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

Abstract

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. On admission, CK levels were > 130 mU/ml (2.16 microkat/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 microkat/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 microkat/l) for GTCS group and -2 +/- 37 mU/ml (-0.03 +/- 0.61 microkat/l) in VVS. An increase of more than 15 mU/ml (0.25 microkat/l) was observed in 11/16 GTCS patients and only in 1/17 VVS patients. Taking an increase of > 15 mU/ml (0.25 microkat/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 microkat/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 microkat/l) (on either day) and/or elevation from the first to the second day of > 15 mU/ml (0.25 microkat/l), there were only 12% false negatives and 12% false positives. 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 microkat/l) is highly indicative of an epileptic event. CK levels above 200 mU/ml (3.33 microkat/l) are unlikely to be the result of VVS.