[Classification of etiologic subtypes for transient ischemic attacks: clinical significance of lacunar transient ischemic attack].

BACKGROUND

Lacunar transient ischemic attack (lacunar TIA) may have been underestimated because of diagnostic difficulties. The aim of our study was to classify TIAs by etiologic subtypes, especially using defined criteria for diagnosis of lacunar TIA and clarify clinical characteristics of lacunar TIA.

METHOD

105 TIA patients out of consecutive 1,244 patients with acute ischemic stroke admitted to our hospital between January 2007 and June 2010 were enrolled in the present study. TIA was defined as an acute focal neurological deficit lasting less than 24 hours, suspected to be of cerebrovascular origin regardless of ischemic lesions on MRI. TIAs were classified to 5 etiologic subtypes; (1) cardioembolic TIA, (2) atherothrombotic TIA, (3) lacunar TIA, (4) other etiologies, and (5) undetermined etiology and clinical characteristics in each subtype and the incidence of recurrent stroke after TIA were investigated. Lacunar TIA was diagnosed if the following criteria were fulfilled; (1) presence of lacunar infarct on MRI and/or the presence of unilateral dysfunction of at least two of three body parts (face, arm, leg) in the absence of cortical dysfunction presumed due to subcortical ischemia. (2) absence of cardiac sources of embolism and large artery atherosclerosis.

RESULTS

In 105 patients with TIA, lacunar TIA was the most frequent etiology (31%) followed by cardioembolic TIA (27%), atherothrombotic TIA (19%), undetermined etiology (18%), and other etiologies (6%). In patients with lacunar TIA, history of repeated TIA was more frequent and systolic blood pressure on admission was higher significantly than in cardioembolic TIA. Six of 105 patients had experienced recurrent stroke after TIA during admission. Among these 6 patients, 3 patients were diagnosed as lacunar infarctions.

CONCLUSIONS

Lacunar TIA was most common TIA subtype in the present study. It is critical to identify lacunar TIA on admission because some patients with lacunar TIAs experience early recurrent stroke.