time, we show that young adult (3 months) and elderly (22 months) mice are together able to restore normal postural-locomotor function following transient unilateral excitotoxic vestibular insult, though with different time courses. This animal study paves way for future, more detailed studies of how the early postural and locomotor disturbances following a unilateral insult are compensated for by various plasticity mechanisms, and in particular how age influences these mechanisms.

About the pathophysiology of acute unilateral vestibular deficit - vestibular neuritis (VN) or peripheral vestibulopathy (PVP)?

OBJECTIVE

To determine whether patients with acute unilateral peripheral vestibulopathy (PVP), often called "vestibular neuritis/neuronitis or neuropathy" (VN) have a vestibular lesion pattern consistent with the distribution of the neurological afferents.

BACKGROUND

Much is known about the clinical nature of PVP, however less so about its etiology and pathogenesis. Due to the frequency with which VN is used to describe the syndrome, an inflammation of the vestibular nerve or of one of its branches is often assumed to be the cause of PVP, though there is insufficient data so far to support this assumption.

METHODS

We conducted a retrospective study of 25 patients who had presented to our clinic with PVP and had all vestibular receptor organs tested shortly after start of symptoms. We analysed their vestibular lesion patterns in order to determine whether they were consistent with the neuritis hypothesis (NH).

RESULTS

The lesion patterns varied conspicuously. 76% did not follow an innervation pattern, thereby contradicting the NH and only 24% had a lesion pattern that either definitely (16%) or probably (8%) supported the NH.

CONCLUSION

These results should remind us to be careful before jumping to quick conclusions about the pathogenetic nature of PVP. With any reason to question VN as the only cause of PVP, we should reconsider the treatment approach to PVP. If the cause probably or even possibly lies inside the vestibular labyrinth, an intratympanic steroid injection might prove to be a more effective measure, even in first-line treatment. If the etiology is unsure, a combination of systemic and intratympanic steroid treatment may be adequate.

Clinical value of 4-hour delayed gadolinium-Enhanced 3D FLAIR MR Images in Acute Vestibular Neuritis

OBJECTIVE

To investigate the clinical significance of 4-hour delayed-enhanced 3.0 Tesla three-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging in acute vestibular neuritis.

STUDY DESIGN

A prospective observational study.

METHODS

Twenty-nine vestibular neuritis patients were enrolled between January 2017 and June 2017. Vestibular function tests, comprising the caloric and video head impulse tests and vestibular-evoked myogenic potential measurements, were performed. Precontrast, 10-minute, and 4-hour delayed-enhanced 3D-FLAIR MR images using double-dose IV gadolinium were obtained. After laterality and extent of inner ear enhancement were defined, the patients were divided into groups based on the patterns of enhancement, and clinical parameters were analyzed according to the groups.

RESULTS

Twenty patients (20 of 29, 69.0%) had obviously asymmetric enhancement of the affected inner ear structures on 4-hour delayed images, whereas only three patients (10.3%) had marked enhancement on 10-minute delayed images. The duration of spontaneous nystagmus (DurSN) was significantly longer in the patients with enhancement, especially with enhancement of the whole inner ear, including the vestibule and semicircular canals (P < 0.033). Spontaneous nystagmus resolved within 12 days in patients without laterality of enhancement, and within 16 days in ipsilesional enhancement confined to the inner auditory canal and fundus. Other results of vestibular function tests did not reveal any significant associations with MR enhancement.

CONCLUSIONS

Contrast enhancement of the vestibular nerve and inner ear structures can be identified on 4-hour delayed-enhanced 3T 3D-FLAIR MR images in acute vestibular neuritis. The extent of inner ear enhancement may be associated with the DurSN.

LEVEL OF EVIDENCE

4. Laryngoscope, 1946-1951, 2018.

Cross-Sectional Vestibular Nerve Analysis in Vestibular Neuritis

Objectives:

We examined the association between the size and cross-sectional area of the superior vestibular nerve as measured on constructive interference in steady-state (CISS) parasagittal magnetic resonance imaging (MRI) and the vestibular nerve function as measured by electronystagmography.

Methods:

The retrospective observational cohort study took place at an academic tertiary referral center. Twenty-six patients who met established clinical and electronystagmographic criteria for vestibular neuritis and who underwent parasagittal CISS MRI were identified. Two blinded investigators measured vestibular nerve height and width bilaterally at the level of the fundus of the internal auditory canal and calculated the cross-sectional nerve areas. The inter-rater reliability and agreement were analyzed. Symptom duration, age, and gender were also examined.

Results:

A statistically significant decrease was observed in both vestibular nerve cross-sectional area and height as compared to the contralateral vestibular nerve. A non–statistically significant trend was observed for a relative decreased cross-sectional nerve area with increased age, as well as a decrease in nerve area with an increase in symptom duration.

Conclusions:

Decreases in both vestibular nerve cross-sectional area and height are observed in patients with unilateral vestibular neuritis as measured on parasagittal CISS MRI.

The vestibulocochlear nerve

The eighth nerve provides sensory connection for balance and sound. Our ability to evaluate its morphology and pathology with magnetic resonance imaging (MRI) has been substantially improved over the past 20 years. This article reviews the relevant anatomy of the eighth nerve. A thorough discussion of the potential pathologic processes affecting its function also is included. Foremost, is a review of acoustic schwannomas, emphasizing the role of imaging in the work-up and ongoing evaluation of these patients. Discussion and examples of the plethora of neoplastic, inflammatory, infectious, congenital, ischemic, and compressive pathologies involving the nerve are included as well.

The value of enhanced magnetic resonance imaging in the evaluation of endocochlear disease

BACKGROUND

Gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear.

STUDY DESIGN

Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000.

RESULTS

Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification.

CONCLUSION

Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management.