All the patients admitted in emergency department for minor traumatized cranial, with antiplatelet therapy, can be included, after checked inclusion and non inclusions criterias. If they are agree, a blood sample for the dosage of S100b will be done.

No other modification of the medical care, all patients will have tomodensitometria, according with recommendations. The aim of the study is to validate the negative predictive value of S100b in this population.

Inclusion Criteria:

• Age > 18 Years old
• Minor traumatic brain injury measured by a Glasgow score between 13 and 15
• Antiplatelet agent therapy
• Free subject without tutorship or curatorship

Exclusion Criteria:

• Age < 18 years old
• Glasgow score <13
• Traumatic brain injury older than 6 hours
• Patient without any social security system
• Patient with renforced protection (tutorship, curatorship, …)