Sudden sensorineural hearing loss with positional vertigo: Initial findings of positional nystagmus and hearing outcomes

The Light Cupula Phenomenon: A Scoping Review

Direction-changing positional nystagmus (DCPN), which refers to the change in the direction of nystagmus with different head positions, is a well-known characteristic of horizontal semicircular canal BPPV. The supine head roll test is commonly used to diagnose horizontal canal BPPV. However, persistent geotropic DCPN observed during this test cannot be explained by the conventional explanations of canalolithiasis or cupulolithiasis. To account for this unique nystagmus, the concept of a "light cupula" has been recently introduced. In this review, we provide an overview of the historical background, clinical features and diagnostic methods, proposed mechanisms, and treatment strategies associated with the light cupula phenomenon based on the available literature to date.

Pathological Study of Light Cupula Syndrome on a Visual Bionic Semicircular Canal

A type of persistent direction-changing positional nystagmus with a null point during head position deflection is known as light cupula syndrome (LCS) in the clinic. To date, the pathogenesis and biomechanical response of human semicircular canals with light cupula syndrome (LCS) (HSCs-LCS) are still unclear. In this study, based on the anatomical structure and size of the one-dimensional human semicircular canal (HSC) and imitating the pathological changes of the endolymph in HSC with LCS, a visual bionic semicircular canal (BSC) with LCS was fabricated using three-dimensional printing technology, hydrogel modification, and target tracking technology. Through theoretical derivation, mathematical models of the HSC-LCS perception process were established. By conducting in vitro experiments on the bionic model, the biomechanical response process of HSC-LCS was studied, and the mathematical models were validated. The results of pulse acceleration stimulation showed that the pathological changes in the density and viscosity of the endolymph could reduce the deformation of the cupula of the BSC-LCS and increase the time constant. The results of the sinusoidal acceleration stimulation showed that the amplitude-frequency gain of the BSC-LCS decreased and the phase difference increased. The BSC-LCS can be used as a tool for pathological research of the HSC-LCS. The results of this study can provide a theoretical basis for clinical diagnosis.

Early treatment for benign paroxysmal positional vertigo secondary to sudden sensorineural hearing loss

Sudden sensorineural hearing loss (SSNHL) accompanied by benign paroxysmal positional vertigo (BPPV) is relatively common in the clinic. There are unified standards for the treatment of primary BPPV with good reduction effect, while there are few studies on the treatment of BPPV secondary to SSNHL within 1 week of onset. The study was to investigate the treatment of BPPV secondary to SSNHL and compare its manual reduction with that of primary BPPV. We selected 90 patients with BPPV accompanied by SSNHL within a week of onset and 210 primary BPPV patients at Hebei Provincial Eye Hospital from June 2020 to December 2022. The former group was divided into the medicine group and manual reduction plus medicine group. The medicines used were extract of Ginkgo biloba leaves injection, betahistine hydrochloride injection and oral prednisone. We contrasted the efficacy respectively for posterior semicircular canal BPPV (psc-BPPV), horizontal semicircular canal BPPV (hsc-BPPV) and multiple semicircular canal BPPV (msc-BPPV). In addition, we compared the manual reduction effect for primary BPPV and manual reduction group, and the evaluation of efficacy are the intensity of nystagmus and the clinical symptoms. In the secondary BPPV group, there was no difference in efficacy between the medicine group and manual reduction group at the 7th-day after reduction for psc-BPPV, hsc-BPPV, and msc-BPPV (P > .05). The immediate effect of reduction was significantly different between the primary BPPV group and the group with SSNHL and BPPV for both psc-BPPV and hsc-BPPV (P < .05), and the effect of the primary BPPV group was better, but it was no difference for msc-BPPV (P > .05). For the treatment of BPPV accompanied by SSNHL within 1 week of onset, the additional reduction therapy showed no benefit, so we need to apply medication for SSNHL.

Light cupula phenomenon: a systematic review

Geotropic direction-changing positional nystagmus (DCPN) is transient in lateral semicircular canal (LSSK) canalolithiasis; it usually cuts off within a minute and fatigues. However, a “light cupula” mechanism has been described for patients with positional vertigo who exhibit a persistent geotropic DCPN without delay or fatigue. When the cupula becomes lighter than the surrounding endolymph, deflection may occur in the cupula under the influence of gravity. The person experiences dizziness and persistent positional nystagmus can be observed while remaining in that position.

In this review, studies investigating the “light cupula phenomenon,” which is a newly defined phenomenon in the literature, were compiled. A systematic literature search was conducted on the light cupula phenomenon in PubMed and Google Scholar databases to illuminate the clinical side of this new phenomenon and reveal its distinctive features. Turkish and English articles published between 2010 and 2021 were scanned; the thesis, reviews, and books were excluded from the study. Forty-eight articles were included in the study.

