What Is Certain When the Stroke Etiology Is Uncertain?

See related article, p 2948. > “Medicine is a science of uncertainty and an art of probability.” > > —William Osler (1849–1919) The great majority of ischemic strokes are due to cardioembolism, largeartery atherosclerotic disease, smallvessel occlusive disease, or other unusual mechanisms (eg, cervical dissection, thrombophilia, etc).1 Nevertheless, in approximately 20% to 40% of patients with stroke, the underlying etiology is not established (called “cryptogenic,” “uncertain,” or “undetermined” stroke).2,3 Limited information is available on longterm outcomes in this specific subgroup.Clinicians wonder about the risk of recurrence and whether death and/or disability in patients with cryptogenic stroke are better or worse compared with those with a determined etiology.In the present study, Nam et al studied 3278 patients with an ischemic stroke with a median followup of 3.4 years.4 Overall, 37% were classified as “undetermined.” Two thirds of patients had a mild stroke (National Institutes of Health Stroke Scale <6) with an overall median National Institutes of Health Stroke Scale of 4. Nearly 40% were exposed to smoking and 31% had diabetes. Interestingly, the authors broke down the undetermined strokes into …