Clinical Assessment of the Nystagmus Fixation Suppression Test: An Experimental Study.

BACKGROUND:  Assessment of nystagmus fixation suppression can be used as an additional diagnostic tool for patients with an acute vestibular syndrome to distinguish between a central or peripheral cause. We investigated the ability of physicians to detect fixation suppression using a nystagmus simulation model. METHODS:  We used a nystagmus simulator to measure the accuracy of the nystagmus fixation suppression test. Fixation suppression was assessed randomly in 6170 trials by 20 otorhinolaryngologists and neurologists, segregated into 2 groups based on their neurootological experience, a beginner and an experienced group. The simulator presented random nystagmus slow velocity (SPV) reductions and presented 3 conditions with either changed nystagmus frequency, amplitude, or both. RESULTS:  The cutoff for the discernment of fixation suppression ranged from 1.2 to 14°/s nystagmus velocity difference. The more intense the baseline nystagmus was, the more difficult was the detection of fixation suppression. There was not significant difference (P >.05) in the cutoff values in the experts group compared to the novices for all 3 different conditions. Both, novices and experts, detected frequency changes easier than differences of the nystagmus amplitude. Test sensitivity was very low (19%-65%) for discernment of small nystagmus velocity differences of <2°/s by experts. CONCLUSION:  In our study, there was no difference between experts and novices in detection of nystagmus suppression by visual fixation. The examiners could only detect large suppression effects at low-intensity baseline nystagmus. Overall, the sensitivity and accuracy of a clinical fixation suppression test is low and the assistance with a video-oculography device is highly recommended.

Positional End-Point Nystagmus in Patients with Diagnosis of Acute Unilateral Vestibulopathy.

INTRODUCTION: Recently, end-point nystagmus, traditionally observed in an upright position, has been identified in the Dix-Hallpike position among healthy subjects, suggesting a physiological origin.However, its characteristics in individuals with vestibular hypofunction remain unexplored. OBJECTIVE: To elucidate the impact of vestibular hypofunction on the characteristics of positional end-point nystagmus. METHODS: Thirty-one patients diagnosed with acute unilateral vestibulopathy according to Bárány Society criteria were selected. A video head impulse test was conducted in all participants, followed by McClure and Dix-Hallpike maneuvers with and without gaze fixation, and with the initial position of the eye in the straight-ahead position or in the horizontal end-point position. Nystagmus direction, sense, latency, slow-phase velocity, and duration were recorded. The relationship between these characteristics and video head impulse test values was analyzed. RESULTS: Positional end-point nystagmus was observed in 92.6% of subjects with vestibular hypofunction, significantly more than in healthy individuals. Nystagmus direction varied depending on the performed positional test and on the vestibulo-ocular reflex gains. Gaze occlusion and the initial horizontal end-point position increased its frequency. CONCLUSION: Vestibular hypofunction influences the manifestation of positional end-point nystagmus. Recognizing this nystagmus can aid in resolving diagnostic uncertainties and preventing the misdiagnosis of benign paroxysmal positional vertigo in subjects with acute unilateral vestibulopathy.

Evaluation of the reliability and validity of the upright head roll test for lateral semicircular canal benign paroxysmal positional vertigo.

BACKGROUND: The upright head roll test (UHRT) is a recently introduced diagnostic maneuver for lateral semicircular canal benign paroxysmal positional vertigo (LSC-BPPV). OBJECTIVE: This study aimed to evaluate the reliability and validity of the UHRT. METHODS: Two separate studies were conducted. Study 1 analyzed 827 results of videonystagmography (VNG) to assess UHRT reliability, and Study 2 analyzed 130 LSC-BPPV cases to evaluate UHRT validity. RESULTS: The inter-test reliability between UHRT and the supine head roll test (SHRT) showed substantial agreement (Cohen's kappa = 0.753) in direction-changing positional nystagmus (DCPN) and almost perfect agreement (Cohen's kappa = 0.836) in distinguishing the direction of DCPN. The validity assessment of UHRT showed high accuracy in diagnosing LSC-BPPV (80.0%) and in differentiating the variant types (74.6%). UHRT was highly accurate in diagnosing the canalolithiasis type in LSC-BPPV patients (Cohen's kappa = 0.835); however, it showed only moderate accuracy in diagnosing the cupulolithiasis type (Cohen's kappa = 0.415). The intensity of nystagmus in UHRT was relatively weaker than that in SHRT (P < 0.05). CONCLUSION: UHRT is a reliable test for diagnosing LSC-BPPV and distinguishing subtypes. However, UHRT has a limitation in discriminating the affected side owing to a weaker intensity of nystagmus than SHRT.

