Acute vertigo: stroke or not?

Acute vestibular syndrome - vertigo, nausea/vomiting, nystagmus and gait unsteadiness - is common, and differentiating posterior circulation stroke from a peripheral cause can be challenging. The National Institute of Health Stroke Scale (NIHSS) does not include acute vestibular syndrome, and early computed tomography scanning cannot rule out acute ischaemia. A positive Head Impulse-Nystagmus-Test of Skew (HINTS) test suggests posterior circulation stroke in acute vestibular syndrome when any of three signs are present: normal horizontal head impulse, gaze-direction nystagmus or eye skew deviation. This systematic review examined the accuracy of positive HINTS in identifying posterior circulation stroke in acute vestibular syndrome patients. We searched MEDLINE (1966 to 21 December 2017), EMBASE (1980 to December 2017), Web of Science and scanned bibliographies. Two authors independently screened relevant articles and extracted data. We included studies where HINTS was used to identify posterior circulation stroke with diagnosis confirmed using magnetic resonance imaging. Six studies (n = 644 patients) were identified. Acute stroke was confirmed in 200 (31.1%) patients. There was a 15-fold increased risk of posterior circulation stroke in patients with positive HINTS test compared to those with no abnormality (RR: 15.84, 95% CI: 5.25-47.79). For any stroke, the pooled sensitivity was 95.5% (95% CI: 92.6-98.4%) and specificity was 71.2% (95% CI: 67.0-75.4%). The data suggest that the HINTS test as one element of clinical evaluation is useful to differentiate posterior circulation stroke from peripheral causes in acute vestibular syndrome. Further studies are needed to validate HINTS as a clinical prediction tool in emergency department settings and selection of patients for reperfusion treatment.

OutcomesVertigo is a common presentation to the Emergency Department (ED) with 5% of presentations due to posterior circulation stroke (PCS). Bedside investigations such as the head impulse test are used...

Background and aimsVertigo is a common presentation to the emergency department (ED) with 5% of presentations due to posterior circulation stroke (PCS). Bedside investigations such as the head impulse test...

Background: Posterior circulation stroke (PCS) accounts for ~20% of ischemic strokes. Existing EMS screening tools lack accuracy in the diagnosis of PCS. We aim to develop an automated screening tool to detect abnormal eye movements in patients presenting with PCS. Methods: As an initial step, we built a portable platform called RoADIE (Rolling Apparatus to Detect Impairment of the Eyes), equipped with eye-tracking software to acquire gaze data from patients presenting with PCS, acute vestibular syndrome, and normal controls. We first performed a validation study in 19 healthy controls comparing calibration (C) vs non-calibration (NC) techniques. Eye movements were captured using a standard H-Test exam. The NC condition was performed first for each volunteer to avoid a learning effect. Correlation between C and NC tests was determined using the Spearman coefficient (r). Results: Conjugate gaze (i.e. ability of eyes to track in unison) demonstrated strong correlation along the horizontal [r = 0.976 (C), 0.922 (NC)] and vertical axes [r= 0.866 (C), 0.881(NC)]. Smooth pursuit (i.e. ability of each eye to track moving target) also showed strong correlation in the horizontal plane: right eye [r = 0.945 (C), 0.946 (NC), left eye [r=0.945 (C), 0.943 (NC)]. Vertical tracking showed moderate correlation: right eye [r=0.652 (C), 0.575 (NC), left eye [r=0.678 (C), 0.550 (NC)]. Conclusion: In this initial validation test of a portable eye tracking platform, we demonstrated strong correlation for both conjugate gaze and smooth pursuit in the horizontal axis, and moderate correlation for eye tracking in the vertical axis. Given similar performance in non-calibrated tests, a calibration procedure may not be necessary for future data capture. Next steps will include validation of the eye tracking device in prospective patients presenting with PCS and acute vestibular syndrome. Acknowledgement: Funding support through AHA Innovative Project Award 19IPLOI34760692

