Early postoperative serum S100β levels predict ongoing brain damage after meningioma surgery: a prospective observational study

INTRODUCTION: Elevated serum levels of S100β, an astrocyte-derived protein, correlate with unfavourable neurological outcomes following cardiac surgery, neurotrauma, and resuscitation. This study evaluated whether pre-/postoperative serum S100β levels correlate with unfavourable clinical and radiological findings in patients undergoing elective meningioma resection. METHODS: In 52 consecutive patients admitted for meningioma surgery, serum S100β levels were determined upon admission and immediately, 24 hours, and 48 hours after surgery. All patients underwent complete pre- and postoperative neurological examination and mini-mental state examination. Radiological evaluation included preoperative magnetic resonance imaging (MRI) and postoperative computed tomography. Tumour volume, brain edema, and bleeding volume were calculated using BrainSCAN™ software. RESULTS: Preoperative S100β levels did not correlate with the tumour characteristics demonstrated by preoperative MRI (for example, tumour volume, edema volume, ventricular asymmetry, and/or midline shift). Preoperative serum S100β levels (0.065 ± 0.040 μg/l) were significantly lower than the levels measured immediately (0.138 ± 0.081 μg/l), 24 hours (0.142 ± 0.084 μg/l), and 48 hours (0.155 ± 0.119 μg/l) postoperatively (p < 0.0001). Significantly greater postcraniotomy S100β levels were observed with prolonged surgery (p = 0.039), deterioration in the mini-mental state examination (p = 0.005, 0.011, and 0.036 for pre versus immediate, 24 hours, and 48 hours postsurgery, respectively), and with postoperative brain computed tomography evidence of brain injury; bleeding was associated with higher serum S100β levels at 24 and 48 hours after surgery (p = 0.046, 95% confidence interval [CI] -0.095 to -0.001 and p = 0.034, 95% CI -0.142 to -0.006, respectively) as was the presence of midline shift (p = 0.005, 95% CI -0.136 to -0.025 and p = 0.006, 95% CI -0.186 to -0.032, respectively). Edema was associated with higher serum S100β levels immediately (p = 0.022, 95% CI -0.092 to -0.007) and at 48 hours after surgery (p = 0.017, 95% CI -0.142 to -0.026). The degree of elevation in S100β levels at 24 and 48 hours after surgery also correlated with the severity of midline shift and edema. CONCLUSION: In patients with meningioma, serum S100β levels perform poorly as an indicator of tumour characteristics but may suggest ongoing postcraniotomy injury. Serum S100β levels may serve as a potentially useful early marker of postcraniotomy brain damage in patients undergoing elective meningioma resection.