The headshake enhances oculomotor response to galvanic vestibular stimulation in healthy subjects.

OBJECTIVE: To investigate whether a headshake applied during galvanic vestibular stimulation (GVS) can enhance GVS-induced nystagmus in healthy subjects. METHODS: In nineteen healthy participants, we evaluated an average slow-phase velocity (aSPV) of nystagmus in a head-still and after the headshake conditions, with/out the bitemporal 2 mA GVS. The GVS was applied also with polarity congruent (supporting) or incongruent (suppressing) to any preexisting spontaneous nystagmus. RESULTS: The orientation of GVS-induced nystagmus depended on GVS polarity. In the head-still condition, the GVS-induced nystagmus in 14 subjects (74%) for congruent and in 12 subjects (63%) for incongruent GVS. During headshake, we recorded nystagmus in 16 subjects (84%) for congruent and 15 subjects (79%) for incongruent GVS. The aSPV of congruent GVS-induced nystagmus was higher (p = 0.0003) by 1.33 (SE 0.26) deg/s for headshake compared to head-still condition. The aSPV of incongruent GVS also induced higher nystagmus (p = 0.0014) by 1.24 (SE 0.28) deg/s for the headshake condition. CONCLUSION: Our study adds a new principle to the knowledge of the central processing of a GVS response in healthy subjects. The GVS-safety profile of current up to 2 mA was sufficient to elicit a significant GVS nystagmus response in a head-still position in 63% and after a headshake in 79%. Compared to the GVS head-still condition, a headshake enhanced the GVS-induced nystagmus more than twice. SIGNIFICANCE: The headshake helps to identify GVS-induced nystagmus, which can be weak or absent during the head-still condition.

Positional nystagmus is observed in the vast majority of healthy individuals.

INTRODUCTION: Benign paroxysmal positional vertigo (BPPV) is a vestibular disease characterized by brief  positional vertigo. When examined, characteristic patterns of positional nystagmus (PN) are found with specific head position changes. Previous studies have shown a high prevalence of PN among vestibular healthy subjects. Considering the current diagnostic criteria of BPPV and the potentially high prevalence of PN in healthy individuals, this raises the question of potential over diagnosing BPPV, if diagnostics are based exclusively upon objective findings. This study aims to determine the prevalence of PN within a healthy, adult population and furthermore include a characterization of the PN observed. METHODS: This is a prospective cross-sectional study. 78 subjects were included. The subjects underwent four standardized positional tests for BPPV in a mechanical rotational chair while using a VNG-goggle to monitor and record eye movements. RESULTS: Positional nystagmus was recorded in 70.5% (55/78) of the subjects. Of the 55 subjects, who presented with PN, 81.8% (45/55) had upbeating PN. The 95th percentile of the maximum a-SPV was found to be 10.4 degrees per second, with a median of 4. Five subjects (6.4%) in total presented with PN mimicking BPPV. CONCLUSION: This study found PN to be a common finding within a healthy, adult population based on the high prevalence of PN in the study population. Upbeating PN mimicking posterior canalolithiasis was found in numerous subjects. The authors recommend a cautious approach when diagnosing BPPV, especially in cases of purely vertical PN (without a torsional component) and if no vertiginous symptoms are present during Dix-Hallpike and Supine Roll Test examinations.

Scale for Ocular Motor Disorders in Ataxia (SODA) in Patients with Multiple System Atrophy.

