|Year : 2019 | Volume
| Issue : 3 | Page : 612-617
Cervical vestibular evoked myogenic potential and video head impulse test findings in benign paroxysmal positional vertigo
Mohammed Elgohary, Iman Eladawy, Shaimaa Elshahat
Audiovestibular Unit, ENT Department, Faculty of Medicine, Al-Zaharaa University Hospital, Al-Azhar University, Cairo, Egypt
|Date of Submission||15-Jul-2019|
|Date of Decision||10-Jun-2019|
|Date of Acceptance||16-Jul-2019|
|Date of Web Publication||10-Feb-2020|
MD of Audio Vestibular Medicine, Lecturer of Audio Vestibular Medicine, Al-Azhar Faculty of Medicine for Girls 6 Elkhabeer Street Elzaytoon Cairo
Source of Support: None, Conflict of Interest: None
Background Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo. Approximately 20% of all dizziness is due to BPPV.
Objective To assess the peripheral vestibular function in a group of patients with BPPV versus group of normal population by using the cervical vestibular evoked myogenic potential (cVEMP) and video head impulse test (vHIT).
Materials and methods This is a comparative cross-sectional study. A total of 60 individuals [20 apparently healthy controls (40 ears) and 40 patients with BPPV, who initially were diagnosed by Dix–Hallpike test/supine roll test], were included in the study. All participants gave their written consent before participation in the study. The control as well as the study group was subjected to basic audiological evaluation and vestibular evaluation.
Results Regarding the vHIT, there was a statistically significant difference between control and study groups regarding the left vertical canal gain and the asymmetry (P<0.005). There was a highly statistical significant difference in cVEMP latencies, amplitude, and asymmetry between patients with BPPV and controls (P<0.001). There was a significant difference in latencies as well as amplitude of both P13 and N23 between the affected ear and the nonaffected ear in patients with unilateral primary BPPV.
Conclusion Significant abnormal cVEMP in BPPV may indicate saccular involvement in the BPPV pathophysiology, which needs more research to prove or disprove it. Abnormal vHIT gain and asymmetry of the left vertical canal only needs more research in a large sample size.
Keywords: benign paroxysmal positional vertigo, cervical vestibular evoked myogenic potential, video head impulse test
|How to cite this article:|
Elgohary M, Eladawy I, Elshahat S. Cervical vestibular evoked myogenic potential and video head impulse test findings in benign paroxysmal positional vertigo. Sci J Al-Azhar Med Fac Girls 2019;3:612-7
|How to cite this URL:|
Elgohary M, Eladawy I, Elshahat S. Cervical vestibular evoked myogenic potential and video head impulse test findings in benign paroxysmal positional vertigo. Sci J Al-Azhar Med Fac Girls [serial online] 2019 [cited 2020 Oct 24];3:612-7. Available from: http://www.sjamf.eg.net/text.asp?2019/3/3/612/278038
| Introduction|| |
Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo; ∼20% of all dizziness is due to BPPV . It is a clinical syndrome characterized by brief recurrent episodes of vertigo triggered by changes in head position with respect to gravity . One of the most accepted theory of its pathophysiology is that it occurs when some of the calcium carbonate crystals (otoconia) are normally embedded in gel in the utricle become dislodged and migrate into one or more of the three fluid-filled semicircular canals, where they are not supposed to be .
Most cases of BPPV are found in isolation and are called ‘primary’ BPPV. This type accounts for ∼50–70% of cases. The other type is called secondary BPPV, and the most common cause of ‘secondary’ BPPV is head trauma, representing 7–17% of all BPPV cases ,.
Vestibular evoked myogenic potential (VEMP) is an electrical potential difference recorded from muscle in response to vestibular stimulation. When the VEMP is recorded from the sternocleidomastoid muscle, it is referred to as cervical vestibular evoked myogenic potential (cVEMP) .
Akkuzu et al.  found a significantly higher frequency of abnormal VEMPs in BPPV compared with the control group. They had an indication, although not statistically significant, that patients with BPPV with abnormal recordings are those with a history of more resistant positional vertigo, leading them to suppose that chronicity of the disease may imply saccular degeneration in addition to the expected utricular degeneration, and state that further studies should include this assumption.
