Evidence for a viral neuropathy in recurrent vertigo

Video Head Impulse Test Findings in Patients With Benign Paroxysmal Positional Vertigo Secondary to Idiopathic Sudden Sensorineural Hearing Loss

Benign paroxysmal positional vertigo (BPPV) is amongst the most common causes of episodic vestibular syndrome. It can be classified as idiopathic and secondary types according to the causative factors, and the underlying mechanism between idiopathic (i-BPPV) and secondary BPPV (s-BPPV) may differ. Idiopathic sudden sensorineural hearing loss (ISSNHL) has been considered as a common inner ear disease that precipitates s-BPPV. Yet, few studies have addressed the functional impairment of the semicircular canal (SCC) system in patients with s-BPPV associated with ISSNHL. Our purpose was to explore the pathophysiological mechanism and investigate the clinical implications of video head impulse test (vHIT) in these patients. Here, the clinical and laboratory data of patients with BPPV secondary to ISSNHL, including the results of vHIT, were retrospectively reviewed, and compared with those of patients with i-BPPV. Pathological vHIT findings (low vestibulo-ocular reflex gain and re-fixation saccade), which mainly affected the posterior SCC, were more common in the s-BPPV group than in the i-BPPV group (41.9 and 0%, respectively). The incidence of horizontal SCC involvement was also higher in the s-BPPV group (45.16 and 16.67%, respectively). Furthermore, patients with s-BPPV showed lower vHIT gains of the posterior and horizontal SCCs in affected ears than in unaffected ears. Compared to i-BPPV, posterior SCC paresis detected by vHIT is more prevalent in BPPV secondary to ISSNHL. This dysfunction may be associated mainly with vestibular impairments caused by ISSNHL, and not with BPPV per se.

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.

Post-COVID-19 Benign Paroxysmal Positional Vertigo

Background

COVID-19 is a disease caused by a new strain of coronavirus (SARS-COVID-19). The WHO first learned about this new virus on December 31, 2019, following a report on a group of cases of “viral pneumonia” in Wuhan, People's Republic of China, and declared a pandemic in March 2020. The disease was an almost complete unknown at the outset, but knowledge of its pathophysiology, clinical picture, and treatment options grew and developed rapidly.

Objective

Dizziness is a very common symptom that patients report in routine clinical practice and one of the significant clinical manifestations of COVID-19. This short report investigated a possible connection between COVID-19 and benign paroxysmal positional vertigo (BPPV).

Methods

We present two cases of benign paroxysmal positional vertigo (BPPV), which developed within two weeks of SARS-COVID-19 infection, manifesting with mild disease severity in early November 2020.

Results

In both cases, the disease manifested by severe, short-lived attacks of vertigo, objective-circular type, with accompanying nausea and vomiting. The symptoms occurred when lying in bed and turning to the right and assuming an upright position. The diagnosis of posterior semicircular canal BPPV (PC-BPPV) was made based on a subjectively and objectively positive right-sided Dix–Hallpike test.

Conclusions

The pathophysiology of post-COVID BPPV is probably similar to that of other viral infections, with some of its specificities such as inducing hypercoagulation and microthrombus formation, which can cause significant circulatory disorders possibly affecting its pathogenesis.

Seasonality and Cardio-Cerebrovascular Risk Factors for Benign Paroxysmal Positional Vertigo

Background: Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo, especially in the elderly. Several studies have revealed a possible seasonality to BPPV. However, whether the seasonality of BPPV also exists in China is unclear. The characteristics of cardio-cerebrovascular risk factors for BPPV in the cold season have not yet been investigated. Objectives: (1) To investigate the seasonality of BPPV; (2) To explore the relationship between cardio-cerebrovascular risk factors and seasonality of BPPV. Methods: A retrospective observational study was performed in Beijing Tiantan Hospital from Jan 2016 to Dec 2018. The study included 1,409 new-onset BPPV patients aged 18-88 years. The demographic data, onset time, and medical history of BPPV were collected. The meteorological data, including temperature, atmospheric pressure, rainfall, and insolation, was obtained from Beijing Meteorological service. The x ² goodness of fit test was used to evaluate whether BPPV patients' numbers were significantly different among different months of the year. The Spearman correlation was used to detect the correlation between numbers of BPPV patients diagnosed monthly with each climatic parameter. The chi-square test for linear-by-linear association were used to investigate the relationship between cardio-cerebrovascular risk factor and seasonality of BPPV. Results: November to next March is the top 5 months with higher BPPV patient numbers (P < 0.001). The numbers of BPPV diagnosed monthly were conversely correlated with temperature and rainfall (r = -0.736, P = 0.010; r = -0.650, P = 0.022, respectively), positively correlated with atmospheric pressure (r = 0.708, P = 0.010), but no significant correlated with insolation. BPPV in the cold season (including January, February, March, November, and December) had a higher proportion, accounting for 54.2% of all BPPV patients. Among BPPV patients with ≥2, 1, and none cardio-cerebrovascular risk factors, the cold season accounted for 57.0, 56.0, 49.8%, respectively. As the number of cardio-cerebrovascular risk factors increased, the proportion of patients in the cold season of BPPV increased (P = 0.025). Conclusions: BPPV patients are seen more in the months with low temperature, low rainfall, and high atmospheric pressure. Compared with the non-cold season, BPPV patients have more risk factors for cardio-cerebrovascular diseases in the cold season.

