In this study, acute stroke was found in 55 of 1,239 patients (4.5%) who presented with dizziness without confirmed neurologic deficits, and most cases (96.3%) were diagnosed as ischemic stroke with a high rate of cerebellum involvement. Although symptom characteristics and laboratory examinations could not be helpful to determine whether further neuroimaging workup was required, an age of over 65 (OR 3.01; 95% CI 1.33 to 6.83) and a previous history of cerebrovascular injury (OR 3.08; 95% CI 1.24 to 7.67) were independent risk factors for onset of acute stroke in this patient population.
Differentiating central from peripheral origins in dizziness is frequently challenging for physicians. In the past, isolated dizziness was considered as a peripheral origin disorder, meaning that patients experiencing this symptom had been excluded from most previous studies on acute stroke research 9. On the contrary, there is a growing body of evidence to suggest that this isolated symptom is in fact caused by a central origin 10–12. A retrospective study by Navi et al. reported that 37 of 907 (4.1%) patients who presented with dizziness also had cerebrovascular injury 12. These data are similar with the data reported in this study (4.5%); however, Navi et al. included all patients with dizziness, irrespective of confirmed neurologic symptoms. Moreover, they found only two patients with isolated dizziness who were diagnosed with stroke and were limited by performing neuroimaging on only 37% of patients. A recent, small retrospective study reported that the incidence of stroke in admitted patients with isolated vertigo was about 11% (25/103) and was higher than in the present study. However, the smaller sample sizes of patients whom underwent MRI make it difficult to quantify the true incidence of stroke in these patients without neurologic deficits.
In this study, most cases of acute stroke were ischemic, and hemorrhage was relatively rare. Among 3 patients with hemorrhage, only 1 patient presented with dizziness without a headache, and the remainder suffered from a headache combined with moderately high systolic blood pressure (above 180 mmHg) at initial presentation. Large cohorts or systematic studies reporting on vertigo caused by hemorrhage do not appear to exist in the literature 13,14, implying that patients with isolated dizziness were considerably less likely to have a primary intracranial hemorrhage. We also found that large artery atherosclerosis was the most frequent classification followed by small vessel occlusion and embolic origin according to the TOAST criteria. The incidence rates of each subtype were different compared with a past population-based epidemiological study 15, which may be a result of the varying distribution of risk factors, including hypertension, diabetes, smoking rates, and a history of cardiac disease. However, because outcome data could be not collected, the differences in survival or recurrence rate according to each subtype could not be confirmed. Nevertheless, our findings confirmed the findings of the previous analysis that the cerebellum was the predominant site of ischemic stroke 16. Additional brain sites affected included the frontal lobe, pons, and parietal lobe; these results added to the recent knowledge that dizziness as a symptom alone could not exclude the occurrence of stroke 17.
We did not find any statistical differences between symptom characteristics and associated presentations. Although non-whirling type dizziness and irrelevance to head positioning appeared to be more prevalent in patients with stroke, these differences were not detected in the multivariate analysis. These results reflect those of the previous study that the effectiveness of symptom assessment in regard to patients with dizziness may be predisposed to under-evaluation of high-risk patients 18. Numerous bedside oculomotor and neurologic examinations, such as Dix-Hallpike, head thrust, and HINTS+, would be a useful method for predicting a serious neurologic disease 19. Alternatively, the results of these examinations tended to be reliable when patients were examined by trained neuro-ophthalmologists, and the consultations to the neurologists for all patients with dizziness may not be available in most clinical fields. Furthermore, we investigated the laboratory results that were usually performed to exclude medical dizziness (e.g., anemia, hypoglycemia, or electrolyte imbalance), and found that none of the data could discriminate the presence of stroke.
The correlation between older patient age and increased risk of stroke, including in patients without confirmed neurologic symptoms, was as predicted. Chase et al. also noted similar findings in their prospective study of patients presenting to the ED 20. Nevertheless, other well-known risk factors, including diabetes mellitus, hyperlipidemia, and protective agents, such as aspirin, warfarin, and new oral anticoagulants, showed an association with the development of stroke in this study. Although atrial fibrillation did not appear to independently coordinate with stroke, we did find a trend toward significant association (adjusted OR 2.40, 95% CI 0.82 to 7.01). Traditionally, atrial fibrillation itself increased the risk of stroke events and recurrence by up to 54.0% in a previous study 21. In addition, we found that the patients with acute stroke had higher proportion of previous cerebrovascular injury. Interestingly, our study population only included patients who had no long-term neurologic deficit after initial stroke presentation, but the recurrence risk increased compared with in patients without previous history of cerebral infarct. Hence, patients with dizziness who are aged over 65 years and have a history of cerebrovascular injury should be considered for further neuroimaging tests.
We note several limitations of this study. Firstly, the single-center, retrospective design, has meant that we could not generalize our results to the wider environments. Secondly, patients who did not visit the ED or had no MRI data could have led to selection bias. Lastly, unmeasured confounding variables, such as smoking history, could have influenced the results.