A clinical scale fully dedicated to evaluating ocular motor abnormalities is required for now. We investigated the utility of a recently developed Scale for Ocular motor Disorders in Ataxia (SODA) in patients with multiple system atrophy (MSA). We prospectively assessed SODA in consecutive patients with MSA between August 2021 and August 2023 at the Korea University Medical Center. The results of the clinical exam-based SODA were compared with those measured using video-oculography (VOG-guided SODA). We also compared the findings with other established clinical scales targeting patients with MSA, including the Unified Multiple System Atrophy Rating Scale (UMSARS) I-II, Movement Disorder Society-Unified Parkinson's Disease Rating Scale motor part (UPDRS-III), Scale for Assessment of Rating of Ataxia (SARA), Composite Autonomic Symptom Score-31 (COMPASS-31), and Composite Autonomic Severity Score (CASS). Twenty patients were enrolled in our study (17 with cerebellar-type MSA and three with Parkinson-type MSA). Scores ranged from 1 to 14 (median [interquartile range (IQR)] = 8 [5-10]). Among the subscales, saccades had a median score of 2.5 (IQR = 1-3), followed by ocular pursuit (1 [0-1]), nystagmus (1 [0-2]), saccadic intrusions (1 [0-1]), vestibulo-ocular reflex (VOR) (0.5 [0-1]), ocular alignment (0 [0-1]), and VOR cancellation (1 [0-1]). The clinical-exam-based SODA (p = 0.020) and VOG-guided SODA (p = 0.034) positively correlated with disease duration. No correlation was found between clinical exam-based SODA and other scales. Skew deviation, gaze-evoked nystagmus, VOR cancellation, and smooth pursuit had the highest precision among the items. Ocular misalignment and spontaneous and positional nystagmus were frequently false positive and were poorly detected with clinical exam-based SODA. Six patients with repeated evaluation exhibited higher scores, along with deterioration documented on other clinical scales. The SODA can reliably predict neurodegeneration as an additional clinical surrogate in MSA.

Capturing nystagmus during vertigo attacks using a smartphone: adherence, characteristics, pearls and pitfalls.

OBJECTIVE: To investigate adherence, characteristics, and first clinical experiences of capturing ictal nystagmus at home, which can be performed to complement the diagnostic process in patients with episodic vestibular symptoms. METHODS: Patients were recruited at a tertiary referral center in case capturing ictal nystagmus could contribute to the diagnostic process (e.g., to detect or rule out BPPV). They were asked to capture ictal nystagmus with their own smartphone at home, using a smartphone-based adapter (Nystagmocatcher, Balansdiagnos, Stockholm, Sweden). All recordings were analyzed by the last author (RvdB), and the adherence, characteristics, and first clinical experiences were evaluated. RESULTS: Seventy patients with vestibular symptoms were asked to participate in this study. Sixty-two (89%) agreed to participate. The median period of participation was 86 days. Fifty-one patients experienced attacks during the study period. Eventually, 51% of them provided eye movement recordings sufficient for analysis. Different types of nystagmus were observed: positional nystagmus related to BPPV, positional nystagmus not related to BPPV, functional eye movements, and the absence of nystagmus or functional eye movements. Capturing ictal nystagmus could contribute to the diagnostic process in several ways, including to detect or rule out BPPV, to detect or rule out vestibular origin of symptoms, to determine the affected side, telemedicine, to monitor attack frequency, and to detect malingering. Furthermore, strict guidance of patients was necessary, which could be time-consuming. CONCLUSION: Capturing ictal nystagmus can contribute to the diagnostic process in several ways, which motivates to rethink current clinical workflow in vestibular medicine. However, strict guidance is necessary and not all patients provide ictal recordings. In an outpatient setting, it would be advised to use ictal nystagmus recordings on indication, to complement the diagnostic process.

Clinical Characteristics of persistent geotropic horizontal direction-changing positional nystagmus: Experience in 189 participants.

BACKGROUND: The etiology and mechanism of persistent geotropic horizontal direction-changing positional nystagmus (DCPN) are still unclear. Whether this pattern of nystagmus is a subtype of benign paroxysmal positional vertigo (BPPV) remains controversial. OBJECTIVE: The goal of this study was to observe the clinical characteristics of persistent geotropic horizontal DCPN involving the lateral semicircular canal. METHODS: The analysis was performed to participants with episodic positional vertigo in our clinic from 2014 to 2021. Participants were included via positional test. We observed and summarized the distribution data, vertigo history, follow-up tests, and recurrence situations of 189 persistent geotropic horizontal DCPN participants. RESULTS: The mean age at the first time showing of persistent geotropic horizontal DCPN was 56±14.7 and more women than men were affected by persistent geotropic horizontal DCPN (female-to-male ratio 2.4 : 1). Overall, 58.7% (57/94) of participants who came for the first-week follow-up test were asymptomatic. Thirty-three participants experienced recurrence (female-to-male ratio: 4.5 : 1). Fifty-three (28.0%) participants experienced the conversion of the patterns of DCPN in the history, the follow-up tests and the recurrence compared to the first showing of persistent geotropic horizontal DCPN. 24(12.1%) participants still experienced persistent geotropic horizontal DCPN attack in the follow-up tests and the recurrences without benign paroxysmal positional vertigo history. CONCLUSION: Persistent geotropic horizontal DCPN affected more women than men. The persistent geotropic horizontal DCPN that with conversion to transient geotropic horizontal DCPN or to persistent apogeotropic horizontal DCPN might be a subtype of BPPV or in a stage of BPPV process. However, the persistent geotropic horizontal DCPN without conversion might be an independent disease that is not related to BPPV.