Are viral-infections associated with Ménière's Disease? A systematic review and meta-analysis of molecular-markers of viral-infection in case-controlled observational studies of MD

Despite considerable research, it remains controversial as to whether viral-infections are associated with Meniere’s Disease (MD), a clinically heterogeneous set of chronic inner-ear disorders strongly associated with endolymphatic hydrops. Here, we investigated whether viral-infections are associated with MD through a systematic review and meta-analysis of observational clinical studies using molecular-diagnostics. Eligible for inclusion were case-controlled studies which ascertained molecular-determinants of past or present viral-infection through either viral nucleic acids or host serological marker in MD cases and non-MD controls. Across online databases and grey literature, we identified 210 potentially relevant articles in the English language, from which a total of 14 articles fully satisfied our eligibility criteria such that meta-groups of 611 MD-cases and 373 controls resulted. The aggregate quality of the modest-sized (14 studies) body of evidence was limited and varied considerably with regards to participant selection, matching, and ascertainment(s) and determinant(s) of viral-infection. Most data identified concerned the human cytomegalovirus (CMV), and meta-analysis of eligible studies revealed that evidence of CMV-infection was associated approximately three-fold with MD compared to controls, however the timing of the infections was indeterminate as the pooled analyses combined antiviral serological markers with viral nucleic acid markers. No association was found for any of HSV-1, -2, VZV, or EBV. Associative analyses of any viral species not aforementioned were precluded by limited data, and thus potential associations between other viral species and MD, especially other than Herpesviridae, are yet to be characterised. Overall, we have found a small association between CMV-infection and MD, however it is to be determined for what sub-groups of MD this finding may be relevant, and ideally the reported association remains would be reproduced by a greater volume of higher quality evidence.

Benign positional vertigo and endolymphatic hydrops: what is the connection?

BACKGROUND

Although benign paroxysmal positional vertigo and endolymphatic hydrops are considered to be distinct diagnoses, a minority of vertiginous patients exhibit features of both conditions. This coincidence has been reported previously in the literature, and is reviewed here in terms of possible aetiology.

RESULTS AND CONCLUSION

A new hypothesis to account for both conditions is offered, implicating free-floating degenerating debris from the otolithic apparatus. It is postulated that the gelatinous/proteinaceous component may account for an osmotically induced hydrops, while the calcified fragments may induce positional vertigo.

Altered chromogranin A circulating levels in Meniere's disease

OBJECTIVES

Meniere's disease (MD) is an inner ear disorder characterized by episodic vertigo, ear fullness, and hearing loss; usually vertigo attacks cluster in specific period. We studied in MD patients the circulating levels of chromogranin A (CgA) and vasostatin-1 (VS-1), secreted by the neuroendocrine system and involved in the regulation of the endothelial barrier function.

METHODS

Serum levels were assessed in 37 MD patients and 36 controls. The ratio between VS-1 and CgA was calculated.

RESULTS

CgA was increased in patients compared to controls (1.46 versus 0.67 nM, p = 0.01) while no difference was detected for VS-1 (0.41 versus 0.39, resp.). CgA levels in patients positively correlated with the frequency of vertigo spells in the previous four weeks (p = 0.008) and negatively with the time in days from the last vertigo attack (p = 0.018). Furthermore, the VS-1/CgA ratio negatively correlated with the frequency of vertigo spells (p = 0.029) and positively correlated with the time from the last attack (p = 0.003).

CONCLUSION

The results indicate that variations of CgA levels, but not of VS-1, occur in the blood of patients with active MD, depending on the frequency of vertigo spells and the time from the last crisis.

Lack of Association between Human Herpesvirus and Vestibular Schwannoma

Objective

To assess for the presence of human herpesvirus (HHV) using immunohistochemical and polymerase chain reaction (PCR) assay in surgically excised vestibular schwannoma (VS) samples.

Study Design

Cross-sectional study.

Setting

A retrospective laboratory-based study of tumors from patients with vestibular schwannoma.

Subjects and Methods

Tissue microarrays (TMAs) representing sporadic and NF2-associated VS from 121 patients, as well as appropriate positive and negative controls, were studied. TMA sections were immunostained using antibodies directed against HHV-1, HHV-2, HHV-3, HHV-4, HHV-5, and HHV-8. PCR was used for the detection of all 8 known human herpesviruses.

Results

There was no detectable HHV (HHV-1, HHV-2, HHV-3, HHV-4, HHV-5, HHV-8) by immunohistochemistry in any of the 121 cases of sporadic and NF2 cases analyzed. These data were further validated by DNA sequence analyses using PCR in a subset of the VS samples, all of which were found to be negative for all HHV.

