Tareq Kass-Hout, MD

 In a study recently published online in Stroke, Kimberly and colleagues found an association between reduced levels of Branched Chain Amino Acids (BCAA) and cerebral ischemia in both animal model and human subjects. Such a novel biomarker will be the first to show changes in circulating plasma metabolites in the setting of cerebral ischemia, which in turn, may provide an insight on the pathogenesis of acute cardioembolic stroke.

The investigators compared plasma and CSF levels of multiple metabolites rats undergoing cerebral ischemia and controls. They also analyzed plasma samples from controls and acute stroke patients. They found significantly lower levels of branched chain amino acids (BCAA; valine, leucine, isoleucine) in rat plasma, rat CSF and human plasma compared to respective controls (16%, 23% and 17%, respectively; p<0.01 for each). Also, in human subjects presenting with acute stroke, lower BCAA levels were correlated with poor neurological outcome (mRS 0-2 versus 3-6, p=0.002). Whether BCAA are in a causal pathway or are an epiphenomenon of ischemic stroke remains to be determined.
There is limited information about changes in metabolism during acute ischemic stroke. Although this study point towards a key role for BCAA in stroke, this correlation in a multivariate regression must be interpreted with caution in such a small patient cohort.