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

Sheng-Chiao Lin; Ming-Yee Lin; Bor-Hwang Kang; Yaoh-Shiang Lin; Yu-Hsi Liu; Chi-Yuan Yin; Po-Shing Lin; Che-Wei Lin

doi:10.21053/ceo.2024.00068

Clinical and Experimental Otorhinolaryngology > Volume 17(4); 2024 > Article

Lin, Lin, Kang, Lin, Liu, Yin, Lin, and Lin: Video Head Impulse Test Coherence Predicts Vertigo Recovery in Sudden Sensorineural Hearing Loss With Vertigo

Original Article

Clinical and Experimental Otorhinolaryngology 2024; 17(4): 282-291.

Published online: November 6, 2024

DOI: https://doi.org/10.21053/ceo.2024.00068

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

Sheng-Chiao Lin^1,^2,^3,⁴

, Ming-Yee Lin^2,^4,⁵, Bor-Hwang Kang^2,³

, Yaoh-Shiang Lin^2,³, Yu-Hsi Liu^2,³, Chi-Yuan Yin^2,⁶, Po-Shing Lin², Che-Wei Lin^1,^7,^8,^9,¹⁰

¹Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, Tainan, Taiwan

²Department of Otorhinolaryngology-Head and Neck Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan

³School of Medicine, National Defense Medical Center, Taipei, Taiwan

⁴School of Medicine, National Sun Yat-sen University, Kaohsiung, Taiwan

⁵Shu-Zen Junior College of Medicine and Management, Kaohsiung, Taiwan

⁶Department of Special Education, College of Education, National Kaohsiung Normal University, Kaohsiung, Taiwan

⁷Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan

⁸Institute of Gerontology, College of Medicine, National Cheng Kung University, Tainan, Taiwan

⁹Institute of Medical Informatics, College of Electrical Engineering and Computer Science, National Cheng Kung University, Tainan, Taiwan

¹⁰Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan

Corresponding author: Che-Wei Lin Department of Biomedical Engineering, College of Engineering, National Cheng Kung University, No.1, University Rd, Tainan City 701, Taiwan
Tel: +886-6-2757575, Email: lincw@mail.ncku.edu.tw

Received March 1, 2024 Revised October 1, 2024 Accepted November 5, 2024

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.

Keywords: Sudden Sensorineural Hearing Loss; Vertigo; Video Head Impulse Test; Wavelet Coherence

INTRODUCTION

Sudden sensorineural hearing loss (SSNHL) is defined as a decrease in sensory hearing of 30 dB or more across three contiguous frequencies within 3 days [1]. Due to the close anatomical proximity of the cochlea and vestibule, 28.8%–40% of patients exhibit concomitant vestibular dysfunction, which includes symptoms such as vertigo, dizziness, or unsteadiness [2,3]. In cases of SSNHL with vertigo (SSNHLV), 11.2% of patients report vestibular symptoms that persist for more than 2 months, indicative of labyrinthitis, which significantly affects their quality of life [4-6]. While the prognostic factors for hearing recovery in SSNHL have been the focus of extensive research over the past decades [7-9], studies on vestibular recovery in SSNHLV are still limited, despite progress in vestibular laboratory research.

Although the video head impulse test (vHIT) evaluates semicircular canal (SCC) function and shows a high prevalence of abnormalities in acute unilateral vestibulopathy, there is no statistically significant correlation between vestibulo-ocular reflex (VOR) gain abnormalities at diagnosis and initial self-reported symptom scales or subsequent symptom recovery, as indicated by previous studies [10-13]. Currently, vHIT analysis involves comparing the ratio of paired eye and head velocities in the time domain. In biomedical research, wavelet coherence analysis (WCA) has been extensively used to study functional connectivity by calculating the correlation in the frequency domain between paired signals similar to those used in vHIT, such as electroencephalogram (EEG), electromyogram, electrocardiogram (ECG), and optical tomography [14-17]. The time series data is transformed into the time-frequency domain using wavelet transform, and WCA is applied to assess the coherence between paired signals. Previous research has investigated the use of coherence in neurological disorders. For instance, both short and long-range coherence in resting-state EEG have been shown to predict the prognosis of unresponsive wakefulness syndrome, and the magnitude of intermuscular coherence has been significantly correlated with clinical symptom severity in patients with Parkinson’s disease [18,19]. In the vestibular system, studies have shown that VOR adaptation is frequency selective [20]. However, adaptive responses after training across various frequencies have not been documented in other vestibular assessments. Moreover, no studies have yet applied time-frequency analysis to VOR to explore outcomes related to vertigo. Among vestibular function tests, given the high cross-spectral resolution of short-term and nonstationary signals, using WCA in vHIT could represent an innovative and appropriate method for assessing VOR function, potentially providing valuable prognostic information for patients with vertigo.

