Lesion Patterns and Possible Implications for Recovery in Acute Unilateral Vestibulopathy

Lindsay-Hemenway Syndrome Involving the Horizontal Semicircular Canal: Some Considerations Upon Residual Canal Afferents in BPPV Secondary to an Ipsilateral Acute Unilateral Vestibulopathy

OBJECTIVE

To describe benign paroxysmal positional vertigo (BPPV) involving the horizontal semicircular canal (HSC) after ipsilateral acute unilateral vestibulopathy (AUVP) and to advance some hypotheses on the underlying pathomechanism.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

A case series of four patients presenting with HSC-BPPV after ipsilateral AUVP with impaired function of the involved canal at the video-head impulse test (vHIT). Ipsilateral sudden sensorineural hearing loss was detected in one case.

INTERVENTION

All patients underwent bedside examination and an instrumental audio-vestibular assessment, including pure-tone audiometry, vHIT, and vestibular-evoked myogenic potentials. Three patients underwent bithermal caloric testing (BCT). Brain magnetic resonance imaging scan was performed in all cases. Successful canal repositioning was conducted.

MAIN OUTCOME MEASURE

Clinical presentation with video recording and audio-vestibular findings.

RESULTS

Secondary HSC-BPPV was observed from 3 weeks to 8 months after the onset of ipsilateral AUVP. Two cases exhibited an apogeotropic variant, whereas two cases presented with a geotropic form. All BPPV resolved after physical therapy. Instrumental audio-vestibular assessment revealed vestibulo-ocular reflex (VOR) impairment for the affected canal on vHIT in all cases, whereas BCT revealed a borderline normal canal paresis.

CONCLUSIONS

BPPV after an AUVP can involve the HSC. A reduced VOR gain in the high-frequency domain attributable to a damage of the type I (phasic) afferents does not exclude the occurrence of a BPPV if type II (tonic) afferents are preserved or slightly impaired. Clinicians should not neglect to evaluate for provoking nystagmus in patients with vestibular symptoms and vestibular hypofunction on vHIT.

Determination of Recovery by Total Restitution or Compensation Using Multifrequency Vestibular Tests and Subjective Functional Scales in a Human Model of Vestibular Neuritis

BACKGROUND

Vestibular Neuritis (VN) can induce unilateral acute vestibular syndrome (AVS). This study aimed to identify predictive factors of recovery from vestibular neuritis considering total restitution and/or compensation.

METHODS

In this longitudinal study, 40 patients were included. The initial assessment, performed within 36 to 72 h from the onset (T0), included medical history taking (general and specific), including screening for cardiovascular risk factors (CVRFs), and a battery of diagnostic vestibular tests, comprising the bithermal caloric test (BCT), video head impulse test (VHIT), and skull vibration-induced nystagmus (SVIN) test. All patients also completed a Dizziness Handicap Inventory (DHI). All assessments were repeated 90 ± 15 days later (T3). Subjective compensation criteria were based on the DHI total score, and objective compensation criteria were based on laboratory test results. Four groups of patients (A, B, C, D) were delineated by combining patients with normal vs. abnormal vestibular tests and patients with normal vs. abnormal DHI.

RESULTS

CVRFs (but not age or body mass index (BMI)) were associated with a poorer recovery of symptoms. The BCT (lateral semicircular canal paresis %), VHIT (lateral semicircular canal gain), and SVINT (nystagmus slow phase velocity) recovered to normal values in 20%, 20%, and 27% of patients, respectively, at T3.

CONCLUSIONS

Vascular risk factors (hypercholesterolemia) are correlated with patients who do not recover their symptoms via either total restitution or compensation. There was no significant difference between high- and low-frequency vestibular tests in patients recovering from their symptoms. Some patients with objective recovery may continue to have persistent subjective symptoms.

Video Head Impulse Test Coherence Predicts Vertigo Recovery in Sudden Sensorineural Hearing Loss With Vertigo

OBJECTIVES

Labyrinthitis significantly reduces quality of life due to prolonged vestibular symptoms in patients experiencing sudden sensorineural hearing loss with vertigo (SSNHLV). This study employed a novel coherence analysis in the video head impulse test (vHIT) to explore vertigo outcomes in SSNHLV patients.

