Superior Versus Inferior Vestibular Neuritis: Are There Intrinsic Differences in Infection, Reactivation, or Production of Infectious Particles Between the Vestibular Ganglia?

Length of the Narrow Bony Channels May Not be the Sole Cause of Differential Involvement of the Nerves in Vestibular Neuritis

OBJECTIVE

To measure the vestibular nerve bony channels, applying a 3D measurement to account for the oblique trajectory of the singular nerve.

BACKGROUND

The clinical syndrome vestibular neuritis affects structures innervated by the superior vestibular nerve more commonly than the inferior vestibular nerve. Anatomical differences such as a longer, narrower bony channel of the superior vestibular nerve may increase its susceptibility to entrapment.

MAIN OUTCOME MEASURES

Length of the narrow segment of each vestibular nerve in which the nerve occupies more than 80% of the bony channel was measured.

RESULTS

Forty six normal ears sectioned in the axial plane were measured. The narrow channel for the lateral semicircular canal (SCC, mean [SD] 2.94 ± 0.54) mm was longer than that of the singular nerve innervating the posterior SCC (1.95 ± 0.58 mm [p < 0.0001]), which also exceeded that of the utricular nerve (1.45 ± 0.36 mm [p < 0.0001]). The nerve to the superior part of the saccule (i.e., Voit's nerve) was 1.14 ± 0.48 mm and that of the inferior saccule was 0.52 ± 0.37 mm.

CONCLUSIONS

The length of the narrow bony channel for the singular nerve is longer than previously reported and exceeds the utricular nerve. Comparing these data with the frequency of clinical lesions in recent literature suggests that, although bony channel length may contribute to differential involvement of the vestibular nerves, other factors may increase susceptibility of the superior vestibular nerve, including redundancy in innervation of the saccule and posterior SCC and anastomoses between the facial nerve and the superior vestibular nerve through which reactivated herpes virus may spread.

Clinical Characteristics of Patients With Dizziness/Vertigo Accompanied by Posterior Semicircular Canal Hypofunction

Objective: To investigate the clinical characteristics of patients with dizziness/vertigo accompanied by loss of the posterior canal(s) (LPC). Methods: Clinical data of 23 patients with LPC were collected. We determined video-head-impulse test (vHIT) gains of all six semicircular canals and correlated vHIT findings with other vestibulo-cochlear tests, including caloric test, ocular and cervical vestibular-evoked myogenic potentials (oVEMP, cVEMP), pure tone audiometry (PTA), and analyzed the differences in clinical manifestations of patients with LPC with different etiologies. Results: LPC was identified in 23 patients. At the time of disease onset, most patients presented with dizziness (47.8%) and vertigo (30.4%) only, and some patients (21.7%) complained of unsteadiness. Among these 23 patients with LPC, there were 14 (60.9%) patients of isolated LPC (ILPC), 21 (91.3%) patients of unilateral LPC (ULPC), and 2 (8.7%) patients of bilateral LPC (BLPC). (1) Among 14 patients with ILPC, 13 (92.9%) patients had unilateral ILPC, the rate of ipsilesional impairment on caloric test, or oVEMP/cVEMP test or PTA ipsilesionally was 53.8% (7/13) in patients with unilateral ILPC. The causes of unilateral ILPC were vertigo/dizziness of unclear origin (38.5%), labyrinthine infarction (15.4%), vestibular migraine (15.4%), and other diseases (30.8%); (2) among 21 patients with ULPC, 7 patients (33.3%) were accompanied with horizontal semicircular canal hypofunction ipsilesionally, the abnormal rate of caloric test, or oVEMP/cVEMP tests or PTA ipsilesionally was 57.1%. The causes of ULPC were vertigo/dizziness of unclear origin (33.3%), autoimmune inner ear disease (14.3%), labyrinthine infarction (14.3%), vestibular neuritis (9.5%), vestibular migraine (9.5%), and other diseases (19.0%); (3) among two patients with BLPC, one patient presented with unsteadiness, the causes of BLPC were vestibular paroxysmia and autoimmune inner ear disease. Conclusion: vHIT is a fast and effective method for assessing LPC, which can be used to detect isolated PC dysfunction. The causes of ILPC were peripheral origin or central origin. Patients with ILPC and ULPC mostly presented with dizziness/vertigo, and ULPC was often accompanied by ipsilateral vestibulo-cochlear impairment.