Outcome of canalith repositioning manoeuvre in benign paroxysmal positional vertigo in children and adolescents: A systematic review.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is a debilitating condition that has been significantly described in adults. Recent data points out that BPPV occurs in children as well. Canalith repositioning manoeuvre (CRM) has shown promising results amongst adult patients with BPPV. OBJECTIVE: We reviewed the literature to determine the outcome of CRM in children and adolescents with BPPV. METHODS: A literature search was conducted over 1 month (March 2022). The primary outcome was defined as the resolution of positional nystagmus and symptoms, and secondary outcomes were determined by the presence of recurrence and the number of attempts of CRM. RESULTS: Ten articles were selected based on our objective and selection criteria. A total of 242 patients were included, with a mean of 10.9 years. BPPV was diagnosed based on history and positional nystagmus in all patients (100%). CRM was performed in 97.9% of patients, whereby 80.5% recovered following a single attempt of CRM. Recurrence of symptoms was identified in 10% of patients with no reported major complications. CONCLUSION: CRM has demonstrated promising results in children and adolescents. The quality of evidence is limited until a better-quality study involving randomised controlled studies with a larger sample size is completed.

Subjective visual vertical deviation in patients with early-onset direction-changing horizontal positional nystagmus.

OBJECTIVE: Otolithic dysfunction is investigated in cases of direction-changing horizontal positional nystagmus (DCHPN) due to peripheral vestibular disorders. METHODS: The static-subjective visual vertical (S-SVV) was conducted in DCHPN cases within 48 h after onset. RESULTS: The absolute values of S-SVV deviations of patients with Light cupula and lateral canal-benign paroxysmal positional vertigo-cupulolithiasis (L-BPPV-Cup) were significantly different from those of healthy subjects (p < 0.001, p < 0.05, respectively), whereas there were no significant differences in those of patients with L-BPPV-Canalolithiasis-geotropic (L-BPPV-Can-g) or L-BPPV-Can-ageotropic (L-BPPV-Can-a) versus healthy subjects. Significant differences were found in S-SVV (+: deviation to the affected side, -: deviation to the unaffected side) between patients with Light cupula and those with L-BPPV-Can-g, L-BPPV-Can-a and L-BPPV-Cup (p < 0.01, p < 0.05, and p < 0.001, respectively), as well as between those with L-BPPV-Can-g and L-BPPV-Cup (p < 0.01). The S-SVV in patients with Light cupula, L-BPPV-Can-g, and L-BPPV-Can-a deviated more to the affected side, whereas that in patients with L-BPPV-Cup deviated more to the unaffected side. CONCLUSION: Mild otolithic dysfunctions were found in patients with DCHPN due to the presence of peripheral vestibular disorders within 48 h after onset. The extent of otolithic (utricular) disorders in patients with DCHPN is estimated in decreasing order as follows: Light cupula > L-BPPV-Cup > L-BPPV-Can-g and L-BPPV-Can-a. Many patients with L-BPPV-Cup likely suffer from disorders of the pars externa of the utricular macula, whereas many patients with L-BPPV-Can-g likely suffer from disorders of the pars interna of the utricular macula. L-BPPV-Can-a and L-BPPV-Can-g must be induced by a common mild utricular disorder.

Analysis of 30 patients with cupulolithiasis of the posterior semicircular canal.

BACKGROUND: The diagnostic characteristics of patients with cupulolithiasis of the posterior semicircular canal are persistent torsional nystagmus in the supine position and persistent torsional nystagmus (opposite direction) in the nose-down position, which are caused by the affected canal becoming gravity sensitive. OBJECTIVE: To investigate the clinical features of posterior cupulolithiasis. MATERIALS AND METHODS: We interviewed 30 consecutive patients with cupulolithiasis of the posterior canal and categorized them by onset time into the following four groups: (1) during sleep; (2) at the time of awakening; (3) morning; and (4) afternoon. We defined disease duration as the period from onset to the day when we detected remission of positional nystagmus. RESULTS: Time of awakening was the most common onset time. The mean disease duration was 18.2 days, and 90% of patients achieved cure within 1 month. CONCLUSIONS: Physicians should take into account the duration of nystagmus, because cupulolithiasis of posterior canal exists. The etiology of posterior cupulolithiasis is closely related to sleep, because time of awakening is the most common onset time of vertigo. Most patients with posterior cupulolithiasis cure within 1 month.

Effect of ocular fixation on positional nystagmus in BPPV patients.

OBJECTIVE: The quantitative suppression rate of positional nystagmus (PN) by ocular fixation (OF) is unknown. This study aims to analyse the effect of OF on the slow phase velocity (SPV) of PN during diagnostic positional manoeuvres (DPMs) with videonystagmography in patients with benign paroxysmal positional vertigo (BPPV). DESIGN: DPMs were performed on 58 patients with BPPV, 33 (56.9%) of whom were women. OF was initiated when PN was most evident, and recording was continued. The mean SPV of three consecutive nystagmus before (F0) and after (F1) OF initiation was calculated. The rate of suppression of PN by OF was found in percent with the formula (F0 - F1) x 100/F0. STUDY SAMPLE: 58 patients were included in this study. RESULTS: The mean age was 56.1 ± 11.2 (range 27-76). F0 and F1 values were calculated as 5.742 ± 5.589 and 1.948 ± 3.424 degrees/second, respectively (p < 0.001). The rate of suppression of PN by OF was found to be 66.1%. CONCLUSIONS: OF significantly suppresses PN during DPMs in BPPV patients. Elimination of OF during DPMs is important for accurate diagnosis.

Less talked variants of benign paroxysmal positional vertigo.

The diagnostic criteria were established for benign paroxysmal positional vertigo (BPPV), the most common vestibular disorder worldwide, by the Barany Society in 2015. This marked an important milestone in the diagnosis and treatment of BPPV. However, there still remain uncertainties and ambiguities regarding the clinical features and pathophysiology of BPPV, and its clinical variants. In this manuscript, we will discuss 1) the emerging and controversial syndromes of BPPV (i.e., canalolithiasis of the anterior canal, cupulolthiasis of the posterior canal, and lithiasis of multiple canals) with updates, 2) atypical nystagmus according to the canal involved (e.g., nystagmus induced by head position changes in the pitch plane in horizontal canal BPPV, and positional downbeat nystagmus in posterior canal BPPV), 3) persistent geotropic positional nystagmus. Consideration of these uncommon types and manifestations of BPPV would broaden our understanding of BPPV pathomechanisms and allow differentiation from central vertigo and nystagmus.

Modeling the effect of gravity on periodic alternating nystagmus.

Periodic alternating nystagmus (PAN) is a rare oscillatory ocular motor disorder. The effects of gravity on the dynamic behavior of PAN can be studied by monitoring the nystagmus while changing head orientation. Previous studies of patients with PAN reached different conclusions about the effect of changing the orientation of the head relative to gravity on the ongoing PAN, either no effect or a damping of the nystagmus within several minutes. What neuronal circuits could account for the difference in the effects of gravity among PAN patients? We modeled how the brain resolves the tilt-translation ambiguity in normal individuals and added an unstable, oscillatory vestibular system generating PAN. PAN was suppressed in our patient in ear-down positions, in a similar pattern to that of a previously reported patient. This effect was simulated by reducing the gain of the projection of the "rotation feedback" loop to the velocity-storage integrator to approximately 5% of its normal value. With normal "rotation feedback" PAN is expected to dissipate quickly as soon as the head is rotated away from upright position. Moreover, by disconnecting the rotation feedback completely (gain = zero) the model simulated PAN that was reported to be unaffected by gravity. Thus, understanding the effect of this single parameter, the gain of the rotation feedback, can explain the observed variability among our own and previous studies.

[Three-dimensional characteristics of torsional nystagmus in induced by posterior semicircular canals canalithasis].