The head impulse test is an important test for examining unilateral vestibular hypofunction. The video head impulse test (vHIT) is a tool that allows recordings of eye and head movements to determine the gain of vestibule-ocular reflex (VOR), and it detects the presence and measures the amplitudes of covert and overt catch-up saccades. The vHIT is more sensitive and specific than the clinical bedside head impulse test .
There are no enough data available regarding the effect of BPPV on vHIT and cVEMP outcome; therefore, we are looking forward to study those findings in BPPV.
| Aim|| |
The following are the aims of the study:
- To compare the cVEMP findings in normal population and patients with BPPV.
- To detect the vHIT findings in patients with BPPV.
| Materials and methods|| |
This study was a comparative case–control study. It involved 60 individuals. There were 20 apparently healthy controls (40 ears), and their age ranged from 20 to 60 years with neither hearing nor vestibular problem. They were chosen from friends and relatives of patients attending the Audiovestibular Unit of Al-Zahraa Hospital. The study group consists of 40 patients with BPPV previously diagnosed by Dix–Hallpike/supine roll test. Patients were recruited from the Audiovestibular Unite, ENT Department Al-Zahraa University Hospital, in the period from May 2016 to May 2018. All participants gave their written consent before participation in the study. An approval from the ethical review board of Al-Azhar Faculty of Medicine (Girls) for this work was obtained in 2016.
The following audiological evaluations were done:
- Full history taking.
- Otological examination.
- Basic audiological tests.
Before testing, patients were instructed to stop any medication that may influence their balance for a period of 48 h.
- Vestibular office test: It includes the following:
- Evaluation of the occular motor system: it includes smooth pursuit, saccades, optokinetic oculomotor test, and gaze tests.
- Evaluation of VOR: It includes head shaking nystagmus, head thrust test, and the alternate cover test.
- Evaluation of vestibulo-spinal reflex: it includes Romberg test, past pointing test, tandem walking, and Fukuda stepping test.
- Dix–Hallpike testing.
- Supine roll test.
- EyeSeeCam System (Biologic Navigator PRO by Interacoustics Company, Denimark) was used in the lateral, left anterior right posterior and right anterior left posterior semicircular canal (SCC) planes. Before testing, we ensured that the patients managed an adequate range of unrestricted, painless angular head rotation. The patient was seated 1.5 m directly in front of a fixation target at eye level. Video google (VOG) goggles were fitted tightly to the patient’s head to reduce goggle slippage. The camera was focused on the eye while the patient fixated on the target. Participants were instructed to fixate on the dot located on the wall. The head was tilted anteriorly by 30°; 6–10 unpredictable head rotations in both directions were performed from a central head position, in the horizontal plane (head rotation 15–20°, duration 150–200 ms, and peak velocity>150°/s), with unpredictable timing and direction to record horizontal VOR.
- For the vertical planes, the patient’s head was rotated 45° to the right (left anterior right posterior test) or left (right anterior left posterior test) while fixating on the target out of the corner of the eye to allow the gaze to be in the plane of the tested canals. Brief, abrupt, forward and backward head impulses, at velocities of 100–150°/s, were then given in the plane of the vertical canals allowing stimulation of the anterior and the posterior SCCs, correspondingly.
