Background: Diagnosis of acute ischemia typically relies on evidence of ischemic lesions on magnetic resonance imaging (MRI), a limited diagnostic resource. We aimed to determine associations of clinical variables and acute infarcts on MRI in patients with suspected low-risk transient ischemic attack (TIA) and minor stroke and to assess their predictive ability.
Methods: We conducted a post-hoc analysis of the Diagnosis of Uncertain-Origin Benign Transient Neurological Symptoms (DOUBT) study, a prospective, multicenter cohort study investigating the frequency of acute infarcts in patients with low-risk neurological symptoms. Primary outcome parameter was defined as diffusion-weighted imaging (DWI)-positive lesions on MRI. Logistic regression analysis was performed to evaluate associations of clinical characteristics with MRI-DWI-positivity. Model performance was evaluated by Harrel's c-statistic.
Results: In 1028 patients, age (Odds Ratio (OR) 1.03, 95% Confidence Interval (CI) 1.01-1.05), motor (OR 2.18, 95%CI 1.27-3.65) or speech symptoms (OR 2.53, 95%CI 1.28-4.80), and no previous identical event (OR 1.75, 95%CI 1.07-2.99) were positively associated with MRI-DWI-positivity. Female sex (OR 0.47, 95%CI 0.32-0.68), dizziness and gait instability (OR 0.34, 95%CI 0.14-0.69), normal exam (OR 0.55, 95%CI 0.35-0.85) and resolved symptoms (OR 0.49, 95%CI 0.30-0.78) were negatively associated. Symptom duration and any additional symptoms/symptom combinations were not associated. Predictive ability of the model was moderate (c-statistic 0.72, 95%CI 0.69-0.77).
Conclusion: Detailed clinical information is helpful in assessing the risk of ischemia in patients with low-risk neurological events, but a predictive model had only moderate discriminative ability. Patients with clinically suspected low-risk TIA or minor stroke require MRI to confirm the diagnosis of cerebral ischemia.
Keywords: magnetic resonance imaging; stroke; transient ischemic attack.