Stroke risk stratification in acute dizziness presentations: A prospective imaging-based study

Abstract

Objective: To estimate the ability of bedside information to risk stratify stroke in acute dizziness presentations.

Methods: Surveillance methods were used to identify patients with acute dizziness and nystagmus or imbalance, excluding those with benign paroxysmal positional vertigo, medical causes, or moderate to severe neurologic deficits. Stroke was defined as acute infarction or intracerebral hemorrhage on a clinical or research MRI performed within 14 days of dizziness onset. Bedside information comprised history of stroke, the ABCD(2) score (age, blood pressure, clinical features, duration, and diabetes), an ocular motor (OM)-based assessment (head impulse test, nystagmus pattern [central vs other], test of skew), and a general neurologic examination for other CNS features. Multivariable logistic regression was used to determine the association of the bedside information with stroke. Model calibration was assessed using low (<5%), intermediate (5% to <10%), and high (≥10%) predicted probability risk categories.

Results: Acute stroke was identified in 29 of 272 patients (10.7%). Associations with stroke were as follows: ABCD(2) score (continuous) (odds ratio [OR] 1.74; 95% confidence interval [CI] 1.20-2.51), any other CNS features (OR 2.54; 95% CI 1.06-6.08), OM assessment (OR 2.82; 95% CI 0.96-8.30), and prior stroke (OR 0.48; 95% CI 0.05-4.57). No stroke cases were in the model's low-risk probability category (0/86, 0%), whereas 9 were in the moderate-risk category (9/94, 9.6%) and 20 were in the high-risk category (20/92, 21.7%).

Conclusion: In acute dizziness presentations, the combination of ABCD(2) score, general neurologic examination, and a specialized OM examination has the capacity to risk-stratify acute stroke on MRI.

© 2015 American Academy of Neurology.

Figures

Figure 1. Study flow diagram

Flow diagram of patient screening, enrollment, and outcome completion. aIn an additional 73 visits, potential participants declined screening. bPatients not included in main analysis, but examination data were included in the interrater agreement analysis. cOf patients who received an MRI (n = 272), the initial MRI was performed for clinical purposes in 158 (58%) and for research purposes in 114 (42%). A research MRI (either first or second study) was performed in 177 (65%) of the patients. The first MRI was performed before the study bedside examination in 15% of patients (42/272). ED = emergency department.

Figure 2. Model calibrations

Calibration for model 1 (A) (including ocular motor 3-category scheme variable) and model 2 (B) (limiting the ocular motor examination to only the nystagmus component). Calibration was assessed using low, intermediate, and high predicted probability risk categories. Light blue bars represent the mean predicted probability of acute infarction or intracerebral hemorrhage (ICH) on MRI within each category. Dark blue bars represent the frequency of observed acute infarction or ICH on MRI within each category. Model 1 distribution of patients (stroke patients/total patients) within each category: low-risk category, 0/86; intermediate-risk category, 9/94; and high-risk category, 20/92. Model 2 distribution of patients (stroke patients/total patients) within each category: low-risk category, 1/109; intermediate-risk category, 7/66; and high-risk category, 21/97. Error bars represent 95% confidence intervals within each category calculated using the exact binomial method for observed stroke and 1,000 bootstrap samples for the predicted probability.