- The average gain of the VOR responses for each canal and the gain asymmetry were calculated. Gain is expressed in terms of eye velocity/head velocity. Gain asymmetry was calculated using a general formula :
Testing of cVEMPs was performed using an auditory evoked response apparatus (Biologic Navigator PRO). The skin was prepared, and surface cup disc electrodes were symmetrically placed, over midpoint of the sternocleidomastoid muscle bilaterally, with active electrode on the ipsilateral muscle, reference electrode on the sternal notch, and ground electrode on the contralateral sternomastoid muscle. The muscle must be contracted to elicit the response, so the patients were instructed to rotate their heads to the opposite side of the stimulated ear as much as possible. The response of the ipsilateral sternocleidomastoid muscle (SCM) muscle to monaural stimuli, 500 Hz tone-bursts, with 1 ms rise–fall time and 5 ms plateau time at 95 dBnHL, was recorded. All stimuli were presented via insert phones at a repetition rate of 5.1/s. The responses of 120 stimuli were recorded and averaged per trial. EMG signals were amplified and band-pass filtered from 10 to 1000 Hz. The first positive deflection was marked as P13 and the first negative deflection after P13 was marked as N23. The latencies and amplitudes of these waves were calculated and recorded. The cVEMPs asymmetry ratio was calculated according to the following formula :
Data were collected, revised, coded, and entered to the statistical package for the social sciences (IBM SPSS) version 23. The quantitative data were presented as mean, SD, and ranges. The qualitative variables were presented as number and percentages. The comparison between groups regarding qualitative data was done by using χ2-test. The comparisons between two independent groups with quantitative data and parametric distribution were done by using independent t-test.
The confidence interval was set to 95% and the margin of error accepted was set to 5%.
So, the P value was considered significant as the following:
P value more than 0.05: nonsignificant, P value less than 0.05: significant, and P value less than 0.01: highly significant.
| Results|| |
There was a statistically significant difference between control and study groups regarding the left vertical canals [left posterior (LP) and left anterior (LA)] gain and asymmetry.
The significant difference is owing to abnormal results in secondary BPPV.
There was no statistical significant difference between control and primary groups.
There was a statistical significant difference between control and primary groups.
There was no statistically significant difference between control and primary group test results.
Cervical evoked myogenic potential results
There was a highly statistically significant difference in P13 latency between the normal and the secondary BPPV, and also there was a statistically significant difference in the P13 amplitude in both primary versus normal and secondary versus normal.
There was a statistical significant difference regarding all the cVEMP parameters between normal versus primary BPPV, as well as normal versus secondary BPPV.
There was a statistically significant difference regarding amplitude of both P13 and N23.
| Discussion|| |
BPPV is the most common cause of vertigo in patients with vestibular disorders . Strupp et al.  reported that among 17718 patients evaluated at their centers, the most common diagnosis was of BPPV at 17.7% (3036). In another research, data collected from 4294 patients with vertigo from 13 countries over 28 months indicated that 26.9% had BPPV .
In this study, 22.2% of the patients with BPPV were identified to have secondary BPPV, presumably owing to head trauma. Acute unilateral vestibular loss and Ménière’s disease have been found in 15 and 10%, respectively. All patients had basic audiological evaluation, including pure tone threshold (dBHL) and speech discrimination (WDS%), which came as normal except in 17 patients. According to configuration of the hearing loss, there were three patients with mild to moderate low-frequency hearing loss and 14 patients with moderate high-frequency hearing loss. All patients in control and study groups have got normal middle ear function and intact acoustic reflexes as expected with the hearing level.
In this study, BPPV owing to right ear involvement was detected in 26 (65%) patients, whereas the left ear BPPV was counted in 11 (27.5%) patients. The bilateral affection was detected only in three (7.5%) patients. These results agreed with a study performed by Brevern et al. .
In this study, 36 of the 40 (90%) patients had posterior canal BPPV, four cases had horizontal canal BPPV (10%), and there was no cases with anterior canal involvement. These results relatively agree with Ruckenstein  and Moon et al. . They reported that the posterior semicircular canal is the most frequent canal to be affected in 61–97% of BPPV cases, because the posterior canal is the most dependent canal.
Video head impulse test results
In this study, vHIT mean gain of the lateral SCC in the control group was 1.02±0.16 and 0.97±0.12, the mean gain of the anterior SCC was 1.02±0.18 and 1.00±0.24, and the mean gain of the posterior canal was 1.00±0.18 and 0.98±0.21, as shown in [Table 1]. This result agrees with Qiongfeng et al.  who found that the VOR gain mean, especially the horizontal value, was very close to the theoretical value of 1.
|Table 1 Mean and SD of horizontal and vertical gains and asymmetric ratios of the video head impulse test|
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In this study, we found that the mean gain and asymmetry of group 2 (primary BPPV) were within normal as in [Table 1]. This can be explained as the disease is mechanical in origin and will not affect the VOR gain. These results agree with Halmagyi and MacDougall  and Alhabib and Saliba . Meanwhile in group 3 (secondary BPPV), four patients showed within normal gain and asymmetry, and six patients showed abnormal gain and asymmetry owing to history of Meniere’s disease and vestibular neuritis. This was approved by post-hoc test in [Table 2], which showed that the significant difference is owing to abnormal results in group 3.
