The gamma isoform of enolase (NSE) is predictive of mortality after cardiopulmonary resuscitation (CPR): comparison with clinical neurologic examination and CT scan of the brain

Introduction

NSE (the gamma isoform of enolase) is released into the cerebrospinal fluid and blood after the occurrence of stroke and anoxia; and correlates with the extent and duration of ischemia in animal models of stroke and the outcome in humans, including neonates, with hypoxic ischemic encephalopathies.

Accordingly, the objective of the current study was: 1) To assess the prognostic significance of plasma concentrations of NSE for early prediction of outcome in patients at risk for anoxic encephalopathy after CPR. 2) To compare the prognostic information provided by NSE measurements with that provided by conventional risk indicators (clinical neurological examination and CT scan of the brain).

Results

Ten patients (age 60.5 years [mean] ± 20.8 [SD]) were enrolled up to now. In two patients CPR was performed due to ventricular fibrillation, in one due to low blood pressure during hemodialysis, in three due to acute myocardial infarction, in three due to cardiac arrest for unknown reason and in one patient due to ketoacidotic coma. Clinical neurological examination, computed tomogram of the brain, and plasma concentration of NSE on the third day after CPR were compared. The clinical neurological examination was differentiated in standardized three levels of midbrain syndrome (MBS) and three levels of bulbar brain syndrome (BBS). Four of the patients had a MBS I, one had a MHS II, two had a MBS III, and three had a BHS III at the third day after CPR. In three patients neurological examination was not reliable due to given anticonvulsive therapy because of early onset of myoclonias. The CT scan of the brain showed only in six patients cerebral edema; in two patients there was no CT scan available because of the deleterious hemodynamic situation; and in two patients ischemic lesions were found, but no edema. The NSE level was elevated in seven of 10 patients (61.0 ± 65.1 ng/ml [range 7.2–194.6]). In three patients the level was normal. Surprisingly the low NSE level found in this patient was associated with a significant swelling due to cerebral edema documented by the neuroimaging study. This patient had the highest neurological score (BBS III). All patients with elevated NSE levels died, one patient of those with normal NSE level died, and the others with normal levels survived. The mean survival time after admission was 12.8 ± 5.0 days. CT scan of the brain and neurologic examination, especially in patients with early onset of myoclonias, were less sensitive than NSE in predicting a poor outcome.

Conclusion

In patients who have been resuscitated after cardiac arrest or other conditions associated with hypotension, increased plasma levels of NSE predict an increased risk of death. NSE measurements appear to provide prognostic information complementary to and possibly superior to that obtained from the neurological examination and CT scan of the brain.