The Role of Video Head Impulse Test (Vhit) in Diagnosing Benign Paroxysmal Positional Vertigo (BPPV)

Abstract

Benign paroxysmal positional vertigo (BPPV) is a common clinical disorder characterized by brief recurrent spells of vertigo often brought about by certain head position changes. General treatment for BPPV is by clinical examination by Dix–Hallpike maneuver, Video head impulse test (VHIT) is a novel test that enhances diagnostic opportunities and enables a clinician to precisely localize the site of vestibular disorders. This interested us to investigate its potential in diagnosis of BPPV.The aim of the present study is to assess the role of Video head impulse test (VHIT) in confirming the clinically diagnosed case of BPPV.All patients above the age of 18 years who were clinically diagnosed with BPPV underwent VHIT and results were correlated with clinical findings. Total 60 patients were studied in the period of 2016–2018.Among the 60 patients clinically diagnosed with BPPV, 41 were males and 19 were females. Majority of patients were in the age group of 51–60 years. Posterior canal is most commonly affected (97%) than anterior and lateral canals in BPPV. In unilateral posterior canal BPPV and bilateral posterior canal BPPV VOR (Vestibulo- ocular reflex) gains was reduced but were not statistically significant. Saccades were present only in 17 cases. There is no relationship between the presence of saccades, the canal involved and the side of the lesion.From the present study we conclude that the currently available equipment for VHIT is not useful in diagnosing BPPV. Also, strongly recommends advanced research on this to record minute changes in VOR gain.

Introduction

Vertigo and/or dizziness are very common complaints for general practitioners and otolaryngologists. Determining the right diagnosis can often be challenging because the presentation of specific vestibular diseases may vary widely. Till date, there is no gold standard investigation for the diagnosis of vertigo [1]. Benign paroxysmal positional vertigo (BPPV) is a commonly dealt disorder characterized by recurrent episodes of vertigo which is often aggravated with certain positional changes of the head. Patients usually complain of giddiness following certain head movements. The episodes of vertigo are brief, lasting only for about ten to thirty seconds. The diagnosis of BPPV is usually based on detailed history and clinical examination. It is confirmed by observing for paroxysmal positional nystagmus with the Dix–Hallpike manoeuver which results in torsional up beating nystagmus when the posterior canal is involved [2]. Introduction of newer techniques such as Video Head Impulse test [VHIT] enhances diagnostic opportunities and permits a clinician to meticulously localize the site of vestibular disorder. In video head impulse test, each semi-circular canal is stimulated physiologically (by movement), and the vestibulo-ocular reflexes are evaluated by the change in direction of eyes in relation to head movements [3, 4]. The aim of the present study is to assess the role of Video head impulse test (VHIT) in confirming the clinically diagnosed case of BPPV.

Materials and Methods

The study design is observational case study. Ethical clearance was taken from Institutional Ethics Committee. Patients aged 18 years or older with complaints of vertigo and who clinically diagnosed as BPPV were the study group. The study was conducted over a period of 2 years from October 2016 till September 2018. Consent for participation for the study was taken (Table 1).

Table 1.

Distribution of canal involvement in patients with clinically diagnosed BPPV

Clinically Diagnosed cases	Right posterior (DH + to right)	Left posterior (DH + to left)	Right anterior (yacovino pasitive)	Left lateral (supine roll test positive)	Bilateral (Right + left posterior)
Number	31	22	1	1	5
Percentage	52%	37%	1.5%	1.5%	8%

Inclusion and Exclusion Criteria

Patients aged 18 years or older and clinically diagnosed with BPPV were the study participants. Patients with restricted movement of the head (degenerative cervical spine), disordered eye mobility (oculomotor palsy), congenital nystagmus, with poor vision and on medication for BPPV for last 5 days were excluded from the study.

Study Design

All the patients presenting to the outpatient department of Otolaryngology Department with vertigo were evaluated. A detailed ENT examination was performed, including Dix-Hallpike test and other positional tests to arrive at a clinical diagnosis of BPPV.