In the clinical management of vestibular disorders, there is a need for a parameter that is associated not only with diagnosing the disease but also with monitoring symptom remission. Our study aims to be the first to employ the novel approach of WCA in vHIT to predict the vestibular prognosis using the visual analog scale (VAS) in a pure cohort of patients with SSNHLV.

MATERIALS AND METHODS

Ethical considerations

The study was carried out in accordance with the guidelines of the Kaohsiung Veterans General Hospital Institutional Review Board in Taiwan (No. KSVGH22-CT4-11 and 22-CT9-12). For the retrospective cohort, all patient identities were removed from the raw data prior to processing, resulting in a waiver of informed consent with KSVGH22-CT4-11. In contrast, for the prospective cohort involving healthy participants, written informed consent was required and obtained under approval KSVGH22-CT9-12.

Patients and study design

A retrospective review of electronic medical records was conducted for patients with SSNHLV who received high-dose ste-roid therapy as their initial treatment at a tertiary medical facility in Taiwan between December 2016 and April 2023. Exclusion criteria included incomplete VAS or Dizziness Handicap Inventory (DHI) data, untreated hearing loss lasting 14 days or longer, retrocochlear pathology, other otologic conditions causing vertigo, or anterior inferior cerebellar artery infarction evident on magnetic resonance imaging. A prospective cohort of healthy volunteers recruited from our hospital staff, without any systemic diseases, otologic diseases, history of head trauma, or vestibular disorders, was enrolled in Taiwan between November 2022 and April 2023. The study group consisted of a total of 48 patients, and the control group comprised 38 healthy individuals who underwent vHITs.

Standard treatment for SSNHL patients consisted of a 14-day course, including 3–4 days of tapering, with either oral prednisolone (1 mg/kg/day, maximum dose of 60 mg/day) or intravenous dexamethasone (5 mg/mL b.i.d.). Patients who did not achieve full hearing recovery received salvage intratympanic dexamethasone injections (5 mg/mL) twice weekly for 2 weeks.

Data collection

In this retrospective study, initial patient assessments included pure tone audiometry (PTA), word recognition scores (WRS), VAS, and DHI evaluations. Weekly monitoring of PTA, WRS, and VAS was performed for 2 months following treatment. For VAS evaluation, the patient was asked to rate the subjective severity of vertigo on a scale from 0 to 10. Vestibular laboratory tests, including the caloric test, cervical and ocular vestibular myogenic evoked potentials (c- and o-VEMP), and vHIT, were completed within 3 days. The primary outcome was the vertigo resolution at 2 weeks and 2 months, which defined as the VAS equal to zero.

Video head impulse test

The ICS Impulse (Otometrics) was utilized to conduct vHIT following the Halmagyi et al.’s recommended protocol [21]. VOR gain was defined as the proportion of eye velocities to peak head velocities. The examiner rapidly and unpredictably rotated the patient’s head within the plane of each SCC pair, approximately 5° in roughly 100 ms. For each of the six SCCs, tests were conducted more than ten times. The asymmetry value was accurately calculated based on contralateral plane pairs, such as right horizontal to left horizontal, left anterior to right posterior, or right anterior to left posterior, using normalized relative gain asymmetry [22,23]. Abnormal results were identified if the vHIT outcomes exceeded the mean and standard deviation of VOR gains and asymmetry values among healthy participants in our hospital.

