Reversible brain ischemia: Lessons from transient ischemic attack

PURPOSE OF REVIEW: In recent years, there has been considerable scientific inquiry regarding transient ischemic attack. In an effort to synthesize at times conflicting data, this paper will review the recent evidence and provide a critical overview of reversible brain ischemia. RECENT FINDINGS: Transient ischemic attack is now understood to indicate a higher risk of recurrence than completed ischemic stroke. Efforts to unravel the mechanisms of this instability following transient ischemic attack using imaging studies have led to new concepts and definitions, and sparked further debate. While imaging has increased diagnostic certainty, it has yet to provide reliable prognostic markers. The evidence suggests that risk of clinical recurrence is most closely linked to the degree to which the initial deficit reverses. From a tissue level, however, there are also data to support the notion of a 'stroke-prone state' following both transient ischemic attack and completed stroke, suggesting that mechanistically they may be less distinct than previously thought. Transient ischemic attack may simply highlight the dynamic nature of all acute ischemic cerebrovascular syndromes. SUMMARY: Reversible brain ischemia is a harbinger for subsequent ischemic stroke. Although recent advances have focused on imaging markers, the most important predictor of risk following brain ischemia is degree of early clinical reversibility.