β-trace protein (prostaglandin D synthase) - a stable and reliable protein in perilymph

OBJECTIVE Beta-trace protein (beta-TP) has been analysed in human cerebrospinal fluid (CSF) and other body fluids. Beta-trace protein is a very sensitive and specific clinical marker and can confirm reliably the presence of CSF in patients with a suspected CSF leakage. DESIGN Perilymph specimens from the scala vestibuli (n=10) and from the lateral semicircular canal (n=4) were taken from patients undergoing stapedotomy or surgery for acoustic neuroma. During post-mortem examinations perilymph specimens from the scala vestibuli (n=70), the scala tympani (n=11), endolymph specimens (n=21) and CSF specimens (n=17) were obtained. All specimens were analyzed by a one-dimensional immunoelectrophoresis using a polyclonal, monospecific antibody. RESULTS Specimens from live surgery showed a mean concentration of 51.5 +/- 48.9 mg/l beta-TP in scala vestibuli perilymph. Specimens from post-mortem examinations revealed a mean concentration of 49.1 +/- 17.7 mg/l in CSF, 71.9 +/- 29.3 mg/l in perilymph and 68.0 +/- 21.7 mg/l in endolymph. There was no evidence of a circadian alteration of beta-TP in CSF or inner ear fluids. CONCLUSIONS Our results demonstrated clearly that beta-TP is contained in human perilymph and endolymph. This is the first published data that point out the aptitude of the beta-TP-test in verifying traces of perilymph, a valuable diagnostic tool for the existence of perilymphatic leaks.