Objective:The three-dimensional direction feature of torsional nystagmus induced by posterior semicircular canal canalithasis （PSC-Can） was recorded and analyzed using three-dimensional video nystagmography （3D-VNG）. Methods:Sixty patients （22 on the left side and 38 on the right side） with PSC-Can were enrolled for torsional nystagmus evoked by Dix-Hallpike test in the affected-side head-hanging and sitting positions, and the direction characteristics of the horizontal, vertical and torsional components were analyzed. Results:Vertical torsional nystagmus was induced in 60 PSC-Can patients in the head-hanging and sitting positions evoked by Dix-Hallpike test, respectively. Horizontal, vertical, and torsional components of were presented in the 3D-VNG. In the head-hanging position, the direction of horizontal component in the left/right PSC-Can nystagmus was contralateral in 46 cases（the other 14 cases were ipsilateral）, the vertical component was upward, and the torsional component was upward/downward, respectively. The intensity of nystagmus induced in the three components in the sitting position is weaker than in the head-hanging position, and the direction of nystagmus was reversed in both vertical and torsional components compared with the head-hanging position. However, the direction of the horizontal component was reversed in 39 cases and not reversed in 21 cases in the sitting position. Conclusion:The horizontal, vertical and torsional components of the torsional nystagmus in PSC-Can patients recorded by 3D-VNG, which provided more comprehensive and objective information for the analysis of PSC-Can and the study of semicircular canal physiological function.

The clinical significance of direction-fixed mono-positional apogeotropic horizontal nystagmus.

Objective: A mono-positional persistent, direction-fixed apogeotropic nystagmus (MPosApoNy) is very challenging for the neuro-otologist. MPosApoNy can be found in patients suffering from a partially compensated acute unilateral vestibulopathy; with a normal caloric test, one can speculate the presence of "trapped" otolithic debris located close to the ampulla of the horizontal semicircular canal. Methods: Among 957 patients suffering from vertigo and dizziness, we selected 53 cases of MPosApoNy. Results: In 28 patients, caloric test showed a canal paresis on the same side of the MPosApoNy. In the remaining 25 cases, MPosApoNy was the only clinical finding. We hypothesised the presence of horizonal canal lithiasis and patients were treated with a Gufoni manoeuvre, followed by a forced prolonged position. Conclusions: Performing bedside examination in a patient suffering from vertigo, the presence of MPosApoNy may be due to: a) facilitation of a subclinical nystagmus due to the mechanism of apogeotropic reinforcement; b) horizontal canal lithiasis with 'trapped' otoliths close to the ampulla. The disappearance of MPosApoNy following a repositioning manoeuvre or conversion in a typical form of canalolithiasis may represent the best method to confirm this hypothesis.

Clinical Interpretation of Positional Nystagmus Provoked by both Dix-Hallpike and Supine Head-Roll Tests.

BACKGROUND: Both the Dix-Hallpike test and the supine head-roll test can provoke positional nystagmus in a group of benign paroxysmal positional vertigo patients, including but not limited to those with multiple canal involvement. This study aimed to determine the incidence and interpret the clinical significance of positional nystagmus provoked by both the Dix-Hallpike and the supine head-roll tests. METHODS: The results of video-nystagmography sessions recorded in the computer database that included both the Dix-Hallpike and the supine head-roll tests were examined. RESULTS: The records belonging to 2880 video-nystagmography sessions of 2387 patients were examined. Nystagmus was detected in both the Dix-Hallpike and the supine head-roll tests of 131 (5.5%) patients. The video images belonging to 142 session records of 122 patients were accessed and further analyzed. The diagnosis was posterior canal BPPV in 9.0%, and lateral canal BPPV in 62.3%. More than one canal was involved in 3.3%, one rehabilitation maneuver was performed in 75.0%, and recurrence was observed in 7.4% of those patients. CONCLUSION: In both geotropic and apogeotropic variants of lateral canal BPPV, nystagmus can be observed during the Dix-Hallpike test in addition to the supine head-roll test. In patients with posterior canal benign paroxysmal positional vertigo, nystagmus can also be observed in the head-roll test. To reach a correct and comprehensive diagnosis and apply appropriate treatment in benign paroxysmal positional vertigo, the Dix-Hallpike test and the head-roll test should be completely performed on both sides, and the results of those tests must be interpreted concomitantly.