Testing for posterior semicircular canal BPPV-Dix Hallpike Manoeuvre: The utility of Dix–Hallpike manoeuvre in diagnosing Posterior Canal BPPV was described in 1952 [5]. In peripheral vertigo, there is a latency of more than 2 s, and will resolve in less than a minute [6]. The participant is seated of the bed so that when he/she is made to lie supine the head is extended over the end of the table. The head is then turned 45º sideways, towards the ear being tested (position A). The patient is then swiftly and carefully brought back into the supine position with head extended almost 30º below the horizontal (position B). The examiner observes the participant’s eyes for nystagmus while the head is held in this position; nystagmus with brief latency (1–5 s) is observed that lasts for shorter duration i.e. typically < 30 s.

Testing for Lateral canal BPPV is achieved by performing the supine roll test. The patient is made to lie supine. Participants head is turned quickly sideways towards the side being tested. Horizontal nystagmus occurs which is geotropic in most of the cases, but it may be apogeotropic too in some cases. Compared with the vertical–torsional nystagmus of posterior canal BPPV, this nystagmus has a shorter latency and stronger intensity compared to the nystagmus occurring in posterior canal BPPV [6]. The straight head-hanging manoeuvre is used to diagnose anterior canal BPPV where the head is extended backwards to a head-hanging position of the end of the bed from seated to supine (Yacovino manoeuvre). Once the diagnosis of BPPV was made and documenting the canal involved, the participants underwent VHIT and the results were correlated with clinical findings. VOR gain and saccades were recorded. The results were recorded on a Microsoft Excel sheet.

Procedure of VHIT: VHIT was performed using ICS impulse system by Otometrics and Otosuite software. During VHIT, the participant was made to sit comfortably in a non-rotating chair. The participants were then asked to visualize a target at eye level on the wall at a distance of one meter. The examiner stands behind the subject and firmly holds the patients head using both hands and abruptly accelerates and then decelerates the head, moving the head rapidly at high speed and then stopping it. Care was taken not exceed 30 degrees in any direction of rotation. The Lateral canals are stimulated by rotating the head sideways and the RALP canals [Right Anterior and Left Posterior] and LARP [Left Anterior and Right Posterior] were stimulated in pairs.

Statistical Analysis

Descriptive analysis of qualitative traits (age, gender) was described using percentage analysis. The study results were statistically analyzed by the use of Fisher’s exact test and Kruskal–Wallis test. The test outcome was assumed to be statistically significant when P value was < 0.05.

Results

Out of 60 participants recruited in the study, 41 were males (68%) and 19 (32%) were females. The youngest patient was 19 years old and oldest was 75. Most of the participants were in the age group of 51–60 years (35%), followed by 41–50 years (25%). Least number of patients was in the age group of 18–30 years. Among the 60 clinically diagnosed BPPV, the right ear was involved in 32 (53%) cases and left ear was involved in 23 (39%) cases. Five (8%) patients had bilateral ear involvement where the Dix-Hallpike test was positive on both the sides with classical peripheral nystagmus.

The right posterior canal was the most common canal affected (52%) followed by left posterior canal (37%). Bilateral posterior canals were involved in 5 (8%) patients. Right anterior canal was involved in 1 (1.5%) case Left lateral canal was involved in 1 (1.5%) case.

Mean VOR gain was compared for all the six semi-circular canals. Ipsilesional and contralesional VOR gain was studied in 53 patients with unilateral posterior Semicircular canal BPPV. (Tables 2, 3) The mean VOR gain was slightly reduced in ipsilesional posterior canal compared to the other canals (P-value not statistically significant). In 5 cases of bilateral posterior canal BPPV, the mean VOR gain for the right side was 0.67, while for the left it was 0.62 (statistically insignificant). In the patient suspected with right anterior canal involvement, the VOR gain on right side was 0.72 and in the contralateral canal it was 0.71. Patient with left lateral canal involvement, the VOR gain was found to be 0.76 in the ipsilateral canal and 0.78 for the contralateral canal. VOR gain for all the canals irrespective of involved canal, the P value was statistically insignificant. VOR gain was < 0.5 in 8 (13%) cases (Table 4).