IntroductionVestibular neuritis (VN) and posterior circulation stroke (PCS) are the commonest causes of acute vestibular syndrome (AVS). We aim to identify discriminators of VN from PCS by testing all five vestibular end-organs in patients presenting with AVS.MethodsThree-dimensional video-head impulse test (v-HIT), cervical and ocular-vestibular evoked myogenic potentials (c-and oVEMP) and subjective visual horizontal (SVH) tests were performed in 22 patients with VN and 22 with PCS. Ipsilesional horizontal, anterior and posterior canal (HC, AC, PC) v-HIT gain and first catch-up saccade characteristics, VEMP amplitude asymmetry-ratios were compared.ResultsAll VN and 6 PCS patients had positive clinical HIT. Mean time to testing was 4.7 days for VN, 7.0 days for PCS. VN mean ipsilesional HC and AC first saccade amplitude was larger, peak-velocities faster and onset latencies earlier compared to PCS (p<0.05). No significant difference between VN and PCS in first saccade characteristics was found in PC. Ipsilesional first saccade amplitude, peak-velocity and duration were significantly different between PCS and controls for all canals (p<0.05). A gain <0.68 and first saccade amplitudes >2.2°separated VN from PCS with sensitivities of 95.5% and 86.4% and specificities of 72.7% and 63.6%. First saccade amplitude of >0.91°identified PCS from controls with sensitivity of 68.2% and specificity of 70%. Abnormality rates for AC cVEMP, BC oVEMP and SVH were 42.9%, 50% and 91% for VN and 38.1%, 9% 72% for PCS.Conclusion v-HIT gain and catch-up saccade metrics are useful separators of VN from PCS. Detailed saccade analysis complements existing vestibular tests.

Intravenous thrombolysis (IVT) is rarely performed in dizzy patients with acute vestibular syndrome (AVS) or acute imbalance (AIS) even if posterior circulation stroke (PCS) is suspected. Decision-making may be affected by uncertainties in discriminating central from peripheral vestibulopathy or concerns of IVT-related harm, particularly intracerebral hemorrhage (ICH), but related studies are missing. Using an in-house register of dizzy patients coming to the emergency room, we identified 29 AVS/AIS patients who presented within 4.5 h after onset, revealed clinical signs indicative of PCS (central oculomotor signs, mild focal abnormalities), and had non-contrast computed tomography (NCCT). Patients treated with IVT (n = 15) were compared to NoIVT patients (n = 14) with regard to clinical and imaging (including perfusion computed tomography, CTP) parameters, occurrence of ICH and short-term clinical outcome (NIHSS improvement; ability to walk independently). IVT and NoIVT patients did not differ in baseline characteristics, central oculomotor signs, or clinical outcome. IVT patients more often exhibited disabling vestibular symptoms (severe dizziness/vertigo, inability to stand unsupported) and focal abnormalities than NoIVT patients. There was no ICH in either group. CTP was performed in 0% of NoIVT versus 80% of IVT patients, seven of twelve revealing posterior circulation hypoperfusion. Comparison of initial hypoperfusion (CTP) and final stroke (NCCT) revealed IVT-related benefit (smaller lesion) in three of seven IVT patients. In AVS/AIS patients with suspected PCS, disabling vestibular symptoms, focal neurological deficits, and hypoperfusion on CTP seem to direct decision-making pro IVT. In our small cohort, there were no significant IVT-related clinical benefits, no IVT-related ICHs, and salvage of brain tissue in some patients.

Clinical and video head impulse test in the diagnosis of posterior circulation stroke presenting as acute vestibular syndrome inthe emergency department.

BackgroundAcute vestibular syndrome usually represents either vestibular neuritis (VN), an innocuous viral illness, or posterior circulation stroke (PCS), a potentially life-threatening event. The video head impulse test (VHIT) is a quantitative measure of the vestibulo-ocular reflex that can distinguish between these two diagnoses. It can be rapidly performed at the bedside by any trained healthcare professional but requires interpretation by an expert clinician. We developed machine learning models to differentiate between PCS and VN using only the VHIT.MethodsWe trained machine learning classification models using unedited head- and eye-velocity data from acute VHIT performed in an Emergency Room on patients presenting with acute vestibular syndrome and whose final diagnosis was VN or PCS. The models were validated using an independent test dataset collected at a second institution. We compared the performance of the models against expert clinicians as well as a widely used VHIT metric: the gain cutoff value.ResultsThe training and test datasets comprised 252 and 49 patients, respectively. In the test dataset, the best machine learning model identified VN with 87.8% (95% CI 77.6%–95.9%) accuracy. Model performance was not significantly different (p = 0.56) from that of blinded expert clinicians who achieved 85.7% accuracy (75.5%–93.9%) and was superior (p = 0.01) to that of the optimal gain cutoff value (75.5% accuracy (63.8%–85.7%)).ConclusionMachine learning models can effectively differentiate PCS from VN using only VHIT data, with comparable accuracy to expert clinicians. They hold promise as a tool to assist Emergency Room clinicians evaluating patients with acute vestibular syndrome.