METHODS

A retrospective review was conducted on 48 SSNHLV patients who completed high-dose steroid treatment between December 2016 and April 2023. Additionally, 38 healthy volunteers were prospectively enrolled from November 2022 to April 2023 at our academic tertiary referral center. The magnitude-squared wavelet coherence between eye and head velocities during the vHIT was measured to assess correlations across frequency bands. Recovery from vertigo, determined by a visual analog scale (VAS) score of 0 at both 2 weeks and 2 months, was analyzed using multivariable Cox regression.

RESULTS

The mean VAS for patients with SSNHLV was 5.73±2.45. Higher coherent frequencies in the horizontal semicircular canal (SCC), posterior SCC, and the mean and minimal coherent frequencies of all three SCCs combined were significantly associated with early complete remission of vertigo 2 weeks posttreatment. In the multivariate analysis, the minimal coherent frequency among the three SCCs emerged as an independent factor (hazard ratio, 2.040; 95% CI, 1.776-2.304). Two months posttreatment, in addition to the previously significant parameters, abnormalities in the vestibulo-ocular reflex (VOR) in the posterior SCC, gains in the horizontal and posterior SCCs, total and overt saccades in the horizontal SCC, coherent frequency in the anterior SCC, and mean VOR gain of all three SCCs combined were also statistically significantly related to total relief from vertigo.

CONCLUSION

The highest minimal coherent frequency among the three SCCs significantly contributed to earlier vertigo relief in patients with SSNHLV. Coherence analysis in vHIT may offer greater sensitivity than time series analysis for predicting the prognosis of vertigo.

The Role of Asymmetry Values, Gain, and Pathological Saccades of the Video Head Impulse Test (vHIT) in Sudden Sensorineural Hearing Loss

OBJECTIVE

The purpose of this study was to evaluate the value of asymmetry values, gain, and pathological saccades of the video head impulse test (vHIT) in sudden sensorineural hearing loss (SSNHL).

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

A total of 226 individuals diagnosed with unilateral definite SSNHL were hospitalized. The assessment included a comprehensive evaluation of medical history, pure-tone test, acoustic impedance, positional test, video nystagmography (VNG), vHIT, vestibular evoked myogenic potentials (VEMPs) and magnetic resonance.

INTERVENTIONS

vHIT, VNG, cVEMP, oVEMP. Statistical analysis was performed with SPSS version 22.0 for Windows.

MAIN OUTCOME MEASURES

The asymmetry values, gain, and pathological saccades of the vHIT.

RESULTS

The abnormal gain of vHIT in anterior, horizontal, and posterior canal in SSNHL patients with vertigo were revealed in 20 of 112 (17.9%), 24 of 112 (21.4%), and 60 of 112 (53.6%), respectively. The vHIT pathological saccades (overt + covert) of anterior, horizontal, and posterior canal in SSNHL patients with vertigo were observed in 5 of 112 (4.6%), 52 of 112 (46.4%), and 58 of 112 (51.8%), respectively. Multivariate analysis indicated that the prognosis of patients with vertigo was correlated with vHIT gain of posterior canal, pathological saccade in horizontal canal, asymmetric ratio of horizontal canal gain, asymmetric ratio of posterior canal gain, Canal paresis (%) on caloric test and spontaneous nystagmus.

CONCLUSION

In the vHIT of patients with SSNHL with vertigo, the posterior canal is most easily affected. Reduced gain of posterior canal, pathological saccade of horizontal canal, and larger asymmetric gain of posterior canal and horizontal canal may be negative prognostic factors.

Application of a Video Head Impulse Test in the Diagnosis of Vestibular Neuritis

In patients presenting in the emergency department with acute vertigo, a rapid and accurate differential diagnosis is crucial, as posterior circulation strokes can mimic acute vestibular losses, leading to inappropriate treatment. The diagnosis of vestibular neuritis is made based on the clinical manifestation and a bedside otoneurological assessment. In the clinical examination, an evaluation of the vestibulo-ocular reflex is the key element; however, the accuracy of the bedside head impulse test depends on the clinician's experience. Thus, new diagnostic methods are needed to objectify and facilitate such rapid vestibular evaluations. The aim of our paper is to provide a comprehensive review of the video head impulse test's application in the diagnosis of vestibular neuritis. Numerous studies have reported advantages that make this method helpful in detailed otoneurological evaluations; in contrast to the bedside head impulse test, it enables an analysis of all six semicircular canals function and records the covert corrective saccades, which are invisible to the naked eye. As a portable and easy diagnostic tool, it is known to improve the diagnostic accuracy in patients with acute vertigo presenting in the emergency department. Moreover, as it evaluates the vestibulo-ocular reflex across different frequencies, as compared to caloric tests, it can be used as an additional test that is complementary to videonystagmography. Recently, several papers have described the application of the video head impulse test in follow-up and recovery evaluations in patients with vestibular neuritis.