Mechanisms underlying light cupula has been explained as the “heavier endolymph hypothesis” with increased endolymph specific gravity due to an acute attack such as labyrinth hemorrhage, insufficient inner ear perfusion, or inflammation in the inner ear; “lighter cupula hypothesis” based on alcohol acting on the cupula earlier and making it lighter than the endolymph; “light particle hypothesis” due to the buoyancy of light debris, which are degenerative, swollen, and inflammatory cells in the endolymph adhering to the cupula and the “altered endolymph/perilymph density ratio hypothesis” that the difference in density between perilymph and endolymph causes light cupula. The pathophysiology of the light cupula phenomenon is still unclear, but it can be thought that all the different hypotheses may be effective in this phenomenon. Therefore, nystagmus characteristics and clinical course should be considered in patients for a more effective diagnosis and treatment process. In addition, the results of the studies show that light cupula may not be an uncommon disease and that some patients with geotropic DCPN can often be misdiagnosed as canalolithiasis LSCC-BPPV.

Clinical Characteristics of Patients with Persistent Apogeotropic and Persistent Geotropic Direction-Changing Positional Nystagmus

Background and Purpose

This study aimed to determine the clinical features, diagnosis, and treatment of patients with persistent geotropic (pG) and persistent apogeotropic (pAG) direction-changing positional nystagmus (DCPN).

Methods

This retrospective study included 30 patients with pG-DCPN and 44 patients with pAG-DCPN. All patients underwent neurological and neurotological examinations, including an evaluation of gaze-evoked nystagmus, eye-movement tests, and assessments of limb ataxia and balance, as well as magnetic resonance imaging to exclude central causes. The characteristics of positional nystagmus were detected using the supine roll test (SRT) and bow-and-lean test (BLT). The null point (NP) at which the nystagmus disappeared was determined. All patients were treated with the barbecue maneuver, and treatment efficacy was evaluated immediately, 1 week, and 1 month after treatment.

Results

The history of diseases associated with atherosclerosis, peripheral vestibular disorders, otological disease, and migraine differed significantly between patients with pG-DCPN and pAG-DCPN. The affected sides of persistent horizontal DCPN can be determined using the SRT and the BLT, while determining the second NP and vestibular function as well as performing an audiological evaluation can be used to assist in identifying the affected side. The efficacy rates immediately and 1 week after treatment with the barbecue maneuver were higher in patients with pAG-DCPN than in patients with pG-DCPN.

Conclusions

pAG-DCPN was more compatible with the characteristics of cupulolithiasis, and pG-DCPN was more likely to be associated with a light cupula rather than canalolithiasis. pAG-DCPN was more likely to be accompanied by a disease associated with atherosclerosis, while pG-DCPN was often accompanied by autoimmune-related diseases and a history of migraine. The associations between pAG-DCPN, pG-DCPN, and the above-mentioned diseases need to be clarified further. The canalith-repositioning maneuver was effective in patients with pAG-DCPN and ineffective in patients with pG-DCPN, but most cases of pG-DCPN are self-limiting.

Feasibility of Using the Video-Head Impulse Test to Detect the Involved Canal in Benign Paroxysmal Positional Vertigo Presenting With Positional Downbeat Nystagmus

Positional downbeat nystagmus (pDBN) represents a relatively frequent finding. Its possible peripheral origin has been widely ascertained. Nevertheless, distinguishing features of peripheral positional nystagmus, including latency, paroxysm and torsional components, may be missing, resulting in challenging differential diagnosis with central pDBN. Moreover, in case of benign paroxysmal positional vertigo (BPPV), detection of the affected canal may be challenging as involvement of the non-ampullary arm of posterior semicircular canal (PSC) results in the same oculomotor responses generated by contralateral anterior canal (ASC)-canalolithiasis. Recent acquisitions suggest that patients with persistent pDBN due to vertical canal-BPPV may exhibit impaired vestibulo-ocular reflex (VOR) for the involved canal on video-head impulse test (vHIT). Since canal hypofunction normalizes following proper canalith repositioning procedures (CRP), an incomplete canalith jam acting as a "low-pass filter" for the affected ampullary receptor has been hypothesized. This study aims to determine the sensitivity of vHIT in detecting canal involvement in patients presenting with pDBN due to vertical canal-BPPV. We retrospectively reviewed the clinical records of 59 consecutive subjects presenting with peripheral pDBN. All patients were tested with video-Frenzel examination and vHIT at presentation and after resolution of symptoms or transformation in typical BPPV-variant. BPPV involving non-ampullary tract of PSC was diagnosed in 78%, ASC-BPPV in 11.9% whereas in 6 cases the involved canal remained unidentified. Presenting VOR-gain values for the affected canal were greatly impaired in cases with persistent pDBN compared to subjects with paroxysmal/transitory nystagmus (p < 0.001). Each patient received CRP for BPPV involving the hypoactive canal or, in case of normal VOR-gain, the assumed affected canal. Each subject exhibiting VOR-gain reduction for the involved canal developed normalization of vHIT data after proper repositioning (p < 0.001), proving a close relationship with otoliths altering high-frequency cupular responses. According to our results, overall vHIT sensitivity in detecting the affected SC was 72.9%, increasing up to 88.6% when considering only cases with persistent pDBN where an incomplete canal plug is more likely to occur. vHIT should be routinely used in patients with pDBN as it may enable to localize otoconia within the labyrinth, providing further insights to the pathophysiology of peripheral pDBN.