WCA and magnitude-squared wavelet coherence

The wavelet transform was applied to evaluate the time-frequency plot of paired eye and head velocities for abrupt time series data, capturing variations in power across different frequencies [24]. After retrieving the time series data of eye and head velocities from ICS Impulse via OtoSuiteV 4.1 (GN Otometrics, Natus), MATLAB R2019b (MathWorks, Inc.) was utilized to characterize the cross wavelet power, defined as the area of a time-frequency plot with high coherent power, obtained from wavelet processing of the autocorrelation function. Torrence and Compo [25] defined and adapted the WCA of two time series data as Rn2( s)=|s( s−1 WnXY( s))|2 s( s−1| WnX( s)|2)⋅s( s−1| WnY( s)|2). The smoothing operator was denoted as S, shere S(W)=S_scale (S_time(W_n(s))). S_scale and S_time stood for the smoothing procedure on the wavelet scale and time axes, respectively. To quantify the correlation between the frequency spectra of two paired abrupt signals, Rn2( s) signifies magnitude-squared wavelet coherence (MSWC), measuring correlation between eye and head velocities in vHIT across various frequency bands, indicating anticipated high common power in cross-spectral analysis. The highest frequency in the wavelet coherence plot with MSWC ≥ 0.9 throughout the entire time period was termed the coherent frequency [26]. The algorithm for WCA of vHIT applied in this study, along with detailed footnotes for each step, has been made publicly available on GitHub (https://github.com/rodafall/WCA_for_vHIT).

Statistical analysis

The statistical software SPSS version 22 (IMB Corp.) was used for all computations. Continuous data were evaluated using oneway analysis of variance, while categorical variables were compared employing Fisher’s exact or Pearson’s chi-square tests. The backward stepwise approach for multivariate analysis was used to identify independent variables. Statistical significance was set at a two-sided P-value of 0.05.

RESULTS

In this study, we included 48 patients diagnosed with SSNHLV and 38 healthy subjects for analysis. The mean ages were 53.66 (standard deviation [SD], 14.17) for the patient group and 48.37 (SD, 16.84) for the control group. The gender distribution was 43.8% male (21 individuals) and 56.3% female (27 individuals) in the patient group, and 47.4% male (18 individuals) and 52.6% female (20 individuals) in the control group. Demographic characteristics and vHIT results for both the study and control groups are presented in Table 1. The average VOR gains for the horizontal, anterior, and posterior SCCs were 0.95, 0.89, and 0.83 in the study group, compared to 1.01, 0.96, and 0.95 in the control group, respectively. The mean coherent frequencies were 5.27 Hz, 6.11 Hz, and 5.10 Hz in the study group and 6.54 Hz, 6.88 Hz, and 7.08 Hz in the control group for the horizontal, anterior, and posterior SCCs, respectively. In the study group, 22.9% of patients (n=11) achieved complete remission of vertigo after 2 weeks of treatment, and 62.5% (n=30) achieved complete remission after 2 months.

Table 2 displays the factors significantly associated with early vertigo recovery at 2 weeks, as identified in the univariate analysis. These factors include the coherent frequencies in the horizontal SCC (P=0.049), the posterior SCC (P=0.001), the mean value (P=0.033), and the minimal value (P=0.002) of the coherent frequencies across all three SCCs. Following a backward stepwise approach in the multivariate analysis, the minimal value of the coherent frequencies among the three SCCs emerged as the independent factor predicting early vertigo remission at 2 weeks (hazard ratio [HR], 2.040; 95% CI, 1.776–2.304) (Table 3). In terms of vertigo recovery at 2 months, the univariate analysis identified several significant factors. These included VOR abnormality in the posterior SCC (P=0.013), VOR gains in both the horizontal and posterior SCCs (P=0.001 and P=0.004, respectively), total and overt saccades in the horizontal SCC (P=0.011 and P=0.006, respectively), and both the mean and minimal VOR gain values across the three SCCs (P=0.001 and P=0.003, respectively). Additionally, the coherent frequencies in the horizontal SCC (P=0.006), the anterior SCC (P=0.026), and the posterior SCC (P=0.003), along with the mean value (P<0.001) and the minimal value (P<0.001) of the coherent frequencies of all three SCCs combined, were also statistically significant factors in vertigo remission. A comparison of vHIT results for vertigo recovery at 2 weeks and 2 months is illustrated in Figs. 1 and 2.

DISCUSSION

Synopsis of key findings

This study identified the minimum value of coherent frequencies across all three SCCs as an independent factor associated with early remission of vertigo in patients with SSNHLV undergoing 2 weeks of high-dose steroid treatment. Increased coherent frequencies in the horizontal and posterior SCCs were associated not only with early recovery of vertigo at 2 weeks but also with a higher remission rate at 2 months. WCA of the vHIT in the time-frequency domain may provide a more comprehensive approach to predicting the prognosis of vestibular symptoms than analysis in the time domain alone. By leveraging the high cross-spectral resolution of transient and non-static signals, power spectrum wavelet coherence plots could be used to enhance vHIT interpretation.

