A Simple Gain-Based Evaluation of the Video Head Impulse Test Reliably Detects Normal Vestibulo-Ocular Reflex Indicative of Stroke in Patients With Acute Vestibular Syndrome

Hyperventilation-Induced Nystagmus in Acute Unilateral Vestibulopathy: A Correlation with Vestibulo-ocular Reflex Gain and Clinical Implication

Hyperventilation-induced nystagmus test (HINT) is capable of generating a response in 77.2% of cases of acute unilateral vestibulopathy (AUVP); both nystagmus toward the affected side (excitatory pattern) and toward the healthy side (inhibitory pattern) have been described. The aim of the study is to investigate the clinical and prognostic role of the test by evaluating its correlation with vestibulo-ocular reflex (VOR) gain. We evaluated 33 AUVP patients by performing the HINT and video head impulse test (V-HIT) during the acute phase and then at 15 and 90 days after the onset of the symptoms. The correlation between the VOR gain of the affected side and test responses was evaluated first, phase by phase, and then considering the pattern shown during the first assessments. Patients with a negative HINT had a higher mean VOR gain than patients with a positive test at both 15 and 90 days. Patients who showed an inhibitory pattern at the first assessment had a continuous improvement in V-HIT performance, while patients with an initial excitatory response had a transient decrease in gain at the subsequent evaluation (P=.001). No difference between these 2 groups emerged at 90 days (P=.09). The finding of a negative HINT during the follow-up correlates with good V-HIT performance and could be an indicator of good recovery. The inhibitory pattern is associated with a subsequent improvement; and it would be indicative of compensation. but, despite this, the prognostic value of the test is limited.

Video head impulse test in stroke: a review of published studies

Accurate and timely diagnosis of posterior circulation stroke in patients with acute dizziness is a challenge that can lead to misdiagnosis and significant harm. The present review sought to identify and describe published research on the clinical application of vHIT in posterior circulation stroke. vHIT, a portable device, has gained prominence in evaluating peripheral vestibular disorders and offers potential applications in diagnosing neurological disorders, particularly posterior circulation stroke. Several studies have shown that vHIT can differentiate between stroke and vestibular neuritis based on VOR gain values, with high sensitivity and specificity. The manuscript also discusses vHIT's performance in differentiating between types of posterior circulation stroke, such as PICA, AICA, and SCA strokes. While vHIT has demonstrated promise, the review emphasizes the need for further research to validate its use as a tool to rule out stroke in acute dizziness patients in the emergency department. In conclusion, the manuscript underscores the potential of vHIT as a valuable addition to the diagnostic arsenal for acute dizziness, particularly in the context of posterior circulation stroke. It calls for further research and wider adoption of vHIT in clinical settings to improve patient care and reduce unnecessary costs associated with misdiagnoses.

The value of saccade metrics and VOR gain in detecting a vestibular stroke

OBJECTIVE

A normal video Head Impulse Test is the gold standard in the emergency department to rule-in patients with an acute vestibular syndrome and a stroke. We aimed to compare the diagnostic accuracy of vHIT metrics regarding the vestibulo-ocular reflex gain and the corrective saccades in detecting vestibular strokes.

METHODS

Prospective cross-sectional study (convenience sample) of patients presenting with acute vestibular syndrome in the emergency department of a tertiary referral centre between February 2015 and May 2020. We screened 1677 patients and enrolled 76 patients fulfilling the inclusion criteria of acute vestibular syndrome. All patients underwent video head impulse test with automated and manual data analysis. A delayed MRI served as a gold standard for vestibular stroke confirmation.

RESULTS

Out of 76 patients, 52 were diagnosed with acute unilateral vestibulopathy and 24 with vestibular strokes. The overall accuracy of detecting stroke with an automated vestibulo-ocular reflex gain was 86.8%, compared to 77.6% for cumulative saccade amplitude and automatic saccade mean peak velocity measured by an expert and 71% for cumulative saccade amplitude and saccade mean peak velocity measured automatically. Gain misclassified 13.1% of the patients as false positive or false negative, manual cumulative saccade amplitude and saccade mean peak velocity 22.3%, and automated cumulative saccade amplitude and saccade mean peak velocity 28.9% respectively.

CONCLUSIONS

We found a better accuracy of video head impulse test for the diagnosis of vestibular strokes when using the vestibulo-ocular reflex gain than using saccade metrics. Nevertheless, saccades provide an additional and important information for video head impulse test evaluation. The automated saccade detection algorithm is not yet perfect compared to expert analysis, but it may become a valuable tool for future non-expert video head impulse test evaluations.

Prospective analysis of video head impulse tests in patients with acute posterior circulation stroke

Background

Video head impulse tests (vHITs), assessing the vestibulo-ocular reflex (VOR), may be helpful in the differential diagnosis of acute dizziness. We aimed to investigate vHITs in patients with acute posterior circulation stroke (PCS) to examine whether these findings could exhibit significant abnormalities based on lesion locations, and to evaluate diagnostic value of vHIT in differentiating dizziness between PCS and vestibular neuritis (VN).