Nystagmus in Ramsay Hunt syndrome with or without dizziness

BACKGROUND

The presence of dizziness has been reported as a negative prognostic factor for recovery of facial palsy in Ramsay Hunt syndrome (RHS). The aim of this study was to investigate the incidence and patterns of nystagmus in RHS patients without dizziness, and discuss possible mechanisms. We also compared the severity and prognosis of facial palsy between RHS patients with and without dizziness.

METHODS

From January 2014 to January 2019, 36 patients diagnosed with RHS (27 with dizziness and 9 without dizziness) were included. Patterns of nystagmus were examined and categorized using video-nystagmography. House-Brackmann(HB) grade of facial palsy was compared between RHS patients with and without dizziness.

RESULTS

Not only RHS patients with dizziness exhibited nystagmus in most cases (96%, 26 of 27) but also as many as 67% (6 of 9) of RHS patients without dizziness exhibited nystagmus, though the intensity was remarkably weak. In both groups of RHS with and without dizziness, direction-fixed nystagmus and direction-changing positional nystagmus were observed. Initial HB grade and recovery of facial palsy after treatment were not significantly different between RHS with and without dizziness.

CONCLUSION

Various patterns of nystagmus including direction-fixed and positional direction-changing nystagmus were observed in RHS patients, and inflammation of the vestibular nerve and inner ear end organs may be responsible for the production of nystagmus in these patients. The results support that the evaluation of vestibular function may be necessary even in RHS patients who do not complain of dizziness or vertigo.

Nystagmus Findings and Hearing Recovery in Idiopathic Sudden Sensorineural Hearing Loss Without Dizziness

OBJECTIVES

To investigate the incidence of nystagmus in patients with sudden sensorineural hearing loss (SSNHL) without dizziness, and to evaluate the correlation of the presence of nystagmus with hearing recovery in those patients.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral academic medical center.

PATIENTS

Thirty-eight patients with SSNHL who did not complained of dizziness were enrolled.

MAIN OUTCOME MEASURE

The presence of nystagmus was evaluated by recording eye movements, and if present, nystagmus was classified as direction-fixed or positional nystagmus. Vestibular function tests were performed, including caloric test.

RESULTS

Of 33 idiopathic SSNHL patients without dizziness, nystagmus was observed in 22 patients (67%), of which 14 patients exhibited direction-fixed nystagmus, and 8 patients exhibited direction-changing nystagmus. Among the 14 patients with direction-fixed nystagmus, 9 displayed the paretic type, and 5 displayed the irritative type. Direction-changing nystagmus (n = 8) was defined as that in which the direction of nystagmus was changed in a supine head-roll test, and the geotropic type and apogeotropic type were observed in two and six patients, respectively. The mean initial pure tone threshold was 58.2 ± 28.1 dB and 57.3 ± 20.0 dB in SSNHL patients with and without nystagmus, respectively, which was not significantly different (p = 0.925). When hearing improvement was compared according to the presence of nystagmus, 39% (8 of 21) of patients with nystagmus were found to belong in the good prognosis group, and 72% (8 of 11) of patients without nystagmus were found to belong in the good prognosis group, which showed marginal statistical significance (p = 0.063).

CONCLUSION

Nystagmus was observed in two-thirds of idiopathic SSNHL patients without dizziness, and the pattern of nystagmus was either direction fixed or direction changing. Because hearing recovery was worse in patients with nystagmus than those without it, the diagnosis of nystagmus, even in SSNHL patients without dizziness, may be important in evaluating the hearing prognosis.

