Editors' note: Prognostic value of “tissue-based” definitions of TIA and minor stroke: Population-based study

Abstract

In their post hoc analysis of the Oxford Vascular Study, Dr. Hurford and colleagues echoed the prognostic importance of the modern, “tissue-based” definition of acute stroke. The investigators observed that adult patients with diffusion-weighted imaging (DWI) changes were more likely to develop a subsequent cerebral infarction when compared with patients without DWI changes, regardless of the initial clinical diagnosis (TIA vs stroke). Compared to patients without DWI changes, those with DWI changes were also more likely to die by 90 days or to die at later follow-up. Although most patients (65%) were imaged within 5 days of symptoms, Dr. Cao et al. emphasized that some DWI lesions may be transient or reversible with antithrombotic or fibrinolytic therapy and some may not indicate true tissue ischemia. The authors of the OxVasc study agree that there is a declining appearance of DWI abnormalities with delayed scans; however, such patients with negative delayed scans may have a significantly lower risk of subsequent cerebral infarction as well. Also worth noting is that the diagnosis of “TIA” has long been plagued by a heterogeneous collection of mysterious mechanisms, in spite of the most sophisticated examination scales and neuroimaging. Drs. Gocan et al. question the final diagnoses of the more than 700 patients who were excluded from the OxVasc study because of a final diagnosis being one other than TIA. The authors affirm that all final diagnoses were validated by an experienced vascular neurologist using the criteria established by the World Health Organization. Irrespective of how one might define TIA, we may conclude that any new DWI lesion would be concerning in a patient with transient neurologic deficits because it may portend a significant risk of future cerebrovascular events and mortality. In their post hoc analysis of the Oxford Vascular Study, Dr. Hurford and colleagues echoed the prognostic importance of the modern, “tissue-based” definition of acute stroke. The investigators observed that adult patients with diffusion-weighted imaging (DWI) changes were more likely to develop a subsequent cerebral infarction when compared with patients without DWI changes, regardless of the initial clinical diagnosis (TIA vs stroke). Compared to patients without DWI changes, those with DWI changes were also more likely to die by 90 days or to die at later follow-up. Although most patients (65%) were imaged within 5 days of symptoms, Dr. Cao et al. emphasized that some DWI lesions may be transient or reversible with antithrombotic or fibrinolytic therapy and some may not indicate true tissue ischemia. The authors of the OxVasc study agree that there is a declining appearance of DWI abnormalities with delayed scans; however, such patients with negative delayed scans may have a significantly lower risk of subsequent cerebral infarction as well. Also worth noting is that the diagnosis of “TIA” has long been plagued by a heterogeneous collection of mysterious mechanisms, in spite of the most sophisticated examination scales and neuroimaging. Drs. Gocan et al. question the final diagnoses of the more than 700 patients who were excluded from the OxVasc study because of a final diagnosis being one other than TIA. The authors affirm that all final diagnoses were validated by an experienced vascular neurologist using the criteria established by the World Health Organization. Irrespective of how one might define TIA, we may conclude that any new DWI lesion would be concerning in a patient with transient neurologic deficits because it may portend a significant risk of future cerebrovascular events and mortality.