Development of a strategy for assessing blood-brain barrier disruption using serum S100 calcium-binding protein B and neuron-specific enolase in early stage of neuroemergencies: A preliminary study.

BACKGROUND: Rapid disease progression in neuroemergencies is associated with blood-brain barrier (BBB) disruption. We investigated a less invasive strategy for assessing BBB status by evaluating S100 calcium-binding protein B (S100B) and neuron-specific enolase (NSE) at early stages of the hypoxic-ischemic brain injury (HIBI) cascade. METHODS: This retrospective study used prospectively collected data from patients with out-of-hospital cardiac arrest (August 2019-July 2021). Albumin specimens obtained from serum and cerebrospinal fluid via arterial catheter and lumbar puncture were used to measure the albumin quotient (Qa), which is widely accepted as the gold standard method for detecting BBB disruption. Serum S100B and NSE levels were measured simultaneously following the return of spontaneous circulation. We conducted linear regression to evaluate the relationship between S100B and Qa and the predictive performance of S100B for abnormal Qa. The primary study outcome was abnormal Qa (>0.007). RESULTS: Forty-one patients were enrolled; 30 showed an abnormal Qa suggestive of BBB disruption. S100B levels were significantly higher than in those with a normal Qa (0.244 µg/L [interquartile range [IQR], 0.146-0.823 vs 0.754 µg/L [IQR, 0.317-2.228], P = .03). We report a positive correlation between serum S100B and Qa (R2 = 0.110; P = .04). The area under the receiver operating characteristics curve (AUROC) evaluating the predictive performance of S100B with respect to abnormal Qa was 0.718 (95% confidence interval, 0.556-0.847). The cutoff value for S100B (with respect to BBB disruption) in the total cohort was 0.283 µg/L (sensitivity, 80.0%; specificity, 72.7%). Subgroup analyses in patients with serum neuron-specific enolase (NSE) levels of <40.8 ng/mL (excluding those with established neuronal cell injury) showed an improved correlation coefficient (R2 = 0.382; P < .01) and predictive performance (AUROC, 0.836 [95% confidence interval, 0.629-0.954]) compared with the total cohort. CONCLUSIONS: Serum S100B obtained at an early stage of the HIBI cascade is associated with abnormal Qa, suggesting BBB disruption. The predictive performance of S100B and the correlation between serum S100B and Qa can be improved using a complementary strategy (i.e., evaluations of S100B and NSE levels) that combines considerations of cell damage in astrocytes and neurons.