Prognostic value of specific neural enolase in head trauma

Purpose

Searching for a correlation between the plasma level of specific neural enolase (SNE) and the prognosis of head trauma in the short term.

Subjects and methods

An open prospective study carried out in a HUC of Tunis over 15 months including 35 patients with head trauma causing a subarachnoid hemorrhage. Criteria of non-inclusion were age <15 years and 3 months, and head trauma requiring neurosurgery. The management was standardized for all patients to avoid secondary cerebral aggression caused by systemic troubles, as recommended by Maas and colleagues. Clinical basic neurologic survey and CT scan monitoring (Fischer and Marshall classification) were repeatedly carried out. A cerebral CT scan was systematically performed 48 hours after hospitalization or in case of aggravation. A surgical operation was performed throughout the period of the study whenever required (orthopedics, digestive surgery, etc.). The plasma level of SNE was measured on the first, third and fifth day of hospitalization, using the ELISA technique with an immunoenzymatic method, sandwich type (kit CanAg Diagnostics), in a Dias Orin automate (Eti-max 3000). (The normal value of enolase used as a reference in our study was considered the average of 47 volunteers' plasma level.) Statistical analysis used the chi-squared test and variance analysis, respectively, for qualitative and quantitative variables. Values are expressed as means ± standard deviation.

Results

Mean age: 39 ± 17 years; sex ratio = 4; 80% of patients had a severe head trauma; mortality: 16 patients (45.7%); mean level of SNE in a 'reference population' was 7.02 ± 3.86 μg/ml with a statistically significant difference (P = 0.001) (pathologic value above 12.5 μg/ml). Seventeen patients (48.56%) had a pathologic SNE plasma level in the first day. All patients (nine) whose SNE plasma level had still been elevated until the third or the fifth day died. The plasma level was higher in patients who died in comparison with that of surviving patients; 25.74 ± 22.39 μg/ml vs 11.51 ± 4.56 μg/ml, with a significant difference (P = 0.032). All dead patients had a higher plasma level of SNE on the fifth day, six of them had a normal value in the first day and then it increased. Patients whose GCS was < 8 had a first-day plasma level so far higher, 24.89 ± 25.27 μg/ml vs 15.25 ± 11.6 μg/ml; but with no significant difference. SNE plasma level was not correlated to the importance of the subarachnoïd hemorrhage (Fischer classification).

Discussion

The persistence of a high plasma level of specific neural enolase or its elevation represents a short-term prognostic factor. Severe patients have higher plasma levels with no significant difference.