Methods

We prospectively recruited consecutive 80 patients with acute PCS and analyzed vHIT findings according to the presence of dorsal brainstem stroke (DBS). We also compared vHIT findings between PCS patients with dizziness and a previously studied VN group (n = 29). Receiver operating characteristic (ROC) analysis was performed to assess the performance of VOR gain and its asymmetry in distinguishing dizziness between PCS and VN.

Results

Patients with PCS underwent vHIT within a median of 2 days from stroke onset. Mean horizontal VOR gain was 0.97, and there was no significant difference between PCS patients with DBS (n = 15) and without (n = 65). None exhibited pathologic overt corrective saccades. When comparing the PCS group with dizziness (n = 40) to the VN group (n = 29), patients with VN demonstrated significantly lower mean VOR gains in the ipsilesional horizontal canals (1.00 vs. 0.57, p < 0.001). VOR gain and their asymmetry effectively differentiated dizziness in the PCS from VN groups, with an area under the ROC curve of 0.86 (95% CI 0.74-0.98) and 0.91 (95% CI 0.83-0.99, p < 0.001), respectively.

Conclusion

Significantly abnormal vHIT results were rare in patients with acute PCS, even in the presence of DBS. Moreover, vHIT effectively differentiated dizziness between PCS and VN, highlighting its potential for aiding differential diagnosis of acute dizziness.

Updates in neuro-otology

PURPOSE OF REVIEW

Recent updates with clinical implications in the field of neuro-otology are reviewed.

RECENT FINDINGS

Important updates relating to several neuro-otologic disorders have been reported in recent years. For benign positional paroxysmal vertigo (BPPV), we provide updates on the characteristics and features of the short arm variant of posterior canal BPPV. For the acute vestibular syndrome, we report important updates on the use of video-oculography in clinical diagnosis. For autoimmune causes of neuro-otologic symptoms, we describe the clinical and paraclinical features of kelch-like protein 11 encephalitis, a newly-identified antibody associated disorder. For cerebellar ataxia, neuropathy, vestibular areflexia syndrome, we report recent genetic insights into this condition.

SUMMARY

This review summarizes important recent updates relating to four hot topics in neuro-otology.

Case report: Spiller syndrome initially mimicking vestibular neuritis

Spiller syndrome is a rare subtype of medial medullary infarction (MMI). Herein, we report on a patient with progressing stroke who presented with the initial features of acute peripheral vestibulopathy and MMI (Spiller syndrome), as confirmed by magnetic resonance imaging (MRI). A 42-year-old man experienced acute persistent vertigo with nausea, vomiting, and severe gait instability for 6 h before presenting to the emergency department. He exhibited spontaneous right-beating horizontal-torsional nystagmus that intensified on rightward gaze. The patient fell to the left side during the Romberg test. Cranial computed tomography (CT) performed immediately upon admission did not provide evidence for ischemia or hemorrhage of the brainstem and cerebellum; however, the symptoms underwent exacerbation 4 h after admission, manifesting as left-sided limb weakness and dysarthria, without dysphagia. Furthermore, bedside examination revealed difficulty in extending the tongue to the right, positive left Babinski's sign, and abnormal vibration and position sense in the paralyzed limb. Head impulse test recording revealed a normal gain in the vestibulo-ocular reflex, and numerous consistent covert corrective saccades were captured upon turning the head to the left side. Cranial MRI depicted an acute infarct confined to the right side of the medial medulla, which met the diagnostic criteria for Spiller syndrome. Our study underscores the importance of considering the possibility of a nucleus prepositus hypoglossi lesion even if the signs and symptoms support the diagnosis of peripheral lesions in patients with acute vestibular syndrome exhibiting vascular risk factors.

