S-100 protein: serum marker of focal brain damage after ischemic territorial MCA infarction

Elevations of protein S-100 (S-100) in cerebrospinal fluid and serum have been reported after cerebral infarctions. The aim of our study was to evaluate the time course of serum S-100 concentrations after territorial middle cerebral artery (MCA) infarctions in correlation with clinical data and prognosis.

S-100 serum levels were serially determined in 26 patients with an acute infarction in the territory of the MCA at day 0 (within 12 hours after onset of symptoms), day 1 (24 hours after stroke onset), and days 2, 3, 4, 5, 7 or 8, and 10 after stroke and in 26 age- and sex-matched control subjects. S-100 assays were performed using a two-site radioimmunoassay technique. The clinical status was documented using the Scandinavian Stroke Scale. The functional deficit 4 weeks after stroke onset was scored by use of the modified Rankin scale. A cranial computed tomography (CCT) was performed initially and at day 4 or 5.

Elevated concentrations of S-100 (> 0.2 microgram/L) were observed in 21 of 26 patients with MCA infarction but in none of the control subjects. S-100 levels peaked at days 2 and 3 after stroke. The S-100 concentrations in serum were significantly higher in patients with severe neurological deficits at admission, with extensive infarctions and a space-occupying effect of ischemic edema as compared with the rest of the population. S-100 values were not significantly correlated with the functional prognosis.

Presence of S-100 in serum after ischemic stroke may be due to combined leakage out of necrotic glial cells and passage through an impaired brain-blood barrier, indicating severe ischemic cell injury. Therefore, S-100 in serum can be used as a peripheral marker of ischemic focal brain damage and may be helpful for therapeutic decisions in acute ischemic stroke.