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

Objective: Beta-trace protein (β-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 β-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 β-TP in CSF or inner ear fluids. Conclusions: Our results demonstrated clearly that β-TP is contained in human perilymph and endolymph. This is the first published data that point out the aptitude of the β-TP-test in verifying traces of perilymph, a valuable diagnostic tool for the existence of perilymphatic leaks.