Table 2.

Showing mean VOR gain in affected SCC when compared with the contralateral side (calculated by VHIT)

Semicircular canal	VOR gain	VOR gain	P-value
	Ipsilesional SCC	Contralesional SCC
Posterior (unilateral) N = 53	0.66 ± 0.16	0.72 ± 0.17	0.06
Anterior N = 1	0.72	0.71
Horizontal N = 1	0.76	0.78

Table 3.

Mean VOR gain in all the canals in posterior SCC BPPV

Semicircular canal	Ipsilesional SCC	Contralesional SCC	P value
Posterior	0.66 ± 0.16	0.72 ± 0.17	0.114
Anterior	0.72 ± 0.11	0.71 ± 0.02	0.85
horizontal	0.76(0.014)	0.78(0.03)	0.28

Table 4.

Showing mean VOR gain as calculated by VHIT test for cases of bilateral posterior SCC BPPV (n = 5)

Semicircular canal	VOR gain	VOR gain	P- value
	Right SCC	Left SCC
Posterior (bilateral) N = 5	0.67 ± 0.12	0.62 ± 0.11	0.07
Anterior N = 1	0.716	0.72
Horizontal N = 1	0.81	0.79

Saccades

Among all 60 cases, saccades were present only in 17 (28%) cases (Table 5), it was absent in 43 (72%) cases which was highly significant for the absence of saccades (P value-0.001) (Table 5).

Table 5.

Showing the presence or absence of saccades

Saccades	Number [n]	Percentage [%]	P- value
Present	17	28%	0.001
Absent	43	72%

P-value = 0.001 (Highly significant)

Discussion

Vertigo is a sensation of subjective spinning of the environment which indicates a lesion within the vestibular system that can be either central or peripheral. Among all the peripheral vestibular disorders that causes vertigo, BPPV has been found to be the most common. Barany was the first to give the description of BPPV in 1921. According to Katsarkas, BPPV contributes around 17% of vertigo in clinical practice [8]. Von Brevern et al. reported that BPPV accounted for up to 8% of cases in patients presenting with vertigo with a lifetime prevalence of 2.4%- and 1-year prevalence of 1.6% [9].

In our study, patients below the age group of 18 were not included as it was not feasible to perform VHIT in that age group. We excluded patients with restricted movements of the head, disordered eye mobility (oculomotor palsy), congenital nystagmus, poor vision and those who were on medication for BPPV within the previous 5 days. Among the 60 participants included in the study, 41 (68%) were males and 19 (32%) were females. We found that there was a male preponderance as opposed to a previous study done by Katsarkas [8] where incidence in females was higher.

In our study, the age of the participants ranged from 19–75 years. Gupta (2015) reported that vertigo is seen in all the age groups from 7–88 years and highest incidence was noted between third to sixth decades of life [10]. Similar results were also seen in our study as the highest incidence was seen in the age group of 51–60 years which comprised of 21 (35%) patients which was followed by the age group of 41–50 that comprised of 15 (25%) patients. An equal distribution was seen in the age group of 31–40 years and above 60 years which was 17% and 16% respectively. The least number of patients were seen in the age group of 18–30 years. This can be attributed to the fact that BPPV is not commonly seen in younger age group.

Dix-Hallpike manoeuvre was performed in all patients and was positive in 97% of cases thus indicating more of a posterior canal involvement. This may be attributed to the fact that canalolithiasis most frequently involves the posterior SCC as it is the most dependent canal [11].

In our study we found that the right ear was affected more i.e. 32 (53%) compared to the left i.e. 23 (39%) patients. A study done by von Brevern et al. (2004) also showed similar results where 54 out of the total 80 patients had right ear BPPV. They mentioned that this could be attributed to the fact that most of the patients tend to sleep on their right side. We also had 5 (8%) patients in whom both ears were involved, which is a rare phenomenon accounting for less than 10% of cases according to the literature [7]. According to Katsarkas [8], bilateral involvement of SCCs is more frequently seen following head injury.