Upbeating Skull Vibration-Induced Nystagmus in a Case of Bilateral Sequential Superior Branch Vestibular Neuritis

Vestibular neuritis is one of the most common reasons that someone may experience an episode of acute spontaneous vertigo, with the majority cases impacting only one ear. Cases of bilateral vestibular neuritis are rare and are thought to account for less than 10% of all cases of vestibular neuritis. Skull vibration testing is an efficient means to screen for asymmetry in vestibular function but is still in its infancy in clinical use. The ideal assessment methods and the typical patterns of skull vibration-induced nystagmus are relatively well understood; however, the presentation of skull vibration-induced nystagmus in atypical labyrinthine pathology is less clear. Skull vibration typically induces a horizontal nystagmus that beats toward the healthy labyrinth in most instances of significant labyrinthine asymmetry. We pose a case report of a patient that's symptomology and clinical test findings are most consistent with bilateral sequential superior branch vestibular neuritis with an upbeating skull vibration-induced nystagmus.

Dissociation between Caloric and Video Head Impulse Tests in Dizziness Clinics

Vestibular assessment tests such as the video head impulse test (vHIT) for the horizontal semicircular canal, and caloric test (Cal), both evaluate horizontal canal function. One would assume that the outcomes for these tests should lead to concordant results, yet several studies have suggested that dissociation can occur in certain pathological conditions. As this topic remains inconclusive, this review aims to analyze the scientific evidence regarding the patterns of hypofunction observed in vHIT and Cal in different otoneurological diseases. A comprehensive review of the literature regarding dissociation between these tests in common neurotological diseases was carried out. Articles were analyzed when data for vHIT and Cal were described in a way that it was possible to calculate discordance rates; both retrospective and prospective studies were analyzed. In this review, the discordance rates were as follows: 56% in Ménière’s disease, 51.5% in vestibular migraine, 37.2% in vestibular schwannoma, and 20.8% in vestibular neuritis. These results highlight the benefit of using both Cal and vHIT, and that they are complementary tests.

Vascular mechanisms in acute unilateral peripheral vestibulopathy: a systematic review

Acute unilateral peripheral vestibulopathy (AUPVP) is a frequent cause of vestibular loss. Several aetiologies have been proposed, but the exact mechanism remains unknown. The aim of this study is a systematic analysis of the literature evaluating the vascular aetiology of AUPVP. A systematic literature search was performed in PubMed, Cochrane Library and Embase, including articles published from January 1^st, 2010 to November 30^th, 2020. Two reviewers independently selected articles investigating a link between AUPVP and vascular disease. The following information was extracted: year of publication, country, level of evidence, assessed vascular risk factors and number of patients. A total of 450 articles was obtained. Eleven articles were retained with 100% agreement between the two reviewers. In a pooled population of 805 patients, the main results were the higher neutrophil to lymphocyte ratio and higher prevalence of vascular risk factors among AUPVP patients. A meta-analysis was not performed because the studies were too heterogeneous in terms of methodology. Indirect arguments for vascular mechanisms in AUPVP were found. These findings indicate that larger prospective well-controlled studies are needed to clarify the vascular aetiology of AUPVP.

The spectrum of acute vestibular neuropathy through modern vestibular testing: A descriptive analysis

•

Video head impulse testing and vestibular evoked myogenic potentials show that acute vestibular neuropathy is heterogeneous.

•

Peripheral vestibular pathway vulnerability is approximately inversely correlated with its proportion of afferent fibers.

•

Caloric testing, while useful, should no longer be considered the gold standard for diagnosing acute vestibular neuropathy.

