Serum neuron-specific enolase and S-100B protein in cardiac arrest patients treated with hypothermia

High serum levels of neuron-specific enolase (NSE) and S-100B protein are known to be associated with ischemic brain injury and poor outcome after cardiac arrest. Therapeutic hypothermia has been shown to improve neurological outcome after cardiac arrest. The aim of this study was to evaluate the effect of therapeutic hypothermia on levels of serum NSE and S-100B protein, their time course, and their prognostic value in predicting unfavorable outcome after out-of-hospital cardiac arrest.

Seventy patients resuscitated from ventricular fibrillation were randomly assigned to hypothermia of 33+/-1 degrees C for 24 hours or to normothermia. Serum NSE and S-100B were sampled at 24, 36, and 48 hours after cardiac arrest. Neurological outcome was dichotomized into good or poor at 6 months after cardiac arrest.

The levels of NSE (P=0.007 by analysis of variance for repeated measurements) but not S-100B were lower in hypothermia- than normothermia-treated patients. A decrease in NSE values between 24 and 48 hours was observed in 30 of 34 patients (88%) in the hypothermia group and in 16 of 32 patients (50%) in the normothermia group (P<0.001). The decrease in NSE values was associated with good outcome at 6 months after cardiac arrest (P=0.005), recovery of consciousness (P<0.001), and survival for at least 6 months after cardiac arrest (P=0.012).

Decreasing levels of serum NSE but not S-100B over time may indicate selective attenuation of delayed neuronal death by therapeutic hypothermia in victims of cardiac arrest.