AHA, ASA redefine stroke

The American Heart Association (AHA) and American Stroke Association (ASA) released an updated definition of stroke, which was published online May 7 in Stroke.

The consensus document noted the lack of a consistent definition for stroke in clinical practice and offered that the clinical definition did not encompass recent advances in science and technology. Thus, AHA and ASA convened a writing group to develop a consensus document.

The update, authored by Ralph L. Sacco, MD, of University of Miami, and colleagues recognizes stroke as a heterogeneous disease that includes cerebral hemorrhages and various subtypes of ischemic stroke.

The group proposed the following new definitions:

• Central nervous system (CNS) infarction—brain, spinal cord or retinal cell death due to ischemia, based on pathological, imaging or objective evidence of cerebral, spinal cord or retinal focal ischemic injury in a defined vascular distribution or clinical evidence of cerebral, spinal cord or retinal focal ischemic injury based on symptoms persisting ≥ 24 hours or until death, other etiologies excluded;
• Ischemic stroke—an episode of neurological dysfunction caused by focal cerebral, spinal or retinal infarction;
• Silent CNS infarction—imaging or neuropathologic evidence of CNS infarction, without a history of acute neurological dysfunction attributable to the lesion;
• Intracerebral hemorrhage—a focal collection of blood within the brain parenchyma or ventricular system, which is not due to trauma, and includes parenchymal hemorrhage after CNS infarction;
• Stroke due to intracerebral hemorrhage—rapidly developing clinical signs of neurologic dysfunction due to a focal collection of blood within the brain parenchyma or ventricular system which is not due to trauma;
• Silent cerebral hemorrhage—a focal collection of chronic blood products within the brain parenchyma subarachnoid space, or ventricular system on neuroimaging or neuropathological examination which is not due to trauma, without a history of acute neurological dysfunction attributable to the lesion;
• Subarachnoid hemorrhage—bleeding into the subarachnoid space;
• Stroke due to subarachnoid hemorrhage—rapidly developing signs of neurologic dysfunction and/or headache due to subarachnoid hemorrhage, which is not caused by trauma;
• Stroke due to cerebral venous thrombosis—Infarction or hemorrhage in the brain, spinal cord or retina due to thrombosis of a cerebral venous structure. Symptoms or signs due to reversible edema without infarction or hemorrhage do not qualify as stroke;
• Stroke, not otherwise specified—an episode of acute neurological dysfunction presumed to be caused by ischemia or hemorrhage, persisting ≥ 24 hours or until death, but without sufficient evidence to be classified as one of the above.

In an accompanying commentary, David T. Asuzu, PhD, of Yale University School of Medicine, and Kevin N. Sheth, MD, of Yale New Haven Hospital, both in New Haven, Conn., wrote, “The Consensus statement provides a much-needed update to our terminology for stroke and takes into account recent advances in medical imaging. The recommendations set forth in the Consensus statement set new clinical benchmarks for the diagnosis and standardized treatment of patients with various subsets of stroke. Additionally, the updated definitions of stroke and TIAs [transient ischemic attacks] constitute a call for standardization of imaging protocols that may be used for patient care, for clinical trials, and for future clinical and epidemiological studies on the prevention and treatment of stroke.”