Objective

Acute vestibular neuropathy (AVN), often referred to as vestibular neuritis, is a cranial neuropathy responsible for a significant proportion of cases of acute vertigo. This study describes the spectrum of lesion patterns in AVN as identified by video head impulse testing (vHIT) which assesses the high frequency vestibulo-ocular reflex function of the semicircular canals, and cervical and ocular vestibular evoked myogenic potentials (VEMPs) which assess otolith function.

Methods

We used vHIT and VEMPs to assess 35 patients with vestibular neuropathy in the acute stage.

Results

Unilateral superior division vestibular nerve involvement was the most common variant (57.1%), followed by unilateral superior and inferior division (28.5%), bilateral superior division (8.5%) and unilateral inferior division (5.7%). We observed a partial inverse correlation between the proportion of afferent fibers from an organelle, and the likelihood that the test of that organelle’s function will be abnormal.

Conclusion

vHIT and VEMPs provide more detailed characterization of lesion pattern in AVN than caloric testing.

Significance

Comparison of lesion patterns from neuro-physiological testing with what is known about the proportional distribution of afferent fibers from the vestibular end-organelles suggests a new, neuro-anatomically based insight regarding susceptibility of these pathways to AVN.

Which Inner Ear Disorders Lie Behind a Selective Posterior Semicircular Canal Hypofunction on Video Head Impulse Test?

OBJECTIVE

To assess all different patterns of associated abnormalities on audiometry, bithermal caloric test (BCT) and cervical/ocular vestibular-evoked myogenic potentials (VEMPs) to air/bone-conduction in patients with selective posterior semicircular canal (PSC) hypofunction and to correlate them with underlying disorders.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

51 patients (23 men, 28 women, mean age 57.5 yr) with isolated PSC deficit (one bilateral).

INTERVENTIONS

Correlation with instrumental data and underlying diagnoses.

MAIN OUTCOME MEASURES

Video-oculographic findings, objective measurements on audiometry, BCT, VEMPs and video-head impulse test (vHIT).

RESULTS

Ongoing or previous acute vestibular loss (AVL) was diagnosed in 13 patients (25.5%, 3 inferior vestibular neuritis, 10 AVL with sudden sensorineural hearing loss [SSNHL]), Meniere's disease (MD) in 12 (23.5%), cerebellopontine angle (CPA) lesion in 9 (17.6%), various causes in 7 (13.7%), benign paroxysmal positional vertigo (BPPV) involving the non-ampullary arm of PSC in 5 cases (9.8%) whereas unknown pathology in 5 (9.8%). Involvement of at least one additional receptor besides PSC was seen in 89.8% of cases. Cochlear involvement was diagnosed in 74.5% with pure-tone average significantly greater in patients with AVL+SSNHL (p < 0.05). Overall involvement of labyrinthine receptors or afferents was highest in patients with AVL+SSNHL (p < 0.01), MD and CPA lesions (p < 0.05).

CONCLUSIONS

Isolated loss of PSC function on vHIT is mostly accompanied by additional labyrinthine deficits that could only be identified through an accurate instrumental evaluation. Assessment of all receptors and afferents should be always pursued to identify the lesion site and better understand the underlying pathophysiological mechanisms.

Enhanced Otolith Function Despite Severe Labyrinthine Damage in a Case of Pneumolabyrinth and Pneumocephalus Due to Otogenic Meningitis Associated With Superior Canal Dehiscence

OBJECTIVE

To describe a rare case of pneumolabyrinth (PNL) and pneumocephalus (PNC) due to otogenic meningitis in a patient with superior canal dehiscence (SCD) resulting in profound sensorineural hearing loss (SNHL), semicircular canals impairment but preservation of SCD-related enhanced otolith function.

PATIENT

A 65-year-old woman with otogenic meningitis.

INTERVENTION

Temporal bone high-resolution computed tomography (CT) scans, brain-magnetic resonance imaging, audiometry, bedside examination, video-head impulse test, and vestibular-evoked myogenic potentials (VEMPs).

MAIN OUTCOME MEASURES

Enhanced otolith function despite canal and cochlear loss.