Acute unilateral vestibulopathy/vestibular neuritis: Diagnostic criteria

This paper describes the diagnostic criteria for Acute Unilateral Vestibulopathy (AUVP), a synonym for vestibular neuritis, as defined by the Committee for the Classification of Vestibular Disorders of the Bárány Society. AUVP manifests as an acute vestibular syndrome due to an acute unilateral loss of peripheral vestibular function without evidence for acute central or acute audiological symptoms or signs. This implies that the diagnosis of AUVP is based on the patient history, bedside examination, and, if necessary, laboratory evaluation. The leading symptom is an acute or rarely subacute onset of spinning or non-spinning vertigo with unsteadiness, nausea/vomiting and/or oscillopsia. A leading clinical sign is a spontaneous peripheral vestibular nystagmus, which is direction-fixed and enhanced by removal of visual fixation with a trajectory appropriate to the semicircular canal afferents involved (generally horizontal-torsional). The diagnostic criteria were classified by the committee for four categories: 1. "Acute Unilateral Vestibulopathy", 2. "Acute Unilateral Vestibulopathy in Evolution", 3. "Probable Acute Unilateral Vestibulopathy" and 4. "History of Acute Unilateral Vestibulopathy". The specific diagnostic criteria for these are as follows:"Acute Unilateral Vestibulopathy": A) Acute or subacute onset of sustained spinning or non-spinning vertigo (i.e., an acute vestibular syndrome) of moderate to severe intensity with symptoms lasting for at least 24 hours. B) Spontaneous peripheral vestibular nystagmus with a trajectory appropriate to the semicircular canal afferents involved, generally horizontal-torsional, direction-fixed, and enhanced by removal of visual fixation. C) Unambiguous evidence of reduced VOR function on the side opposite the direction of the fast phase of the spontaneous nystagmus. D) No evidence for acute central neurological, otological or audiological symptoms. E) No acute central neurological signs, namely no central ocular motor or central vestibular signs, in particular no pronounced skew deviation, no gaze-evoked nystagmus, and no acute audiologic or otological signs. F) Not better accounted for by another disease or disorder."Acute Unilateral Vestibulopathy in Evolution": A) Acute or subacute onset of sustained spinning or non-spinning vertigo with continuous symptoms for more than 3 hours, but not yet lasting for at least 24 h hours, when patient is seen; B) - F) as above. This category is useful for diagnostic reasons to differentiate from acute central vestibular syndromes, to initiate specific treatments, and for research to include patients in clinical studies."Probable Acute Unilateral Vestibulopathy": Identical to AUVP except that the unilateral VOR deficit is not clearly observed or documented."History of acute unilateral vestibulopathy": A) History of acute or subacute onset of vertigo lasting at least 24 hours and slowly decreasing in intensity. B) No history of simultaneous acute audiological or central neurological symptoms. C) Unambiguous evidence of unilaterally reduced VOR function. D) No history of simultaneous acute central neurological signs, namely no central ocular motor or central vestibular signs and no acute audiological or otological signs. E) Not better accounted for by another disease or disorder. This category allows a diagnosis in patients presenting with a unilateral peripheral vestibular deficit and a history of an acute vestibular syndrome who are examined well after the acute phase.It is important to note that there is no definite test for AUVP. Therefore, its diagnosis requires the exclusion of central lesions as well as a variety of other peripheral vestibular disorders. Finally, this consensus paper will discuss other aspects of AUVP such as etiology, pathophysiology and laboratory examinations if they are directly relevant to the classification criteria.

Videooculography “HINTS” in Acute Vestibular Syndrome: A Prospective Study

Objective

A three-step bedside test (“HINTS”: Head Impulse-Nystagmus-Test of Skew), is a well-established way to differentiate peripheral from central causes in patients with acute vestibular syndrome (AVS). Nowadays, the use of videooculography gives physicians the possibility to quantify all eye movements. The goal of this study is to compare the accuracy of VOG “HINTS” (vHINTS) to an expert evaluation.

Methods

We performed a prospective study from July 2015 to April 2020 on all patients presenting at the emergency department with signs of AVS. All the patients underwent clinical HINTS (cHINTS) and vHINTS followed by delayed MRI, which served as a gold standard for stroke confirmation.

Results

We assessed 46 patients with AVS, 35 patients with acute unilateral vestibulopathy, and 11 patients with stroke. The overall accuracy of vHINTS in detecting a central pathology was 94.2% with 100% sensitivity and 88.9% specificity. Experts, however, assessed cHINTS with a lower accuracy of 88.3%, 90.9% sensitivity, and 85.7% specificity. The agreement between clinical and video head impulse tests was good, whereas for nystagmus direction was fair.

Conclusions

vHINTS proved to be very accurate in detecting strokes in patients AVS, with 9% points better sensitivity than the expert. The evaluation of nystagmus direction was the most difficult part of HINTS.

Head impulse testing in bilateral vestibulopathy in patients with genetically defined CANVAS

BACKGROUND

To investigate the association between disease duration and the severity of bilateral vestibulopathy in individuals with complete or incomplete CANVAS (Cerebellar Ataxia with Neuropathy and Vestibular Areflexia Syndrome) and biallelic RFC1 repeat expansions.

METHODS

Retrospective analysis of clinical data and the vestibulo-ocular reflex quantified by the video head impulse test in 20 patients with confirmed biallelic RFC1 repeat expansions.

RESULTS

Vestibulo-ocular reflex gain at first admittance 6.9 ± 5.0 years after disease onset was 0.16 [0.15-0.31] (median [interquartile range]). Cross-sectional analysis revealed that gain reduction was associated with disease duration. Follow-up measurements were available for ten individuals: eight of them exhibited a progressive decrease of the vestibulo-ocular reflex gain over time. At the first visit, six of all patients (30%) did not show clinical signs of cerebellar ataxia.

CONCLUSIONS

Our data suggest a pathological horizontal head impulse test, which can easily be obtained in many outpatient clinics, as a sign of bilateral vestibulopathy in genetically confirmed CANVAS that can precede clinically accessible cerebellar ataxia at least in a subset of patients. The presumably continuous decline over time possibly reflects the neurodegenerative character of the disease. Thus, genetic testing for RFC1 mutations in (isolated) bilateral vestibulopathy might allow disease detection before the onset of cerebellar signs. Further studies including a wider spectrum of vestibular function tests are warranted in a prospective design.