BackgroundThis study aimed to determine the clinical significance of acute vestibular syndrome (AVS)/acute imbalance syndrome (AIS) in posterior circulation stroke (PCS) and how it should be addressed in the thrombolysis code.MethodsOur institution has recently changed its thrombolysis code from one that is generous to AVS/AIS to one that is exclusive. The subjects in this study were patients with PCS who presented before this transition (May 2016 to April 2018, period 1) and those who presented after (January 2019 to December 2020, period 2) with an onset-to-door time of 4.5 h. Hyperacute stroke treatment was compared between the two periods. The clinical significance of AVS/AIS was evaluated by dichotomizing the patients' clinical severity to minor or major deficits, then evaluating the significance of AVS/AIS in each group. Presenting symptoms of decreased mental alertness, hemiparesis, aphasia (anarthria), or hemianopsia were considered major PCS symptoms, and patients who did not present with these symptoms were considered minor PCS.ResultsIn total, 114 patients presented in period 1 and 114 in period 2. Although the code activation rate was significantly lower in period 2 (72.8% vs. 59.7%), p = 0.04, there were no between-group differences in functional outcomes (mRS score at 3 months; 1 [0–3] vs. 0 [0–3], p = 0.18). In 77 patients with PCS and AVS/AIS, the difference in code activation rate was not significant according to changes in thrombolysis code. In minor PCS, AVS/AIS was associated with lower NIHSS scores, lower early neurological deterioration rates, and favorable outcomes. In major PCS, while AVS/AIS was not associated with outcomes, the majority of cases were prodromal AVS/AIS which simple vertigo and imbalance symptoms were followed by a major PCS symptom.ConclusionsThis study failed to show differences in outcome in patients with PCS according to how AVS/AIS is addressed in the stroke thrombolysis code. In patients with minor PCS, AVS/AIS was associated with a benign clinical course. Prompt identification of prodromal AVS/AIS is essential.

The interpretation of video head-impulse tests (video-HITs) can often be complicated, limiting their clinical utility in acute vestibular syndrome. We aimed to determine video-HIT findings in patients with posterior circulation strokes (PCSs) and vestibular neuritis (VN). We retrospectively analyzed the results of video-HITs in 59 patients with PCS. Irrespective of the actual lesion revealed later on MRIs, ipsilateral and contralateral sides were assigned according to the direction of slow phase of spontaneous nystagmus (SN). Then, the patterns of video-HIT findings were classified according to the vestibulo-ocular reflex (VOR) gain for the horizontal canals; (1) ipsilaterally positive, (2) contralaterally positive, (3) bilaterally normal, and (4) bilaterally positive. The abnormal responses were further defined into (5) wrong-way saccades, (6) perverted, and (7) early acceleration followed by premature deceleration. We also analyzed the asymmetry of the corrective saccadic amplitude between the sides, calculated from the sum of cumulative saccadic amplitudes on both sides. The results were compared with video-HIT results from 71 patients with VN. Video-HITs were normal in 32 (54%), ipsilaterally positive in 11 (19%), bilaterally positive in 10 (17%), and contralaterally positive in 6 (10%) patients with PCS. Wrong-way saccades were more frequently observed in VN than in PCS (31/71 [44%] vs 5/59 [8%], p < 0.001). Saccadic amplitude asymmetry was greater in VN than in PCS (median 100% [interquartile range 82-144, 95% CI 109-160] vs 0% [-29 to 34, -10 to 22, p < 0.001]). When differentiating VN from PCS, the sensitivity was 81.7%, and specificity was 91.5% at the cutoff value of 71% for saccadic amplitude asymmetry with an area under the curve (AUC) of 0.91 (95% CI 0.86-0.97). The AUC for saccadic amplitude asymmetry was larger than that for the ipsilateral VOR gain (p = 0.041) and other parameters. Patients with PCS may show various head-impulse responses that deviate from the findings expected in VN, which include normal, contralaterally positive, and negative saccadic amplitude asymmetry (i.e., greater cumulative saccadic amplitude contralaterally). A thorough analysis of corrective saccades in video-HITs can improve the differentiation of PCS from VN even before MRIs.