Strengths of the study

To the best of our knowledge, this study may be the first to apply WCA to vHIT for assessing vestibular prognosis in patients with SSNHLV. Introducing this innovative method into the vestibular laboratory could enhance the resolution of synchrony for VOR signals. Additionally, previous research on prognostic factors for vestibular recovery in SSNHLV is scarce. Our study concentrated on a specific cohort of SSNHLV patients who received standard high-dose steroid treatment and assessed the impact on SCCs using both objective vHIT and self-reported vertigo symptom scales.

Comparisons with other studies

Coherence analysis has been predominantly employed in biomedical signal processing, including applications in neurology (EEG), cardiology (heart rate variability from ECG), and gynecology (intrauterine pressure) [27]. Studies on sensorimotor reflexes similar to the VOR, including the postural proprioceptive reflex, Achilles tendon stretch reflex, and corticomuscular coherence in stimulation-evoked hand muscle contraction, have highlighted the advantages of using frequency/phase-discriminant and amplitude-independent coherence measures [28-30]. Compared to Fourier coherence, wavelet coherence offers improved time-frequency resolution, enabling it to more effectively track abrupt and episodic coherence between nonstationary neural signals [31,32]. Therefore, our study employed WCA for VOR signals in the vHIT.

Previous research has shown that the severity of certain neurological disorders correlates with frequency characteristics in coherence analysis of EEG [33-35]. Therefore, the WCA of vHIT might more sensitively determine the severity of vestibular damage compared to time series data analysis in vHIT. In our prognostic analysis of VOR gain using time series analysis, the horizontal and posterior SCC VOR gains (P=0.001 and P=0.004) and the mean and minimal VOR gains across all three SCCs (P=0.001 and P=0.003) were significantly associated with vertigo recovery at 2 months, but not with early recovery at 2 weeks. However, the prognostic analysis using WCA at 2 weeks and 2 months revealed that coherent frequencies in the horizontal SCC (P=0.006 and P=0.049), posterior SCC (P=0.003 and P=0.001), mean value (P<0.001 and P=0.033), and minimal value (P<0.001 and P=0.002) of all three SCCs combined were significantly associated with symptom remission at 2 months and also correlated with early recovery of vertigo at 2 weeks. Although VOR gain and saccades may be associated with coherent frequency, the coherent frequency in the vHIT’s WCA demonstrated superior prognostic value compared to individual VOR gain or saccades due to its frequency-discriminant power. Fig. 3 illustrates the MSWC varying with changes in amplitude and frequency, and a patient from our cohort who did not experience vertigo recovery after 2 weeks of treatment. This patient exhibited a normal VOR gain (1.13), several saccades, and a notably lower coherent frequency (3.36 Hz) in the posterior SCC. The MSWC quantifies the correlation between the frequency spectra of paired head and eye velocities in the vHIT. Since the head motion frequency in vHIT is fixed, impaired VOR or catchup saccades, which alter the eye motion frequency, could result in a lower coherent frequency.

Investigating the prognostic potential of vHIT in SSNHLV, especially in cases indicative of labyrinthitis due to poor vestibular recovery, is critically important [36]. For prognostic assessment, previous studies have established that both the DHI and VAS are significantly correlated and validated tools for assessing symptom severity during the acute phase of unilateral vestibulopathy [37,38]. The VAS offers advantages such as ease of use, rapid assessment, and the ability to accurately reflect subjective experiences. Earlier research has shown that lower VOR gains in vHIT are significantly associated with poorer vestibular recovery, as evaluated using DHI and VAS in cases of vestibular neuritis [12,39]. Although the recovery timeline for vertigo is similar in both SSNHLV and vestibular neuritis, the affected vestibular end organs differ markedly between the two conditions [40,41]. A recent study compared vHIT results between vestibular neuritis and SSNHLV. The rates of abnormality in vestibular neuritis for posterior, horizontal, and anterior SCCs were 29.03%, 77.42%, and 32.26%, respectively, while in SSNHLV, they were 52.63%, 21.05%, and 5.26%, respectively [42]. Our study, which focused exclusively on a cohort of SSNHLV patients, yielded similar findings. The posterior SCC was the most affected (45.8%, n=22), followed by the horizontal SCC and the anterior SCC, both at 18.8% (n=9 each), as determined by VOR gains and gain asym-metries within paired SCCs. The average VOR gain of the posterior SCCs in our study group was notably lower (0.83±0.29) compared to that of the anterior SCC (0.89±0.25) and the horizontal SCC (0.95±0.22). The observed results, particularly the abnormal VOR gains in the posterior SCC, are consistent with previous research on vHIT data in SSNHLV patients. These findings likely reflect the distinct pathogenic mechanisms underlying the two diseases [40].