We had 31 (52%) cases clinically diagnosed with right posterior canal BPPV (Dix- Hallpike test was positive to right) and 22 (37%) cases with left posterior canal BPPV (Dix-Hallpike test was positive to left). We had 1 (1.5%) case each of left lateral canal & right anterior canal involvement clinically diagnosed with the supine-roll test and Yacovino manoeuvre respectively. According to previous literature anterior canal is the least affected SCC in BPPV. According to Chung et al. [12], involvement of posterior canal was around 61.8%, lateral canal was 35.3% and anterior canal was 2.9%. They had observed a negative correlation between the frequency of lateral SCC BPPV and duration of symptoms.

The video head impulse test (VHIT) is a novel revolutionary test that evaluates the function of all the six semicircular canals through observation and recording of eye responses during head movement in both the horizontal and vertical axes. Fallahnezhad et al. [13] mentioned that VHIT enables to quantitatively assess the function of individual SCC and it provides specific information about the angular VOR. They further added that testing SCC in BPPV may be beneficial but it tends to be affected by artefacts. Therefore, it should be performed with great precision.

Mangabeira Albernaz et al. [14] in a study involving 200 participants observed that VHIT can be utilized to promptly diagnose vestibular disorders and to assess the involvement of the SCC especially the anterior and posterior SCCs. They observed low VOR gain in vestibular neuronitis. They observed that VHIT was normal in 12 out of 14 patients diagnosed with BPPV. In one patient who was newly diagnosed with BPPV with a previous history of undergoing labyrinthectomy, VOR gain was reduced in anterior and posterior SCC.

In our study, mean VOR gain of the posterior, anterior and horizontal canal was compared in the ipsilesional and contralesional side. As per the operating guidelines for the ICS Impulse (Otometrics, Denmark), VOR gain < 0.5 was defined as abnormal. Ipsilesional and contralesional mean VOR gain was studied in 53 patients with unilateral posterior SCC BPPV. In our study, the mean VOR gain was slightly reduced in ipsilesional posterior canal compared to other canals. P value was calculated using Fishers exact test but was not found to be statistically significant. Fallahnezhad et al. [13] had done a similar study in which they had investigated the VOR gain, gain asymmetry and saccades in posterior canal BPPV. They reported that the VOR gain in the direction of the posterior semi-circular canal may be reduced in patients with PSCC-BPPV. However, compared to our study their sample size was smaller i.e.,29 patients and they had only included posterior canal BPPV patients. This study defined a VHIT gain of < 0.8 for lateral canals and < 0.7 for vertical canals. In all cases, gain asymmetry was calculated using the same formula: (GSCc– GSCi)/(GSCc + GSCi). A positive value indicated that the contralesional gain was greater than the ipsilesional, and vice versa.

We also had 5 cases of bilateral BPPV which is a relatively rarer phenomenon in which the Dix Hallpike test was positive on both the sides. The mean VOR gain for the right side was found to be 0.67 while for the left side it was 0.62. P-value was found to be statistically insignificant. We had one case with right anterior canal involvement diagnosed with Yacovino manoeuvre in which the gain was observed to be 0.72 in the ipsilesional canal and 0.71 in the contralesional canal. We also observed one case with left lateral canal involvement diagnosed with supine roll test. The VOR gain was found to be 0.76 in the ipsilesional canal and 0.78 in the contralateral canal. In 8 (13%) patients, VOR gain was < 0.5. For the observed VOR gain in all the canals, p value was found to be statistically insignificant. Among all our cases, saccades were present in only 17 (28%) of cases. We found that there is no relationship between the presence of saccades, the canal involved and the side of the lesion.

Conclusions

Clinical diagnosis is the gold standard diagnostic method for BPPV. VHIT shows low VOR gain in affected semicircular canal compared to the normal canals, which was not statistically significant. We conclude that the currently available equipment for VHIT is not useful in diagnosing BPPV. However, further research on this is needed so that minute changes in VOR gain can be recorded which may aid in diagnosis and management of BPPV.

Compliance with Ethical Standards

Conflict of interest

The authors declare no conflict of interest.