When the Room Is Spinning: Experience of Vestibular Neuritis by a Neurotologist

Disrupted Rotational Perception During Simultaneous Stimulation of Rotation and Inertia

Two vestibular signals, rotational and inertial cues, converge for the perception of complex motion. However, how vestibular perception is built on neuronal behaviors and decision-making processes, especially during the simultaneous presentation of rotational and inertial cues, has yet to be elucidated in humans. In this study, we analyzed the perceptual responses of 20 participants after pairwise rotational experiments, comprised of four control and four test sessions. In both control and test sessions, participants underwent clockwise and counterclockwise rotations in head-down and head-up positions. The difference between the control and test sessions was the head re-orientation relative to gravity after rotations, thereby providing only rotational cues in the control sessions and both rotational and inertial cues in the test sessions. The accuracy of perceptual responses was calculated by comparing the direction of rotational and inertial cues acquired from participants with that predicted by the velocity-storage model. The results showed that the accuracy of rotational perception ranged from 80 to 95% in the four control sessions but significantly decreased to 35 to 75% in the four test sessions. The accuracy of inertial perception in the test sessions ranged from 50 to 70%. The accuracy of rotational perception improved with repetitive exposure to the simultaneous presentation of both rotational and inertial cues, while the accuracy of inertial perception remained steady. The results suggested a significant interaction between rotational and inertial perception and implied that vestibular perception acquired in patients with vestibular disorders are potentially inaccurate.

The "Vestibular Eye Sign"-"VES": a new radiological sign of vestibular neuronitis can help to determine the affected vestibule and support the diagnosis

INTRODUCTION

Nystagmus is a valuable clinical finding. Although nystagmus is often described by the direction of its quick phases, it is the slow phase that reflects the underlying disorder. The aim of our study was to describe a new radiological diagnostic sign called "Vestibular Eye Sign"-VES. This sign is defined as an eye deviation that correlates with the slow phase of nystagmus (vestibule pathological side), which is seen in acute vestibular neuronitis and can be assessed on a CT head scan.

MATERIALS AND METHODS

A total of 1250 patients were diagnosed with vertigo in the Emergency Department at Ziv Medical Center (ED) in Safed, Israel. The data of 315 patients who arrived at the ED between January 2010 and January 2022 were collected, with criteria eligible for the study. Patients were divided into 4 groups: Group A, "pure VN", Group B, "non-VN aetiology", Group C, BPPV patients, and Group D, patients who had a diagnosis of vertigo with unknown aetiology. All groups underwent head CT examination while in the ED.

RESULTS

In Group 1, pure vestibular neuritis was diagnosed in 70 (22.2%) patients. Regarding accuracy, VES (Vestibular Eye Sign) was found in 65 patients in group 1 and 8 patients in group 2 and had a sensitivity of 89%, specificity of 75% and a negative predictive value of 99.4% in group 1-pure vestibular neuronitis.

CONCLUSION

VN is still a clinical diagnosis, but if the patient undergoes head CT, we suggest using the "Vestibular Eye Sign" as a complementary sign. As per our findings, this is a valuable sign on CT imaging for diagnosing the pathological side of isolated pure VN. It is sensitive to support a diagnosis with a high negative predictive value.

Effect of a False Inertial Cue in the Velocity-Storage Circuit on Head Posture and Inertia Perception

The velocity-storage circuit participates in the vestibulopostural reflex, but its role in the postural reflex requires further elucidation. The velocity-storage circuit differentiates gravitoinertial information into gravitational and inertial cues using rotational cues. This implies that a false rotational cue can cause an erroneous estimation of gravity and inertial cues. We hypothesized the velocity-storage circuit is a common gateway for all vestibular reflex pathways and tested that hypothesis by measuring the postural and perceptual responses from a false inertial cue estimated in the velocity-storage circuit. Twenty healthy human participants (40.5 ± 8.2 years old, 6 men) underwent two different sessions of earth-vertical axis rotations at 120°/s for 60 s. During each session, the participants were rotated clockwise and then counterclockwise with two different starting head positions (head-down and head-up). During the first (control) session, the participants kept a steady head position at the end of rotation. During the second (test) session, the participants changed their head position at the end of rotation, from head-down to head-up or vice versa. The head position and inertial motion perception at the end of rotation were aligned with the inertia direction anticipated by the velocity-storage model. The participants showed a significant correlation between postural and perceptual responses. The velocity-storage circuit appears to be a shared neural integrator for the vestibulopostural reflex and vestibular perception. Because the postural responses depended on the inertial direction, the postural instability in vestibular disorders may be the consequence of the vestibulopostural reflex responding to centrally estimated false vestibular cues.SIGNIFICANCE STATEMENT The velocity-storage circuit appears to participate in the vestibulopostural reflex, which stabilizes the head and body position in space. However, it is still unclear whether the velocity-storage circuit for the postural reflex is in common with that involved in eye movement and perception. We evaluated the postural and perceptual responses to a false inertial cue estimated by the velocity-storage circuit. The postural and perceptual responses were consistent with the inertia direction predicted in the velocity-storage model and were correlated closely with each other. These results show that the velocity-storage circuit is a shared neural integrator for vestibular-driven responses and suggest that the vestibulopostural response to a false vestibular cue is the pathomechanism of postural instability clinically observed in vestibular disorders.

Spontaneous nystagmus with an upbeat component: Central or peripheral vestibular disorders?

Objective

To determine the topical diagnosis and etiologies of spontaneous nystagmus (SN) with an upbeat component.

Methods

We retrospectively recruited 43 patients with SN with an upbeat component at a university hospital in China from 2020 to 2022. SN with an upbeat component was divided into pure upbeat nystagmus (UBN), SN with a predominant upbeat component, and SN with a non-predominant upbeat component. We analyzed their clinical and neurotologic findings and the final diagnosis.

Results

Fourteen (32.6%) of them showed pure UBN, while 29 (67.4%) exhibited SN mixed with an upbeat component, mixed upbeat-horizontal in 15, mixed upbeat-horizontal-torsional in 13, and upbeat-torsional in the remaining one. Pure UBN and SN with a predominant upbeat component were more common in central than in peripheral vestibular disorders [16 (80.0%) vs. 0 (0%), Chi-Square test, p < 0.001]. Central vestibular disorders were diagnosed in 20 (46.5%) patients, peripheral in 14 (32.6%), and undetermined in nine (20.9%) patients. The underlying causes mainly included acute unilateral peripheral vestibulopathy (n = 11), posterior circulation infarction (n = 9), benign recurrent vertigo (n = 4), vestibular migraine (VM, n = 3), and VM of childhood (n = 2).

Conclusion

SN with an upbeat component can be seen in both central and peripheral vestibular disorders. Pure UBN was a characteristic sign of central vestibular dysfunction. Central vestibular disorders should be highly suspected when patients show pure UBN or SN with a predominant upbeat component.

The frequency and relationship with vestibular function test results of positional preference in acute vestibular neuritis

Objective

To assess the prevalence and relationship with vestibular function test results of positional preference in acute vestibular neuritis (VN).

Methods

We prospectively recruited 33 patients with VN during the acute phase. We assessed the severity of vertigo with a visual analog scale (VAS) and the degree of spontaneous nystagmus (SN) during sitting, the head rolling to the affected, and the healthy side. Patients performed other vestibular function tests, including ocular and cervical vestibular evoked myogenic potential (VEMP), on the same day or the next day of VNG testing.

Results

Twelve patients (12/33, 36%) with VN complained of more severe vertigo during lying on the affected side compared to the healthy side under visual fixation. Compared to patients without positional preference (without positional preference group), patients with positional preference (with positional preference group) showed a significantly higher VAS and maximal slow phase velocity (SPV) of SN at all positions except lying on the lesion side. However, there was no difference in the SPV gap between the two groups. 30% (10/33) of patients with VN complained of more severe vertigo while lying on the affected side compared to the healthy side without visual fixation. Maximal SPV of SN was not different between the two groups. There was no other significant difference in both canalith and otolith function test results between the two groups regardless of the visual fixation.

Conclusions

One-third of patients with acute VN had more severe vertigo while lying on the affected side than in the supine position. The positional preference was not directly related to the SN intensity or VEMP results. The positional preference might reflect the otolith damage in the setting of activation of the sustained otolith system, not the transient otolithic system.

New onset episodic vertigo as a presentation of vestibular neuritis

Objective

Vestibular neuritis (VN) is a common peripheral cause of acute vestibular syndrome, characterized by sustained vertigo and gait instability, persisting from 1 day to several weeks. With the widespread use of comprehensive vestibular function tests, patients with VN and non-sustained vertigo have drawn attention. In this study, we retrospectively analyzed the clinical presentation of patients with VN and episodic vertigo, aiming to expand the atypical clinical features of VN.

Methods

This retrospective study enrolled 58 patients with VN. Among them, 11 patients with more than 3 remissions per day, each lasting over 1 h were assigned to the episodic vertigo (EV) group, and 47 subjects without significant relief into the sustained vertigo (SV) group. Demographic information, clinical manifestations and data of supplementary examinations were collected and statistically analyzed. These patients were followed up 1 year after discharge to gather prognostic information.

Results

The incidence of spontaneous nystagmus (SN) and proportion of severe vertigo (Dizziness Handicap Inventory questionnaire score >60) in the SV group were significantly higher than those in the EV group. Spearman correlation showed that with a longer disease course, the velocity of overt saccade was smaller (p < 0.05, Rs = −0.263) in all patients with VN.

Conclusion

The non-sustained manifestations in VN overlap with a wider spectrum of other vestibular disorders and stroke-related vertigo, which add an additional layer of complexity to the differential diagnosis of new onset episodic vertigo. By retrospectively analyzing the clinical characteristics and vHIT parameters, our study has expounded on the atypical features and potential pathophysiological mechanism of episodic syndromes in VN. VOR gain and saccades measured by vHIT could be reliable indicators for vestibular rehabilitation process.

The pharmacological treatment of acute vestibular syndrome

Acute vestibular syndrome (AVS) represents a clinical picture that involves urgent management due to the important procession of symptoms accompanying the event, which can be positively or negatively influenced by therapeutic choices and intervention timing. This forces a differential diagnosis and therapeutic choices to be made in conditions that are not always favorable and often not in the specialist field. In this work, we will examine in detail the pharmacological therapeutic possibilities, correlating them to the differential and, as far as possible, to the etiological diagnosis. In particular, the pharmacological possibilities for the two main conditions we can face will be investigated, namely, vestibular neuritis and posterior circulation stroke.

Vestibular Rehabilitation Therapy and Corticosteroids for Vestibular Neuritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background and Objectives: Besides corticosteroids, clinicians found that vestibular rehabilitation therapy (VRT) has a potential effect on vestibular neuritis (VN) improvement. This study aimed to investigate the efficacy of both corticosteroid therapy (CT) compared to VRT, and each group compared to their combination (CT vs. (CT+VRT) and VRT vs. (CT + VRT). Materials and Methods: Systematic searches were performed in PubMed, CINAHL, and Scopus for randomized controlled trials (RCTs) reporting the administration of at least CT and VRT for VN. The outcome of interest was VN’s subjective and objective improvement parameters. Results: Four RCTs involving a total of 182 patients with VN were eligible for systematic review and meta-analysis. The weighted mean difference (WMD) of canal paresis (objective parameter) in the CT group is significantly lower than in the VRT group after a 1 month follow-up (8.31; 95% CI: 0.29, −16.32; p = 0.04; fixed effect). Meanwhile, the WMD of Dizziness Handicap Inventory (DHI) (subjective parameter) in the VRT group is significantly lower than in the CT group after a 1 month follow-up (−3.95; 95% CI: −7.69, −0.21; p = 0.04; fixed effect). Similarly, the WMD of DHI in the combination group (CT+VRT) is significantly lower than in the CT group after a 3 month follow-up (3.15; 95% CI: 1.50, 4.80; p = 0.0002; fixed effect). However, there is no significant difference in all outcomes after 12 months of follow-ups in all groups (CT vs. VRT, CT vs. combination, and VRT vs. combination). Conclusions: This study indicates that CT enhances the earlier canal paresis improvement, as the objective parameter, while VRT gives the earlier DHI score improvement, as the subjective parameter. However, their long-term efficacy does not appear to be different. VRT has to be offered as the primary option for patients with VN, and corticosteroids can be added to provide better recovery in the absence of its contraindication. However, whether to choose VRT, CT, or its combination should be tailored to the patient’s condition. Future studies are still needed to revisit this issue, due to the small number of trials in this field. (PROSPERO ID: CRD42021220615).

Video Head Impulse Test (vHIT): Value of Gain and Refixation Saccades in Unilateral Vestibular Neuritis

The aim of this study was to evaluate gain and refixation saccades (covert and overt) using a video head impulse test (vHIT) in the horizontal and vertical planes in patients after the onset of unilateral acute vestibular neuritis (AVN). Thirty-five patients were examined in the acute stage of AVN and at follow-up (range, 6–30 months); a control group of 32 healthy subjects also participated. At onset, the mean gain was significantly lower on the affected side in all of the semi-circular canal planes, mainly in the horizontal canal plane, and saccades (covert and overt) were more prevalent in the horizontal compared to the vertical canal planes. Multi-canal affection occurred more frequently (80% for gain, 71% for saccades) than isolated canal affection. At follow-up, which ranged from 6 to 30 months, the gain was recovered in all of the canals (anterior in 50%, horizontal in 42.8%, and posterior canal in 41.1% of cases), while covert and overt saccades were reduced in the horizontal and vertical planes. However, covert saccades were still recorded in a greater proportion (69%) than overt saccades (57%) in the horizontal plane and at a lower rate in the vertical planes. The compensatory mechanisms after AVN mainly involve the horizontal canal, as the refixation saccades—especially covert ones—were more frequently recorded in the horizontal than vertical canals.