A 66-year-old hypertensive and diabetic male presented with acute vestibular syndrome for three days. HINTS plus examination was performed. The horizontal head impulse test was positive on the left side. Video oculography showed centripetal nystagmus on gaze testing in the dark and test of skew was negative. There was no new hearing loss on the finger rub test. On neurological examination, he had severe postural instability and saccadic smooth pursuit. Radio-imaging studies were conducted to rule out the possibility of stroke. CT brain showed infarction in the territory of the medial branch of the right posterior inferior cerebellar artery. MRI brain confirmed the diagnosis. Thus, posterior circulation stroke can present with acute vestibular syndrome mimicking acute unilateral vestibulopathy. However, the presence of associated neurological symptoms like gait ataxia, centripetal nystagmus and vascular risk factors pointed towards a central cause. Clinical evaluation suggesting a peripheral lesion should never be taken in isolation and needs to be correlated with other associated signs. We describe centripetal nystagmus without fixation as a new oculomotor sign in acute vestibular syndrome.

This review article aims to provide an evidence-based approach to evaluating the patient who presents with acute prolonged, spontaneous vertigo in the context of the acute vestibular syndrome (AVS). Differentiation of posterior circulation stroke (PCS) presenting as an AVS has been regarded as an important diagnostic challenge for physicians involved in acute care. Current evidence suggests that a targeted approach to history taking and physical examination with emphasis on the oculomotor examination, more specifically the HINTS (Head Impulse/Nystagmus/Test-of-skew) examination battery, yields a higher sensitivity for the diagnosis of PCS than even standard magnetic resonance imaging with diffusion-weighted imaging. However, most studies have only validated the utility of the HINTS examination when performed by experts, who interpret the most powerful component of HINTS, namely the head impulse test (HIT), considerably different to the novice. Several investigations useful in the differentiation of the AVS are becoming more accessible and portable, such as videooculography with Frenzel goggles and video head impulse testing (vHIT), which allows for the quantitative assessment of the HIT. In clinical practice, vHIT has already become accepted as standard of care in the evaluation of AVS.

Acute vestibular syndrome (AVS) is a common clinical presentation. Common causes include peripheral, self-limiting labyrinthine disorders, but a significant proportion are caused by posterior circulation stroke (PoCS). Delineating between a peripheral versus central cause in AVS is challenging for acute care physicians, but a simple, three-step bedside test known collectively as the HINTS examination may be useful. Substantial evidence supports the use of the HINTS examination in detection of PoCS in AVS, but it is important that performer is trained and experienced to ensure reliability of the test's results. There is some evidence that video-assisted HINTS examination may help to improve HINTS performance, but further research is needed. This review is a practical guide for acute care physicians in regards to when to perform the HINTS examination, how to interpret its findings, limitations and practical considerations.

This article provides a practical approach to acute vestibular syndrome while highlighting recent research advances. Acute vestibular syndrome is defined as sudden-onset, continuous vertigo lasting longer than 24 hours with associated nausea and vomiting, all of which are worsened with head movement. Acute vestibular syndrome is provoked by a variety of central and peripheral causes, the most common of which are vestibular neuritis and acute stroke (posterior circulation). A clinical approach focusing on timing, associated history, and ocular motor findings can improve diagnostic accuracy and is more sensitive and specific than early neuroimaging. Because of the shared neurovascular supply, both peripheral and central vestibular disorders can manifest overlapping signs previously considered solely peripheral or central, including vertical skew, nystagmus, abnormal vestibular ocular reflex, hearing loss, and gait instability. Although acute vestibular syndrome is typically benign, stroke should be considered in every person with acute vestibular syndrome because it can act as a harbinger of stroke or impending cerebellar herniation. Treatment is focused on physical therapy because the evidence is minimal for the long-term use of medication. The diagnosis of acute vestibular syndrome first requires the elimination of common medical causes for dizziness. Next, underlying pathology must be determined by distinguishing between the most common causes of acute vestibular syndrome: central and peripheral vestibular disorders. Central vestibular disorders are most often the result of ischemic stroke affecting the cerebellar arteries. Peripheral vestibular disorders are assumed to be caused mostly by inflammatory sources, but ischemia of the peripheral vestibular apparatus may be underappreciated. By using the HINTS Plus (Head Impulse test, Nystagmus, Test of Skew with Plus referring to hearing loss assessment) examination in addition to a comprehensive neurologic examination, strokes are unlikely to be missed. For nearly all acute vestibular disorders, vestibular physical therapy contributes to recovery.

In reply: