Introduction: Patients with moderate traumatic brain injury (TBI) (Glasgow Coma Scale, GCS, 9-13) or minor TBI (GCS 14-15) are at risk for subsequent neurological deterioration. Serum protein S-100 is believed to reflect brain damage following TBI. In patients with normal or minor CT scan abnormalities on admission, we tested whether the determination of serum protein S-100 beta could predict secondary neurological deterioration.
Methods: Sixty-seven patients with moderate or minor TBI were prospectively studied. Serum samples were collected on admission within 12 hours postinjury to measure serum protein S-100 levels. Neurological outcome was assessed up to seven days after trauma. Secondary neurological deterioration was defined as two points or more decrease from the initial GCS, or any treatment for neurological deterioration.
Results: Nine patients had a secondary neurological deterioration after trauma. No differences in serum levels of protein S-100 were found between these patients and those without neurological aggravation (n=58 patients): 0.93 microg/l (0.14-4.85) vs 0.39 microg/l (0.04-6.40), respectively. The proportion of patients with abnormal levels of serum protein S-100 at admission according to two admitted cut-off levels (>0.1 and >0.5 microg/l) was comparable between the two groups of patients. Elevated serum levels of protein S-100 were found in patients with Injury Severity Score (ISS) of more than 16 (n=23 patients): 1.26 microg/l (0.14-6.40) vs 0.22 microg/l (0.04-6.20) in patients with ISS less than 16 (n=44 patients).
Discussion: The dosage of serum protein S-100 on admission failed to predict patients at risk for neurological deterioration after minor or moderate TBI. Extracranial injuries can increase serum protein S-100 levels, then limiting the usefulness of this dosage in this clinical setting.