Video-Oculography to Guide Neuroimaging for Dizziness and Vertigo

Characteristics and risk of stroke in emergency department patients with acute dizziness

Background

Acute dizziness is a common symptom in the emergency department (ED), with strokes accounting for 3 %-5 % of cases. We investigated the risk of stroke in ED patients with acute dizziness and compared stroke characteristics diagnosed during and after the ED visit.

Methods

We identified adult patients with acute dizziness, vertigo, or imbalance using a hospital research-based database. Patients with abdominal or flank pain were used as the comparison group. Patients with dizziness were 1:1 matched to comparison patients. Each patient was traced for up to one year until being hospitalized for a stroke.

Results

Out of the 24,266 eligible patients, 589 (2.4 %) were hospitalized for stroke during the ED visit. For the remaining 23,677 patients, the risk of stroke at 7, 30, 90, and 365 days after ED discharge was 0.40 %, 0.52 %, 0.71 %, and 1.25 % respectively. Patients with dizziness had a higher risk of stroke compared to the comparison group at 7, 30, 90, and 365 days. The risk ratios decreased from 5.69 (95 % confidence interval [CI], 3.34-9.68) to 2.03 (95 % CI, 1.65-2.49). Compared to patients hospitalized for stroke during the ED visit, those hospitalized for stroke after the ED visit had greater stroke severity despite a lower initial triage acuity. Patients with early stroke (≤7 days) after ED discharge were less likely to have hypertension, diabetes, hyperlipidemia, and atrial fibrillation. They mostly experienced posterior circulation stroke. Patients with late stroke (>7 days) were older and less likely to have hypertension and hyperlipidemia but more likely to have a history of prior stroke and ischemic heart disease. Their strokes were mainly located in the anterior circulation territory.

Conclusions

The risk of stroke after ED discharge was higher in patients with dizziness than in the comparison group, with gradually decreasing risk ratios in the following year. Patients hospitalized for stroke during and after the ED visit had different profiles of vascular risk factors and clinical characteristics.

Three-dimensional characteristics of nystagmus induced by low frequency in semicircular canals of healthy young people

Objective

The study aimed to analyze the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people, and to determine the reference range of nystagmus slow phase velocity (SPV) and its asymmetry.

Materials and methods

Fifty-two healthy volunteers (26 males and 26 females, aged 17-42 years, average 23.52 ± 6.59), were recruited to perform the manual triaxial rotation testing with a 3D-Videonystagmography (3D-VNG) device (VertiGoggles (ZT-VNG-II), Shanghai ZEHNIT Medical Technology Co., Ltd., Shanghai, China) using a 0.3 Hz prompt beat and a 90° amplitude, respectively. The induced nystagmus around the Z-, X-, and Y-axes were recorded in the yaw, pitch, and roll planes. The directions and slow phase velocities of the horizontal, vertical, and torsional components of the induced nystagmus under different semicircular canal combinations (the left lateral and right lateral semicircular canal combination, bilateral anterior semicircular canals, bilateral posterior semicircular canals combination, and the anterior and posterior semicircular canals combination of each ear), as well as their asymmetry, were taken as the observation indexes to analyze the characteristics of the nystagmus vectors of different combinations.

Results

Fifty-two healthy volunteers had no spontaneous nystagmus. The characteristic nystagmus was induced by the same head movement direction in all three axial rotation tests. The SPVs of the left and right nystagmus were 44.45 ± 15.75°/s and 43.79 ± 5.42°/s, respectively, when the subjects' heads were turned left or right around the Z-axis (yaw). The SPVs of vertically upward and downward nystagmus were 31.67 ± 9.46°/s and 30.01 ± 9.20°/s, respectively, when the subjects' heads were pitched around the X-axis (pitch). The SPVs of torsional nystagmus, with the upper poles of the eyes twisting slowly to the right and left ears (from the participant's perspective), were 28.99 ± 9.20°/s and 28.35 ± 8.17°/s, respectively, when the subjects' heads were turned left or right around the Y-axis (roll). There was no significant difference in the SPVs of nystagmus induced by the same rotation axis in two opposite directions (p > 0.05). The reference ranges for the slow phase velocities (SPVs) of nystagmus induced by the triaxial rotation testing were as follows: For the Z-axis (yaw), the SPVs were 13.58-75.32°/s for leftward head rotation and 13.56-74.02°/s for rightward head rotation. For the X-axis (pitch), the SPVs were 13.13-50.21°/s for upward head nystagmus and 11.98-48.04°/s for downward head nystagmus. For the Y-axis (roll), the SPVs were 10.97-47.02°/s for the left-sided head rotation and 12.34-44.35°/s for the right-sided head rotation.

Conclusion

This study clarified the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people. It also established a preliminary reference range of SPVs and SPV asymmetry of nystagmus induced by the vertical semicircular canal. It can further provide a basis for the mechanism of semicircular canal-induced nystagmus and the traceability of nystagmus in patients with otogenic vertigo. It is shown that the portable 3D-VNG eye mask can be used for the manual triaxial rotation testing to achieve the evaluation of the low-frequency angular vestibulo-ocular reflex (aVOR) function of the vertical semicircular canal, which is convenient, efficient, and practical.