The vHIT assessed the function of SCCs within the physiological frequency range of 5–7 Hz [43]. During time-frequency analysis in the study group, the average coherent frequencies from lowest to highest were observed in the posterior SCC (5.10±2.43), the horizontal SCC (5.27±2.00), and the anterior SCC (6.11±1.77). Both VOR functions in the posterior and horizontal SCCs were significantly more impaired than in the anterior SCC within the WCA. Among the 11 patients with coherent frequencies lower than 5 Hz in both the posterior and horizontal SCCs in our cohort, none experienced early recovery of vertigo at 2 weeks (0%), and only three patients achieved vestibular recovery at 2 months (27.3%). These results were substantially lower than the average rates for early (29.0%) and late (83.9%) recovery in the total cohort. Although the etiology of SSNHLV remains debated, the higher rates of impaired horizontal and posterior SCCs in SSNHLV as indicated by the WCA could suggest the involvement of perfusion territories of the common cochlear artery and the vestibulocochlear artery [44,45]. Further studies exploring the hypothesis of an inferior prognosis due to vascular events or poor steroid treatment delivery as a result of distal blood supply are warranted [46,47].

Previous studies that explored the relationship between vHIT results and vertigo prognosis typically focused on analyzing the VOR gain from individual SCCs or solely from the representative horizontal SCC [12,48,49]. In examining the damage to SCCs and vestibular prognosis in patients potentially suffering from labyrinthitis, our study found that a higher minimum coherent frequency across all three SCCs was associated with a 2.040-fold increase in the likelihood of earlier symptom resolution of vertigo at 2 weeks in patients with SSNHLV. The prognostic accuracy of vHIT results may improve by concentrating on the most severely affected SCC rather than assessing each SCC individually.

Limitations of the study

This research had several limitations. First, it was a retrospective study conducted at a single tertiary referral hospital, which limited the participant pool. Second, our study primarily assessed subjective vestibular remission using the VAS as the endpoint during follow-ups. Although previous research has shown that both the DHI and VAS are significantly correlated and validated for monitoring subjective recovery during the acute phase of unilateral vestibulopathy, future prospective studies should include both DHI and vHIT in follow-up evaluations to gain a deeper understanding of categorized vertigo recovery and changes in WCA of vHIT. Lastly, for clinical application, determining and exploring the coherent frequency cut-off value associated with early vertigo relief, as well as the time-frequency plots, could benefit from a larger sample size in future studies.

Conclusions

In patients with SSNHLV, the highest minimal coherent frequency among the three SCCs in vHIT strongly predicts earlier recovery from vertigo. The WCA of vHIT, due to its superior time-frequency resolution, may be more sensitive than time series analysis in evaluating vertigo prognosis. When analyzing vertigo remission outcomes based on vHIT results, the WCA of the most severely affected SCC could provide more accurate and effective assessments than examining each SCC individually. Incorporating frequency-specific WCA into routine vHIT assessments could lead to the development of more targeted therapeutic approaches in the future.

HIGHLIGHTS

▪ The presence of labyrinthitis leads to inferior quality of life due to prolonged vestibular symptoms experienced by patients with sudden sensorineural hearing loss with vertigo.

▪ Novel wavelet coherence analysis quantifying the degree of correlation between eye and head velocities across various frequencies in the video head impulse test revealed significant associations between coherent frequencies in semicircular canals and early vertigo remission.

▪ The higher minimal coherent frequency among all three semicircular canals was the independent predictor of vertigo relief in patients with sudden sensorineural hearing loss with vertigo was.

▪ Wavelet coherence analysis in video head impulse test demonstrated enhanced sensitivity for predicting vertigo prognosis compared to traditional time series analysis methods in patients with sudden sensorineural hearing loss.

CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

Notes

AUTHOR CONTRIBUTIONS

Conceptualization: SCL, CWL. Data curation: SCL, MYL, BHK, YSL, YHL, CYY, PSL, CWL. Formal analysis: SCL. Investigation: SCL, CWL. Methodology: SCL, CWL. Project administration: SCL, CWL. Resource: SCL. Supervision: CWL. Validation: CWL. Visualization: SCL. Writing–original draft: SCL. Writing–review & editing: SCL, CWL. All authors read and agreed to the published version of the manuscript.

ACKNOWLEDGMENTS

This study was partly supported by the Kaohsiung Veterans General Hospital (grant No. VGHKS112-046).

Fig. 1.

Video head impulse test results depicting vertigo recovery at the 2 weeks by (A) coherent frequency and (B) vestibulo-ocular reflex (VOR) gain. SCC, semicircular canal.

Fig. 2.

Video head impulse test results depicting vertigo recovery after 2 months by (A) coherent frequency and (B) vestibulo-ocular reflex (VOR) gain. SCC, semicircular canal.

Fig. 3.

(A) Illustration of the magnitude-squared wavelet coherence (MSWC) varying with changes in amplitude and frequency. (B-D) A patient with no recovery of vertigo after 2 weeks of treatment demonstrated normal vestibulo-ocular reflex (VOR) gain (1.13), several compensatory saccades, and an evidently lower coherent frequency (3.36 Hz) in the posterior semicircular canal (SCC). (A) MSWC diminished with inconsistent amplitudes or frequencies in paired signals. (B) Horizontal SCC: VOR gain=1.17 and coherent frequency=6.85 Hz. (C) Anterior SCC: VOR gain=1.47 and coherent frequency=8.38 Hz. (D) Posterior SCC: VOR gain=1.13 and coherent frequency=3.36 Hz.

Table 1.

Comparison of demographics and vHITs in patients with sudden sensorineural hearing loss with vertigo and healthy individuals

Variable	Study group (n=48)	Control group (n=38, 76 ears)	P-value
Age (yr)	53.66±14.17	48.37±16.84	0.126
Sex			0.738
Male	21 (43.8)	18 (47.4)
Female	27 (56.3)	20 (52.6)
vHIT of the horizontal SCC
VOR gain	0.95±0.22	1.01±0.13	0.076
Coherent frequency	5.27±2.00	6.54±0.98	<0.001
Total saccade	48.92±36.59	23.89±28.56	<0.001
Covert saccade	6.77±10.14	4.80±10.16	0.327
Overt saccade	43.88±36.15	19.98±25.40	<0.001
vHIT of the anterior SCC
VOR gain	0.89±0.25	0.96±0.14	0.068
Coherent frequency	6.11±1.77	6.88±0.99	0.010
Total saccade	4.44±10.73	7.52±12.42	0.178
Covert saccade	3.40±10.28	6.95±11.57	0.101
Overt saccade	1.02±3.10	0.82±4.17	0.786
vHIT of the posterior SCC
VOR gain	0.83±0.29	0.95±0.12	0.012
Coherent frequency	5.10±2.43	7.08±0.85	<0.001
Total saccade	23.73±28.88	6.16±13.11	<0.001
Covert saccade	5.58±10.07	4.71±13.07	0.708
Overt saccade	18.94±29.11	1.45±3.88	<0.001
Caloric test abnormality	30 (62.5)	NA	NA
c-VEMP abnormality	20 (41.7)	NA	NA
o-VEMP abnormality	14 (29.2)	NA	NA

Values are presented as mean±standard deviation or number (%).

vHIT, video head impulse test; SCC, semicircular canal; VOR, vestibulo-ocular reflex; c-VEMP, cervical vestibular myogenic evoked potential; o-VEMP, ocular vestibular myogenic evoked potential.

Table 2.

