The patients of this prospective study were selected from a sample of patients who were admitted to the emergency room of the University Hospital RWTH Aachen with an unclear impairment of consciousness. Only patients who later on were diagnosed as having experienced a GTCS or a syncope and whose serum lactate concentrations had been measured within 2 hours after the event were enrolled in the study. The investigators compared the specificity and sensitivity of the serum lactate concentrations at admission with the CK concentration at admission and the CK follow-up taken 10 to 48 hours after the event.