Impaired Duration Perception in Patients With Unilateral Vestibulopathy During Whole-Body Rotation

This study aimed to evaluate vestibular perception in patients with unilateral vestibulopathy. We recruited 14 patients (9 women, mean age = 59.3 ± 14.3) with unilateral vestibulopathy during the subacute or chronic stage (disease duration = 6 days to 25 years). For the evaluation of position perception, the patients had to estimate the position after whole-body rotation in the yaw plane. The velocity/acceleration perception was evaluated by acquiring decisions of patients regarding which direction would be the faster rotation after a pair of ipsi- and contra-lesional rotations at various velocity/acceleration settings. The duration perception was assessed by collecting decisions of patients for longer rotation directions at each pair of ipsi- and contra-lesional rotations with various velocities and amplitudes. Patients with unilateral vestibulopathy showed position estimates and velocity/acceleration discriminations comparable to healthy controls. However, in duration discrimination, patients had a contralesional bias such that they had a longer perception period for the healthy side during the equal duration and same amplitude rotations. For the complex duration task, where a longer duration was assigned to a smaller rotation amplitude, the precision was significantly lower in the patient group than in the control group. These results indicate persistent impairments of duration perception in unilateral vestibulopathy and favor the intrinsic and distributed timing mechanism of the vestibular system. Complex perceptual tasks may be helpful to disclose hidden perceptual disturbances in unilateral vestibular hypofunction.

Update on current diagnosis and treatment of vestibular neuritis

Vertigo is the sensation of self-motion of the head or body when no self-motion is occurring or the sensation of distorted self-motion during an otherwise normal head movement. Representative peripheral vertigo disorders include benign paroxysmal positional vertigo, Ménière disease, and vestibular neuritis. Vestibular neuritis, also known as vestibular neuronitis, is the third most common peripheral vestibular disorder after benign paroxysmal positional vertigo and Ménière disease. The cause of vestibular neuritis remains unclear. However, a viral infection of the vestibular nerve or ischemia of the anterior vestibular artery is known to cause vestibular neuritis. In addition, recent studies on immune-mediated mechanisms as the cause of vestibular neuritis have been reported. The characteristic clinical features of vestibular neuritis are abrupt true-whirling vertigo lasting for more than 24 hours, and no presence of cochlear symptoms and other neurological symptoms and signs. To accurately diagnose vestibular neuritis, various diagnostic tests such as the head impulse test, bithermal caloric test, and vestibular-evoked myogenic potential test are conducted. Various treatments for vestibular neuritis have been reported, which are largely divided into symptomatic therapy, specific drug therapy, and vestibular rehabilitation therapy. Symptomatic therapies include generalized supportive care and administration of vestibular suppressants and antiemetics. Specific drug therapies include steroid therapy, antiviral therapy, and vasodilator therapy. Vestibular rehabilitation therapies include generalized vestibular and customized vestibular exercises.

Can Dyssynergia of Vestibulosympathetic and Baroreflexes Cause Vestibular Syncope? The Hypothesis Based on the Velocity-Storage Function

The mechanism of vestibular syncope, the syncope occurring during the vertigo attacks, remains uncertain. This study aims to clarify the mechanism of vestibular syncope by pursuing the function of vestibular system in cardiovascular autonomic control and by defining neuro-hemodynamic changes in vestibular syncope. By integrating the velocity-storage (VS) circuit in the brainstem and cerebellum, we propose that the vestibular syncope develops as a result of dyssynergia of the vestibulosympathetic and baroreflexes in which centrally estimated downward inertial acceleration during the vertigo attacks acts as a trigger. Recognition of the vestibular disorders as a possible cause of syncope would allow proper managements for prevention of further syncope and related complications in patients with vestibular disorders.

Nanoparticles for the Treatment of Inner Ear Infections

The inner ear is sensitive to various infections of viral, bacterial, or fungal origin, which, if left untreated, may lead to hearing loss or progress through the temporal bone and cause intracranial infectious complications. Due to its isolated location, the inner ear is difficult to treat, imposing an acute need for improving current therapeutic approaches. A solution for enhancing antimicrobial treatment performance is the use of nanoparticles. Different inorganic, lipidic, and polymeric-based such particles have been designed, tested, and proven successful in the controlled delivery of medication, improving drug internalization by the targeted cells while reducing the systemic side effects. This paper makes a general presentation of common inner ear infections and therapeutics administration routes, further focusing on newly developed nanoparticle-mediated treatments.