High-resolution MRI findings in patients with capsular warning syndrome

Capsular warning syndrome (CWS) is rare (1.5% of TIA presentations) but has a poor prognosis (7-day stroke risk of 60%). Up to date, the exact pathogenic mechanism of CWS has not been fully understood. We report the clinical presentations and high-resolution MRI (HR MRI) findings of two cases with capsular warning symptoms.

Case 1 was a 63-year-old man with a history of hypertension with recurrent episodes of left hemiparesis and dysarthria lasting 10 ~ 30 minutes. Case 2 was a 54-year-old woman with repetitive episodes of transient left hemiparesis and dysarthria lasting about 10 minutes. Capsular infarctions on DWI were demonstrated in the territory of a lenticulostriate artery in both 2 patients. HR MRI disclosed atherosclerotic plaques on the ventral wall of the MCA where enticulostriate arteries were arisen from, although traditional digital subtraction angiography showed normal. Aggressive medical therapy with dual antithrombotic agents and statin was effective in these two cases.

Our HR MRI data offer an insight into the pathophysiology of CWS which might be caused by atherosclerotic plaque in non-stenotic MCA wall. HR MRI might be a useful modality for characterizing atherosclerotic plaques in the MCA and detecting the pathophysiology of the CWS.