RESULTS

The patient developed right profound SNHL and acute labyrinthitis. Imaging showed middle ear inflammatory tissue, right PNL and PNC despite lack of bony fractures. Bilateral SCD and tegmen dehiscence were detected. The patient underwent mastoidectomy, drainage of effusion, and surgical repair of tegmen dehiscence. Exploratory tympanotomy was uneventful. She was treated with intravenous antibiotics and dexamethasone for 3 weeks with improvement of general condition. At 3-weeks follow-up, right profound SNHL persisted with global hypofunction for ipsilateral semicircular canals and selective impairment for left superior canal activity at video-head impulse test. Surprisingly, both cervical and ocular-VEMPs exhibited bilaterally abnormal amplitudes and reduced thresholds, consistently with preserved SCD-related macular hypersensitivity to sounds even on the affected side.

CONCLUSIONS

This case report exhibits a unique clinical scenario as it offers interesting insights concerning PNL aetiology despite lack of either bony fractures or barotrauma and PNC likely conveyed intracranially by SCD. Moreover, it provides an unusual pattern of functional dissociation among inner-ear receptors showing enhanced otolith function despite severe labyrinthine damage.

Acute Vestibular Syndrome

PURPOSE OF REVIEW

This article provides a practical approach to acute vestibular syndrome while highlighting recent research advances.

RECENT FINDINGS

Acute vestibular syndrome is defined as sudden-onset, continuous vertigo lasting longer than 24 hours with associated nausea and vomiting, all of which are worsened with head movement. Acute vestibular syndrome is provoked by a variety of central and peripheral causes, the most common of which are vestibular neuritis and acute stroke (posterior circulation). A clinical approach focusing on timing, associated history, and ocular motor findings can improve diagnostic accuracy and is more sensitive and specific than early neuroimaging. Because of the shared neurovascular supply, both peripheral and central vestibular disorders can manifest overlapping signs previously considered solely peripheral or central, including vertical skew, nystagmus, abnormal vestibular ocular reflex, hearing loss, and gait instability. Although acute vestibular syndrome is typically benign, stroke should be considered in every person with acute vestibular syndrome because it can act as a harbinger of stroke or impending cerebellar herniation. Treatment is focused on physical therapy because the evidence is minimal for the long-term use of medication.

SUMMARY

The diagnosis of acute vestibular syndrome first requires the elimination of common medical causes for dizziness. Next, underlying pathology must be determined by distinguishing between the most common causes of acute vestibular syndrome: central and peripheral vestibular disorders. Central vestibular disorders are most often the result of ischemic stroke affecting the cerebellar arteries. Peripheral vestibular disorders are assumed to be caused mostly by inflammatory sources, but ischemia of the peripheral vestibular apparatus may be underappreciated. By using the HINTS Plus (Head Impulse test, Nystagmus, Test of Skew with Plus referring to hearing loss assessment) examination in addition to a comprehensive neurologic examination, strokes are unlikely to be missed. For nearly all acute vestibular disorders, vestibular physical therapy contributes to recovery.

Prognosis after acute unilateral vestibulopathy: Usefulness of the suppression head impulse paradigm (SHIMP)

OBJECTIVES

This cross-sectional study aims to describe the features of the suppression head impulse paradigm (SHIMP) in acute unilateral vestibulopathy (AUV) and to define its role in predicting the recovery of patients.

METHODS

Thirty patients diagnosed with AUV were retrospectively analyzed. The dizziness handicap inventory score and video head impulse test parameters performed 4-8 weeks from the AUV onset constituted the main outcome measures. Patients with a worse recovery (Group 1) and patients who recovered spontaneously (Group 2) were compared.

RESULTS

The SHIMP vestibulo-ocular reflex (VOR) gain was statistically significantly lower than the conventional head impulse paradigm (HIMP) VOR gain (P <  0.001). The SHIMP VOR gain was negatively correlated with the DHI (P <  0.001) and was positively correlated with the HIMP VOR gain (P <  0.001) and the SHIMP overt saccades (%) (P <  0.001). Patients with a worse recovery exhibited the following: higher DHI (P <  0.001), lower SHIMP and HIMP VOR gain (P <  0.001 and P = 0.007, respectively), and lower SHIMP and greater HIMP overt saccade prevalence values (P = 0.007 and P = 0.032, respectively).

CONCLUSIONS

The SHIMP and HIMP help in improving our approach to AUV. SHIMP appears to better identify the extent of the vestibular damage in patient suffering from AUV than HIMP and could provide interesting information about the course of the disease. Particularly, the analysis of SHIMP VOR gain and overt saccade prevalence would provide useful information about the recovery of patients.

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.