In this study, on comparing the vHIT gain and symmetry of affected right post canal with the control group, we found that all were within normal range ([Table 3]). However, on comparing the gain and symmetry of left post canal with our control group, there was a statistically significant difference between the two groups ([Table 4] and [Table 5]). This agrees with Qiongfeng et al.  who stated that patients with BPPV may show an acute semicircular canal function change, but may only be a brief functional change, but why it was found only on the left there is nothing to explain it in literatures, and it needs more research on a bigger sample.
|Table 3 Comparison between affected right posterior canal in primary group and normal right posterior canal in control group regarding gain and asymmetric ratio|
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|Table 4 Comparison between affected left posterior canal in the primary group and normal left posterior canal in the control group regarding gain and asymmetric ratio|
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|Table 5 Comparison between affected posterior canal right and left in the primary group and normal posterior canal in the control group as regards, gain and asymmetric ratio|
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Cervical vestibular evoked myogenic potential results
In this study, we found abnormal cVEMP responses in 30% of patients with BPPV compared with 5.4% abnormality in normal participants. This agrees with the previous work of Akkuzu et al. . The mean latencies of P13 and N23 in the control participants were 15.02±1.08 and 24.87±2.3 ms, respectively, as shown in [Table 6]. These findings agree with Colebatch et al.  and Cheng and Murofushi .
|Table 6 Post-hoc by LCD test shows significance in cervical evoked myogenic potential test of the nonaffected ear|
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In this study when comparing the cVEMP parameters in the BPPV side with the control group including P13 latency and amplitude and N23 latency and amplitude, the study revealed that there is a significant difference between patients with BPPV and controls along the two parameters ([Table 6] and [Table 7]). These results agree with the study of Hong et al.  who stated that patients with BPPV show abnormal cVEMPs finding, with significantly prolonged P13 and N23 latencies and lower amplitude compared with their control group. Moreover, the abnormal findings are irrespective to the involved semicircular canal. The researcher went on to suggest a possible role of the utricle in the VEMP reflex arc 
|Table 7 Post-hoc by LCD test to show significance in cervical evoked myogenic potential test of the affected ears|
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In this study, comparing cVEMP parameters in the ear affected with BPPV and the nonaffected ear in same group including P13 latency and amplitude, and N23 latency and amplitude, the study revealed that there is statistical significant difference between both sides including reduced amplitude ([Table 8]). This agrees with Yang et al. , who found that cVEMP amplitudes are decreased in patients with BPPV, which may signify neuronal degenerative changes in the macula of the saccule.
|Table 8 Comparison of cervical evoked myogenic potential test results between affected and nonaffected ear in primary benign paroxysmal positional vertigo|
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Longo et al.  stated that the prolonged latencies that found can be correlated with age. Several studies have shown a prolongation in cVEMP latencies in patients over the age of 50–60 years, indicating that aging affects the human saccular and/or inferior vestibular nerve function .
| Conclusion|| |
- History and the physical examination (Dix–Hallpike and Supine Roll test) are considered the gold standard for the diagnosis of BPPV.
- vHIT is a complementary test for other vestibular tests, especially caloric test.
- Abnormal cVEMP parameters in BPPV may be due to saccular involvement or due to aging process.
- vHIT still needs further study to see the evolution of the VOR gain with the progression of the vestibular disease.
- Further studies of cervical and ocular VEMP are recommended in patients with BPPV to help in the assessment of the progress of BPPV.
- Cervical VEMP could be performed before and after BPPV rehabilitation exercise to detect the effect of rehabilitation exercises on the cVEMP parameters.
- A larger sample size is needed in future research.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]