The promise and potential pitfalls of serum biomarkers for ischemic stroke and transient ischemic attack

Ischemic stroke and transient ischemic attack can be difficult to diagnose clinically, and both acute and preventive therapies carry some risk. Serum biomarkers could increase diagnostic certainty by helping to distinguish cerebral ischemia from common mimics such as focal seizure, complicated migraine, and psychogenic spells. Biomarkers could also identify patients at high risk for future vascular events, which would aid in management decisions.

There are many potential obstacles to finding these biomarkers, which are reviewed here, including the blood brain barrier, confounding by other conditions, and imperfect gold standards for use in validation. Diagnostic biomarkers are likely to be molecules found predominantly in brain tissue with rapid entry into the blood, whereas risk-stratification biomarkers may be related to the concept of an active atherosclerotic plaque. Many promising serum molecules have been examined in small series of patients with cerebrovascular disease.

Large series examining many candidate molecules will be needed to find valid biomarkers, and this should be followed by use in future intervention trials to prove their utility.