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

Introduction

NSE 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 objectives of the current study were (1) to assess the prognostic significance of plasma concentrations of NSE for early prediction of outcome in patients at risk for anoxic encephalopathy after cardiopulmonary resuscitation (CPR), and (2) to compare the prognostic information provided by NSE measurements with that provided by conventional risk indicators (clinical neurological examination and computerised tomography [CT] scan of the brain).

Results

Twenty-one patients (age 62.0 years [mean] ± 16.7 [SD]) after CPR due to different reasons were enrolled up to now. Clinical neurological examination differentiated four standardized levels of midbrain syndrome (MBS) and two levels of bulbar brain syndrome (BBS). CT scan of the brain, and plasma concentration of NSE on the third day after CPR were compared. Three of the patients had MBS I, two had MBS II, two had MBS III, one had MBS IV, no one had BBS I and six had BBS III. In seven patients neurological examination was not reliable due to the given anticonvulsive therapy because of early onset of myoclonias and due to sedation due to hemodynamic instability. The CT scan of the brain showed in eight patients cerebral edema, in two patients ischemic lesions, and in one patient no pathological changes. In 10 patients no CT scan was available because of the deleterious hemodynamic situation on the third day. The NSE level was elevated in 16 of 21 patients (80.9 ± 69.5 ng/ml; range 17.6–224.5 ng/ml). NSE was elevated in seven of eight patients with edema of the brain detected by CT scan. One patient with edema of the brain had a normal NSE level but the neurological examination showed a BBS II. Seven of eleven patients with BBS II had elevated NSE levels. Eight patients with elevated NSE levels died. Only two patients of those with normal NSE level died, and one had neurological symptoms at time of demission. In all patients except one with further neurological symptoms who survived, NSE levels were elevated. CT scan of the brain and neurologic examination were less sensitive than NSE in predicting a poor outcome.

Conclusion

In patients after CPR for different reasons, increased plasma levels of NSE predict an increased risk of a poor outcome. NSE measurements appear to provide prognostic information complementary, and possibly superior, to that obtained from the neurological examination and CT scan of the brain.