Demographic data and univariate analysis of recovery of vertigo in patients with sudden sensorineural hearing loss with vertigo (n=48)

Variable	2-Week recovery			2-Month recovery
Variable	Yes (n=11)	No (n=37)	P-value	Yes (n=30)	No (n=18)	P-value
Age (yr)	57.7±7.8	52.5±15.4	0.287	52.5±14.4	55.5±14.0	0.483
Sex			0.498^a)			0.940
Male	6 (54)	15 (40)		13 (43)	8 (44)
Female	5 (46)	22 (60)		17 (57)	10 (56)
CCIS			1.000^a)			0.711^a)
0–1	9 (82)	30 (81)		25 (83)	14 (78)
≥2	2 (18)	7 (19)		5 (17)	4 (22)
Initial VAS	5.1±2.0	5.9±2.6	0.335	5.2±2.1	6.6±2.8	0.073
Initial DHI	49.1±25.1	48.2±23.0	0.914	44.1±23.8	55.7±20.8	0.094
Caloric test abnormality	9 (82)	21 (57)	0.171^a)	16 (53)	14 (78)	0.090
c-VEMP abnormality	4 (36)	16 (43)	0.741^a)	10 (33)	10 (56)	0.131
o-VEMP abnormality	4 (36)	10 (27)	0.708^a)	7 (23)	7 (39)	0.251
vHIT of the horizontal SCC
Abnormality	1 (9)	8 (22)	0.662^a)	3 (10)	6 (33)	0.063^a)
Coherent frequency	6.3±1.2	5.0±2.1	0.049	6.0±1.4	4.1±2.3	0.006
VOR gain	1.0±0.1	0.9±0.2	0.293	1.0±0.2	0.8±0.2	0.001
Total saccade	44.4±33.1	50.3±37.9	0.643	38.7±32.5	65.9±37.6	0.011
Covert saccade	5.0±7.5	7.3±10.8	0.515	6.0±10.3	8.0±10.0	0.521
Overt saccade	39.4±29.1	45.2±38.3	0.642	33.0±30.9	61.9±37.8	0.006
vHIT of the anterior SCC
Abnormality	1 (9)	8 (22)	0.662^a)	5 (17)	4 (22)	0.711^a)
Coherent frequency	6.3±1.4	6.1±1.9	0.690	6.6±1.4	5.3±2.1	0.026
VOR gain	1.0±0.3	0.9±0.2	0.307	0.9±0.3	0.8±0.2	0.077
Total saccade	10.6±19.9	2.6±5.0	0.213	5.9±13.1	2.0±3.9	0.227
Covert saccade	8.9±19.6	1.8±4.4	0.256	4.9±12.7	0.9±2.7	0.104
Overt saccade	1.6±3.9	0.8±2.9	0.459	1.0±3.1	1.1±3.2	0.878
vHIT of the posterior SCC
Abnormality	3 (27)	18 (49)	0.304^a)	9 (30)	12 (67)	0.013
Coherent frequency	6.6±1.1	4.7±2.5	0.001	5.9±2.1	3.8±2.4	0.003
VOR gain	0.9±0.2	0.8±0.3	0.299	0.9±0.3	0.7±0.2	0.004
Total saccade	22.2±23.2	24.2±30.6	0.842	19.5±23.7	30.8±35.5	0.242
Covert saccade	9.9±8.9	4.3±10.1	0.105	7.3±11.1	2.8±7.5	0.136
Overt saccade	12.3±21.8	20.9±30.9	0.393	12.5±22.0	29.7±36.4	0.082
Mean coherent frequency	6.4±1.0	5.2±1.7	0.033	6.1±1.1	4.4±1.7	<0.001
Minimal coherent frequency	5.6±1.1	3.6±2.0	0.002	4.9±1.9	2.7±1.4	<0.001
Mean VOR gain	1.0±0.2	0.9±0.2	0.194	1.0±0.2	0.8±0.2	0.001
Minimal VOR gain	0.8±0.2	0.7±0.2	0.100	0.8±0.2	0.6±0.2	0.003

Values are presented as mean±standard deviation or number (%).

CCIS, Charlson comorbidity index score; VAS, visual analog scale; DHI, Dizziness Handicap Inventory; c-VEMP, cervical vestibular myogenic evoked potential; o-VEMP, ocular vestibular myogenic evoked potential; vHIT, video head impulse test; SCC, semicircular canal; VOR, vestibulo-ocular reflex.

^a) Fisher’s exact test.

Table 3.

Multivariate analysis with the backward stepwise method for recovery of vertigo at the 2-week mark (n=48)

Variable	Hazard ratio (95% CI)	P-value
Coherent frequency of the horizontal SCC	-	0.899
Coherent frequency of the posterior SCC	-	0.910
Mean coherent frequency	-	0.194
Minimal coherent frequency	2.040 (1.776–2.304)	0.007

SCC, semicircular canal.

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