Vestibular Nerve Atrophy After Vestibular Neuritis - Results from a Prospective High-Resolution MRI Study

PURPOSE

 Sudden unilateral peripheral vestibular deficit is mostly termed vestibular neuritis (VN), even if its cause or the exact location of the lesion remains unclear. Thus, therapy is mostly symptomatic. We aimed to prove if there is peripheral atrophy after VN with persistent canal paresis.

METHODS

 After approval by the ethics committee and according to the declaration of Helsinki and with informed consent, ten patients with persistent canal paresis after VN and ten age-matched healthy controls were included. High-resolution measurement (in-plane resolution 0.2 mm) of the internal auditory canal (IAC) using a 3 D CISS sequence at 3 Tesla was performed. The course of the pertaining nerves was reconstructed in the 3 D dataset and the measurement was performed at 60 % of the length of the IAC. The cross-sectional areas of the superior (SVN) and inferior vestibular nerve (IVN) were taken independently by two blinded readers.

RESULTS

 The interrater difference regarding the area was 22 %. We found significant atrophy of the SVN with a 24 % smaller area (p = 0.026) and found a smaller ratio of SVN/IVN on the symptomatic side (p = 0.017). Concerning single subject data, only 5 patients showed extensive atrophy of the NVS, while 5 patients did not. The time since symptom onset did not significantly influence the atrophy.

CONCLUSION

 MRI measuring of the area of the NVS after VN could detect atrophy after VN. However, only 5 patients exhibited marked atrophy, while the other 5 patients did not. With the background of stringent inclusion criteria (more than 6 months of symptom duration and proven persistent canal paresis), one has to wonder if there might be different etiologies behind the apparently identical symptoms.

KEY POINTS

  · MRI measuring of the area of the NVS after VN could detect atrophy after VN. · Only half of the 10 researched patients showed atrophy, while the other patients did not. · There are different etiologies to be suspected for VN.

CITATION FORMAT

· Freund W, Weber F, Schneider D et al. Vestibular Nerve Atrophy After Vestibular Neuritis - Results from a Prospective High-Resolution MRI Study. Fortschr Röntgenstr 2020; 192: 854 - 861.

Peripheral Vestibulopathy Presenting as Acute Vertigo and Spontaneous Nystagmus with Negative Video Head Impulse Test

OBJECTIVE

To analyze acute vertigo showing spontaneous nystagmus with negative video head impulse test (vHIT).

STUDY DESIGN

Retrospective chart analysis.

SETTING

Tertiary referral hospital.

SUBJECTS AND METHODS

Over 16 months, 155 patients were identified with acute vertigo with spontaneous nystagmus. Of these 155, 30 (19.4%) were enrolled in this study because they did not show gain loss or catch-up saccades in both sides of the horizontal vHIT. Results of vestibular function tests (videonystagmography, horizontal vHIT, caloric test, and cervical vestibular-evoked myogenic potential [cVEMP]) and pure tone audiometry were analyzed. For all cases, magnetic resonance imaging with diffusion-weighted imaging was checked.

RESULTS

Patients consisted of 17 with Ménière's disease and 7 with sudden sensorineural hearing loss with vertigo (SSNHL_V), and only 3 patients were finally diagnosed as having acute vascular stroke. Except for the loss of hearing on the lesion side, the direction of nystagmus or cVEMP asymmetry showed very different results. All 7 patients with SSNHL_V did not have canal paresis in the caloric test, but cVEMP amplitude was smaller on the lesion side for 6 patients.

CONCLUSIONS

For patients with acute vertigo presenting spontaneous nystagmus with negative horizontal vHIT, it is important not only to focus on the diagnosis of acute vascular stroke but also to evaluate hearing because of the high possibility of Ménière's disease or SSNHL_V.

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.

A Case of Bilateral Atrophy of the Inferior Vestibular Nerves

: We report a case of a 62-year-old woman who was found to have bilateral atrophy of the inferior vestibular nerves on magnetic resonance imaging (MRI) after presenting to our clinic with 6 years of intermittent vertigo and residual unsteadiness. The nerve atrophy may be associated with an episode of vestibular neuritis, a common cause of vertigo that exclusively involves the inferior vestibular nerve in less than 3% of cases. While MRI may demonstrate vestibular nerve enhancement in cases of acute vestibular neuritis, no single MRI finding has been demonstrated consistently among cases of acute or chronic vestibular neuritis. Physical therapy is likely an effective long-term treatment for this patient to achieve central compensation for symptomatic relief.