EDITORIAL

www.nature.com/clinicalpractice/cardio Acute cerebrovascular syndrome: time for new terminology for acute Gregory W Albers

A transient ischemic attack (TIA) has tradition- I believe it is transient symptoms’ or ‘transient symptoms ally been defined as a sudden, focal neurologic time to follow with ’. deficit of presumed vascular origin lasting less I believe it is time to follow the lead of than 24 h. The assumptions that TIAs do not the lead of our our cardiovascular colleagues and adopt result in permanent brain injury and that TIA cardiovascular the concept of an ‘acute cerebrovascular symptoms disappear because of prompt spon- colleagues syndrome’. This label could serve as an taneous reperfusion have existed for many and adopt umbrella term for all patients who present years. Symptoms lasting more than 24 h are the concept with symptoms suggestive of abrupt focal considered to reflect and disruption of the blood supply to the brain. represent a . These long-established of an ‘acute Following diagnostic evaluation, patients can definitions are, however, no longer compat- cerebrovascular then be subdivided into the categories of acute ible with current concepts of brain ischemia; syndrome’. brain ischemia, acute brain hemorrhage, or a ischemic symptoms lasting more than a few nonvascular diagnosis. Acute brain ischemia hours often result in brain infarction, irrespec- can be further separated into TIA or stroke on tive of the time course of clinical resolution. In the basis of whether infarction occurs, with TIA 2002 a group of cerebrovascular specialists, defined as a transient episode of neurologic therefore, proposed that TIA be redefined as dysfunction caused by focal brain or retinal “…a brief episode of neurologic dysfunction ischemia without acute infarction, and ischemic caused by focal brain or retinal ischemia, with stroke defined as infarction of central nervous clinical symptoms typically lasting less than system tissue. one hour, and without evidence of acute infarc- Like angina episodes, TIAs typically last tion” (Albers GW et al. [2002] N Engl J Med less than 1 h but occasionally can last many 21: 1713–1716). On the basis of this definition, hours. The above definition eliminates arbitrary the term ‘stroke’ is appropriate for an ischemic time limits; if brain imaging or other diagnostic episode that results in cerebral infarction, studies document acute infarction then the diag- regardless of duration. nosis of ischemic stroke is confirmed regardless This new definition has been endorsed and of symptom duration. Neuroimaging and diag- accepted by many cerebrovascular experts nostic laboratory criteria for cerebral infarction and incorporated into the study design of need to be clearly defined, and this remains a several major clinical trials. Others, however, challenge. Diagnostic capabilities and tech- have questioned the value of the new definition niques are rapidly evolving; therefore, specific and raised multiple concerns. A common criti- criteria for documenting cerebral infarction will cism involves the phrase “typically lasting less GW Albers is an also evolve, just as the criteria for diagnosing Advisory Board than one hour”, as it is estimated that about member of Nature have evolved over time. 20% of TIAs last longer than 1 h. Another issue Clinical Practice Diagnostic certainty will depend on the extent of is that currently there is no well-accepted and Cardiovascular the evaluation individual patients receive, which widely available gold standard for documenting Medicine. is typical of many medical diagnoses. small brain . Some experts have The concept of an acute cerebrovascular suggested that episodes of brief duration (<24 h) Competing interests syndrome parallels the accepted approach for The author declared he has associated with small infarctions represent no competing interests. cardiac ischemia and provides a framework high-risk, unstable conditions that should be for incorporating future advances in stroke www.nature.com/clinicalpractice separately classified as ‘cerebral infarction with doi:10.1038/ncpcardio0679 diagnosis.

OCTOBER 2006 VOL 3 NO 10 NATURE CLINICAL PRACTICE CARDIOVASCULAR MEDICINE 521

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