Guidelines for reasonable and appropriate care in the emergency department 3 (GRACE-3): Acute dizziness and vertigo in the emergency department

This third Guideline for Reasonable and Appropriate Care in the Emergency Department (GRACE-3) from the Society for Academic Emergency Medicine is on the topic adult patients with acute dizziness and vertigo in the emergency department (ED). A multidisciplinary guideline panel applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and strength of recommendations regarding five questions for adult ED patients with acute dizziness of less than 2 weeks' duration. The intended population is adults presenting to the ED with acute dizziness or vertigo. The panel derived 15 evidence-based recommendations based on the timing and triggers of the dizziness but recognizes that alternative diagnostic approaches exist, such as the STANDING protocol and nystagmus examination in combination with gait unsteadiness or the presence of vascular risk factors. As an overarching recommendation, (1) emergency clinicians should receive training in bedside physical examination techniques for patients with the acute vestibular syndrome (AVS; HINTS) and the diagnostic and therapeutic maneuvers for benign paroxysmal positional vertigo (BPPV; Dix-Hallpike test and Epley maneuver). To help distinguish central from peripheral causes in patients with the AVS, we recommend: (2) use HINTS (for clinicians trained in its use) in patients with nystagmus, (3) use finger rub to further aid in excluding stroke in patients with nystagmus, (4) use severity of gait unsteadiness in patients without nystagmus, (5) do not use brain computed tomography (CT), (6) do not use routine magnetic resonance imaging (MRI) as a first-line test if a clinician trained in HINTS is available, and (7) use MRI as a confirmatory test in patients with central or equivocal HINTS examinations. In patients with the spontaneous episodic vestibular syndrome: (8) search for symptoms or signs of cerebral ischemia, (9) do not use CT, and (10) use CT angiography or MRI angiography if there is concern for transient ischemic attack. In patients with the triggered (positional) episodic vestibular syndrome, (11) use the Dix-Hallpike test to diagnose posterior canal BPPV (pc-BPPV), (12) do not use CT, and (13) do not use MRI routinely, unless atypical clinical features are present. In patients diagnosed with vestibular neuritis, (14) consider short-term steroids as a treatment option. In patients diagnosed with pc-BPPV, (15) treat with the Epley maneuver. It is clear that as of 2023, when applied in routine practice by emergency clinicians without special training, HINTS testing is inaccurate, partly due to use in the wrong patients and partly due to issues with its interpretation. Most emergency physicians have not received training in use of HINTS. As such, it is not standard of care, either in the legal sense of that term ("what the average physician would do in similar circumstances") or in the common parlance sense ("the standard action typically used by physicians in routine practice").

Diagnostic accuracy of neuroimaging in emergency department patients with acute vertigo or dizziness: A systematic review and meta-analysis for the Guidelines for Reasonable and Appropriate Care in the Emergency Department

BACKGROUND

Patients presenting to the emergency department (ED) with acute vertigo or dizziness represent a diagnostic challenge. Neuroimaging has variable indications and yield. We aimed to conduct a systematic review and meta-analysis of the diagnostic test accuracy of neuroimaging for patients presenting with acute vertigo or dizziness.

METHODS

An electronic search was designed following patient-intervention-control-outcome (PICO) question, (P) adult patients with acute vertigo or dizziness presenting to the ED; (I) Neuroimaging including Computed tomography (CT), CT Angiogram (CTA), Magnetic Resonance Imaging (MRI), Magnetic Resonance Angiogram (MRA), and Ultrasound (US); (C) MRI/clinical gold standard; (O) central causes (stroke, hemorrhage, tumor, others) versus peripheral causes of symptoms. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was used to assess certainty of evidence in pooled estimates.

RESULTS

We included studies that reported diagnostic test accuracy. Articles were assessed in duplicated. From 6,309 titles, 460 articles were retrieved, and 12 included. Non-contrast CT scan: 6 studies, 771 patients, pooled sensitivity 28.5% (95%CI 14.4-48.5%, moderate certainty) and specificity 98.9% (95%CI 93.4-99.8%, moderate certainty). MRI: 5 studies, 943 patients, sensitivity 79.8% (CI 71.4-86.2%, high certainty) and specificity 98.8% (CI 96.2-100%, high certainty). CTA: 1 study, 153 patients, sensitivity 14.3% (CI 1.8-42.8%) and specificity 97.7% (CI 93.8-99.6%). CT had higher sensitivity than CTA (21.4% and 14.3%) for central etiology. MRA: 1 study, 24 patients, sensitivity 60.0% (CI 26.2-87.8%) and specificity 92.9% (CI 66.1-99.8%). US: 3 studies, 258 patients, sensitivity ranged from 30-53.6%, specificity from 94.9-100%.

CONCLUSION

Non-contrast CT has very low sensitivity and MRI will miss approximately one in five patients with stroke if imaging is obtained early after symptom onset. Neuroimaging should not be used as the only tool for ruling out stroke and other central causes in patients with acute dizziness or vertigo presenting to the ED.