Direction-fixed and Direction-changing Positional Nystagmus in Ramsay Hunt Syndrome

OBJECTIVES

To investigate the incidence of positional nystagmus (PN) using a head-roll test in patients with Ramsay Hunt syndrome with vertigo (RHS_V) and discuss possible mechanisms.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral academic medical center.

PATIENTS

Twenty-eight patients with RHS_V were enrolled.

MAIN OUTCOME MEASURE

Eye movements were recorded at positions of head roll to the right or left, and PN was classified as direction-fixed or direction-changing. Vestibular function tests including caloric test were performed.

RESULTS

Direction-fixed nystagmus beating away from the affected side was the most common type of PN (61%), followed by direction-changing geotropic type (18%), direction-fixed nystagmus beating toward the affected side (14%), and direction-changing apogeotropic type (7%). The duration of nystagmus was longer than 60 seconds in all patients exhibiting direction-changing PN. Postcontrast T1-weighted internal auditory canal (IAC) magnetic resonance imaging showed enhancement of not only the facial and vestibulocochlear nerves, but also the inner ear structures or dura along the IAC, suggesting inflammatory changes within the labyrinthine membrane or IAC dura.

CONCLUSION

Although direction-fixed PN was more commonly observed (75%), direction-changing PN was also observed in some RHS_V patients (25%). The mechanism of direction-changing PN may be, at least in part, explained by the alteration of specific gravity of the lateral semicircular canal cupula or endolymph due to inflammation in the inner ear membrane.

Dialysis disequilibrium syndrome revisited: Feeling "Disequilibrated" due to inner ear dyshomeostasis?

Dizziness is one of the most common hemodialysis-associated symptoms, and has been thought to be caused by cerebral edema or intravascular hypovolemia. However, the possibility of a peripheral vestibular disturbance due to hemodialysis has not been addressed as a cause of hemodialysis-associated dizziness. In the present study, we propose a new hypothesis accounting for hemodialysis-associated dizziness, i.e., the decrease in serum osmolality due to rapid removal of urea during dialysis causes inner ear fluid dyshomeostasis, leading to density difference between perilymph and endolymph.

Density difference between perilymph and endolymph: A new hypothesis for light cupula phenomenon

Light cupula is an emerging concept accounting for positional nystagmus. It can be diagnosed when persistent geotropic direction-changing positional nystagmus (PG DCPN) is observed in a head-roll test. Although hypotheses explaining light cupula phenomenon such as "light debris", "lighter cupula", and "heavier endolymph" have been proposed, the mechanism underlying light cupula has not been clearly elucidated yet. In the present study, we proposed a new hypothesis accounting for light cupula, i.e., density difference between perilymph and endolymph could elicit characteristic PG DCPN in a head-roll test. We also discussed the mechanism how membranous canal containing endolymph became buoyant within the perilymphatic space under constant influence of gravity when the density of perilymph was higher than that of endolymph.

Patterns of nystagmus conversion in sudden sensorineural hearing loss with vertigo

The patients with sudden sensorineural hearing loss (SSNHL) may complain of vertigo. Although there have been many reports on SSNHL with vertigo (SSNHL_V), changes in the pattern of nystagmus have not been studied as yet. This study is a retrospective study and aims to investigate the characteristic changes in type of nystagmus and clinical features in patients with SSNHL_V who experienced a change in their nystagmus pattern during follow-up. Among 50 patients with SSNHL_V between January 2012 and December 2015, we identified 15 patients with SSNHL_V whose pattern of nystagmus changed. Initial nystagmus was classified into 5 subgroups: paretic type, irritative type, persistent geotropic direction-changing positional nystagmus (PG-DCPN), persistent apogeotropic direction-changing positional nystagmus (PA-DCPN), and posterior semicircular canal benign paroxysmal positional vertigo. The most common pattern of initial nystagmus was PG-DCPN (n = 7). The change of initial nystagmus pattern occurred on day 2 to 75 from symptom onset, and 2 (of 15) patients showed further conversion. The most common pattern of final nystagmus was PA-DCPN (n = 9). Hearing improvement after treatment was not significantly different (P = .59) between SSNHL_V patients with nystagmus change (25 ± 17 dB, n = 15) and those without nystagmus change (28 ± 18 dB, n = 35). In conclusion, clinician's attention is required in evaluating the vertigo symptom in patients with SSNHL_V because the initial patterns of nystagmus can be converted to another type of nystagmus. The presence of nystagmus change during follow-up may not be a prognosticator for hearing recovery in patients with SSNHL_V.

Is the modified cupulolith repositioning maneuver effective for treatment of persistent geotropic direction-changing positional nystagmus?

OBJECTIVE

Clinicians sometimes see patients with relatively persistent geotropic direction-changing positional nystagmus (DCPN) as a variant of lateral semicircular canal-benign paroxysmal positional vertigo (LSCC-BPPV). Recently, the concept of a "light cupula" in the lateral semicircular canal, exhibiting persistent geotropic DCPN, has been introduced. However, the underlying pathogenesis of light cupula is not known. We investigated the efficacy of a modified cupulopathy repositioning maneuver (mCuRM), designed to reduce light debris attached to the cupula in patients with persistent geotropic DCPN.

STUDY DESIGN

Retrospective cohort study.

METHODS

Participants included 65 patients with a persistent geotropic DCPN: 35 underwent treatment (mCuRM group), and 30 were followed-up but received no treatment (No CuRM group). We compared the therapeutic and survival rate of persistent geotropic DCPN between two groups.

RESULTS

On Day 1, the persistent geotropic DCPN did not resolve in either group. On the first and second follow-up days, persistent geotropic DCPN was observed in 28 (80%) and 21 (60%) of patients, respectively, in the mCuRM group, and in 28 (93.3%) and 24 (80%) patients, respectively, in the no mCuRM group. The differences between groups were not statistically significant. Furthermore, no between-group differences were found in the time from diagnosis to resolution of nystagmus, or the time from symptom onset to resolution of nystagmus. Kaplan-Meier analysis of the time course of persistent geotropic DCPN resolution from the day of diagnosis and day of symptom onset revealed no significant differences between the groups.

CONCLUSION

Our findings indicate that mCuRM had no therapeutic benefit for a persistent geotropic DCPN and suggest that the pathophysiology of persistent geotropic DCPN is less likely to be a light debris attached to the cupula.

Vestibular Dysfunctions in Sudden Sensorineural Hearing Loss: A Systematic Review and Meta-analysis

Background

Sudden sensorineural hearing loss (SSHL) not only involves cochlear function but might also be accompanied by vestibular disturbances. The assessment of vestibular function could be of great relevance in SSHL.

Objective

To investigate the prevalence of vestibulocochlear lesions in SSHL and the correlation of specific vestibular organs with hearing prognosis.

Data sources

A complete literature search of eligible studies in the PubMed and EMBASE databases was performed.

Study selection

For our aim, studies that focused on vestibular examination in the case of SSHL were retrieved, including caloric tests, cervical vestibular-evoked myogenic potential (cVEMP) tests, or ocular vestibular-evoked myogenic potential (oVEMP) tests.

Results

Of the 18 studies included, a caloric test was performed in 16 studies, cVEMP in 13 studies, and oVEMP in 5 studies, and together the studies included a total population of 1,468 subjects. The scores on the Agency for Healthcare Research and Quality (AHRQ) questionnaire ranged from 6 to 11. These results indicated that the most commonly damaged vestibular organ in SSHL was the utricle and superior vestibular pathway (U + S) followed by the lateral semicircular canal and superior vestibular pathway (LSC + S), the saccule and inferior vestibular pathway (S + I), and the cochlea only (C only). The meta-analysis indicated that SSHL patients with vertigo have a statistically increased risk of vestibular organ lesions compared with those without vertigo, including the LSC + S subgroup (OR = 4.89, 95% CI = 1.20-19.93, I² = 80%, p = 0.03) and the S + I subgroup (OR = 3.58, 95% CI = 1.61-7.95, I² = 0%, p = 0.002). The pooled possibility of hearing recovery within the LSC + S lesion group was less than half that of the non-LSC + S lesion group (OR = 0.24, 95% CI = 0.11-0.52, I² = 68%, p = 0.0003).

Conclusion

This study shows the relevance of vestibular damage concomitant with SSHL and that SSHL patients with vertigo are at an increased risk of vestibular organ lesions compared with patients without vertigo. LSC + S lesions thus appear to be a critical variable that influence the possibility of hearing improvement in SSHL.

The Light Cupula: An Emerging New Concept for Positional Vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common type of positional vertigo. A canalolithiasis-type of BPPV involving the lateral semicircular canal (LSCC) shows a characteristic direction-changing positional nystagmus (DCPN) which beats towards the lower ear (geotropic) on turning the head to either side in a supine position. Because geotropic DCPN in LSCC canalolithiasis is transient with a latency of a few seconds, the diagnosis can be challenging if geotropic DCPN is persistent without latency. The concept of “light cupula” has been introduced to explain persistent geotropic DCPN, although the mechanism behind it requires further elucidation. In this review, we describe the characteristics of the nystagmic pattern in light cupula and discuss the current evidence for possible mechanisms explaining the phenomenon.