Conclusions

The data offer no support for an association between HHV and the development of sporadic or NF2-associated VS in humans.

The role of cyclooxygenase in multiplication and reactivation of HSV-1 in vestibular ganglion neurons

Reactivation of latent herpes simplex type 1 (HSV-1) and nerve inflammation have been shown to be involved in vertigo-related vestibular pathogenesis. Treatments of such diseases have been less than perfect. Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to suppress reactivation of HSV-1 in trigeminal ganglions. However, whether this drug can affect reactivation of HSV-1 in vestibular ganglions is unclear. Due to the difficulties of constructing in vivo animal models, in this study, we developed a vestibular ganglion culture system, in which vestibular neurons were latently or lytically infected with HSV-1. Indomethacin and celecoxib were selected to measure their effects on HSV-1. Trichostatin A was used to reactivate HSV-1 in latently infected neurons. Cycloxygenase-2, which is the target of NSAIDs, was induced by HSV-1 in the lytically infected cultures, with an increase of 14-fold. Although it appeared that indomethacin and celecoxib showed limited but concentration-dependent inhibition effects on viral production under our condition, indomethacin decreased reactivation rate of HSV-1 by about 20%. Though more in vitro or in vivo studies are needed to confirm the effects of the drugs, our study may provide a potential way to investigate the mechanism of HSV-related vestibular pathogenesis as well as new treatments of vertigo-related diseases.

Prophylactic valacyclovir in a patient with recurrent vestibular disturbances secondary to vestibular neuritis

A 57-year-old woman with herpes labialis and previously diagnosed with vestibular neuritis experienced recurrences of vertigo and disequilibrium. Initially preceded by oral herpes outbreaks or upper respiratory infections, these recurrences became spontaneous and more frequent. Vestibular function demonstrated a 25% decrease in energy function in the right and the patient had left beating nystagmus on positional maneuver. Her reoccurrences of vestibular disturbances were followed up. Concurrently, she was prescribed daily valacyclovir (500 mg, 1 per day) given for the prevention of herpes labialis outbreaks by her primary care physician. Recurrences of disequilibrium stopped completely as well as oral herpes outbreaks.

Clinical characteristics and natural course of recurrent vestibulopathy: a long-term follow-up study

OBJECTIVES/HYPOTHESIS

To investigate the clinical characteristics and the natural course of recurrent vestibulopathy (RV).

STUDY DESIGN

Retrospective study.

METHODS

During the period April 2002 to February 2008, we reviewed the clinical records of 98 patients diagnosed with RV. All patients were approached by telephone and using a questionnaire. The analysis included age, sex distribution, natural history, pure-tone audiometry, caloric response, age at onset, and the characteristics of vertigo.

RESULTS

Median follow-up was 63.1 months (range, 24-103 months). Patients had a mean age at onset of 39 years and a mean duration of 4.2 years. An obvious female predilection was found, and unilateral caloric paresis (≥ 25%) was seen in 35%. Of the 98 patients, symptoms resolved in 82% but were unchanged in 12%. RV developed to Ménière's disease in four patients and to migraine in two. No patient with RV developed a central nervous system disease or benign paroxysmal positional vertigo during follow-up.

CONCLUSIONS

The study suggests that in the majority of cases, vertigo spontaneously resolves and that the risks of development to Ménière's disease or migraine are low.

Cultured vestibular ganglion neurons demonstrate latent HSV1 reactivation

OBJECTIVES/HYPOTHESIS

Vestibular neuritis is a common cause of both acute and chronic vestibular dysfunction. Multiple pathologies have been hypothesized to be the causative agent of vestibular neuritis; however, whether herpes simplex type I (HSV1) reactivation occurs within the vestibular ganglion has not been demonstrated previously by experimental evidence. We developed an in vitro system to study HSV1 infection of vestibular ganglion neurons (VGNs) using a cell culture model system.

STUDY DESIGN

basic science study.

RESULTS

Lytic infection of cultured rat VGNs was observed following low viral multiplicity of infection (MOI). Inclusion of acyclovir suppressed lytic replication and allowed latency to be established. Upon removal of acyclovir, latent infection was confirmed with reverse-transcription polymerase chain reaction and by RNA fluorescent in situ hybridization for the latency-associated transcript (LAT). A total of 29% cells in latently infected cultures were LAT positive. The lytic ICP27 transcript was not detected by reverse-transcription polymerase chain reaction (RT-PCR). Reactivation of HSV1 occurred at a high frequency in latently infected cultures following treatment with trichostatin A (TSA), a histone deactylase inhibitor.

CONCLUSIONS

VGNs can be both lytically and latently infected with HSV1. Furthermore, latently infected VGNs can be induced to reactivate using TSA. This demonstrates that reactivation of latent HSV1 infection in the vestibular ganglion can occur in a cell culture model, and suggests that reactivation of HSV1 infection a plausible etiologic mechanism of vestibular neuritis.