Serum S100B predicts a malignant course of infarction in patients with acute middle cerebral artery occlusion.

BACKGROUND AND PURPOSE Early predictors of infarct volume may improve therapeutic decisions in patients with acute cerebral ischemia. We investigated whether measurements of serum astroglial protein S100B can predict a malignant course of infarction in acute middle cerebral artery (MCA) occlusion. METHODS We included 51 patients (24 women, mean age 69.1+/-12.4 years) admitted within 6 hours after stroke symptom onset caused by proximal MCA occlusion, as shown by magnetic resonance angiography (n=39), intra-arterial angiography (n=4), or transcranial duplex sonography (n=8). Blood samples were drawn at hospital admission and 8, 12, 16, 20, and 24 hours after symptom onset. Serum S100B concentrations were determined using a fully automated immunoluminometric assay. A malignant course of infarction was defined as the occurrence of clinical signs of cerebral herniation within the first 7 days of treatment or the clinical decision to perform decompressive hemicraniectomy caused by critical space-occupying swelling as detected by repeated neuroimaging. RESULTS Sixteen patients developed malignant infarction (31%). Beginning with the 12-hour value, mean S100B serum concentrations were significantly higher in patients with a malignant course compared with those without (12 hours 1.23+/-1.24 versus 0.29+/-0.45 microg/L; 16 hours 1.80+/-1.65 versus 0.38+/-0.53 microg/L; 20 hours 1.90+/-1.53 versus 0.44+/-0.48 microg/L; and 24 hours 2.41+/-1.59 versus 0.57+/-0.66 microg/L; all P<0.001). A 12-hour S100B value >0.35 microg/L predicted malignant infarction with 0.75 sensitivity and 0.80 specificity. A 24-hour value >1.03 microg/L provided 0.94 sensitivity and 0.83 specificity. CONCLUSIONS The serum marker S100B can predict a malignant course of infarction in proximal MCA occlusion. This finding may improve the identification and monitoring of patients at particularly high risk for herniation.