Beta-trace protein in pediatric otitis media with effusion

The middle ear cleft connects by membranes to the inner ear and the subarachnoid space particularly in infants. In order to gain more insight about the permeability between the two compartments we quantified the concentration of beta-trace protein - a highly specific marker for CSF and perilymph but not for serum and mucosal effusion - in middle ear secretions from children with otitis media with effusion.

One-hundred and three patients were included and 93 samples from secretory otitis media were collected during myringotomy or explorative tympanotomy. Thirty-eight patients of 103 had to be excluded (36.9%). Of the 93 collected samples from 65 subjects, 82 viscous samples were pre-diluted 1:1 with tyloxapol. In spite of the attempt to pre-dilute the viscous samples, 30 glue-like samples of 93 were not applicable for nephelometry. The final analysis was made on 63 samples of 52 subjects (median age 3 years) which were quantified for beta-trace protein using immunonephelometry.

In 3/63 samples the beta-trace protein values were below the detection range (<0.2 mg/L) and in 1/63 it was beyond with 18.3mg/L. The median beta-trace protein value for 59 samples within the measuring range was 2.4 mg/L, range 0.2-14.2.

In pediatric middle ear effusions, the beta-trace protein concentration was found to have a high range compared to other body fluids from other studies. In other studies, the values for serum (0.59 mg/L) or mucosal secretion (0.003-0.12 mg/L) were lower and the values in CSF (18.4 mg/L) or perilymphatic fluid (23.5 mg/L) were highest. This finding might indicate a weak barrier between the cerebrospinal fluid space or inner ear fluid compartments on the one side and the tympanic cavity on the other side given the condition of otitis media with effusion. The detection of beta-trace protein might be important to assess the risk of impending complications.