Sequential serum creatine kinase determination differentiates vaso-vagal syncope from generalized tonic-clonic seizures

Materials and methods - In a prospective study we evaluated patients with first generalized tonic-clonic seizure (GTCS) (n = 16, age: 31 ± 11 years, 8 women) and patients with vaso-vagal syncope (VVS) (n = 17, age: 32 ± 13 years, 8 women), diagnosed on the basis of past history and clinical presentation who had serum creatine kinase (CK) levels assessed at admission to the emergency room and 24-26 h later. Patients with physical injuries were excluded. Results - On admission, CK levels were >130 mU/ml (2.16 μkat/l) in 25% (4/16) GTCS vs 6% (1/17) VVS patients; 24 h later, the figures were 56% (9/16) vs 12% (2/17) respectively. For GTCSD patients CK level >200 mU/ml (3.33 μkat/l) had a sensitivity and specificity of 0.12 and 0.94 on the first day, and 0.25 and 1.0 respectively on the second day. The change in the CK level from the first to the second day was 155 ± 266 mU/ml (2.58 ± 4.43 μkat/l) for GTCS group and -2 ± 37 mU/ml (-0.03 ± 0.61 μkat/l) in VVS. An increase of more than 15 mU/ml (0.25 μkat/l) was observed in 11/16 GTCS patients and only in 1/17 VVS patients. Taking an increase of >15 mU/ml (0.25 μkat/l) as a cut-off value, the sensitivity of this figure is 0.69 and specificity 0.94. An increase of >15 mU/ml (0.25 μkat/l) in CK level among the patients with normal CK on both days was seen in 50% of GTCS but in none with VVS. Using the criteria of CK levels >200 mU/ml (3.33 μkat/l) (on either day) and/or elevation from the first to the second day of >15 mU/ml (0.25 μkat/l), there were only 12% false negatives and 12% false positives. Conclusions - We conclude that a higher increase in CK levels from the first to the second day occurs in GTCS as compared to VVS, and even when both sequential tests are within the normal range, an increase of at least 15 mU/ml (0.25 μkat/l) is highly indicative of an epileptic event. CK levels above 200 mU/ml (3.33 μkat/l) are unlikely to be the result of VVS.